Insecticidal activity and the mechanism of action of three phenylpropanoids isolated from the roots of Piper sarmentosum Roxb

Volatilomics of Capsicum pubescens Plants Infested by Solenopsis geminata: Unraveling the Role of Oleic and Palmitic Acids in Plant-Fire Ant Interaction

Solenopsis geminata is an aggressive pest of manzano pepper (Capsicum pubescens) crops. Herein, we report on the volatilomics profiling of manzano pepper plants obtained during S. geminata infestation by solid-phase microextraction coupled with gas chromatography-mass spectrometry. As a result, 68 volatile organic compounds were identified from ants, non-infested plants, and infested plants, including terpenes, esters, steroids, aldehydes, phenylpropanoids, and fatty acids. As a remarkable finding, oleic and palmitic acids were the main compounds released during ant infestation. These fatty acids were evaluated as biocidal or repellent agents under in vitro and in situ conditions. From these experiments, the biocidal effect of palmitic acid was more potent (median lethal dose [LC50], 0.97 mg/cm2) than that of oleic acid (LC50, 5.03 mg/cm2) on S. geminata workers. Nevertheless, only oleic acid had a repellent effect under in situ conditions (p < 0.01). Our results represent new insights into the role of both fatty acids in manzano pepper defense mechanisms.

Insecticidal and Repellent Activity of Piper crassinervium Essential Oil and Its Pure Compounds Against Imported Fire Ants (Hymenoptera: Formicidae)

Piper crassinervium Kunth (Piperaceae) essential oil (EO) was evaluated for its toxicity and repellency against red imported fire ants (RIFA), Solenopsis invicta Buren, and a hybrid (HIFA) of red (S. invicta) and black (S. richteri Forel) imported fire ants. Through bioactivity-guided fractionation, two major components, elemicin and myristicin, were isolated from the EO. Removal of treated sand in a digging bioassay was used as the criterion for repellency. The EO showed significantly higher repellency at concentrations of 7.8 µg/g against RIFA and HIFA workers, as compared to the DEET (N,N-diethyl-meta-toluamide) or ethanol control. Elemicin exhibited repellency at 3.9 and 7.8 µg/g against RIFA and HIFA workers, respectively, whereas myristicin was active at 7.8 µg/g against both species. DEET failed at 31.25 µg/g against RIFA and 15.6 µg/g against HIFA. The EO showed LC50 values of 97.9 and 73.7 µg/g against RIFA and HIFA workers, respectively. Myristicin was more toxic against RIFA and HIFA with LC50 values of 54.3 and 35.3 µg/g, respectively. Elemicin showed 20-40% mortality at the highest screening dose of 125 µg/g. Fipronil exhibited the highest toxicity against RIFA and HIFA, with LC50 of 0.43 and 0.51 µg/g, respectively. Different formulations of these natural products should be evaluated to explore their use potential under natural field conditions.

Comparative metabolite analysis of Piper sarmentosum organs approached by LC-MS-based metabolic profiling

Piper sarmentosum Roxb. (Piperaceae) is a traditional medicinal and food plant widely distributed in the tropical and subtropical regions of Asia, offering both health and culinary benefits. In this study the secondary metabolites in different organs of P. sarmentosum were identified and their relative abundances were characterized. The metabolic profiles of leaves, roots, stems and fruits were comprehensively investigated by liquid chromatography high-resolution mass spectrometry (LC-HR-MS) and the data subsequently analyzed using multivariate statistical methods. Manual interpretation of the tandem mass spectrometric (MS/MS) fragmentation patterns revealed the presence of 154 tentatively identified metabolites, mostly represented by alkaloids and flavonoids. Principle component analysis and hierarchical clustering indicated the predominant occurrence of flavonoids, lignans and phenyl propanoids in leaves, aporphines in stems, piperamides in fruits and lignan-amides in roots. Overall, this study provides extensive data on the metabolite composition of P. sarmentosum, supplying useful information for bioactive compounds discovery and patterns of their preferential biosynthesis or storage in specific organs. This can be used to optimize production and harvesting as well as to maximize the plant's economic value as herbal medicine or in food applications.

Exploring the Larvicidal and Adulticidal Activity against Aedes aegypti of Essential Oil from Bocageopsis multiflora

This study investigates the chemical composition of the essential oil obtained from the leaves of Bocageopsis multiflora (Mart.) R.E.Fr (Annonaceae), examining its effectiveness in combating both the larvae and adult forms of Aedes aegypti mosquitoes. Additionally, for a deeper understanding of the insecticidal activity, toxicity properties and molecular docking calculations were conducted using the main compounds of this essential oil. GC/MS analysis revealed the presence of 26 constituents, representing 95.2% of the essential oil, with the major components identified as the sesquiterpenes α-selinene, β-selinene, and β-elemene. Larvicidal assays demonstrated potent activity of this essential oil with significant LC50 values of 40.8 and 39.4 μg/mL at 24 and 48 h, respectively. Adulticidal assessments highlighted strong efficacy with LC50 of 12.5 µg/mL. Molecular docking analysis identified optimal interaction activities of α-selinene and β-selinene with key Aedes proteins. The in silico studies comparing synthetic insecticides with the major sesquiterpenes of the essential oil revealed that β-selinene exhibited a significantly higher binding affinity compared to the other two sesquiterpenes. Also, ADMET studies of the three main sesquiterpenes indicated acceptable drug-like properties. In these findings, safety evaluations showed low toxicity and skin sensitization for the main sesquiterpenes, contrasting with commercial synthetic insecticides. Therefore, in silico analyses suggest promising interactions with Aedes proteins, indicating its potential as an effective alternative to conventional insecticides These results show the larvicidal and adulticidal potential of the essential oil from Bocageopsis multiflora against Aedes aegypti, supported by its predominant constituents, α-selinene, β-selinene and β-elemene.

Lutein Production by Halophilic Microalgae Using Anaerobic Digestate as the Substrate and Its Potential Application as a Biopesticide

Production of value-added products from waste anaerobic digestate is economically and environmentally important for sustainable development of industrial process and products. In this study halophilic microalgae, Chlorella vulgaris 92001, Chlorella vulgaris 50291, Chlorella vulgaris 10241 and Tetraselmis indica, were initially screened for lutein production using synthetic dairy digestate (DD), municipal digestate (MD) and poultry digestate (PD) as no-cost substrates. Screening and optimization of parameters, such as dilution, pH, MgCl2, NaCl, NaHCO3 and inoculum concentration for maximum lutein production were further performed employing statistically designed Plackett-Burman and response surface methodology. Cultivation of C. vulgaris 92001 in a split column photobioreactor under optimum culture condition showed increase in lutein production by 2.36-fold in batch mode. The influence of different hydraulic retention time (HRT) values of 150, 130, 100 and 90 h on lutein production was evaluated in continuous mode with the split column photobioreactor. Lutein produced using the synthetic poultry digestate showed good potential biopesticide activity against Spodoptera litura (fall armyworm). Overall, this study demonstrated bioprocess development to produce lutein using synthetic anaerobic digestate from marine algae and its potential application as a biopesticide.

The Repellent Capacity against Sitophilus zeamais (Coleoptera: Curculionidae) and In Vitro Inhibition of the Acetylcholinesterase Enzyme of 11 Essential Oils from Six Plants of the Caribbean Region of Colombia

The repellent capacity against Sitophilus zeamais and the in vitro inhibition on AChE of 11 essential oils, isolated from six plants of the northern region of Colombia, were assessed using a modified tunnel-type device and the Ellman colorimetric method, respectively. The results were as follows: (i) the degree of repellency (DR) of the EOs against S. zeamais was 20-68% (2 h) and 28-74% (4 h); (ii) the IC50 values on AChE were 5-36 µg/mL; likewise, the %inh. on AChE (1 µg/cm3 per EO) did not show any effect in 91% of the EO tested; (iii) six EOs (Bursera graveolens-bark, B. graveolens-leaves, B. simaruba-bark, Peperomia pellucida-leaves, Piper holtonii (1b*)-leaves, and P. reticulatum-leaves) exhibited a DR (53-74%) ≥ C+ (chlorpyrifos-61%), while all EOs were less active (8-60-fold) on AChE compared to chlorpyrifos (IC50 of 0.59 µg/mL). Based on the ANOVA/linear regression and multivariate analysis of data, some differences/similarities could be established, as well as identifying the most active EOs (five: B. simaruba-bark, Pep. Pellucida-leaves, P. holtonii (1b*)-leaves, B. graveolens-bark, and B. graveolens-leaves). Finally, these EOs were constituted by spathulenol (24%)/β-selinene (18%)/caryophyllene oxide (10%)-B. simaruba; carotol (44%)/dillapiole (21%)-Pep. pellucida; dillapiole (81% confirmed by 1H-/13C-NMR)-P. holtonii; mint furanone derivative (14%)/mint furanone (14%)-B. graveolens-bark; limonene (17%)/carvone (10%)-B. graveolens-leaves.

Macaronesian Plants as Promising Biopesticides against the Crop Pest Ceratitis capitata

Ceratitis capitata is responsible for significant economic losses in the fruit production industry, and the market lacks biopesticides that are effective but also cheaper and less contaminating, with fewer negative impacts on the environment. In this regard, the present study suggests as potential options ethanolic extracts from several Macaronesian plants, which inhibit the oviposition and are toxic to C. capitata, and whose preparation involve a non-toxic solvent (i.e., ethanol), low energy expenditure and cheap apparatus (i.e., maceration at room temperature). Among the evaluated species, the extracts of Hedychium gardnerianum, Cistus symphytifolius and Salvia canariensis are the most active (50 mg/mL), revealing an increase in C. capitata adults' mortality from 21.15% to 27.41% after 72 h, a value statistically identical to azadirachtin (25.93%) at the recommended concentration (0.88 mg/mL). Considering the quantity and biomass available to prepare a biopesticide in the future, and the level of activity, the ethanolic extract of H. gardnerianum was fractionated and each fraction tested. The water fraction at 50 mg/mL proved to be more effective than the original extract, both in terms of mortality (57.69%), with LT50 = 72.5 h, and oviposition deterrence (83.43%), values statistically higher than those obtained by azadirachtin at 0.88 mg/mL. Analysis of this fraction by HPLC-MS/MS showed that it is mainly composed of glycosylated derivatives of quercetin and myricetin in addition to some triterpenes. These findings highlight some Macaronesian species, and in particular, the more polar fraction of H. gardnerianum ethanolic extract, as promising and ecological alternatives to conventional insecticides, for use in the integrated management of the C. capitata pest.

Insecticidal efficacy and possibility of Combretum trifoliatum Vent. (Myrtales: Combretaceae) extracts in controlling Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

BACKGROUND

The fall armyworm Spodoptera frugiperda (J.E. Smith), is an important pest of agronomical crops. It is interesting to discover secondary metabolites in plants that are environmentally safer than synthetic pesticides. For this purpose, Combretum trifoliatum crude extract and its isolated compounds were investigated for their insecticidal activities against S. frugiperda.

RESULTS

The median lethal dose (LD50 ) was evaluated in the second-instar larvae using the topical application method. The isolated compounds, apigenin and camphor, demonstrated a highly toxic effect on larvae at a lower LD50 dose than crude extract. Moreover, when the larvae were exposed to crude extract concentrations, the development to pupa and adult stages was reduced by more than 50%. The ovicidal toxicity was examined using a hand sprayer. The extract concentration 5, 10, and 20 μg/egg significantly decreased the egg hatchability. In addition, crude extract showed a significant difference in inhibiting acetylcholinesterase (AChE) activity while crude extract and camphor showed significant inhibitory effects on carboxylesterase (CE) and glutathione-S-transferase (GST) activities.

CONCLUSION

The crude ethanol extract of Combretum trifoliatum was toxic to S. frugiperda in terms of larval mortality, negatively affecting biological parameters, and decreasing egg hatchability. Additionally, the activities of cholinergic and detoxifying enzymes were affected by crude extract and its isolated compounds. These results highlight that Combretum trifoliatum might be efficient as a bioinsecticide to control S. frugiperda. © 2023 Society of Chemical Industry.

Osteogenic Potential and Bioactive Profiles of Piper sarmentosum Ethanolic Extract-Treated Stem Cells

Piper sarmentosum is a well-known traditional herbal plant in various diseases treatments. Multiple scientific studies have also reported various biological activities exhibited by the plant's extract, such as antimicrobial, anticarcinogenic and antihyperglycemic activities, and, in addition, a bone protective effect in ovariectomized rats has been reported. However, no known Piper sarmentosum extract is involved in osteoblast differentiation using stem cells. Our study aims to identify the potential of P. sarmentosum ethanolic extract to induce osteoblast differentiation of human peripheral blood stem cells. Prior to the assay, the proliferation ability of the cells was observed for 14 days and the presence of hematopoietic stem cells in the culture was determined by the expression of SLAMF1 and CD34 genes. During the differentiation assay, the cells were treated with P. sarmentosum ethanolic extract for 14 days. Osteoblast differentiation was examined using an (alkaline phosphatase) ALP assay, by monitoring the expression of osteogenic gene markers and by von Kossa staining. The untreated cells served as the negative control, while cells treated with 50 µg/mL ascorbic acid and 10 mM β-glycerophosphate acted as the positive control. Finally, the determination of the compound profile was performed using a gas chromatography-mass spectrometry (GC-MS) analysis. The isolated cells were able to proliferate for 14 days during the proliferation assay. The expression of hematopoietic stem cell markers was also upregulated during the 14 days assay. Following the differentiation induction, the ALP activity exhibited a significant increase (p < 0.05) from day 3 of the differentiation assay. A molecular analysis also showed that the osteogenic markers ALP, RUNX2, OPN and OCN were upregulated compared to the positive control. The presence of mineralized cells with a brownish-stained morphology was observed, indicating the mineralization process increased in a time-dependent manner regardless of the concentration used. There were 54 compounds observed in the GC-MS analysis, including β-asarones, carvacrol and phytol, which have been shown to possess osteoinductive capacities. Our results demonstrate that the ethanolic extract of P. sarmentosum can induce osteoblast differentiation of peripheral blood stem cells. The extract contains potent compounds which can potentially induce the differentiation of bone cells, i.e., osteoblasts.

Insecticidal activity of the organotellurium 2-Phenylethynyl-Butyltellurium on the Drosophila melanogaster model

2-Phenylethynyl-Butyltellurium (PEBT) is a synthetic organotellurium compound that has shown various pharmacological properties on mammals without any signs of toxicity, but its effects on insects have not been reported before. Therefore, the aim of this study was to assess whether acute exposure to PEBT would promote an insecticidal effect against Drosophila melanogaster. The flies were exposed to three concentrations of PEBT (0.325 µmol L-1, 1.300 µmol L-1, and 5.200 µmol L-1) and a control solution (vehicle), using 450 flies per treatment (three repetitions of 150 flies), for 48 hours. Negative geotaxis and open field tests were performed (in vivo) after 24 and 48h, and acetylcholinesterase (AChE) activity was assessed (ex vivo) after 48h. Also, the mortality rate, 50% Lethal Concentration (LC50), 80% Lethal Concentration (LC80), and 95% Lethal Concentration (LC95) were calculated. Our results show that PEBT presented insecticidal activity against Drosophila melanogaster at all tested concentrations, which caused locomotor impairment and increased acetylcholinesterase activity in the flies' heads.

Insecticidal Activity of a Component, (-)-4-Terpineol, Isolated from the Essential Oil of Artemisia lavandulaefolia DC. against Plutella xylostella (L.)

Plutella xylostella (L.) is one of the most serious pests of cruciferous vegetables. Our previous work demonstrated that the essential oil of Artemisia lavandulaefolia DC. exhibits promising insecticidal activities against P. xylostella. This study further characterizes the key components that are responsible for the insecticidal effect. In total, 47 compounds (96.52% of the total compounds) were identified from the total oil using GC-MS, and the major compounds were eucalyptol (21.57%), D(+)-camphor (17.33%), (-)-4-terpineol (9.96%) and caryophyllene oxide (10.96%). Among them, (-)-4-terpineol showed significantly larvicidal and fumigant activities against P. xylostella. The LD₅₀ of (-)-4-terpineol was 43.15 mg/mL at 12 h and 31.22 mg/mL at 24 h for 3rd instar larvae, and the LC₅₀ for adults was 8.34 mg/mL at 12 h and 7.35 mg/mL at 24 h. In addition, the adults treated with (-)-4-terpineol showed varying degrees of inhibitory activity toward glutathione S-transferase, catalase, acetylcholinesterase and Na⁺/K⁺-ATPase at different post-treatment intervals and concentrations. The results indicate that (-)-4-terpineol has promising insecticidal activities against P. xylostella, and it has good inhibitory effects on the four enzymes of P. xylostella adults.

Exploring Contact Toxicity of Essential Oils against Sitophilus zeamais through a Meta-Analysis Approach

Sitophilus zeamais is a primary pest of maize. Our aim was to perform a qualitative review and meta-analyses with 56 scientific articles published from 1 January 2000 to 1 October 2022 dealing with direct (topical application) and indirect (impregnation of essential oils, EOs, onto filter paper or maize grains) contact toxicity of EOs against S. zeamais. Three independent meta-analyses of single means of LD50 (direct contact) and LC50 (indirect contact) were conducted using a random effect model. Essential oils more frequently evaluated were those belonging to Asteraceae, Apiaceae, Lamiaceae, Myrtaceae, Piperaceae, and Rutaceae. The LC50 global mean values were 33.19 µg/insect (CI95 29.81-36.95) for topical application; 0.40 µL/cm2 (CI95 0.25-0.65) for filter paper indirect contact; and 0.50 µL/g maize (CI95 0.27-0.90) for maize grains indirect contact. The species Carum carvi, Salvia umbratica, Ilicium difengpi, Periploca sepium, Cephalotaxus sinensis, Murraya exotica, Rhododendron anthopogonoides, Ruta graveolens, Eucalyptus viminalis, Ocotea odorifera, Eucalyptus globulus, Eucalyptus dunnii, Anethum graveolens, Ilicium verum, Cryptocarya alba, Azadirachta indica, Chenopodium ambrosioides, Cupressus semperivens, Schinus molle, Piper hispidinervum, Mentha longifolia, and Croton pulegiodorus showed LC50 or LD50 values lower than the global means, indicating good insecticidal properties. Our results showed that EOs have great potential to be used as bioinsecticides against S. zeamais.

Insecticidal activity of the essential oil of Piper corcovadensis leaves and its major compound (1-butyl-3,4-methylenedioxybenzene) against the maize weevil, Sitophilus zeamais

BACKGROUND

Sitophilus zeamais is one of the most economically impactful pests, attacking various grains and processed foods. Control of this insect has been achieved using synthetic insecticides, exacerbated and careless use of which has led to the development of resistant insect populations, toxicity to non-target organisms and environmental contamination. In this study, Piper corcovadensis leaf essential oil (PcLEO) and its major compound, 1-butyl-3,4-methylenedioxybenzene (BMDB), were investigated as alternative insecticidal agents against S. zeamais.

RESULTS

Characterization of PcLEO showed the presence of 40 compounds. The major components were the phenylpropanoid BMDB (35.77%) and the monoterpenes α-pinene (14.95%) and terpinolene (6.23%). PcLEO and BMDB were toxic by fumigation (half-maximal lethal concentration [LC₅₀ ]: 9.46 and 0.85 μl L^-1 of air, respectively), by contact (half-maximal lethal dose [LD₅₀ ]: 9.38 and 6.16 μg g^-1 of insect, respectively) and ingestion (LC₅₀ : 16.04 and 14.30 mg g^-1 , respectively). In the ingestion test, both PcLEO and BMDB promoted the loss of insect biomass and had a strong deterrent effect. In addition, both were able to inhibit trypsin and α-amylase activities.

CONCLUSION

PcLEO and BMDB exhibited insecticidal activity against S. zeamais, with a toxic effect by fumigation, contact and ingestion, in addition to food deterrence and inhibiting trypsin and α-amylase activities, suggesting their potential for use in the control of this pest.

Statistical approach to synthesise biogenic silica nanoparticles from rice husk and conjugated with Justicia adhatoda extract as green, slow-release biocide

Biogenic silica synthesised from rice husk was used as a controlled release system of an eco-friendly biocide consisting of a Justicia adhatoda extract. Fourier-transform infrared spectroscopy (FTIR) indicated the presence of ester bonds between the silica support and the conjugated Justicia adhatoda extract. Surface area analysis and microscopy confirmed a high level of Justicia adhatoda extract loading in the silica support. The phytochemical investigation of Justicia adhatoda was done by Gas chromatography-mass spectrometry (GC-MS) spectroscopy. Moreover, compared with the naked biogenic silica nanoparticles, a better thermal stability was determined for the conjugated system of the extracted compounds. Trial of kinetic release of silica: Justicia adhatoda ∼29% of loaded Justicia adhatoda was released within 1 h and then the rate of release became slow. Net release of Justicia adhatoda was observed up to 50% within 7 h. The Justicia adhatoda compounds released from silica also showed the improved mortality rate against stored product pest rice weevil (Sitophilus oryzae).

Larvicidal Activity of Essential Oils From Piper Species Against Strains of Aedes aegypti (Diptera: Culicidae) Resistant to Pyrethroids

The continuous and indiscriminate use of insecticides has been responsible for the emergence of insecticide resistant vector insect populations, especially in Aedes aegypti. Thus, it is urgent to find natural insecticide compounds with novel mode of action for vector control. The goal of this study was to investigate the larvicidal activity of essential oils (EOs) from Piper species against A. aegypti characterized as resistant and susceptible strains to pyrethroids. The EOs from leaves of 10 Piper species were submitted to the evaluation of larvicidal activity in populations of A. aegypti in agreement with the (World Health Organization, 2005) guidelines. The resistance of the strains characterized by determining the lethal concentrations (LCs) with the insecticide deltamethrin (positive control). The major compounds of the EOs from Piper species was identified by GC-MS. The EOs from Piper aduncum, P. marginatum, P. gaudichaudianum, P. crassinervium, and P. arboreum showed activity of up to 90% lethality at 100 ppm (concentration for screening). The activities of the EOs from these 6 species showed similar LCs in both susceptible strain (Rockefeller) and resistant strains (Pampulha and Venda Nova) to pyrethroids. The major compounds identified in the most active EO were available commercially and included β-Asarone, (E)-Anethole, (E)-β-Caryophyllene, γ-Terpinene, p-Cymene, Limonene, α-Pinene, and β-Pinene. Dillapiole was purified by from EO of P. aduncum. The phenylpropanoids [Dillapiole, (E)-Anethole and β-Asarone] and monoterpenes (γ-Terpinene, p-Cymene, Limonene, α-Pinene, and β-Pinene) showed larvicidal activity with mortality between 90 and 100% and could account for the toxicity of these EOs, but the sesquiterpene (E)-β-Caryophyllene, an abundant component in the EOs of P. hemmendorffii and P. crassinervium, did not show activity on the three populations of A. aegypti larvae at a concentration of 100 ppm. These results indicate that Piper's EOs should be further evaluated as a potential larvicide, against strains resistant to currently used pesticides, and the identification of phenylpropanoids and monoterpenes as the active compounds open the possibility to study their mechanism of action.

Piper capitarianum essential oil: a promising insecticidal agent for the management of Aedes aegypti and Aedes albopictus

Mosquitoes are responsible for serious public health problems worldwide, and as such, Aedes aegypti and Aedes albopictus are important vectors in the transmission of dengue, chikungunya, and Zika in Brazil and other countries of the world. Due to growing resistance to chemical insecticides among populations of vectors, environmentally friendly strategies for vector management are receiving ever more attention. Essential oils (EOs) extracted from plants have activities against insects with multiple mechanisms of action. These mechanisms hinder the development of resistance, and have the advantages of being less toxicity and biodegradable. Thus, the present study aimed to evaluate the chemical composition of the EOs obtained from Piper capitarianum Yunck, as well as evaluating their insecticidal potential against Aedes aegypti and A. albopictus, and their toxicity in relation to Artemia salina. The yields of the EOs extracted from the leaves, stems, and inflorescences of P. capitarianum were 1.2%, 0.9%, and 0.6%, respectively, and their main constituents were trans-caryophyllene (20.0%), α-humulene (10.2%), β-myrcene (10.5%), α-selinene (7.2%), and linalool (6.0%). The EO from the inflorescences was the most active against A. aegypti and A. albopictus, and exhibited the respective larvicidal (LC₅₀ = 87.6 μg/mL and 76.1 μg/mL) and adulticide activities (LC₅₀ = 126.2 μg/mL and 124.5 μg/mL). This EO was also the most active in the inhibition of AChE, since it presented an IC₅₀ value of 14.2 μg/mL. Its larvicidal effect was observed under optical and scanning electron microscopy. Additionally, non-toxic effects against A. salina were observed. Docking modeling of trans-caryophyllene and α-humulene on sterol carrier protein-2 (SCP-2) suggests that both molecules have affinity with the active site of the enzyme, which indicates a possible mechanism of action. Therefore, the essential oil of P. capitarianum may be used in the development of new insecticide targets for the control of A. aegypti and A. albopictus in the Amazonian environment.

Piper sarmentosum Roxb.: A review on its botany, traditional uses, phytochemistry, and pharmacological activities

ETHNOPHARMACOLOGICAL RELEVANCE

Piper sarmentosum Roxb. (Piperaceae) is a traditional medicinal plant widely distributed in India, Malaysia, Thailand, and the southeastern coastal areas of China including Fujian, Guangdong, and Guizhou. It has been used for centuries for the treatment of wind-cold cough, fever, rheumatism arthralgia, diarrhea dysentery, postpartum foot swelling, stomachache, toothache, diabetes, and traumatic injury.

AIMS OF THE REVIEW

To critically anayze the literature for the botany, traditional uses, phytochemistry, pharmacology, toxicity, and clinical trials of P. sarmentosum in order to provide a scientific consensus for further research and discovery of potential candidate drugs.

MATERIALS AND METHODS

The contents of this review were sourced from electronic databases including PubMed, SciFinder, Web of Science, Science Direct, Elsevier, Google Scholar, Chinese Knowledge On frastructure (CNKI), Wanfang, Chinese Scientific and Technological Periodical Database (VIP), Chinese Biomedical Database (CBM), Cochrane Controlled register of Clinical Trials, Clinical Trials. gov, and Chinese Clinical Trial Registry. Chinese medicine books published over the years were used to elucidate the traditional uses of P. sarmentosum and additional information was also collected from Yao Zhi website (https://db.yaozh.com/).

RESULTS

Phytochemical analyses of the chemical constituents of P. sarmentosum include essential oil, alkaloids, flavonoids, lignans, and steroids. The literature supports the ethnomedicinal uses of P. sarmentosum for the treatment of cold, gastritis, and rheumatoid joint pain, and further confirms its relatively new pharmacological activities, including anti-inflammatory, antineoplastic, and antipyretic activities. Other biological roles such as anti-osteoporosis, antibacterial, antidepressant, anti-atherosclerotic, and hypoglycemic activities have also been reported. However, the methodologies employed in individual studies are limited.

CONCLUSIONS

There is convincing evidence from both in vitro and in vivo studies supporting the traditional use of P. sarmentosum and it is imperative that natural bioactive compounds are examined further. More efforts should be focused on the pharmacodynamic constituents of P. sarmentosum to provide practical basis for quality control, and additional studies are needed to understand the mechanism of their action. Further studies on the comprehensive evaluation of medicinal quality and understandings of serum chemistry, multi-target network pharmacology, and molecular docking technology of P. sarmentosum are of great importance and should be considered.

Chemical composition and larvicidal activity against Aedes mosquitoes of essential oils from Arisaema fargesii

BACKGROUND

Dengue fever is caused by the spread of dengue virus by Aedes mosquito vectors. Currently, the most effective way to control dengue is by preventing mosquitoes from spreading the disease. Arisaema fargesii is a Chinese herbal medicine commonly used to repel mosquitoes. In our laboratory, anti-mosquito chemical components were extracted from A. fargesii, and the effects of these substances on mosquito larvae were examined.

RESULTS

In total, 48 compounds corresponding to 98.79% of the total oil were identified and the major compounds identified were linalool (12.38%), carvacrol (8.27%), eugenol (5.21%), and β-selinene (5.36%). Essential oil had larvicidal activity against Ae. aegypti and Ae. albopictus with LC₅₀ values of 40.49 mg/L, 47.01 mg/L, respectively. The LC₅₀ values of carvacrol, eugenol, linalool and β-selinene were 32.78, 56.34, 70.56, 136.03 mg/L against Ae. aegypti larvae, and 39.08, 52.07, 82.34, 151.74 mg/L, respectively, against Ae. albopictus larvae. Biochemical assays of Aedes larvae showed that the activities of acetylcholinesterase (AChE), monooxygenases (MO), glutathione-S-transferase (GST), p-Nitrophenyl acetate (p-NPA) esterase, α-esterase and β-esterase were significantly affected by carvacrol. Essential oil induced the detoxification mechanism for the action of GST and MO.

CONCLUSION

The result indicates that essential oil of A. fargesii and its isolated constituent have good inhibitory effects on the defense enzymes of Aedes mosquito larvae. A. fargesii essential oil can be used to control Aedes mosquito larvae to prevent the spread of dengue fever. © 2019 Society of Chemical Industry.

Antifeedant Activities of Lignans from Stem Bark of Zanthoxylum armatum DC. against Tribolium castaneum

The speciation of a methanolic extract of Zanthoxylum armatum stem bark has enabled the isolation and characterization of 11 known lignans. Among them, five compounds (6, 8-11) are reported in this plant for the first time. All of the chemical structures were elucidated on the basis of NMR spectral analysis. Additionally, their antifeedant activities against Tribolium castaneum were evaluated scientifically. Among them, asarinin (1), with an EC50 of 25.64 ppm, exhibited a much stronger antifeedant activity than the positive control, toosendanin (EC50 = 71.69 ppm). Moreover, fargesin (2), horsfieldin (3), and magnolone (10), with EC50 values of 63.24, 68.39, and 78.37 ppm, showed almost the same antifeedant activity as the positive control. From the perspective of structure-effectiveness relationship, compounds with the chemical group of methylenedioxy exhibited higher antifeedant activities and have potential to be developed into novel antifeedants or potential lead compounds to protect food and crops in storage.