Chemical Composition, Toxicity, and Repellency of Essential Oils from Three Hedychium Species Against Stored-Product Insects

Stored products are constantly infested by insects, so finding eco-friendly bioinsecticides for insect management is important. The work aimed to assess the insecticidal and repellent activity of essential oil (EO) from Hedychium glabrum S. Q. Tong, Hedychium coronarium Koen., and Hedychium yunnanense Gagnep. against Tribolium castaneum, Lasioderma serricorne, and Liposcelis bostrychophila. Results showed that 88 chemical components were identified in the extracted Hedychium EOs, indicating that they exhibited diversity in components. According to principal component analysis (PCA), the composition of the EO from the H. yunnanense stem and leaf (EOHYSL) was significantly different from other EOs due to the different organs and species. The biological activity also varied continuously with plant species and organs. Only the EO of H. yunnanense (EOHY) showed strong fumigant toxicity. While in the contact tests, EOHGR showed the strongest toxicity effect on L. bostrychophila, with a LC50 value of 71.76 μg/cm2, which was closest to the positive control (Pyrethrin). All EOs had remarkable repellent activities against the three target insects, and repellency increased with concentration. According to the results of the comprehensive score, EOHY had the highest potential, which ranged from 0.7999 to 0.8689. Thus, Hedychium EOs possess potential biorational traits to be biological insecticides.

Physicochemical comparison of chitin characteristics in three major stored-product beetle pests: Implications for biofumigant toxicity

The present study investigates the chitin properties of stored-product insect pests and their association with the fumigant toxicity of garlic essential oil. Chitin isolates of Callosobruchus maculatus, Sitophilus oryzae, and Tribolium castaneum adults were characterized using FT-IR, XRD, EA, SEM-EDS, and NMR techniques. Fumigant toxicity assay was performed under airtight condition in glass vial. The S. oryzae contains highest chitin content (19 %), followed by T. castaneum (10 %) and C. maculatus (8 %). The degree of crystallinity was lower in C. maculatus (67.13 %) than in S. oryzae (77.05 %) and T. castaneum (76.56 %). Morphologically, C. maculatus chitin displayed a flat lamellar surface with pores, while S. oryzae and T. castaneum exhibited densely arranged microfibrils based surfaces. Fumigant toxicity assays revealed varied susceptibility levels, C. maculatus exhibited higher susceptibility (0.27 μL/L air of LC50) compared to S. oryzae and T. castaneum (14.35 and 3.74 μL/L air of LC50, respectively) to garlic essential oil. The higher chitin content, greater crystallinity, and densely arranged structures in S. oryzae might contribute to its tolerance towards fumigant. Additionally, physico-chemical properties and penetration potentiality of the bioactive constituents might be linked to the toxicity in insects. Understanding these relations can enrich knowledge of chitin's role in fumigant toxicity mechanism.

Antiedema and antinociceptive potential of the essential oil of Pectis elongata Kunt (Asteraceae) from the Brazilian Amazon

ETHNOPHARMACOLOGICAL RELEVANCE

Pectis elongata, a herbaceous species that is known in northern Brazil as "cominho" or "limãozinho", is traditionally used in the region for the treatment of fevers, colds, hypotension, genitourinary and gastric disorders, and pain.

AIM OF THE STUDY

Determine the chemical composition and acute oral toxicity and evaluate whether Pectis elongata essential oil (PeEO) has antiedema and antinociceptive activity.

MATERIALS AND METHODS

The chemical composition was determined using gas chromatography coupled to mass spectrometry (GC/MS) and the degree of toxicity determined by the LD50. The antiedema and antinociceptive potential was evaluated via the λ-carrageenan-induced paw edema test and formalin test, respectively.

RESULTS

Citral (geranial and neral) was characterized as a major component of the PeEO, representing 89% of the total identified compounds. According to OECD criteria (2002), the EO was considered non-toxic since it presented LD50 values over 2000 mg kg-1. Its antiedema potential was observed at doses of 200 and 400 mg kg-1 (p ≤ 0.05). At a dose of 400 mg kg-1, PeEO also showed antinociceptive potential (p ≤ 0.05), both in the neurogenic phase and in the inflammatory phase.

CONCLUSIONS

PeEO, which is rich in citral, did not induce any characteristic signs of acute oral toxicity and was also efficient in reducing carrageenan-induced paw edema, in addition to presenting antinociceptive potential and acting on both central and peripheral pain. It is thus a promising candidate for the development of a new herbal medicine with anti-inflammatory and analgesic action.

Potential fumigant toxicity of essential oils against Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) and its egg parasitoid Trichogramma evanescens (Hymenoptera: Trichogrammatidae)

Sitotroga cerealella is a serious pest of a wide range of stored cereal grains. An essential element of an integrated pest control approach is the application of plant oils as a substitute for chemical insecticides. This study aimed to investigate the fumigant toxicity of Allium sativum and Mentha piperita essential oils against S. cerealella adult moths and the egg parasitoid Trichogramma evanescens. Gas chromatography-mass spectrometry analyses detected that Diallyl trisulfide (37.97%) and DL-Menthol (47.67%) as main compounds in A. sativum and M. piperita, respectively. The results showed that, A. sativum at 10.0, 5.0, and 2.5 µL/L air resulted in 100% insect mortality after 24 h exposure. The concentrations of 10.0 and 5.0 µL/L air of M. piperita oil resulted in 100 and 96% insect mortality, respectively. The parasitoid adult emergence in the F1 reduced when exposed to LC99 of A. sativum and M. piperita oils by 10.89 and 9.67%, respectively. Also, the parasitism of emerged parasitoid decreased by 9.25 and 5.84% (class I-harmless), respectively. Therefore A. sativum and M. piperita have the potential to be used as bio-fumigant for the management of S. cerealella and can be used alongside the T. evanescens in integrated pest management.

Predictive toxicological effects of Artemisia absinthium essential oil on hepatic stellate cells

Medicinal plants are important worldwide, considering their properties for treating diseases; however, few studies have evaluated their toxicological potential. Among them, Artemisia absinthium is frequently used to treat liver diseases, because its essential oil has several popular therapeutic properties. Based on this information, in the present study, we investigated molecular connectors of physiological effects of the Artemisia absinthium essential oil on human hepatic stellate cell line, LX-2, to explore the potential toxicity of the plant on liver cells. LX-2 is a cellular model to investigate mechanisms of liver fibrosis; then, to analyze the essential oil effects LX-2 was cultured under different conditions, treated or not with the essential oil at 0.4 μg/μL for 24 h. Next, fluorescence microscopy analyses, gene expression measurements, and biochemical approaches revealed that the essential oil reduced pro-fibrogenic markers; however, disrupt lipid metabolism, and cause cellular stress, by the activation of cellular detoxification and pro-inflammatory processes. In conclusion, the hepatic stellate cells incubated with the essential oil present an antifibrotic potential, supporting its popular use; however, the combined results suggest that the essential oil of Artemisia absinthium should be used with caution.

Comparing the sensitivity of aquatic organisms relative to Daphnia sp. toward essential oils and crude extracts: A meta-analysis

Interest on aromatic and medicinal plants (AMP)-based products, especially crude extracts (CE) and essential oils (EO), has increased over recent years due to their bioactive and biopesticide properties, though a variety of these compounds is environmentally damaging. Aquatic organisms can easily be exposed to the toxicological risks of AMP-based products, but research exploring existing ecotoxicity data to non-target organisms is limited. The present study aimed to, for the first time, systematically review published evidence on the acute/short-term toxicity (LC50, EC50 or IC50) of CE and EO from AMP, comparing sensitivity of aquatic organisms. Eleven studies that reported the sensitivity of aquatic taxa and Daphnia sp. to CE and/or EO, were included in the review, contributing with 27 effect sizes, calculated as the response ratio R (EcotoxicityAquatTaxa/EcotoxicityDaphnia). Meta-analytic technics were used to estimate the overall sensitivity of aquatic taxa relative to Daphnia sp. while identifying moderators [plant preparation (CE or EO), extraction type, plant part, plant family, and aquatic taxa identity] potentially affecting relative sensitivities. The overall effect size R was 1.51 (95 % CI = 0.97 to 2.34, N = 27), indicating a non-significant difference in the toxicity of CE and EO to aquatic taxa relative to Daphnia sp. However, the high heterogeneity among individual effect sizes (I2 = 99 %) suggested opposing responses of aquatic taxa relative to Daphnia sp. The magnitude of effects (R) was strongly influenced only by plant family. Daphnia sp. arose as a potential model organism for assessing the ecotoxicity of CE and EO, along with the fish Danio rerio and the crustacean Thamnocephalus platyurus, while Artemia sp. seems a relevant alternative for a preliminary screening. Likewise, the current study sheds light on the (underestimated) toxicity of CE and EO to aquatic ecosystems and that much remains to be uncovered, providing insights and recommendations for future research.

Essential oil from leaves of Croton blanchetianus Baill does not present acute oral toxicity, has antigenotoxic action and reduces neurogenic and inflammatory nociception in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Croton blanchetianus Baill., popularly known as "marmeleiro preto", is an endemic plant from Brazil, being found mainly in the Northeast region. In traditional medicine, the use of medicines based on the leaves of this plant has been reported for the treatment of inflammatory processes, pain, urethral pain, gastrointestinal disorders, rheumatism and headache.

AIM OF THE STUDY

The present work describes the chemical characterization, as well as toxicological evaluation and antinociceptive activity of an essential oil of C. blanchetianus leaves (EOCb).

MATERIALS AND METHODS

The chemical constituents of the oil were identified by gas chromatography coupled to mass spectrometry (GC-MS). In vitro hemolytic activity was tested using mouse blood. Acute toxicity in mice was assessed by the oral or intraperitoneal administration of a single dose of 2000 mg/kg b.w. EOCb (1000 and 2000 mg/kg) was also evaluated for genotoxicity and antigenotoxicity in vivo using the micronucleus test. The antinociceptive activity of EOCb (25, 50 and 100 mg/kg) was evaluated through the abdominal writhing, formalin and tail flick tests.

RESULTS

The chemical characterization indicated as major components α-pinene (21.23%), β-phelandrene (13.92%), terpinolene (13.01%) and germacrene D (10.89%). EOCb did not cause hemolysis and was also neither toxic nor genotoxic, while protected the animals' bone marrow cells from damage caused by cyclophosphamide in oral treatment. However, all animals died after 15 min of intraperitoneal treatment. There was a reduction in the number of abdominal contortions (69.43-89.41%) as well as in licks in the first (38.77-84.47%) and second (59.75-90.74%) phases of the formalin test. In the latter case, the effects were reduced by naloxone and glibenclamide, indicating action via the opioid system and blockage of K+ channels. The latency time in the tail flick test also increased significantly.

CONCLUSION

In conclusion, ingestion of EOCb proved to be safe when administered orally; however, it was lethal intraperitoneally. Additionally, EOCb protected mouse blood cell DNA against the action of cyclophosphamide and showed an antinociceptive effect via the opioid system and dependent on K+ channels.

Critical assessment of the endocrine potential of Linalool and Linalyl acetate: proactive testing strategy assessing estrogenic and androgenic activity of Lavender oil main components

The acyclic linear monoterpenes Linalool (Lin) and Linalyl acetate (LinAc) occur in nature as major constituents of various essential oils such as lavender oils. A potential endocrine activity of these compounds was discussed in literature including premature thelarche and prepubertal gynecomastia due to lavender product use. This study aims to follow-up on these critical findings reported by testing Lin and LinAc in several studies in line with current guidance and regulatory framework. No relevant anti-/ER and AR-mediated activity was observed in recombinant yeast cell-based screening tests and guideline reporter gene in vitro assays in mammalian cells. Findings in the screening test suggested an anti-androgenic activity, which could not be confirmed in the respective mammalian cell guideline assay. Mechanistic guideline in vivo studies (Uterotrophic and Hershberger assays) with Lin did not show significant dose related changes in estrogen or androgen sensitive organ weights and a guideline reproductive toxicity screening study did not reveal evident effects on sex steroid hormone sensitive organ weights, associated histopathological findings and altered sperm parameters. Estrous cycling and mating/fertility indices were not affected and no evident Lin-related steroid hormone dependent effects were found in the offspring. Overall, the initial concerns from literature were not confirmed. Findings in the yeast screening test were aberrant from follow-up guideline in vitro and in vivo studies, which underlines the need to apply careful interpretation of single in vitro test results to support a respective line of evidence and to establish a biologically plausible link to an adverse outcome.

Fumigant toxicity of four essential oils against the carob moth Ectomyelois ceratoniae Zeller and the Mediterranean flour moth Ephestia kuehniella

Eucalyptus leucoxylon, Rosmarinus officinalis, berries, and leaves of Schinus molle essential oils were analysed using GC-MS techniques and assessed for their fumigant toxicity against adults, larvae, and eggs of Ectomyelois ceratoniae and Ephestia kuehniella. Results showed that E. leucoxylon contained Spathulenol, p-Cymene, and Cryptone as major compounds. GC - MS analyses showed that the major compounds of R. officinalis essential oil were 1,8-Cineole, Camphor, and α-pinene. I-Phellandrene, t-Muurolol, and Phellandrene were the major components of the S. molle leaves; while I-Phellandrene, Limonen, and δ-Cadinene were the major components of the S. molle berries. S. molle berries were the most efficient followed by R. officinalis against E. ceratoniae and E. kuehniella. The most effective tested essential oil against E. ceratoniae larvae was S. molle berries. Results on the ovicidal and larvicidal effects of the tested oils demonstrated that R. officinalis was the most effective essential oil against E. kuehniella eggs.

Essential oils as green promising alternatives to chemical preservatives for agri-food products: New insight into molecular mechanism, toxicity assessment, and safety profile

Microbial food spoilage caused by food-borne bacteria, molds, and associated toxic chemicals significantly alters the nutritional quality of food products and makes them unpalatable to the consumer. In view of potential adverse effects (resistance development, residual toxicity, and negative effects on consumer health) of some of the currently used preservative agents and consumer preferences towards safe, minimally processed, and chemical-free products, food industries are looking for natural alternatives to the chemical preservatives. In this context, essential oils (EOs) showed broad-range antimicrobial effectiveness, low toxicity, and diverse mechanisms of action, and could be considered promising natural plant-based antimicrobials. The existing technical barriers related to the screening of plants, extraction methods, characterization, dose optimization, and unpredicted mechanism of toxicity in the food system, could be overcome using recent scientific and technological advancements, especially bioinformatics, nanotechnology, and mathematical approaches. The review focused on the potential antimicrobial efficacy of EOs against food-borne microbes and the role of recent scientific technology and social networking platform in addressing the major obstacles with EOs-based antimicrobial agents. In addition, a detailed mechanistic understanding of the antimicrobial efficacy of EOs, safety profile, and risk assessment using bioinformatics approaches are summarized to explore their potential application as food preservatives.

Antinociceptive and anti-inflammatory activities of essential oil of the leaves of Amburana cearensis (Allemão) A.C. Smith. from the semi-arid region of Northeastern Brazil

ETHNOPHARMACOLOGICAL RELEVANCE

Amburana cearensis (Allemão) A.C. Smith is a medicinal plant with wide distribution in South America, popularly known in Brazil as "cumaru" or "amburana de cheiro". In folk medicine, in the semi-arid region of Northeastern Brazil, infusions, teas and decoctions of leaves of Amburana cearensis have their practical use for treating fever, gastrointestinal disorders, inflammation, and inflammation pain. However, none of the ethnopharmacological properties has been scientifically evaluated using volatile compounds obtained from its leaves (essential oil).

AIM OF THE STUDY

This study investigated the chemical composition, acute oral toxicity, and antinociceptive and anti-inflammatory activities of the essential oil from the leaves of A. cearensis.

MATERIAL AND METHODS

The acute toxicity of the essential oil was investigated in mice. The antinociceptive effect was evaluated using the formalin test and, abdominal writhing induced by acetic acid, being investigated the possible mechanisms of action involved in antinociception. The acute anti-inflammatory effect was investigated through models of carrageenan-induced peritonitis, yeast-induced pyrexia, and carrageenan- and histamine-induced paw inflammation.

RESULTS

No acute toxicity was observed at doses up to 2000 mg/kg; p.o. The antinociceptive effect was statistically equal to morphine. In the formalin assay, the oil showed analgesic activity in the neurogenic and inflammatory phases, having as mechanisms the cholinergic, adenosinergic system, and ATP-sensitive potassium channels (K-ATP). In peritonitis, a reduction in TNF-α and IL-1β levels and leukocyte migration were observed. The antipyretic effect was statistically superior to dipyrone. The reduction in paw edema was statistically superior to the standard in both models.

CONCLUSION

The results obtained not only support the traditional use of the species in inflammatory conditions and pain in folk medicine but also demonstrate that this is a rich source of phytocomponents such as germacrone, which can be used as a natural and sustainable therapeutic agent with industrial applications.

Silicon dioxide nanoparticles suppress copper toxicity in Mentha arvensis L. by adjusting ROS homeostasis and antioxidant defense system and improving essential oil production

Copper (Cu) is an essential micronutrient for plants; however, the excessive accumulation of Cu due to various anthropogenic activities generates progressive pollution of agricultural land and that causes a major constraint for crop production. Excess Cu (80 mg kg-1) in the soil diminished growth and biomass, photosynthetic efficiency and essential oil (EO) content in Mentha arvensis L., while amplifying the antioxidant enzyme's function and reactive oxygen species (ROS) production. Therefore, there is a pressing need to explore effective approaches to overcome Cu toxicity in M. arvensis plants. Thus, the present study unveils the potential of foliar supplementation of two distinct forms of silicon dioxide nanoparticles (SiO2 NPs) i.e., Aerosil 200F and Aerosil 300 to confer Cu stress tolerance attributes to M. arvensis. The experiment demonstrated that applied forms of SiO2 NPs (120 mg L-1), enhanced plants' growth and augmented the photosynthetic efficiency along with the activities of CA (carbonic anhydrase) and NR (nitrate reductase), however, the effects were more accentuated by Aerosil 200F application. Supplementation of SiO2 NPs also exhibited a beneficial effect on the antioxidant machinery of Cu-disturbed plants by raising the level of proline and total phenol as well as the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX) and glutathione reductase (GR), thereby lowering ROS and electrolytic leakage (EL). Interestingly, SiO2 NPs supplementation upscaled EO production in Cu-stressed plants with more pronounced effects received in the case of Aerosil 200F over Aerosil 300. We concluded that the nano form (Aerosil 200F) of SiO2 proved to be the best in improving the Cu-stress tolerance in plants.

Spatial Variation in Yield, Chemical Composition, and Phytotoxic Activity of Cistus ladanifer Essential Oils

Cistus ladanifer L. (rockrose) is a widespread shrub species of the Mediterranean region with products highly valued by the perfume and cosmetics industry. In this research, the variability in yield, chemical composition and phytotoxic activity of C. ladanifer essential oils collected from 12 plots belonging to four natural populations and settled on two different types of edaphic substrates were evaluated. The essential oils were analyzed by GC-MS. The essential oil content ranged from 0.19 to 0.42 mL/100 g. The volatile profiles were found to be rich in oxygenated sesquiterpenes and oxygenated monoterpenes. PCA analysis clustered the samples into two groups that were mainly attributed to the type of substrate on which the plants grow. Furthermore, CCA and correlation analysis revealed that soil organic matter was the most effective edaphoclimatic driver accounting for these high levels of variation in essential oil yield and composition. Finally, C. ladanifer essential oils showed strong phytotoxic activity on R. sativus seedlings, indicating its potential use as a natural bio-herbicide in agriculture. The results showed that the effect associated to local edaphoclimatic conditions not only impacted on the quality and quantity of the essential oil, but also on the industrial uses derived from its biological activities.

Evaluation of 28-day repeated doses oral toxicity of essential oil from Psidium glaziovianum Kiaersk leaves on various biological parameters in Swiss mice

Only a small number of the many medicinally important species in the genus Psidium L. have had their safety assessed. Psidium glaziovianum, a plant native to Brazil, is reported to exert antinociceptive and anti-inflammatory effects; however, there are no apparent reports of long-term safety following administering of repeated doses. The aim of this study was to examine the effects of 28-day oral of treatment at 250, 500 or 1,000 mg/kg Psidium glaziovianum essential oil (PgEO) on behavioral and physiological parameters in male and female Swiss mice. First, PgEO was chemically characterized by gas chromatography mass spectrometry (GC-MS). The following parameters were examined: motor activity, body temperature, blood glucose, urine, hematology, biochemistry, histology, and oxidative stress. Characterization of PgEO revealed 48 components which were dominated by sesquiterpenes 1,8-cineol (24.29%), α-pinene (19.73%) and β-pinene (17.31%). Data showed that PgEO treatment in mice increased activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) without markedly affecting body weight, hematological or biochemical parameters, as well as water or food consumption. Administration of PgEO in repeated daily dosages over 28 days did not significantly alter exploratory or locomotor activities. Based upon our findings, PgEO administration daily for 28 days, exhibited low toxicity and absence of effects on the nervous system. Data demonstrated that PgEO produced hypoglycemic and antioxidant actions which need to be considered in safety assessment.

Drosophila melanogaster as a model for studies related to the toxicity of lavender, ginger and copaiba essential oils

This study addresses the current trend of essential oils in alternative medicine using the non-chordate model Drosophila melanogaster. Following the three R's principles, it proposes non-chordate models to fill knowledge gaps on essential oil toxicity. Copaiba, lavender, and ginger essential oils are evaluated for effects on D. melanogaster lifespan, climbing ability, and brain structure, while their anti-inflammatory properties are also analyzed. Results show dose-related differences: higher concentrations (0.25% v/v) cause brain deterioration and impaired climbing, while lower concentrations (0.0625% v/v for copaiba and ginger; 0.125% for lavender) have no effect on climbing or brain structure. Lavender oil significantly extends lifespan and maintains anti-inflammatory activity when ingested, underscoring its therapeutic potential. These findings highlight the importance of D. melanogaster as a model for studying essential oil properties, potentially replacing chordate models. In addition, this research advances alternative remedies for currently incurable diseases, with lavender oil emerging as a promising candidate for drug discovery.

Acute toxicity of essential oils of Aloysia triphylla (L'Hér.) Britton, Lippia gracilis Schauer, and Piper aduncum L. in Colossoma macropomum (Cuvier, 1818)

The aim of this study was to determine the acute toxicity of the essential oils (EOs) of Aloysia triphylla, Lippia gracilis and Piper aduncum in juvenile tambaqui (Colossoma macropomum), and evaluate the possible histopathological alterations in their gills. For the acute toxicity tests, juvenile tambaqui (n=24/treatment) were distributed in six treatments with three replicates, which comprised the control and five EO concentrations of A. triphylla (60, 80, 100, 120 and 140 mg L-1), L. gracilis (35, 40, 45, 50 and 55 mg L-1) and P. aduncum (42.5, 45, 47.5, 50 and 52.5 mg L-1), with an exposure period of 4 h. The mortality rate and severity of damage to the tambaqui gills were proportional to the increase in the concentration of the EO, with LC50-4 h values estimated at 109.57 mg L -1 for A. triphylla, 41.63 mg L -1 for L. gracilis and 48.17 mg L -1 for P. aduncum. The main morphological damages observed in the gills of the tambaqui exposed to the three EOs, were Grade I: hypertrophy and hyperplasia of lamellar epithelial cells, lamellar fusion, epithelial detachment, capillary dilation and constriction, proliferation of chloride cells and mucosal cells and edema; in low frequency Grade II damage as epithelial rupture and lamellar aneurysm. Necrosis (Grade III damage) was observed only in gill lamellae exposed to P. aduncum EO (47.5, 50.0 and 52.5 mg L-1). Concentrations of EOs below LC50-4 h can be used sparingly, for short periods of exposure for the treatment of diseases in tambaqui breeding.

In silico molecular modeling, neuro-behavioral profile, and toxicity assessment of the essential oil of Ferula gummosa Boiss. as an anti-seizure agent

ETHNOPHARMACOLOGICAL RELEVANCE

Ferula gummosa Boiss., known in Persian as "Baridje," belongs to the Apiaceae family. All parts of this plant, especially the root, contain galbanum. Galbanum, the oleo-gum resin of F. gummosa, is one of the essential traditional herbal medicines in Iran, which is used as a tonic for epilepsy and chorea, memory enhancement, gastrointestinal diseases, and wound healing.

AIM OF THE STUDY

We investigated the toxicity, anticonvulsant effects, and molecular modeling of the essential oil (EO) distilled from the oleo-gum resin of F. gummosa.

MATERIALS AND METHODS

Gas chromatography-mass spectrometry was used to identify the EO components. The cytotoxicity of EO on HepG2 cell lines was assessed by the MTT method. Male mice were arranged as follows: negative control groups (sunflower oil (10 ml/kg, i.p.) or saline (10 ml/kg, p.o.)), EO groups (0.5, 1, 1.5, and 2.5 ml/kg, p.o.), and positive control groups (ethosuximide (150 mg/kg, p.o.) or diazepam (1.0 or 2 mg/kg, i.p.)). The motor coordination and neurotoxicity of EO were studied using the rota-rod test. Open-field, novel object recognition, and passive avoidance learning tests were used to investigate the effect of EO on locomotor activity and memory function. An acute pentylenetetrazole-induced seizure model was utilized to evaluate the anticonvulsant properties of the EO. The interaction of the EO main components with the GABA_A receptor was investigated by coarse-grained molecular dynamics simulations.

RESULTS

β-pinene, sabinene, α-pinene, and ρ-cymene were the main components of EO. The IC₅₀ of the EO at 24, 48, and 72 h was found to be 59.90, 12.96, and 3.93 μl/ml, respectively. No adverse effects were observed in memory, motor coordination, and locomotor activity in mice treated with EO. Administration of EO (1, 1.5, and 2.5 ml/kg) improved survival rates in mice receiving pentylenetetrazole (PTZ; to induce an epileptic seizure). Sabinene was able to bind to the binding site of benzodiazepines at the GABA_A receptor.

CONCLUSIONS

Acute treatment with the EO of F. gummosa caused antiepileptic effects and could effectively increase the survival rate in PTZ-treated mice with no significant toxicity.

Impact of dietary supplementation with Cinnamomum cassia essential oil on silver catfish (Rhamdia quelen): Toxicological effects and muscle antioxidant and fatty acid profiles

The aim of this study was to determine the biological effects of dietary supplementation with 0.05% and 0.1% cinnamon essential oil extracted from Cinnamomum cassia on silver catfish (Rhamdia quelen). The final body weight, weight gain, and specific growth rate were significantly higher in fish supplemented with 0.05% cinnamon essential oil than in the control(untreated) group. Muscle reactive oxygen species and lipid peroxidation levels were significantly lower in fish supplemented with 0.05% cinnamon essential oil but higher at the 0.1% concentration. Muscle antioxidant capacity against peroxyl radicals (ACAP) and superoxide dismutase activity were significantly higher in fish supplemented with 0.05% cinnamon essential oil, while ACAP levels were lower in fish supplemented with 0.1%. The total saturated fatty acid content was significantly higher in the muscle of supplemented fish than in controls, while the total monounsaturated fatty acid content was significantly higher only in fish fed 0.1% cinnamon essential oil. Finally, the total content of polyunsaturated fatty acids was significantly lower in fish fed 0.1% essential oil. Thus, data demonstrated that 0.05% C. cassia essential oil improves fish health by improving performance and muscle oxidant/antioxidant status. Higher doses of cinnamon essential oil produced oxidative stress in muscle, suggesting toxicity at the 0.1% level. Although this cinnamon essential oil diet exerted positive health effects, this diet impaired the muscle fatty acid profile, suggesting adverse impacts on human health.

Bio-molluscicidal potential and biochemical mechanisms of clove oil and its main component eugenol against the land snail, Theba pisana

The land snail, Theba pisana is a serious pest that adversely affects various crops in sustainable agriculture. Essential oils and their constituents represent an environmentally sound alternative to synthetic pesticides. Our study aimed to investigate the lethal and sub-lethal toxicity of clove oil and its main component eugenol to understand the mechanisms underlying its toxic action against T. pisana. The GC-MS profile of the clove oil composition was characterized. In the laboratory experiment, LD₅₀ of clove oil and eugenol via the contact testing were determined after 48 and 72 h. Moreover, sub-lethal effects of clove oil or eugenol on the survivors following the exposure of snails to the 25 and 50% of the LD₅₀/48 and 72 h were evaluated through using snail tissues for biochemical measurments. The GC-MS analysis showed that eugenol (64.87%) was the major constituent present in the oil. The results also showed that LD₅₀ values at 48 and 72 h were 2006.5 and 1493.5 μg/g b.w for oil and 239.6 and 195.3 μg/g b.w for eugenol, respectively. Compared to control, the sub-lethal effects of clove oil or eugenol at 48 and 72 h showed a significant increase in reduced glutathione (GSH) levels. Catalase (CAT) and glutathione-S-transferase (GST) activities significantly elevated in oil- or eugenol-treated snails, except at low dose after 48 h. After two exposure times, snails exposed to oil or eugenol at both sub-lethal effects had considerably higher γ-glutamyltransferase (γ-GT) and aspartate aminotransferase (AST) activities. Moreover, markedly augmentation in alkaline phosphatase (ALP) and alanine aminotransferase (ALT) activities at all exposure times, with the exception of snails treated with low dose of eugenol after 48 h was observed. Both clove oil and eugenol at the tested doses caused a significant inhibition in acetylcholinesterase (AChE) activity at two exposure times. Our findings highlight the potential of clove oil and eugenol, as an efficient natural molluscicide alternative to its synthetic counterparts for snail control.

[Retrospective surveys on intoxications with essential oils]

OBJECTIVES

Non-conventional medicines are not devoid of toxicity and it is relevant to establish an inventory of the general public's knowledge of essential oils. The objective is to identify the profile of the victims of a poisoning, the ways of administration and the symptoms as well as the incriminated essential oils.

METHODS

Two surveys, for the general public and health professional, were distributed (January-March 2019). In addition, data from the Angers poison control center for the period 2017-2018 were analyzed and compared with the data from our study.

RESULTS

Our surveys gathered 623 and 59 answers. The data of the poison control center of Angers counted 741 intoxications. The precautions for use and contra-indications of essential oils are not well known since 5% of the respondents identified them correctly. Our data show that using a mixture increases the risk of intoxication (P<0.02). The most cited essential oils in case of intoxication are Eucalyptus, Tea tree and Lavender. The symptoms mainly concern a cutaneous application (75%) and remain of short duration and without gravity. Concerning the intoxications referenced to the poison control center in Angers, the same essential oils are involved, the oral route is mostly used (70%) and the symptoms listed for 74% of intoxications concern oropharyngeal, ocular, abdominal and skin pain.

CONCLUSION

The delivery of essential oils is not harmless and the data obtained both through our surveys and the processing of data from the poison control center of Angers show that they must be used with caution.

Exploration of Synergistic Pesticidal Activities, Control Effects and Toxicology Study of a Monoterpene Essential Oil with Two Natural Alkaloids

With the increasing development of pest resistances, it is not easy to achieve satisfactory control effects by using only one agrochemical. Additionally, although the alkaloid matrine (MT) isolated from Sophora flavescens is now utilized as a botanical pesticide in China, in fact, its pesticidal activities are much lower in magnitude than those of commercially agrochemicals. To improve its pesticidal activities, here, the joint pesticidal effects of MT with another alkaloid oxymatrine (OMT) (isolated from S. flavescens) and the monoterpene essential oil 1,8-cineole (CN) (isolated from the eucalyptus leaves) were investigated in the laboratory and greenhouse conditions. Moreover, their toxicological properties were also studied. Against Plutella xylostella, when the mass ratio of MT and OMT was 8/2, good larvicidal activity was obtained; against Tetranychus urticae, when the mass ratio of MT and OMT was 3/7, good acaricidal activity was obtained. Especially when MT and OMT were combined with CN, the significant synergistic effects were observed: against P. xylostella, the co-toxicity coefficient (CTC) of MT/OMT (8/2)/CN was 213; against T. urticae, the CTC of MT/OMT (3/7)/CN was 252. Moreover, the activity changes over time of two detoxification enzymes, carboxylesterase (CarE) and glutathione S-transferase (GST) of P. xylostella treated with MT/OMT (8/2)/CN, were observed. In addition, by scanning electron microscope (SEM), the toxicological study suggested that the acaricidal activity of MT/OMT (3/7)/CN may be related to the damage of the cuticle layer crest of T. urticae.

Compositions analysis and insecticidal activity of Aconitum polycarpum Chang ex W.T.Wang petroleum ether fractions and essential oils

ETHNOPHARMACOLOGICAL RELEVANCE

The Aconitum genus plants as a natural pesticide for insecticide and rodent control has been recorded in Chinese folk. However, the insecticide effect, mechanism, and active composition of Aconitum polycarpum Chang ex W.T.Wang have not been studied further.

AIM OF THE STUDY

This study was designed to analyze the chemical composition, evaluate contact toxicity of petroleum ether extracts (PEEs) and essential oils (EOs) of A. polycarpum, and further explore their possible insecticidal mechanism.

MATERIALS AND METHODS

The roots of A. polycarpum were extracted with 90% methanol, and then extracted with petroleum ether to obtain PEEs; the EOs was extracted by distillation. The chemical compositions of PEEs and EOs were analyzed by GC-MS. Contact toxicity was evaluated by the immersion method. Exploring insecticidal mechanisms through in vitro enzyme inhibitory activity.

RESULTS

12 compounds were identified from PEEs by GC-MS, mainly including aliphatic (94.8%), the main compositions were Octadecadienol (ODO) (aliphatic, 53.2%) and L-Ascorbyl dipalmitate (LADP) (aliphatic, 36.1%). 24 compounds were identified in EOs. About 44.6% of the identified components were terpenoids and their derivatives, and the rest were mainly aliphatic (34.7%) and phenols (3.0%). The main chemical components were L (-)-Borneol (LB) (terpenoid, 28.3%), LADP (aliphatic, 19.1%), and Isoborneol (terpenoid, 9.1%). The contact toxicity indicated that the PEEs showed great contact toxicity against Spodoptera exigua (LC₅₀ = 126.2 mg/L). Meanwhile, LADP (LC₅₀ = 128.1 mg/L) and ODO (LC₅₀ = 121.3 mg/L) was similar to that of Cyhalothrin (LC₅₀ = 124.2 mg/L) in contact toxicity. In addition, we found that LADP and ODO exhibited excellent inhibitory activity against CarE (IC₅₀ = 58.0, 56.1 mg/L, respectively) by measuring in vitro enzyme inhibitory activity, which was superior than Cyhalothrin (IC₅₀ = 68.1 mg/L).

CONCLUSIONS

The chemical compositions and contact toxicity of EOs and PEEs of A. polycarpum were analyzed and evaluated, and their insecticidal mechanisms were preliminarily discussed for the first time. It proved PEEs of A. polycarpum and its main components (LADP and ODO) exhibited excellent contact toxicity against S. exigua, and CarE was identified as a potential target for contact toxicity. This study indicated that the insecticidal activity of petroleum ether extracts from A. polycarpum is quite promising, and provides a practical and scientific basis for the development and application of botanical pesticides.

Eugenia gracillima essential oil has pharmaceutical applications in pain and inflammation without toxic effects in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Eugenia gracillima is widely used by the population in the manufacture of pulps and jellies, with popular reports of its use in the treatment of infections in the urinary system, respiratory and dermatological problems. A previous study reports that EO from E. gracillima leaves proved to be a promising antioxidant agent in combating the promastigote forms of protozoa. Despite this, this species has been little studied due to its pharmacological properties.

STUDY OBJECTIVE

In this study, an essential oil extracted (EO) from Eugenia gracillima leaves was evaluated for its acute toxicity and anti-inflammatory, antinociceptive and behavioral effects in mice.

METHODS

The EO was obtained by hydrodistillation, and the composition analysis was performed by gas chromatography coupled to mass spectrometry. Acute toxicity assessment was performed with observation of hematological parameters and histopathological evaluation, as well as tests to investigate antinociceptive, anti-inflammatory activities and behavioral effects.

RESULTS

Chromatographic analysis showed D-germacrene (16.10%), γ-muurolene-g (15.60%) and bicyclogermacrene (8.53%) as the majority of compounds. In the toxicity evaluation, no death or physiological changes were observed in mice treated with a single oral dose of up to 5000 mg/kg, and it did not lyse erythrocytes in vitro. The hematological parameters evaluated were not changed after treatment; however, 5,000 mg/kg promoted an increase in transaminase levels. In the histopathological evaluation, only the animals that received the dose of 5000 mg/kg showed discrete leukocyte infiltration around the centrilobular vein in the liver. Antinociceptive activity was detected through tests of acetic acid-induced writhing, formalin, and tail flick, promoted in part by the opioid receptor pathway. In the evaluation of anti-inflammatory activity, a reduction in inflammation was observed in the paw edema test and a decrease in the migration of leukocytes and neutrophils in the peritonitis test. The open field and elevated plus maze tests showed that EO did not affect the animals' motor functions or exploratory activity.

CONCLUSION

It was concluded that the essential oil of E. gracillima has potential for the development of pharmaceutical formulations with analgesic and anti-inflammatory actions in non-toxic concentrations.

Identification of bioactive compounds and cytogenotoxicity of the essential oil from the leaves of Croton heliotropiifolius Kunth

Croton heliotropiifolius Kunth, popularly known as "quince" and "velame," contains a high concentration of volatile oils in the leaves, and widely used in folk medicine as an antiseptic, analgesic, sedative, anti-inflammatory, spasmolytic and local anesthetic. The objectives of this investigation were to (1) identify the phytochemical compounds and (2) assess the cytogenotoxicity of the essential oil extracted from the leaves of C. heliotropiifolius Kunth. The oil was extracted utilizing hydrodistillation and phytochemical profile determined using gas chromatography and mass spectrometry (GCMS). In the toxicogenetics analysis, Allium cepa roots were exposed to 1% dimethylsulfoxide or methylmethanesulfonate (MMS, 10 µg/ml) negative and positive controls, respectively, and to C. heliotropiifolius oil at 6 concentrations (0.32; 1.6; 8; 40; 200 or 1000 µg/ml). The phytochemical profile exhibited 40 chromatographic bands, and 33 compounds identified. α-pinene (16.7%) and 1,8-cineole (13.81%) were identified as the major compounds. Some of these identified secondary metabolites displayed biological and pharmacological activities previously reported including antiseptic, analgesic, sedative, anti-inflammatory as well insecticidal, antiviral, anti-fungal actions. In the A. cepa test, C. heliotropiifolius leaves oil induced cytotoxicity at concentrations of 0.32, 1.6 or 200 µg/ml and genotoxicity at 200 or 1000 µg/ml as evidenced by increased presence of micronuclei and significant chromosomal losses. Based upon our observations data demonstrated that the essential oil of C. heliotropiifolius leaves contain monoterpene hydrocarbons, and oxygenated monoterpenes, sesquiterpenes, and oxygenated sesquiterpenes which are associated with cytotoxic and genotoxic responses noted in on A. cepa cells.

Immune-antioxidant trait, growth, splenic cytokines expression, apoptosis, and histopathological alterations of Oreochromis niloticus exposed to sub-lethal copper toxicity and fed thyme and/or basil essential oils enriched diets

Two experiments were conducted in this study, using 250 Oreochromis niloticus (O. niloticus) (average weight 30.28 ± 0.27 g). The first experiment was conducted to investigate the 96-h lethal concentration 50 (LC₅₀) of copper chloride (CuCl₂) using the probit analysis, seventy fish was divided into seven different concentration of CuCl₂ (0, 22, 23, 24, 25, 26, and 27 mg/L), the accurate Cu concentrations were (1.23, 5.36, 6.02, 6.98, 7.05, 7.93, 8.12 mg/L Cu). The second experiment was conducted for investigating the effect of dietary supplementation with thyme (Thymus vulgaris, T. vulgaris) and sweet basil (Ocimum basilicum, O. basilicum) essential oils (TEO and BEO respectively) against sub-lethal Cu exposure (1/10 96-h LC₅₀ of CuCl₂). About 180 fish was divided into six groups in triplicate (10 fish/replicate, 30 fish/group). Group 1 (C) was kept as a control group with no Cu exposure and was fed the control basal diet. Group 2 (C-Cu) was fed the control basal diet and simultaneously exposed to 1/10 of the 96 h LC₅₀ of CuCl₂ (2.574 mg/L) as a sub-lethal concentration of Cu, where the realistic Cu concentration was 3.976 mg/L. Group 3 (TEO) and group 4 (BEO) were fed the diets fortified with 1%TEO and BEO, respectively without exposure to Cu. Group 5 (TEO-Cu) and group 6 (BEO-Cu) were fed the diets fortified with 1%TEO and 1%BEO, respectively, and simultaneously exposed to 1/10 of the 96 h LC₅₀ of CuCl₂ (2.574 mg/L). The growth and behavioral performance, immunological response and its related gene expression, antioxidant status, stress biomarker indicators, apoptosis biomarkers, and histopathological alteration were investigated. The results of the first experiment showed that the 96-h LC₅₀ of CuCl₂ in O. niloticus was 25.740 mg/L with lower and upper confidence limits of 25.152 and 26.356 mg/L, respectively. The results of the second experiment showed that sub-lethal Cu exposure induced growth retardation (lowered final body weight, total weight gain, and specific growth rate %), behavioral abnormalities (slower swimming activity and feeding performance), immunosuppression (lowered nitric oxide, complement-3, lysozyme, total proteins, albumin, and globulin), and lowering the hepatic antioxidant functions (higher MDA, and lower SOD, CAT, and GPx) in the exposed fish. Furthermore, alteration in the immune-related genes expression (down-regulation of IL-10 and TGF-β and up-regulation of IL-1β, IL-6, IL-8, and TRL-4), hepato-renal dysfunction (elevated ALT, AST, urea, and creatinine), and high levels of serum stress indicators (cortisol and glucose) were markedly evident. sub-lethal Cu toxicity induced significant up-regulation of apoptosis biomarkers involving, nuclear factor-κβ (NF-κβ), Bcl-2 Associated X-protein (BAX), meanwhile, the expression of B-cell lymphoma 2 (BCL2) and Proliferating cell nuclear antigen (PCNA) was remarkably down-regulated. In addition, apoptosis was also evident by histopathological investigation of branchial, hepatic, and renal sections. TEO and/or BEO dietary supplementation mitigate the destructive impacts of sub-lethal Cu exposure in O. niloticus, depending on the results of our study, it could be concluded that TEO and BEO with a 1% dietary level could be a promising antioxidant, immunostimulant, anti-stress factors, and anti-apoptosis mediators against heavy metal contaminants (Cu) in O. niloticus, providing a solution to the problem of aquatic bodies pollution, consequently aiding in the development of aquaculture industry.

Toxicity of the essential oil from Tetradenia riparia (Hochstetter.) Codd (Lamiaceae) and its principal constituent against malaria and dengue vectors and non-target animals

Malaria and dengue are diseases transmitted by mosquitoes of the genera Anopheles and Aedes resistant to commercial insecticides, which are toxic to non-target animals. Alternatively, eco-friendly strategies have focused on searching for essential oil (EO) from plants to control these mosquitoes. In this aspect, this study was carried out to investigate the toxicity of the EO from Tetradenia riparia and its main constituent against Anopheles and Aedes larvae and non-target animals Toxorhynchites haemorrhoidalis and Gambusia affinis. The mechanism of the larvicidal action of the EO and its main compound was investigated by the acetylcholinesterase (AChE) inhibition. The EO from T. riparia was extracted by hydrodistillation with yield of 1.4 ± 0.17%. The analysis of the EO by GC-MS and GC-FID revealed fenchone (38.62%) as the main compound. The EO (100 ppm) showed larvicidal activity against Anopheles and Aedes larvae (91 to 100% of mortality) (LC₅₀ from 29.31 to 40.76 ppm). On the other hand, fenchone (10 ppm) showed more activity (89 to 100% of mortality) (LC₅₀ from 5.93 to 7.00 ppm) than the EO. The EO and fenchone caused the inhibition of AChE (IC₅₀ from 1.93 to 2.65 ppm), suggesting the inhibition of this enzyme as a possible mechanism of larvicidal action. Regarding toxicity, the EO (1000 ppm) and fenchone (100 ppm) showed low toxicity against T. haemorrhoidalis and G. affinis (9 to 74% of mortality) (LC₅₀ from 170.50 to 924.89 ppm) (SI/PSF from 17.99 to 31.91) than the α-cypermethrin (0.52 ppm) which was extremally toxic against these non-target animals (100% of mortality, LC₅₀ from 0.22 to 0.29 ppm). This significant larvicidal activity of the T. riparia EO and its main constituent, along with the low toxicity towards non-target organisms indicate these samples as a possible eco-friendly alternative for the control of malaria and dengue vectors.

Effect of thyme essential oil and its two components on toxicity and some physiological parameters in mulberry pyralid Glyphodes pyloalis Walker

Extensive usage of synthetic pesticides has proved to be destructive to all living being and the resurgence of pest resistance. Compounds derived from certain plants are usually safer compared to chemical control of pest. The present study thus intended to use Thymus vulgaris essential oil (EO) and two of its derivatives including thymol and carvacrol in order to see their deleterious effects on Glyphodes pyloalis (Walker). We also studied the oil components. This pest has recently become a serious concern for the silk industry. Our results showed that the thyme EO contain several components including thymol (26.9%), ρ-Cymene (14.54%), linalool (13.39%) and carvacrol (5.7%). Our toxicity tests revealed an estimated LD₅₀ values for thyme EO, thymol and carvacrol 2.82, 32.18 and 56.54 μg/larva, respectively. However, the thyme EO was more toxic than its two tested compounds. The activity of certain detoxifying enzymes such as α- and β-esterase, glutathione S-transferase and cytochrome P450 were significantly inhibited by thymol-treated larvae compared to the control group. Similarly, the activity of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase and alkaline phosphatases enzymes in thymol-treated larvae decreased while the activity of acid phosphatases increased. Our results suggest that thyme EO and its components have potential for the control of G. pyloalis larvae in mulberry orchards, where no synthetic chemicals are allowed.

Anti-inflammatory, antipyretic efficacy and safety of inhaled Houttuynia cordata thunb. essential oil formulation

ETHNOPHARMACOLOGICAL RELEVANCE

Houttuynia cordata Thunb. (H. cordata) is a well-known folk traditional Chinese medicine that is renowned for its use in the management of inflammatory respiratory diseases and pneumonia. Its essential oils have demonstrated their anti-inflammatory efficacy in vitro, however, their in vivo biological effects via inhalation have not been elucidated.

AIM OF THE STUDY

This study aims to evaluate the anti-inflammation and toxicology of H. cordata essential oil-containing formulation, H16 aerosol in vivo.

MATERIALS AND METHODS

A laser diffraction particle size analyser and a Next Generation Impactor were used to measure the mass median aerodynamic diameter (MMAD) of the H16 aerosol. The anti-inflammatory and antipyretic effects of the H16 aerosol were evaluated in the xylene-evoked ear oedema and Brewer's yeast-induced fever models, respectively. The biological safety of the H16 aerosol was evaluated by acute toxicity and local toxicity tests in animal models.

RESULTS

Our data showed that the MMAD of the bioactive aerosol was 3-5 μm, which implied tracheal and pharyngeal deposits. Significant anti-inflammatory and antipyretic effects were also observed in the animal models treated with H16 aerosol. The maximum tolerable dose of H16 in rats was >2.5 mL/kg. Irritation was not found on respiratory tract mucosa in the local toxicity test.

CONCLUSIONS

Taken together, the present study suggested that H16 could be delivered in the form of aerosol and possessed its antipyretic and anti-inflammatory effects. This study provides a new perspective for the development of a new herbal aerosol therapy and herbal modernization.

Eucalyptus oil nanoemulsions against eggs and larvae of Haemonchus contortus

Haemonchus contortus is a highly pathogenic and prevalent helminth that causes many deaths in sheep herds. Anthelmintics are usually employed to overcome this issue; however, they do not guarantee immediate and lasting efficacy because of the occurrence of drug-resistant parasites. Among substances that are used in scientific studies for parasitic control, essential oils are known to have different pharmacological properties. However, they demonstrate instability owing to several factors, and therefore, nanoemulsification is considered an alternative to control the instability and degradability of these compounds. The objective of this study was to evaluate the cytotoxicity of nanoemulsions containing essential oil of Eucalyptus globulus against the blood of healthy sheep and to verify their activity against the parasite H. contortus in sheep. The results presented adequate nanotechnological characteristics (diameter 72 nm, PDI 0.2, zeta -11 mV, and acidic pH) and adequate morphology. Further, the corona effect and cytotoxic profiles of the free oil and nanoemulsion against blood cells from healthy sheep were evaluated. The tests results did not present a toxicity profile. For evaluating efficacy, we observed an important anthelmintic action of the nanoemulsion containing oil in comparison to the free oil; the results demonstrate a potential role of the nanoemulsion in the inhibition of egg hatchability and the development of larvae L1 to L3 (infective stage). Based on these results, we developed an important and potential anthelmintic alternative for the control of the parasite H. contortus.

Acute toxicity of Zanthoxylum bungeanum against two stored product insects and synergistic interactions between two major compounds limonene and linalool

In order to find and develop new botanical pesticides against storage pests, components of the essential oil (EO) from Zanthoxylum bungeanum were identified by GC-MS and their insecticidal activity against the stored product pests were studied. The EO was obtained by steam distillation. Results showed that EO was rich in limonene (23.67), linalool (21.76) and linalyl anthranilate (10.87). In contact assays, linalool exhibited strongest toxicity to red flour beetle adult (LD₅₀ = 17.06 μg/adult) and larvae (LD₅₀ = 16.42 μg/larvae), and linalool was the most active one against the Lasioderma serricorne (LD₅₀ = 15.36 μg/larvae). Then limonene and linalool showed different levels of fumigant activities against the two insect species. Synergism effect existed in the proportion of contact assays against Tribolium castaneum adults, and additive was observed in the proportion of 7:1 against T. castaneum larvae. This work provides important information for the development and utilization of Z. bungeanum and suggests that the EO of Z. bungeanum has the potential to serve as bio-insecticides for controlling pest damage in stored products.

Biological activities and gene expression of detoxifying enzymes in Tribolium castaneum induced by Moutan cortex essential oil

Tribolium castaneum is one of the most harmful storage pests in the world. The aim of this study was to determine the chemical composition, repellent, and contact activities of Moutan cortex essential oil against this insect pest. In addition, the effects of Moutan cortex were examined on the expressions of three major detoxifying enzyme genes in T. castaneum. Four components were identified in this essential oil by gas chromatography-mass spectrometry (GC-MS), which was predominantly paeonol (99.13%). Paeonol exerted significant repellent activity against T. castaneum, which was more potent than the positive control N.N-diethyl-meta-toluamide (DEET). The most significant contact toxicity was observed at 24 h after exposure to paeonol. Further, quantitative real-time PCR (qRT-PCR) was used to assess expression changes in three detoxification enzyme genes in T. castaneum, including carboxylesterase (CarE), glutathione S-transferase (Gst) and cytochrome P4506BQ8 (Cyp6bq8). Among these, Gst was most highly up-regulated after treatment with paeonol with the highest expression level of 4.9-fold (Rps18 as internal reference gene) greater than control at 24 h following treatment. Data indicated that Gst might play a critical role in metabolic detoxification of toxic xenobiotics. Taken together, our findings might lay a foundation for development of paeonol as a potential natural repellent or pesticide to control storage pests.

Cytotoxicity of Cymbopogon citratus (DC) Stapf fractions, essential oil, citral, and geraniol in human leukocytes and erythrocytes

ETHNOPHARMACOLOGY RELEVANCE

Our recently published paper demonstrated that ethyl acetate fractions obtained from Cymbopogon citratus (DC.) Stapf (C. citratus) leaves, which are consumed as infusion in folk medicine due to their therapeutic properties, are rich in polyphenols and exhibit promising antioxidant activity by acting through different mechanisms in vitro. However, studies regarding the toxicity of these fractions are necessary to investigate their safe use in future biomedical applications.

AIM OF THE STUDY

This study aimed to investigate the toxicity of ethyl acetate (obtained in acidic and basic conditions and after the essential oil removal from the leaves) and chloroform fractions, essential oil, and its pure constituents, citral and geraniol.

MATERIALS AND METHODS

The toxicity of C. citratus samples was evaluated by using Artemia salina (A. salina) and human blood cells (leukocytes and erythrocytes).

RESULTS

The A. salina lethality assay demonstrated that C. citratus fractions were moderately toxic with LC₅₀ values ranging from 146.12 to 433.15 μg mL^-1, whereas the essential oil and isolated compounds were highly toxic with LC₅₀ lower than 100 μg mL^-1. Leukocyte viability decreased after incubation in the presence of the fractions obtained after the essential oil removal from the plant leaves, as well as in the presence of essential oil, citral and geraniol. The same samples increased the osmotic fragility of erythrocytes, and field emission gun scanning electron microscopy (FESEM) analysis revealed significant changes in cell morphology. Interestingly, our results suggest that the previous removal of essential oil from plant leaves facilitated the extraction of cytotoxic compounds from C. citratus.

CONCLUSIONS

It was demonstrated that C. citratus ethyl acetate and chloroform fractions, essential oil, as well citral and geraniol were considered toxic to A. salina, cytotoxic to human blood cells and showed to induce alterations in the erythrocyte membrane at higher concentrations. These fractions will be further investigated to identify the phytochemicals involved in the observed cytotoxic effects and explored using in vivo models.

The sweet wormwood essential oil and its two major constituents are promising for a safe control measure against fall webworm

The fall webworm, Hyphantria cunea (Drury), is a harmful polyphagous global defoliator. The major chemical components of Artemisia annua essential oil (EO) was found to contain (±)-camphor (16.42%), 1,8-cineole (6.22%), α-pinene (6%), caryophyllene (5.19%), and α-selinene (5.17%). The highest toxicity was recorded for EO of A. annua (LD₅₀ = 305.05 μg/larva), followed by (±)-camphor (LD₅₀ = 465.03 μg/larva) and 1,8-cineole (LD₅₀ = 573.49 μg/larva). The binary mixtures of compounds expressed a weaker activity compared to individuals. The (±)-camphor was found to be antagonistic to 1,8-cineole. The biochemical compounds of treated larvae were also determined. The activity level of alanin and aspartate aminotransferase decreased sharply while acid and alkaline phosphatase increased. Activity of lactate dehydrogenase was significantly higher than the control group at 24 h, but decreased significantly after 48 h in all treatments. The activity of esterases were decreased in the treated larvae. The glutathione S-transferase significantly increased in all time intervals. Overall the current results suggest that the sweet wormwood (A. annua) EO and its components could be a safe and environmentally friendly approach in possible control of fall webworm (H. cunea).

Molluscicidal and cercaricidal activities of the essential oil of Dysphania ambrosioides (L.) Mosyakin & Clemants: Implications for the control of schistosomiasis

Schistosomiasis is one of the most important tropical diseases. A fundamental strategy to control its spread is the use of natural products against its vectors, which are snails of the genus Biomphalaria. The present study evaluated the chemical composition, the molluscicidal and cercaricidal effects, and the ecotoxicity of the essential oil from the aerial parts of Dysphania ambrosioides (L.) Mosyakin & Clemants (DAEO). The essential oil was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). Molluscicidal and cercaricidal activities were determined by the immersion method. Environmental toxicity was assessed from bioassays using Artemia salina larvae and Danio rerio fish. DAEO presented a 0.8% yield. The GC-MS analysis revealed the predominance of hydrocarbon monoterpenes in the oil. A total of 32 constituents was identified, with α-terpinene (50.69%) being the major compound, followed by p-cymene (13.27%) and ascaridole (10.26%). DAEO was active against adult Biomphalaria glabrata snails and demonstrated lethal effect against Schistosoma mansoni cercariae, with LC₅₀ values of 25.2 (22.7-27.8) and 62.4 (61.8-62.9) μg/mL, respectively. Regarding toxicity to non-target aquatic organisms, the oil showed LC₅₀ values of 86.9 (84.7-87.6) and 18.6 μg/mL (15.5-22.8) for A. salina and D. rerio, respectively. DAEO proved to be a promising natural product for the control of schistosomiasis, acting on both the vectors and the etiological agent of the disease. However, the use of the oil is safer in transmission sites where there are no non-target organisms, as it has showed toxicity to D. rerio fish.

Risk assessment of in vitro cytotoxicity, antioxidant and antimicrobial activities of Mentha piperita L. essential oil

The objective of this study was to determine the chemical composition as well as antioxidant, antibacterial, and cytotoxic properties of the essential oil of Mentha piperita L. (peppermint). Fifteen chemical constituents were identified in the essential oil, for a total of 99.99% of the compounds. The essential oil exhibited antimicrobial activity against two Gram-positive bacteria Staphylococcus aureus and Listeria monocytogenes. The minimum inhibitory concentration (MIC) of essential oil of Mentha piperita L. for Staphylococcus aureus and Listeria monocytogenes was 1.84 μg/ml, whereas the minimum bactericidal concentration (MBC) values were 3.7 and 7.43 μg/ml, respectively. The oil displayed potent antioxidant activity inhibiting up to approximately73% of 2,2'-azinothiobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals. In the cytotoxicity assay, the highest essential oil concentration (100 μg/ml) resulted in viability of approximately 90% human epidermal keratinocyte (HaCaT) cells. With respect to antitumor activity in C6 rat glioma cells, there was significant reduction in cell viability: 56-74% in 24 hr, and 71-77% in 48 hr. Data suggest that in presence of the essential oil of Mentha piperita L. antioxidant, antibacterial, antitumor and non-cytotoxic properties were noted.

Toxicity of Selected Monoterpenes and Essential Oils Rich in These Compounds

Monoterpenes make up the largest group of plant secondary metabolites. They can be found in numerous plants, among others, the Lamiaceae family. The compounds demonstrate antioxidative, antibacterial, sedative and anti-inflammatory activity, hence, they are often employed in medicine and pharmaceuticals. Additionally, their fragrant character is often made use of, notably in the food and cosmetic industries. Nevertheless, long-lasting studies have revealed their toxic properties. This fact has led to a detailed analysis of the compounds towards their side effects on the human organism. Although most are safe for human food and medical applications, there are monoterpene compounds that, in certain amounts or under particular circumstances (e.g., pregnancy), can cause serious disorders. The presented review characterises in vitro and in vivo, the toxic character of selected monoterpenes (α-terpinene, camphor, citral, limonene, pulegone, thujone), as well as that of their original plant sources and their essential oils. The selected monoterpenes reveal various toxic properties among which are embryotoxic, neurotoxic, allergenic and genotoxic. It is also known that the essential oils of popular plants can also reveal toxic characteristics that many people are unaware of.

Ecotoxicity of plant extracts and essential oils: A review

Plant-based products such as essential oils and other extracts have been used for centuries due to their beneficial properties. Currently, their use is widely disseminated through a variety of industries and new applications are continuously emerging. For these reasons, they are produced industrially in large quantities and consequently they have the potential to reach the environment. However, the potential effects that these products have on the ecosystems' health are mostly unknown. In recent years, the scientific community started to focus on the possible toxic effects of essential oils and plant extracts towards non-target organisms. As a result, an increasing body of knowledge has emerged. This review describes the current state of the art on the toxic effects that essential oils and plant extracts have towards organisms from different trophic levels, including producers, primary consumers, and secondary consumers. The majority of the studies (76.5%) focuses on the aquatic environment, particularly in aquatic invertebrates (45.1%) with only 23.5% of the studies focusing on the potential toxicity of plant-derived products on terrestrial ecosystems. While some essential oils and extracts have been described to have no toxic effects to the selected organisms or the toxic effects were only observable at high concentrations, others were reported to be toxic at concentrations below the limit set by international regulations, some of them at very low concentrations. In fact, L(E)C₅₀ values as low as 0.0336 mg.L^-1, 0.0005 mg.L^-1 and 0.0053 mg.L^-1 were described for microalgae, crustaceans and fish, respectively. Generally, essential oils exhibit higher toxicity than extracts. However, when the extracts are obtained from plants that are known to produce toxic metabolites, the extracts can be more toxic than essential oils. Overall, and despite being generally considered "eco-friendly" products and safer than they synthetic counterparts, some essential oils and plant extracts are toxic towards non-target organisms. Given the increasing interest from industry on these plant-based products further research using international standardized protocols is mandatory.

Lethal and behavioural effects of a green insecticide against an invasive polyphagous fruit fly pest and its safety to mammals

Plant essential oil-based insecticides, with special reference to those that may be obtained from largely available biomasses, represent a valuable tool for Integrated Pest Management. However, the sublethal effects and the potential effects on aggressive insect traits of these green insecticides are understudied. Herein, the lethal and sub-lethal effects of the carlina oxide, constituting more than 97% of the whole Carlina acaulis (Asteraceae) root essential oil (EO), were determined against an invasive polyphagous tephritid pest, Ceratitis capitata (medfly). The carlina oxide was formulated in a mucilaginous solution containing carboxymethylcellulose sodium salt, sucrose, and hydrolysed proteins, showing high ingestion toxicity on medfly adults. The behavioural effects of carlina oxide at LC₁₀ and LC₃₀ were evaluated on the medfly aggressive traits, which are crucial for securing reproductive success in both sexes. Insecticide exposure affected the directionality of aggressive actions, but not the aggression escalation intensity and duration. The EO safety to mammals was investigated by studying its acute toxicity on the stomach, liver, and kidney of rats after oral administration. Only the highest dose (1000 mg/kg) of the EO caused modest neurological signs and moderate effects on the stomach, liver, and kidney. The other doses, which are closer to the practical use of the EO when formulated in protein baits, did not cause side effects. Overall, C. acaulis-based products are effective and safe to non-target mammals, deserving further consideration for eco-friendly pesticide formulations.

Evaluation of the phytotoxic effect of the essential oil from Artemisia absinthium

The chemical profile and the phytotoxicity of Artemisia absinthium essential oil (EO) were investigated to evaluate its potential value as a biopesticide for food safety purposes. A total of 54 compounds were identified in A. absinthium EO, with the most abundant constituents being eucalyptol (25.59%), linalool (11.99%), and β-myrcene (10.05%). The EO, linalool, and a mixture of three major components exhibited potent suppressive activity against four receiver species; however, eucalyptol and β-myrcene showed a much weaker effect. Bioassay-guided fractionation led to the isolation of linalool as the major active compound responsible for the EO's phytotoxicity. Subsequent scanning electron microscopy (SEM) analysis revealed that linalool significantly inhibited root-hair formation and metaxylem development. This is the first report on the determination of linalool as the major active phytotoxic compound in A. absinthium EO, as well as the elucidation of its mechanism of phytotoxicity from the perspective of root structure changes in the receiver species. Our results suggest that both the EO and its major constituents have potential value as environmentally friendly herbicides.

Fumigant toxicity and biochemical effects of selected essential oils toward the red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae)

Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) is an insect popularly known as the red flour beetle, it is widely distributed worldwide and can cause serious damage to stored grains. Chemical control is the most used method for managing this pest, however, some substances are toxic to mammals and the environment. Therefore, the development of new effective and safe insecticides is necessary. Essential oils (EOs) can be considered as a potential alternative in the development of pesticides due to their physicochemical properties and varied effects against insects. In the current study, was determined the fumigant toxicity and biochemical effects of selected essential oils against T. castaneum. The 23 selected EOs were characterized by GC-MS and their fumigant lethal concentrations were determined. An exploratory Cluster analysis was performed to find a relationship between fumigant toxicity and chemical composition. Finally, the inhibition of the catalytic activity of acetylcholinesterase (AChE), glutathione S-transferase (GST) and catalase (CAT) was evaluated using protein homogenates obtained from T. castaneum. The results indicated that EOs with the highest fumigant potential were those with greater diversity in their composition, while the least active EOs presented mainly monoterpenes. The most active EOs were those obtained from Foeniculum vulgare and Zanthoxylum monophyllum with LC₅₀ values of 16.23 and 18.54 μL/L air respectively. Regarding the inhibition of the enzymatic activity of the 23 EOs evaluated at 500 μL/L, only two caused an inhibition greater that 50% on AChE, which corresponded to EOs from Piper nigrum and Rosmarinus officinalis. Likewise, EOs from C. sinensis, Piper aduncum and Zanthoxylum monophyllum were the only ones able to inhibiting GST activity by more than 50%. Respecting CAT inhibition, 7 EOs caused and inhibition greater than 50%, highlighting those from Lavandula angustifolia, C. sempervirens and Eucalyptus sp. These results show that the EOs evaluated in this study seems to be a promising bio-controller of T. castaneum since have high fumigant toxicity and exert different mechanisms of action.

Transcriptome profile of Haemaphysalis longicornis (Acari: Ixodidae) exposed to Cymbopogon citratus essential oil and citronellal suggest a cytotoxic mode of action involving mitochondrial Ca2+ overload and depolarization

Haemaphysalis longicornis is an ixodid tick species of medical and veterinary importance. Investigation into the acaricidal activities of botanicals have increased recently but information about their molecular mechanism of action is scarce. Here, RNA-seq analysis of the ticks exposed to Cymbopogon citratus essential oil and citronellal was performed and the responsive genes were identified. More than 6.39 G clean reads with Q₂₀ ≥ 94.88% were obtained for each H. longicornis sample, with an average GC content of 50.94%. Using the Trinity method, 166,710 unigenes with a mean length of 869 bp and a maximum contig length of 29,156 bp were obtained. The upregulation of genes was concentration-dependent in most of the treated groups. Many genes responsive to C. citratus oil and citronellal were stress-related and they include genes associated with adrenergic signaling/calcium channels, cGMP-PKG signaling, apoptosis, focal adhesion, ECM-receptor interaction, ubiquitin-mediated proteolysis, mTOR signaling pathway, and longevity regulating pathway. The upregulation of genes (CACNAID, ADCY9, TPM1, and MYH6) associated with calcium channels suggests a neurotoxic mode of action, whereas, the upregulation of apoptosis-associated genes (CYC, DRONC, CASP7, CASP9, BCL2L1, bcl-xL, etc.) suggests a cytotoxic mode of action. The metabolism of C. citratus essential oil generates oxidative stress which increases the intra-mitochondrial free Ca²⁺ and triggers the formation of reactive oxygen species (ROS) that culminates to mitochondrial depolarization, ATP depletion, and either necrotic or apoptotic death. The neurotoxic and cytotoxic effects exhibited by the monoterpenes in H. longicornis is vital and could be exploited for the advancement of acaricide development and eco-friendly tick control.

Toxicity of Varronia curassavica Jacq. Essential Oil to Two Arthropod Pests and Their Natural Enemy

This study aimed to evaluate the toxicity of the Varronia curassavica Jacq. essential oil to two cosmopolitan and polyphagous pest species, the two-spotted spider mite (Tetranychus urticae Koch) and the green aphid (Myzus persicae Sulzer). Additionally, we tested the essential oil toxicity to a generalist predatory insect, the green lacewing Ceraeochrysa cubana Hagen. The treatments consisted of four essential oil concentrations (0.25, 0.5, 0.75 and 1.0%) and one control (Tween® 80 + water). At 0.75% concentration, the V. curassavica essential oil caused the highest mortalities for both pests. The concentration of 1.0% of the essential oil interfered mainly in the rates of oviposition and egg hatching and caused a decrease in the instantaneous population growth rate (r_i) of T. urticae. Survival of the C. cubana was not affected by the highest tested concentration of the essential oil (1%). Tested concentrations V. curassavica essential oil were toxic to T. urticae and M. persicae, but not to the predator C. cubana.

FEMA GRAS assessment of natural flavor complexes: Origanum oil, thyme oil and related phenol derivative-containing flavoring ingredients

In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavor ingredients, mostly consisting of a variety of essential oils and botanical extracts. This publication, seventh in the series, re-evaluates NFCs with constituent profiles dominated by phenolic derivatives including carvacrol, thymol and related compounds using a constituent-based procedure first published in 2005 and updated in 2018. The procedure is based on the chemical characterization of each NFC as intended for commerce and the estimated intake of the constituent congeneric groups. The procedure applies the threshold of toxicological concern (TTC) concept and evaluates relevant data on absorption, metabolism, genotoxic potential and toxicology of the constituent congeneric groups and the NFC under evaluation. Herein, the FEMA Expert Panel affirmed the generally recognized as safe (GRAS) status of seven phenolic derivative-based NFCs, Origanum Oil (Extractive) (FEMA 2828), Savory Summer Oil (FEMA 3013), Savory Summer Oleoresin (FEMA 3014), Savory Winter Oil (FEMA 3016), Savory Winter Oleoresin (FEMA 3017), Thyme Oil (FEMA 3064) and Thyme White Oil (FEMA 3065) under their conditions of intended use as flavor ingredients.

Salicylic acid-mediated alleviation of soil boron toxicity in Mentha arvensis and Cymbopogon flexuosus: Growth, antioxidant responses, essential oil contents and components

Boron (B) toxicity is a notable abiotic hindrance that restricts crop productivity by disturbing several physiological and biochemical processes in plants. This study was aimed to elucidate the role of salicylic acid (SA) in conferring tolerance to B stress in Mentha arvensis and Cymbopogon flexuosus. Boron toxicity led to a considerable decrease in shoot height and root length, fresh and dry mass of shoot and root, and physiological and biochemical parameters. However, exogenously applied SA relieved the adverse effects caused by B toxicity and led to an increase in growth parameters under B stress and non-stress conditions. The treatment of B resulted in its increased accumulation in roots and shoots of both the plants which, in turn, caused oxidative damage as evident by increased content of malondialdehyde and catalase, peroxidase, superoxide dismutase and glutathione reductase enzyme activities. However, exogenous SA supply significantly affected antioxidant enzyme activities and protected the plants from excess B. Moreover, the essential oil content of two selected plants declined under B toxicity and significantly enhanced in SA-treated stressed plants. The contents of menthol and menthyl acetate in M. arvensis were lowered in B stressed plants which significantly improved in SA treated B-stressed and in their respective SA alone treatment. Similarly, citral-A and citral-B content of C. flexuosus declined under B toxicity, however, SA reversed the negative effects of B toxicity on essential oil components. This assessment stipulated the promising role of exogenously applied SA in alleviating B toxicity in M. arvensis and C. flexuosus by improving antioxidant machinery and limiting B uptake which protects the structural integrity of leaves and also helps in increasing essential oil content.

Transcriptomic Analysis of Drug-Resistance Acinetobacter baumannii under the Stress Condition Caused by Litsea cubeba L. Essential Oil via RNA Sequencing

Litsea cubeba L. essential oil(LCEO) can affect the growth of drug-resistance bacteria. However, research on stress response of drug-resistant A. baumannii under sub-lethal LCEO concentrations had been limited so far. Therefore, transcriptomic analysisof A. baumannii under 1/2 minimum inhibitory concentration (MIC, 0.54 mg/mL) of LCEO was performed. Results of transcriptomic analysis showed that 320/352 genes were significantly up/down-regulated, respectively, in LCEO-treated A. baumannii. Both up and down-regulated genes were significantly enriched in three GO terms (oxidation-reduction process; oxidoreductase activity; oxidoreductase activity, acting on the CH-CH group of donors), which indicated that the redox state of A. baumannii was significantly affected by LCEO. LCEO may also inhibit aerobic respiration, synthesis of ketone bodies and the metabolism of some amino acids while, meanwhile, promoting fatty acid degradation of A. baumannii according to Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. The permeability and the stress of cell membrane of A. baumannii were significantly affected by LCEO. After crystal violet dyeing, the biofilm formation of A. baumannii was promoted/inhibited by extremely low/relatively high concentration of LCEO, respectively. LCEO and chloramphenicol have synergistic growth inhibitory effect against A. baumannii according to the Fractional Inhibitory Concentration Index (FICI) value = 0.375. Our results indicate that the growth of A. baumannii was inhibited by LCEO, and give insights into the stress response of A. baumannii under sub-lethal concentrations of LCEO. These results provided evidence that A. baumannii was inhibited by LCEO, and expanded knowledges of stress response of A. baumannii under sub-lethal concentration of LCEO.

Caralluma europaea (Guss) N.E.Br.: A review on ethnomedicinal uses, phytochemistry, pharmacological activities, and toxicology

ETHNOPHARMACOLOGICAL RELEVANCE

Caralluma europaea (Guss) N.E.Br. (Apocynaceae), is a medicinal plant distributed in Morocco, Algeria, Tunisia, Libya, Egypt, Jordan, Spain, and Italy. The different parts of the plant are used traditionally to treat various diseases such as diabetes mellitus, flu, caught, kidney stones, cysts, respiratory infection, cancer, digestives disorders, urogenital infections, metabolic disorders, and cardiovascular problems.

AIM OF THE REVIEW

In this review, previous reports on C. europaea concerning its morphological description, geographical distribution, ethnomedicinal uses, phytochemistry, pharmacological properties, and toxicological studies were critically summarized.

MATERIALS AND METHODS

A systematic review of the literature on C. europaea was performed by searching the scientific databases Science Direct, PubMed, Scopus, and Google Scholar.

RESULTS

In traditional medicine, C. europaea used to treat several illnesses including diabetes, cancer, and kidney stones. Our analysis of the previous reports confirmed the scientific evidence of C. europaea ethnomedicinal uses, especially the antidiabetic activity. However, there was no clear correlation between previous pharmacological reports on C. europaea and its other ethnomedicinal uses in the treatment of kidney stones, flu, caught, metabolic, digestive, cardiovascular and respiratory disorders. The essential oils and extracts of C. europaea exhibited several in vitro and in vivo pharmacological properties such as antidiabetic, antioxidant, anti-inflammatory, analgesic, anti-proliferative, antibacterial, antimicrobial, toxicological, and immunomodulatory effects. Phytochemical characterization of C. europaea revealed the presence of several classes of secondary metabolites such as terpenoids, polyphenols, and flavonoids compounds. Finally, the food preservative ability of the extracts and essential oil obtained from C. europaea has been fully discussed.

CONCLUSION

Ethnomedicinal surveys indicated the use of C. europaea for the treatment of numerous diseases. Pharmacological reports showed that C. europaea exhibited significant antidiabetic, antioxidant, anti-inflammatory, analgesic, anti-proliferative, antibacterial, antimicrobial, and immunomodulatory effects. Further studies on the phytochemistry of bioactive compounds should be performed by using bioactivity-guided isolation strategy and improve their biological potency as well as scientific exploitation of traditional uses. An in-depth investigation is needed to valid the food preservative properties.

Acaricidal, Insecticidal, and Nematicidal Efficiency of Essential Oils Isolated from the Satureja Genus

The overuse of synthetic pesticides in plant protection strategies has resulted in numerous side effects, including environmental contamination, food staff residues, and a threat to non-target organisms. Several studies have been performed to assess the pesticidal effects of plant-derived essential oils and their components, as partially safe and effective agents, on economically important pests. The essential oils isolated from Satureja species are being used in medicinal, cosmetic, and food industries. Their great potential in pest management is promising, which is related to high amounts of terpenes presented in this genus. This review is focused on the acute and chronic acaricidal, insecticidal, and nematicidal effects of Satureja essential oil and their main components. The effects of eighteen Satureja species are documented, considering lethality, repellency, developmental inhibitory, and adverse effects on the feeding, life cycle, oviposition, and egg hatching. Further, the biochemical impairment, including impairments in esterases, acetylcholinesterase, and cytochrome P450 monooxygenases functions, are also considered. Finally, encapsulation and emulsification methods, based on controlled-release techniques, are suggested to overcome the low persistence and water solubility restrictions of these biopesticides. The present review offers Satureja essential oils and their major components as valuable alternatives to synthetic pesticides in the future of pest management.

Pesticidal efficacy, mode of action and safety limits profile of essential oils based nanoformulation against Callosobruchus chinensis and Aspergillus flavus

The study explores the pesticidal efficacy, mode of action, and safety limit profile of essential oils-based formulation using the combination of Myristica fragrans (M), Bunium persicum (B), and Zanthoxylum alatum (Z) (1:1:1 v/v/v) and their nanoformulation (Ne-MBZ) against the Callosobruchus chinensis, Aspergillus flavus and aflatoxin B₁ production. Linalool, γ-terpinene, and cuminaldehyde were identified as the major compounds of the formulation (MBZ) by Gas chromatography-mass spectrometry (GC-MS). Nanoencapsulation of developed formulation (Ne-MBZ) was prepared using chitosan and characterized by scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and Fourier transform infrared spectroscopy (FTIR). The pesticidal efficacy of nanoformulation (Ne-MBZ) against C. chinensis IC₅₀ (0.14 μl/ml), A. flavus (0.8 μl/ml) and AFB₁ (0.8 μl/ml) was significantly higher in both in-vitro and in-situ conditions than the sum of their individual revealing a notable synergistic effect. Besides, the detailed mode of pesticidal action and safety limit profile were explored using biochemical, in-silico and ADMET (absorption, distribution, metabolism, excretion, and toxicity) approaches.

Plant essential oil constituents enhance deltamethrin toxicity in a resistant population of bed bugs (Cimex lectularius L.) by inhibiting cytochrome P450 enzymes

Plant essential oils (EOs) are secondary metabolites derived from aromatic plants that are composed of complex mixtures of chemical constituents. EOs have been proposed as one of the alternative methods for bed bug (Cimex lectularius L.) control. In insecticide resistant mosquitoes and tobacco cutworm, EOs synergize pyrethroid toxicity by inhibiting detoxification enzymes. However, whether EOs and their constituents enhance pyrethroid toxicity in C. lectularius has remained unknown. Therefore, this study was designed to (i) determine the effects of binary mixtures of deltamethrin (a pyrethroid insecticide) with EOs or EO constituents or EcoRaider® (an EO-based product) on mortality of insecticide resistant and susceptible bed bugs, and (ii) evaluate the effects of EO constituent pre-treatment on detoxification enzyme activities of resistant and susceptible populations. Topical bioassays with binary mixtures of deltamethrin and individual EOs (e.g., thyme, oregano, clove, geranium or coriander oils) or their major constituents (e.g., thymol, carvacrol, eugenol, geraniol or linalool) or EcoRaider® at doses that kill approximately 25% of bed bugs caused significant increases in mortality of resistant bed bugs. However, in the susceptible population, only coriander oil, EcoRaider®, thymol, and carvacrol significantly increased the toxicity of deltamethrin. Detoxification enzyme assays with protein extracts from bed bugs pre-treated with EO constituents suggested selective inhibition of cytochrome P450 activity in the resistant population, but no impacts were observed on esterase and glutathione transferase activities in either population. Inhibition of P450 activity by EO constituents thus appears to be one of the mechanisms of deltamethrin toxicity enhancement in resistant bed bugs.

Chemical composition and phytotoxicity of essential oils of Croton doctoris S. Moore (Euphorbiaceae)

Essential oils from the stems and leaves of Croton doctoris were analyzed by gas chromatography and mass spectrometry, resulting in 22 identified compounds. The effects of these essential oils on the germination, root and shoot growth, total chlorophyll content, potential root respiration, peroxidase activity, catalase, superoxide dismutase, and mitotic index in lettuce and onion were determined. Antioxidant, antimicrobial, and cytotoxic activity were also investigated. The results revealed that the stem oil consisted of 15 compounds, of which caryophyllene oxide (24.5%) and E-caryophyllene (13.3%) were the major constituents. The leaf oil contained E-caryophyllene (39.6%) and α-humulene (13.2%) as major compounds. The oils inhibited the germination and growth of lettuce and onion seedlings and reduced chlorophyll content, root respiration, and cell division. They also caused oxidative stress, indicated by the increased activity of the evaluated antioxidant enzymes. These abnormal physiological processes contributed to the inhibition of plant growth. The most pronounced phytotoxic effects were observed in the stem oil. The cytotoxicity tests indicated that leaf oil was more active than stem oil, resulting from the presence of biologically active sesquiterpenes that inhibit the growth of cancer cells.