Chemical characterization and antifungal activity of essential oil of capitula from wild Indian Tagetes patula L

The Impact of Plant Essential Oils on the Growth of the Pathogens Botrytis cinerea, Fusarium solani, and Phytophthora pseudocryptogea

Essential oils (EOs) extracted from aromatic and medicinal plants have the potential to inhibit the growth of various pathogens and, thus, be useful in the control of dangerous diseases. The application of environmentally friendly approaches to protect agricultural and forestry ecosystems from invasive and hazardous species has become more significant in last decades. Therefore, the identification and characterization of essential oils with a strong inhibitory activity against aggressive and widespread pathogens are of key importance in plant protection research. The main purpose of our study is to evaluate the impact of essential oils originating from different genotypes of bee balm, mint, and marigold on Botrytis cinerea, Fusarium solani, and Phytophthora pseudocryptogea. Twelve essential oils, including five EOs originating from Monarda fistulosa, one oil each from Monarda russeliana, Mentha longifolia, Mentha piperita, Tagetes patula, and Tagetes erecta, and two EOs from Tagetes tenuifolia were derived by steam or water distillation. The chemical composition of the tested EOs was determined by GS-MS analyses and their corresponding chemotypes were identified. The most effective against all three pathogens were determined to be the EOs originating from M. fistulosa and M. russeliana. B. cinerea, and P. pseudocryptogea were also significantly affected by the M. piperita essential oil. The most efficient EOs involved in this investigation and their potential to control plant pathogens are discussed.

Preservative effect of gelatin/chitosan-based films incorporated with lemon essential oil on grass carp (Ctenopharyngodon idellus) fillets during storage

The present study investigated the effect of fish gelatin/chitosan-based (FG/CS-based) films incorporated with lemon essential oil (LEO) on grass carp fillets in terms of moisture status, total volatile basic nitrogen (TVB-N), and microbial community succession during chilled (4 °C) and iced (0 °C) storage. Low-field nuclear magnetic resonance (LF-NMR) revealed that the active films remarkably inhibited moisture transformation from being the immobilized to free water in grass carp fillets, accompanied with the reduced T22 relaxation time. Besides, magnetic resonance imaging (MRI) detected a higher density of proton in the treated fish samples, indicating that the active films could improve the water-holding capacity of fish samples. Moreover, high-throughput 16S rRNA sequencing suggested that the FG/CS-based films loaded with LEO efficiently decreased the relative abundance of the bacterial genera Shewanella and Aeromonas in grass carp fillets, with minimal accumulation of TVB-N during storage. Additionally, the low storage temperature (0 °C) could further enhance the preservative effect of the active films on the fish samples, which together prolonged their shelf-life to 18 days. Overall, the combination of the active films and iced storage could provide a promising strategy to preserve grass carp fillets.

Candida albicans Reactive Oxygen Species (ROS)-Dependent Lethality and ROS-Independent Hyphal and Biofilm Inhibition by Eugenol and Citral

Candida albicans is part of the normal human flora but is most frequently isolated as the causative opportunistic pathogen of candidiasis. Plant-based essential oils and their components have been extensively studied as antimicrobials, but their antimicrobial impacts are poorly understood. Phenylpropenoids and monoterpenes, for example, eugenol from clove and citral from lemon grass, are potent antifungals against a wide range of pathogens. We report the cellular response of C. albicans to eugenol and citral, alone and combined, using biochemical and microscopic assays. The MICs of eugenol and citral were 1,000 and 256 μg/mL, respectively, with the two exhibiting additive effects based on a fractional inhibitory concentration index of 0.83 ± 0.14. High concentrations of eugenol caused membrane damage, oxidative stress, vacuole segregation, microtubule dysfunction and cell cycle arrest at the G₁/S phase, and while citral had similar impacts, they were reactive oxygen species (ROS) independent. At sublethal concentrations (1/2 to 1/4 MIC), both oils disrupted microtubules and hyphal and biofilm formation in an ROS-independent manner. While both compounds disrupt the cell membrane, eugenol had a greater impact on membrane dysfunction. This study shows that eugenol and citral can induce vacuole and microtubule dysfunction, along with the inhibition of hyphal and biofilm formation. IMPORTANCE Candida albicans is a normal resident on and in the human body that can cause relatively benign infections. However, when our immune system is severely compromised (e.g., cancer chemotherapy patients) or underdeveloped (e.g., newborns), this fungus can become a deadly pathogen, infecting the bloodstream and organs. Since there are only a few effective antifungal agents that can be used to combat fungal infections, these fungi have been exposed to them over and over again, allowing the fungi to develop resistance. Instead of developing antifungal agents that kill the fungi, some of which have undesirable side effects on the human host, researchers have proposed to target the fungal traits that make the fungus more virulent. Here, we show how two components of plant-based essential oils, eugenol and citral, are effective inhibitors of C. albicans virulence traits.

Changes in Quercetin Derivatives and Antioxidant Activity in Marigold Petals (Tagetes patula L.) Induced by Ultraviolet-B Irradiation and Methyl Jasmonate

Marigold petals contain numerous antioxidative flavonoids and carotenoids that can be affected by environmental stressors. There is yet no detailed study on the relationship between phytochemical accumulation and stressors in marigold petals. This study evaluated quercetin derivatives and antioxidant activity in marigold petals in response to ultraviolet-B (UV-B) irradiation and methyl jasmonate (MeJA) treatment. The limiting UV-B radiation intensity and MeJA dose that caused no wilting damage under 1-h daily treatment for 10 days were <2 W∙m−2∙s−1 and <10 mM, respectively. Marigold petals contained three major flavonoids, quercetin-7-O-glucoside (Q7G, 6.6 mg∙g−1dw), quercetin-3-O-glucoside (Q3G, 62.7 mg), and quercetin (26.6 mg), possessing different antioxidant potential and exhibiting the highest power in quercetin and next value in Q7G. Single UV-B irradiation exerted a limited effect on the changes in the content of the three quercetin derivatives, whereas combined treatment with 1 W UV-B radiation and 5 mM MeJA resulted in the highest total quercetin content, showing >20% increase compared to that without treatment. This increase primarily resulted in an increase in quercetin content. MeJA treatment positively affected the increase in Q3G and Q7G contents in a dose-dependent manner during the 10-d experimental period but exerted no considerable effect on quercetin accumulation. The antioxidant activity was increased when flowers were exposed to mild MeJA treatment of 5−10 mM. UV-B irradiation decreased the antioxidant activity of marigold petals, but this decrease could be compensated by MeJA treatment.

Pesticidal Activity and Mode of Action of Monoterpenes

Synthetic pesticides are often associated with issues such as pest resistance, persistent residue, nontarget toxicity, and environmental issues. Therefore, the research and development of novel, safe, and effective pesticides has become a focus in pesticide discovery. Monoterpenes are secondary plant metabolites that commonly have multiple action targets and have been used in aromatherapy, alternative medicine, and food industries. Some are highly potent and stereoselective. They can potentially be botanical pesticides and serve as lead candidates for the design and synthesis of new monoterpenoid pesticides for agricultural applications. This article reviews publications and patents found in SciFinder Scholar between 2000 and May 2021 on monoterpenes and mainly focuses on pesticidal activities of frequently studied monoterpenes and their modes of action. The presented information and our views are hopefully useful for the development of monoterpenes as biopesticides and monoterpenoid pesticides.

Antimicrobial Potential and Chemical Profiling of Leaves Essential Oil of Mentha Species Growing under North-West Himalaya Conditions

Mentha essential oil is one of the most utilized essential oil in the food and pharmaceutical industries. The present study reports the chemical composition and antibacterial properties of leaf essential oils of Mentha species. Further, the effect of the harvesting period on essential oil yield was also investigated. Firstly, the cultivated Mentha piperita and wild Mentha longifolia, revealed significant differences in their chemical profile. M. longifolia essential oil was characterized with endo-borneol (1.12-6.2%), caryophyllene (2.72-7.03%), isopipertenone (0.07-0.36%), germacrene D (0.98-3.22%), 3-cyclopentene-1-one,2-hydroxy-3-(3-methyl-2-butenyl)- (21.91-56.72%) and piperitone oxide (8.96-39.31%), whereas, M. piperita leaves essential oil was found rich in isomenthone (5.97-6.75%), 1-menthone (7.32-18.32%) and menthol (18.03-58.53%), etc. The essential oils of both Mentha species exhibited strong antimicrobial activity as evaluated using poisoned food technique, dry weight method, and disc diffusion method against Candida albicans, Fusarium oxysporum, Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli. Secondly, the maximum essential oil yield was observed in July month, 0.63±0.01 and 0.56±0.01%, respectively for M. piperita and M. longifolia.

Antifungal Activity of Essential Oils from Three Artemisia Species against Colletotrichum gloeosporioides of Mango

Post-harvest diseases of mango reduce fruit quality and cause severe yield losses with completely unmarketable fruits. The most common diseases of mangos are anthracnose (Colletotrichum gloeosporioides). In this study, the antibacterial activities of essential oils from Artemisia scoparia, Artemisia lavandulaefolia, and Artemisia annua against C. gloeosporioides were tested. The results showed that the essential oil of A. scoparia was more effective by the agar diffusion method; the EC₅₀ value was 9.32 µL/mL. The inhibition rate was 100%, at a concentration of 10 μL/mL, through the spore germination method. The morphological changes of the mycelium were observed by scanning electron microscopy (SEM), the mycelia treated with essential oils showed shrinking, deformity, fracture, and dryness through SEM. A. scoparia essential oil was inoculated in vivo and subjected to paroxysm testing under natural conditions. A. scoparia had significantly inhibitory activity, and the inhibition rate was 66.23% in vivo inoculation tests after 10 days. The inhibition rate was 92.06% in the paroxysm test under natural conditions after 15 days. Finally, A. acoparia essential oil was analyzed by gas chromatography-mass spectrometry. The main compounds were 2-ethenyl-Naphthalene (23.5%), 2,4-pentadiynyl-Benzene (11.8%), 1,2-dimethoxy-4-(2-propenyl)-Benzene (10.0%), β-Pinene (8.0%), and 1-methyl-4-(1-methylethyl)-1,4-Cyclohexadiene (6.3%). The results have revealed the potential use of A. scoparia essential oil against post-harvest fungal pathogens C. gloeosporioides.

Raw and Fermented Alfalfa Brown Juice Induces Changes in the Germination and Development of French Marigold (Tagetes patula L.) Plants

Organic and ecological farming programs require new and efficient biostimulants with beneficial properties for the sustainable and safe production of seedlings and ornamental plants. We examined the effect of non-fermented and lacto-fermented alfalfa brown juice (BJ) on seed germination and the vegetative, physiological, and anatomical properties of French marigold (Tagetes patula L. 'Csemő') plants which were treated with 0.5-10% fermented and non-fermented BJ, with tap water applied as a control. Applying 0.5% fermented BJ significantly improved seed germination compared with non-fermented BJ, resulting in an increase of 9.6, 11.2, 10.9, and 41.7% in the final germination percent, germination rate index, germination index, and vigor index, respectively. In addition, it increased the root and shoot length by 7.9 and 16.1%, respectively, root and shoot dry mass by 20 and 47.6%, respectively, and the number of leaves by 28.8% compared to the control. Furthermore, an increase in contents of water-soluble phenol, chlorophyll a and b, and carotenoid was reported upon the application of 0.5% fermented BJ, while peroxidase activity decreased. Our results prove that alfalfa BJ can be enrolled as a biostimulant as part of the circular farming approach which supports the sustainable horticultural practice.

Evaluation of Seven Essential Oils as Seed Treatments against Seedborne Fungal Pathogens of Cucurbita maxima

Essential oils are gaining interest as environmentally friendly alternatives to synthetic fungicides for management of seedborne pathogens. Here, seven essential oils were initially tested in vivo for disinfection of squash seeds (Cucurbita maxima) naturally contaminated by Stagonosporopsis cucurbitacearum, Alternaria alternata, Fusarium fujikuro, Fusarium solani, Paramyrothecium roridum, Albifimbria verrucaria, Curvularia spicifera, and Rhizopus stolonifer. The seeds were treated with essential oils from Cymbopogon citratus, Lavandula dentata, Lavandula hybrida, Melaleuca alternifolia, Laurus nobilis, and Origanum majorana (#1 and #2). Incidence of S. cucurbitacearum was reduced, representing a range between 67.0% in L. nobilis to 84.4% in O. majorana #2. Treatments at 0.5 mg/mL essential oils did not affect seed germination, although radicles were shorter than controls, except with C. citratus and O. majorana #1 essential oils. Four days after seeding, seedling emergence was 20%, 30%, and 10% for control seeds and seeds treated with C. citratus essential oil (0.5 mg/mL) and fungicides (25 g/L difenoconazole plus 25 g/L fludioxonil). S. cucurbitacearum incidence was reduced by ~40% for plantlets from seeds treated with C. citratus essential oil. These data show the effectiveness of this essential oil to control the transmission of S. cucurbitacearum from seeds to plantlets, and thus define their potential use for seed decontamination in integrated pest management and organic agriculture.

Antineoplastic potential and chemical evaluation of essential oils from leaves and flowers of Tagetes ostenii Hicken

Breast and cervical cancer represent a major problem of women's global public health. Here, we investigated the chemical composition of essential oils from leaves and flowers of T. ostenii and the antineoplastic potential in a cervical cancer and breast cancer cell line, SiHa and MCF-7; and non-tumoral cells, HaCat. The chemical analysis revealed a predominance of oxygenated monoterpenes in both essential oils. The IC50 after 24 h of treatment was 72 ng/mL for EO 1 and 83 ng/mL for EO 2 in SiHa cells. For MCF-7 the IC50 was 174.3 ng/mL for EO 1. For HaCat cells it was 54.45 ng/mL for EO 1 and 20.83 ng/mL for EO 2. A synergistic effect with both essential oils and cisplatin was also verified. SiHa cells had their wound healing capacity reduced after 48 h of treatment with EO 2 and both essential oils were able to significantly inhibit the adhesion process and clonogenic ability after 24 h of treatment. Our results suggest a long-lasting inhibitory activity in SiHa cells because of the low recovery capacity of cells after treatment withdrawal. Flow cytometer with annexin V/propidium iodide demonstrated a majority cell death through late apoptosis after 24, 48 and 72 hours of treatment.

Actividad anti-proliferativa de Aloysia sonorensis sobre líneas celulares de cáncer

Aloysia sonorensis, planta perene de la costa sur de Sonora, México, conocida como “Mariola”, ha sido utilizada para el tratamiento de enfermedades como resfriado, fiebre y dolor de estómago. Además, algunas especies del género Aloysia han mostrado actividad antiproliferativa contra líneas celulares cancerosas. Debido a ésto, el objetivo del presente trabajo fue determinar la actividad antiproliferativa de Aloysia sonorensis contra líneas celulares cancerosas e identificar los compuestos responsables de esta actividad. Las partes aéreas de la planta se extrajeron con metanol, el cual fue fraccionado con solventes orgánicos. Se determinó la actividad antiproliferativa del extracto metanólico, y sus fracciones, contra diferentes líneas celulares cancerosas, usando el método del MTT. La subfracción FH12 mostró citotoxicidad selectiva con valores de IC50 de 2.84 y 12.12 µg/mL contra las líneas celulares cancerosas RAW 264.7 y HeLa, respectivamente. La subfracción FH22 mostró valores de IC50 de 6.32 y 13.87 µg/mL contra las líneas celulares cancerosas M12.C3.F6 y HeLa, respectivamente. La fracción FAc1 mostró valores de IC50 de 9.42 y 8.93 µg/mL contra las líneas celulares cancerosas RAW 264.7 y M12.C3.F6, respectivamente. Se determinó la presencia del monoterpeno Piperitenona durante el proceso de fraccionamiento biodirigido.

Traditional uses, Phyto-chemistry and pharmacological activities of Tagetes Patula L

ETHNO-PHARMACOLOGICAL RELEVANCE

Tagetes patula L. an important medicinal plant of Asteraceae family is worldwide distributed and reported for its folkloric use in various disorders like skin, eye problems, injury and stomach issues by different communities of China, Nepal, India, Bangladesh and Pakistan.

AIM OF THIS REVIEW

The present review has focused the ethnomedicinal and traditional uses of T. patula with special reference to Asian countries. Chemical constituents and pharmacological aspects of T. patula was explored. After reading the review the researchers may able to find new insights to further investigate this plant.

REVISION OF LITERATURE

Google scholar, PubMed, and Science direct, were the major search engines used to get relevant information based on articles and books.

RESULTS

and Discussion: The ethno-botanical aspects were recorded, the pharmacological aspects like antioxidant, anti-inflammatory, antimicrobial, anti-parasitic and anti-diabetic potentials evaluated both in vivo and in vitro is described. The toxicity or allergic manifestation with the use of the plant is also a section in the article. It is a rich source for thiophene derivatives, flavonoids, carotenoids, terpenes and terpenoids. Various gaps were pointed out for researchers that need to be investigated.

CONCLUSION

Various traditional uses have been reported in Asian countries that need to be scientifically investigated in depth and several pharmacological activities have been reported for the T. patula but more detailed and mechanism-based studies linked to a particular lead compound need to be targeted in future.

Limonene, a Chemical Compound Related to the Resistance of Eucalyptus Species to Austropuccinia psidii

The fungus Austropuccinia psidii is a major pathogen of Eucalyptus spp. that damages mainly early-stage leaves. Resistant clones are the most widely used control measure for the rust disease caused by A. psidii. Essential oils produced in the plant-host cells are associated with resistance. However, the chemical characteristics of Eucalyptus leaves at different stages of maturity, associated with resistance or susceptibility to A. psidii, need to be determined. The aims of this study were to characterize the chemical composition of essential oils in Eucalyptus leaves at three developmental stages of clones of three E. urophylla × E. grandis hybrids that exhibit different resistance levels to rust and to identify probable resistance-related compounds from them. The rust severity following inoculation and the quantity and quality of the essential oil extracted by hydrodistillation were determined at the first, third, and fifth leaf stages of the three clones. Identification of the compounds present in the essential oil was determined by gas chromatography coupled with mass spectrometry. No rust was observed on the three leaf stages of the resistant clone or on the fifth leaf stage of the susceptible clones. Limonene was found at high percentages in essential oils from the three leaf stages of the resistant clone and at low percentages in the susceptible clones. In vitro and in vivo tests indicated that low limonene percentages stimulated A. psidii urediniospore germination and were not fungitoxic, whereas high percentages caused complete inhibition of germination and degenerative changes in fungal reproductive structures. The limonene present in Eucalyptus leaves can be considered a chemical compound related to the rust resistance of Eucalyptus spp.

Antibacterial activity of Litsea cubeba essential oil and its mechanism against Botrytis cinerea

Litsea cubeba essential oil (LCEO) extracted from the fruit of the Litsea tree is a broad-spectrum bacteriostatic agent that has been used to treat ailments for thousands of years in China. The objective of our study was to assess the inhibitory effect of LCEO on Botrytis cinerea, a fungus that causes the putrification of fruits and vegetables. After being treated with 1.0% LCEO, the electrical conductivity of the fungal cells increased, and the contents of soluble reducing sugars and proteins slowly increased over treatment time. After being treated for 48 h with 1.0% LCEO, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images clearly showed damage to hyphae cells when compared with the normal growth of the control groups. Additional studies showed that the ergosterol content in the cell membrane significantly decreased with an increase in the LCEO concentration, and the electrophoretic bands of the proteins assayed using the sodium dodecyl sulfate-polyacrylamide gel electrophoresis method significantly changed at different LCEO concentrations. LCEO damaged the cell membrane and changed the cell membrane permeability, leading to the changes in some components in the cytoplasm, such as soluble reducing sugars, proteins, and ergosterol. In general, the antimicrobial activity of LCEO is attributable to a unique pathway and involves a series of events both on the surface and within the cytoplasm of the fungal cell.

Tagetes spp. Essential Oils and Other Extracts: Chemical Characterization and Biological Activity

Tagetes (marigold) is native to America, and its cultivation currently extends to other countries in Africa, Asia, and Europe. Many species of this genus, such as T. minuta, T. erecta, T. patula, and T. tenuifolia, are cultivated as ornamental plants and studied for their medicinal properties on the basis of their use in folk medicine. Different parts of the Tagetes species are used as remedies to treat various health problems, including dental, stomach, intestinal, emotional, and nervous disorders, as well as muscular pain, across the world. Furthermore, these plants are studied in the field of agriculture for their fungicidal, bactericidal, and insecticidal activities. The phytochemical composition of the extracts of different Tagetes species parts are reported in this work. These compounds exhibit antioxidant, antiinflammatory, and enzyme inhibitory properties. Cultivation and the factors affecting the chemical composition of Tagetes species are also covered. In the current work, available literature on Tagetes species in traditional medicine, their application as a food preservative, and their antimicrobial activities are reviewed.

Surface characterisation and reaction kinetics of silver nanoparticles mediated by the leaf and flower extracts of French marigold (Tagetes patula)

In this study, French marigold's leaf and flower were used for the synthesis of silver nanoparticles (SNPs) in order to explore their potentials towards bioreduction of Ag⁺ to Agᵒ. The as-synthesised SNPs were characterised using UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction, transmission electron microscopy, and zeta-potential analysis. The results obtained showed that the particles are polydispersed with sizes in the range 15.8-42.8 nm. The bioreduction was believed to be due to the amides, aldehyde functional groups, and essential oils present in the extracts as confirmed by the FTIR analysis. The growth mechanism involved in the reaction was studied which revealed oriented attachment (OA) onwards Ostwald ripening in the case of the flower-mediated synthesis and typical OA in the leaf-mediated synthesis. The studied kinetics of the particle formation showed that the reaction is possibly a pseudo-first-order reaction with some diffusion-controlled mechanism which is driven by high surface area to volume ratio in both the leaf- and flower-mediated synthesis.

Biological activity of Cymbopogon schoenanthus essential oil

INTRODUCTION

A number of plant species, including Cymbopogon schoenanthus, are traditionally used for the treatment of various diseases. C. schoenanthus is currently, traded in the Saudi markets, and thought to have medicinal value. This study aimed at investigating the biological activities of C. schoenanthus against both Gram-positive and Gram-negative bacteria and to identify its chemical ingredients.

MATERIALS AND METHODS

The inhibitory effects of water extracts of C. schoenanthus essential oils were evaluated against ten isolates of both Gram-positive and Gram-negative bacteria using the agar well diffusion and dilution methods. The minimum inhibitory concentration (MIC) was assayed using the Broth microdilution test on five of the ten isolates. The death rates were determined by the time kill assay, done according to the Clinical Laboratory Standards Institute (CLSI) guidelines. The chemical composition of the essential oils of the plant was performed using GC/MS.

RESULTS

The C. schoenanthus essential oil was effective against Escherichia coli, Staphylococcus aureus, methicillin-sensitive (MSSA) S. aureus (MRSA) and Klebsiella pneumoniae. The essential oil was not effective against Staphylococcus saprophyticus at the highest concentration applied of >150 μg/ml. The MIC values were as follows: 9.37 μg/ml for E. coli 4.69 μg/ml for S. aureus (MRSA), 2.34 mg/ml for MSSA and 2.34 μg/ml for K. pneumoniae. The time-kill assay indicated that there was a sharp time dependent decline in K. pneumoniae counts in the presence of the oil. This is in contrast to a gradual decline in the case of S. aureus under the same conditions. The eight major components of the essential oil were: piperitone (14.6%), cyclohexanemethanol (11.6%), β-elemene (11.6%), α-eudesmol (11.5%), elemol (10.8%), β-eudesmol (8.5%), 2-naphthalenemethanol (7.1%) and γ-eudesmol (4.2%).

CONCLUSION

The results of the present study provide a scientific validation for the traditional use of C. schoenanthus as an antibacterial agent. Future work is needed to investigate and explore its application in the environmental and medical fields. In addition, to evaluating the efficacy of the individual ingredients separately to better understand the underlying mechanism.

Activity of Tagetes minuta Linnaeus (Asteraceae) essential oil against L3 Anisakis larvae type 1

OBJECTIVE

To evaluate in vitro effects of Tagetes minuta L. essential oil (TEO) on L3 Anisakis larvae type 1.

METHODS

In order to evaluate the potential use of Tagetes minuta essential oil against L3 Anisakis larvae three different media were tested: 1) a saline solution (SS); 2) an industrial marinating solution (MS); 3) sunflower seeds oil (SO). For each media and concentrations of TEO (0.1%, 0.5%, 1.0% and 5.0% v/v), 20 parasites were introduced into plastic Petri dishes (diameter 90 mm) and maintained at room temperature. As controls, larvae were maintained without TEO under identical experimental conditions in SS, MS and SO. A total of 900 larvae were tested. The normalized mean viability, LT100, LT50 and the percentage of inactivation at 24 h were calculated.

RESULTS

In vitro tests revealed a complete inactivation of parasites in saline solution after 2 h with 5% and 1% of TEO. In marinating solution, a complete inactivation of parasites was observed after 4 h at all concentrations used. A slower activity for all TEO concentration was reported in SO.

CONCLUSIONS

The results obtained, showing a strong activity against Anisakis larvae, confirm TEO as a larvicidal agent in the treatment of human anisakidosis and in the industrial marinating process.

Effects and possible mechanism of tea tree oil against Botrytis cinerea and Penicillium expansum in vitro and in vivo test

The purpose of this study was to investigate the antifungal activities and possible mechanisms of tea tree oil (TTO) against Botrytis cinerea and Penicillium expansum in vitro and in vivo. The results show that TTO exhibits dose-dependent antifungal activity against both pathogens, but P. expansum is less sensitive than B. cinerea to TTO not only in the in vitro test but also in artificially inoculated cherry fruits. TTO vapor treatment reduced the decay caused by these pathogens in inoculated cherry fruits, but the effect on P. expansum was less than that on B. cinerea. While the total lipid and ergosterol contents of the cell membrane are greater in P. expansum than in B. cinerea, TTO treatment lowers the total lipid content in the membranes of both species by well over 50%, and ergosterol content is reduced to a greater extent in B. cinerea than in P. expansum. In both pathogens, TTO alters mycelial morphology and cellular ultrastructure. Oxygen consumption measurements show that TTO inhibits respiratory metabolism via the tricarboxylic acid cycle pathway in both pathogens, though more severely in B. cinerea than in P. expansum. The relatively decreased sensitivity of P. expansum to TTO may be due to the fact that TTO causes less disruption of the cell membrane in this organism, and higher inhibition the respiratory metabolism to the extent observed in B. cinerea.

Chemical Composition and Biting Deterrent Activity of Essential Oil of Tagetes patula (Marigold) against Aedes aegypti

The hydrodistilled leaf essential oil (EO) of Tagetes patula L. was analyzed by GC-FID and GC-MS. The main components of the oil were characterized as caryophyllene oxide (18.4%), β-caryophyllene (18.0%) and spathulenol (9.1%). The EO was screened for its biting deterrent activity against Aedes aegypti L. using the in vitro K&D module system. T. patula EO exhibited good biting deterrent activity. The results suggest that these sesquiterpenes may contribute to biting deterrent activity, but the role of minor components cannot be excluded. T. patula EO also showed 100, 90 and 10% mortality at dosages of 125, 62.5 and 31.25 ppm, respectively, in 1-day-old larvae of Ae. aegypti.

Solidago canadensis L. Essential Oil Vapor Effectively Inhibits Botrytis cinerea Growth and Preserves Postharvest Quality of Strawberry as a Food Model System

This study investigated the anti-fungal properties of Solidago canadensis L. essential oil (SCLEO) against Botrytis cinerea in vitro, and its ability to control gray mold and maintain quality in strawberry fruits. SCLEO exhibited dose-dependent antifungal activity against B. cinerea and profoundly altered mycelial morphology, cellular ultrastructure, and membrane permeability as evaluated by scanning electron microscopy, transmission electron microscopy, and fluorescence microscopy. SCLEO vapor at 0.1 mL/L maintained higher sensory acceptance and reduced decay of fresh strawberry fruit, and also reduced gray mold in artificially inoculated fruit. SCLEO treatment did not, however, stimulate phenylalanin ammonia-lyase, polyphenol oxidase, or chitinase, enzymes related to disease resistance. This suggests that SCLEO reduces gray mold by direct inhibition of pathogen growth. SCLEO vapor may provide a new and effective strategy for controlling postharvest disease and maintaining quality in strawberries.

Efficacy of Mentha spicata essential oil in suppression of Aspergillus flavus and aflatoxin contamination in chickpea with particular emphasis to mode of antifungal action

The present study reports in vivo antifungal and antiaflatoxigenic efficacy of Mentha spicata essential oil (EO) against toxigenic Aspergillus flavus strain LHP(C)-D6 in chickpea food system up to 12 months of storage. In addition, the mode of antifungal action of EO was also determined to understand the mechanism of fungal growth inhibition. The in vivo study with different concentrations of M. spicata EO showed dose-dependent decrease in fungal colony count as well as aflatoxin B1 concentration. The EO caused >50% protection in inoculated sets and >70% protection in uninoculated sets of chickpea food system against A. flavus at 1.0 μL mL(-1) air concentration. However, at the same concentration, EO caused 100% inhibition to aflatoxin B1 production in both sets when analyzed through high-performance liquid chromatography (HPLC). The antifungal target of EO in fumigated cells of A. flavus was found to be the plasma membrane when analyzed through electron microscopic observations and ions leakage test. The EO fumigated chickpea seeds showed 100% seed germination and seedling growth after 12 months of storage. Based on these observations, M. spicata EO can be recommended as plant-based preservative for safe protection of food commodities during storage conditions against fungal and most importantly mycotoxin contaminations.

Antifungal, antiradical and cytotoxic activities of extractives obtained from Tagetes patula L. (Asteraceae), a potential acaricide plant species

Tagetes patula L. shows a complex chemical composition, ranging from glycosylated flavonoids and thiophenes in extracts until terpenoids in the essential oil. In the present study, due to this rich flavonoidic constitution, its antioxidant potential was determined, having shown values of antiradical percentage superior to reference compounds, mainly the extracts prepared with flowers. Previous studies performed emphasized the acaricide potential of T. patula and thus, the present study aimed to verify the action of extractives obtained from aerial parts on growth of entomopathogenic fungi related to biological control of brown dog tick Rhipicephalus sanguineus and the action against pathogenic fungi closely associated with pets. None of the samples inhibited the growth of strains of Beauveria bassiana or Metarhizium anisopliae, enabling feasible future studies of synergism on acaricide activity of formulations containing fungi and extracts. The antimicrobial activity of ethanolic extract of flowers (FlEtOH70%) against Microsporum canis and Trichophyton rubrum was significant (193.3 μg/mL and 253.9 μg/mL, respectively), as well as ethanolic extract from aerial parts (APEtOH70%) against T. rubrum (312.5 μg/mL). In order to ensure the safety of a topical formulation containing the extractives of T. patula, the cytotoxic potential of these samples were tested in murine macrophages cells. At higher concentrations all extracts were quite lethal, with IC50 ranging from 210.96 μg/mL to 468.75 μg/mL for APEtOH70% and FlEtOH70%, respectively. These results suggest that the application of a product containing T. patula extractives in the control of ticks could be used, at principle, only on the environment.

Influence of α-terpineol on the growth and morphogenesis of Penicillium digitatum

BACKGROUND

Plant essential oils could act effectively against postharvest diseases, α-terpineol, a typical terpenoid of plant essential oils, exhibited strong antifungal activity in against Penicillium italicum, but the possible action mechanism remains undetermined. In present study, α-terpineol was evaluated for antibacterial activity against Penicillium digitatum along with the mode of their antibacterial action.

RESULTS

The results showed that mycelial growth of P. digitatum was strongly inhibited by α-terpineol, with the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of 2.00 and 8.00 µl/ml, respectively. Scanning electron microscopy observation revealed that α-terpineol obviously altered the morphology of P. digitatum hyphae by causing the loss of cytoplasm and distortion of mycelia. A rapid increase in the membrane permeability of P. digitatum was observed after treated with MIC or MFC of α-terpineol, evidenced by the release of cell constituents, the extracellular conductivity, and the extracellular pH. In addition, α-terpineol apparently induced a decrease in total lipid contents of P. digitatum cells, indicating the destruction of cell membrane structures after treatment.

CONCLUSIONS

Based on our study, α-terpineol might affect the cell wall synthesis and lead to the disruption of cell wall. The cell wall disruption affected fungal morphogenesis, the integrity of membrane and leakage of intracellular components, these results suggested that α-terpineol treatment inhibited the growth of P. digitatum.

Antifungal modes of action of tea tree oil and its two characteristic components against Botrytis cinerea

AIMS

The essential oil of Melaleuca alternifolia (tea tree) has been evaluated as a potential eco-friendly antifungal agent against Botrytis cinerea. In this study, we investigated the antifungal activity and mode of action of tea tree oil (TTO) and its components against B. cinerea.

METHODS AND RESULTS

Of the components we tested in contact phase, terpinen-4-ol had the highest antifungal activity, followed by TTO, α-terpineol, terpinolene, then 1,8-cineole. As one of characteristic components of TTO, terpinen-4-ol treatment led to pronounced alterations in mycelial morphology, cellular ultrastructure, membrane permeability under scanning electron microscope, transmission electron microscope and fluorescent microscope, and also reduced the ergosterol content of fungi. As another characteristic component, 1,8-cineole caused serious intracellular damage but only slightly affected B. cinerea otherwise. When terpinen-4-ol and 1,8-cineole were used together, the synergistic antifungal activity was significantly higher than either component by itself.

CONCLUSIONS

The results of our study confirmed that terpinen-4-ol and 1,8-cineole act mainly on the cell membranes and organelles of B. cinerea, respectively, and when combined are similar to TTO in antifungal activity due to their differences.

SIGNIFICANCE AND IMPACT OF THE STUDY

Understanding the mechanism of terpinen-4-ol and 1,8-cineole antifungal action to B. cinerea is helpful for investigation on their synergistic effect and explaining antifungal action modes of TTO.

A Multi-Target Approach toward the Development of Novel Candidates for Antidermatophytic Activity: Ultrastructural Evidence on α-Bisabolol-Treated Microsporum gypseum

Multi-target strategies are directed toward targets that are unrelated (or distantly related) and can create opportunities to address different pathologies. The antidermatophytic activities of nine natural skin lighteners: α-bisabolol, kojic acid, β-arbutin, azelaic acid, hydroquinone, nicotinamide, glycine, glutathione and ascorbyl tetraisopalmitate, were evaluated, in comparison with the known antifungal drug fluconazole, on nine dermatophytes responsible for the most common dermatomycoses: Microsporum gypseum, Microsporum canis, Trichophyton violaceum, Nannizzia cajetani, Trichophyton mentagrophytes, Epidermophyton floccosum, Arthroderma gypseum, Trichophyton rubrum and Trichophyton tonsurans. α-Bisabolol showed the best antifungal activity against all fungi and in particular; against M. gypseum. Further investigations were conducted on this fungus to evaluate the inhibition of spore germination and morphological changes induced by α-bisabolol by TEM.

Volatile Constituents of the Fruit and Roots of Cymbopogon olivieri

The essential oil contents of the fruit and roots of Cymbopogon olivieri growing wild in south of Iran were found to be 0.7 % and 0.4% (v/w), respectively based on the fresh weight. The oils were analyzed by GC and GC–MS. Forty and twenty six constituents, representing 93.1 % and 93.4% of the oils were identified, respectively. The major components of the C. olivieri fruit oil were identified as piperitone (44.1%), α-terpinene (13.7%), neral (6.3%), elemol (5.6%) and β-eudesmol (5.3%). while the main components of that of roots were characterized as piperitone (20.6%), α-muurolol (9.5%), β-eudesmol (8.5%), selina-6-en-4-ol (7.9%), 5-epi-7-epi-α-eudesmol (6.8%) and elemol (5.8%).

Citral exerts its antifungal activity against Penicillium digitatum by affecting the mitochondrial morphology and function

This work investigated the effect of citral on the mitochondrial morphology and function of Penicillium digitatum. Citral at concentrations of 2.0 or 4.0 μL/mL strongly damaged mitochondria of test pathogen by causing the loss of matrix and increase of irregular mitochondria. The deformation extent of the mitochondria of P. digitatum enhanced with increasing concentrations of citral, as evidenced by a decrease in intracellular ATP content and an increase in extracellular ATP content of P. digitatum cells. Oxygen consumption showed that citral resulted in an inhibition in the tricarboxylic acid cycle (TCA) pathway of P. digitatum cells, induced a decrease in activities of citrate synthetase, isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, succinodehydrogenase and the content of citric acid, while enhancing the activity of malic dehydrogenase in P. digitatum cells. Our present results indicated that citral could damage the mitochondrial membrane permeability and disrupt the TCA pathway of P. digitatum.

Plant essential oils as active antimicrobial agents

Essential oils derived from plants have been recognized for decades to exhibit biological activities, including antioxidant, anticancer, and antimicrobial attributes. Antimicrobial activities of these natural plant materials have been intensively explored in recent years, mainly in response to the overwhelming concern of consumers over the safety of synthetic food additives. Gram-negative organisms are believed to be slightly less sensitive to essential oils than Gram-positive bacteria. Generally, a higher concentration is required to obtain the same efficacy in foods than in synthetic media. The combinations of different types of essential oils or with other food additives have been found to potentially exhibit synergistic if not additive effects. This suggests a cost-efficient and wholesome alternative to both food industry and consumers, at the same time adhering to the hurdle technology in inhibiting proliferation of foodborne pathogens. This review aims to examine the conventional methods commonly used for assessment of antimicrobial activities of essential oils and phytochemicals, the use of these substances as antimicrobials in food products, factors that affect their efficacy, synergism between components or with available food preservatives as well as the challenges and future directions of using essential oils and phytochemicals as natural food preservatives.

Fumigant antifungal activity of Corymbia citriodora and Cymbopogon nardus essential oils and citronellal against three fungal species

Corymbia citriodora and Cymbopogon nardus essential oils samples were analyzed by GC and GC-MS and their qualitative and quantitative compositions established. The main component of essential oils of C. citriodora and C. nardus was citronellal, at 61.78% and 36.6%, respectively. The essential oils and citronellal were tested for their fumigant antifungal activity against Pyricularia (Magnaporthe) grisea, Aspergillus spp., and Colletotrichum musae. The minimum inhibitory concentration (MIC) ranged from 100 to 200 ppm for the essential oils and 25 to 50 mg · mL(-1) for citronellal. The contact assay using the essential oils and citronellal showed growth inhibition of the three fungal species. However, a concentration of 1.47 mg · mL(-1) only reduced the inhibition of Aspergillus growth to 90% at 14 days of exposure. For the fumigant assay, 0.05, 0.11, and 0.23 mg · mL(-1) of essential oils and citronellal drastically affected growth of P. grisea, Aspergillus spp., and C. musae. Harmful effects on the sporulation and germination of the three fungi were seen, and there was complete inhibition at 0.15 mg · mL(-1) with both oils and citronellal. This showed that the crude component of essential oils of C. citriodora and C. nardus markedly suppressed spore production, germination, and growth inhibition of P. grisea, Aspergillus spp., and Colletotrichum musae.

The possible mechanism of antifungal action of tea tree oil on Botrytis cinerea

AIMS

Tea tree oil (TTO) has been confirmed in previous study as a potential natural antifungal agent to control Botrytis cinerea and grey mould in fresh fruit. However, the mechanism of its action has not been clearly revealed, and some hypotheses mainly depended on the results obtained from the bacterial test. For the antifungal mechanism, the effect of TTO on the mycelium morphology and ultrastructure, cell wall and membrane, and membrane fatty acid composition of B. cinerea was investigated in vitro experiments.

METHODS AND RESULTS

Tea tree oil in vapour or contact phase exhibited higher activity against the mycelial growth of B. cinerea. Observations using scanning electron microscope and transmission electron microscope revealed that the mycelial morphology and ultrastructure alternations caused by TTO are the markedly shriveled or flatted empty hyphae, with thick cell walls, ruptured plasmalemma and cytoplasmic coagulation or leakage. Furthermore, TTO caused significantly higher alkaline phosphatase activity after 4-h treatment and markedly higher absorbance at 260 nm and electric conductivity in the external hyphae of fungi after 16-h treatment. Moreover, decreased unsaturated/saturated fatty acid ratio of the fungal membrane was also observed after TTO treatment.

CONCLUSIONS

The methodology used in this study confirmed that the cell wall destroyed firstly in the presence of TTO, and then the membrane fatty acid composition changed, which resulted in the increasing of membrane permeability and releasing of cellular material. The above findings may be the main reason for TTO's antifungal ability to B. cinerea.

SIGNIFICANCE AND IMPACT OF THE STUDY

Understanding the mechanism of TTO antifungal action to B. cinerea is helpful for its commercial application on the preservation of fresh fruit and vegetables.

Chemical characterization and acaricide potential of essential oil from aerial parts of Tagetes patula L. (Asteraceae) against engorged adult females of Rhipicephalus sanguineus (Latreille, 1806)

Rhipicephalus sanguineus, commonly known as the brown dog tick, is one of the most widely distributed species of tick. In dogs, it can cause anemia and provide the transmission of pathogenic microorganisms such as Babesia canis, Ehrlichia canis, Hepatozoon canis, Anaplasma platys, and Mycoplasma haemocanis. To man, it can transmit the intracellular parasites Rickettsia rickettsii and Rickettsia conorii, the causative agents of the Rocky Mountain spotted fever in the Americas and Mediterranean and spotted fever in Europe and North Africa. Its control is performed by applying synthetic formulations composed of pyrethroids; however, continued use of these products results in environmental damage and acquisition of resistance. Alternatively, studies with botanical insecticides have been increasingly recurrent. Therefore, this study aimed to test the efficacy of essential oil of Tagetes patula, a ruderal species widely described in the literature for its insecticidal properties, in engorged females of R. sanguineus by the adults immersion test (AIT) and impregnated paper disk test (IPDT). The essential oil used, through gas chromatography coupled to mass spectrometry, revealed the presence of 55 compounds, being the 4-vinyl guaiacol and gamma terpinene the majority ones. The AIT compared to the IPDT was more efficient in inhibiting oviposition of tick; however, the eggs laid by the females submitted to saturated atmosphere with essential oil, from IPDT, not hatched, interrupted their development cycle. Besides being a pioneer work, the results presented here contributes to new researches, aiming the incorporation of essential oil in an acaricide for use in the environment.

In vitro antifungal activity of dehydrozingerone and its fungitoxic properties

The efficacy of Dehydrozingerone (DZ; dehydroderivative of zingerone) as an antifungal agent and its mode of action against food spoilage fungal pathogens was studied and presented. DZ is a constituent of ginger (Zingiber officinale rhizomes) and structural half analogue of curcumin. Its efficacy against Aspergillus oryzae, Aspergillus flavus, Aspergillus niger, Aspergillus ochraceus, Fusarium oxysporum and Penicillium chrysogenum was evaluated. Effect of DZ on the growth and sporulation of A. ochraceus was also studied. The fungal species were susceptible to DZ and the minimum inhibitory concentration and fungicidal concentration ranged from 755 to 911 μM and 880 to 1041 μM respectively. The mycelial and spore germination was significantly inhibited; reduction in the weight of the cell mass, carbohydrate, protein, DNA and RNA constituents in the cells isolated from cultures of A. ochraceus grown with DZ were observed. Scanning electron microscopy studies revealed morphological observations such as cell lysis, inhibition and morphological alterations in hyphae and sporulation in A. ochraceus on treatment with DZ.

PRACTICAL APPLICATION

Current investigations revealed that DZ is a potential antifungal agent and can find application as an additive or adjuvant in food and pharmaceutical industries after appropriate toxicological studies.