Toxicity of Kadsura coccinea (Lem.) A. C. Sm. Essential Oil to the Bed Bug, Cimex lectularius L. (Hemiptera: Cimicidae)

Characterization of the volatile profile and its estrogenic activity in Kadsura coccinea fruit

ETHNOPHARMACOLOGICAL RELEVANCE

The fruit of Kadsura coccinea (Lem.) A. C. Smith is an ethnomedicine used to treat abnormal menstruation, menopausal syndrome, and female infertility among the Dong Nationality in China.

AIM OF THE STUDY

Our study aimed to identify the volatile oil profiles of the K. coccinea fruit and elucidate their estrogenic activity.

MATERIALS AND METHODS

The peel volatile oil (PeO), pulp volatile oil (PuO), and seed volatile oil (SeO) of K. coccinea were extracted using hydrodistillation and qualitatively analyzed using gas chromatography-mass spectrometry (GC-MS). Estrogenic activity was evaluated in vitro using cell assay and in vivo using immature female rats. Serum 17β-Estradiol (E2) and follicle-stimulating hormone (FSH) levels were detected using ELISA.

RESULTS

In total, 46 PeO, 27 PuO, and 42 SeO components representing 89.96%, 90.19%, and 97% of the total composition, respectively, were identified. The compounds with the highest content in PeO, PuO, and SeO were β-caryophyllene, γ-amorphene, and n-hexadecanoic acid, respectively. PeO induced proliferation of MCF-7 cells with an EC₅₀ of 7.40 μg/mL. Subcutaneous administration of 10 mg/kg PeO significantly increased the weight of the uteri in immature female rats, with no effect on serum E2 and FSH levels. PeO acted as an agonist of ERα and ERβ. PuO and SeO showed no estrogenic activity.

CONCLUSION

The chemical compositions of PeO, PuO, and SeO of K. coccinea are different. PeO is the main effective fraction for estrogenic activities, providing a new source of phytoestrogen for the treatment of menopausal symptoms.

Essential Oils in Urban Insect Management-A Review

The allures of city life have culminated in the rise of urban populations resulting in conditions that promote the establishment of certain insect pests. Globally, the public health significance of these urban insect pests is enormous, ranging from billions of dollars to loss of lives. Most chemical insecticides no longer provide the anticipated level of control, and significant insecticide resistance has been reported. Therefore, there has been a spike in interest for alternatives to conventional insecticides. Among them, natural products from plants such as essential oils (EOs) and essential oil components (EOCs) have enjoyed the most attention owing to widespread reports of efficacy and toxicity even against insecticide-resistant urban insects. Yet, there is no comprehensive synthesis on the extent and impact of the management of urban insects using EOs or EOCs. Such a review is highly relevant since it provides a means to assess the extent of progress made, shortfalls, limitations, and prospects. More so, we hope it can be used to make informed decisions and develop relevant policies reliably. We present the ranges of insecticidal effects of EOs, EOCs, and commercially available EO-based products from laboratory and field studies. Finally, we discuss the gaps in our knowledge and prospects for the sustainable use of EOs.

Chemical Composition and Biological Activities of Essential Oils from the Leaves, Stems, and Roots of Kadsura coccinea

The chemical composition and biological activities of the essential oils from the leaves, stems, and roots of Kadsura coccinea (K. coccinea) were investigated. The essential oils were extracted by hydro distillation and analyzed by gas chromatography mass spectrometry (GC-MS) and gas chromatography with flame ionization detector (GC-FID). Antioxidant activities of the essential oils were examined with DPPH radical scavenging assay, ABTS cation radical scavenging assay, and ferric reducing antioxidant power assay. Antimicrobial activities were evaluated by determining minimum inhibitory concentrations (MIC) and minimum microbiocidal concentrations (MMC). Acetylcholinesterase and butyrylcholinesterase inhibitory activity of the essential oils were also tested. A total of 46, 44, and 47 components were identified in the leaf, stem, and root oils, representing 95.66%, 97.35%, and 92.72% of total composition, respectively. The major compounds of three essential oils were α-pinene (16.60-42.02%), β-pinene (10.03-18.82%), camphene (1.56-10.95%), borneol (0.50-7.71%), δ-cadinene (1.52-7.06%), and β-elemene (1.86-4.45%). The essential oils were found to have weak antioxidant activities and cholinesterase inhibition activities. The essential oils showed more inhibitory effects against Staphylococcus aureus (S. aureus) than those of other strains. The highest antimicrobial activity was observed in the root oil against S. aureus, with MIC of 0.78 mg/mL. Therefore, K. coccinea essential oils might be considered as a natural antibacterial agent against S. aureus with potential application in food and pharmaceutical industries.

Extensive Metabolite Profiling in the Unexploited Organs of Black Tiger for Their Potential Valorization in the Pharmaceutical Industry

Black tiger (Kadsura coccinea (Lem.)) has been reported to hold enormous pharmaceutical potential. The fruit and rhizome of black tiger are highly exploited in the pharmaceutical and other industries. However, the most important organs from the plant such as the leaf and stem are considered biowastes mainly because a comprehensive metabolite profile has not been reported in these organs. Knowledge of the metabolic landscape of the unexploited black tiger organs could help identify and isolate important compounds with pharmaceutical and nutritional values for a better valorization of the species. In this study, we used a widely targeted metabolomics approach to profile the metabolomes of the K. coccinea leaf (KL) and stem (KS) and compared them with the root (KR). We identified 642, 650 and 619 diverse metabolites in KL, KS and KR, respectively. A total of 555 metabolites were mutually detected among the three organs, indicating that the leaf and stem organs may also hold potential for medicinal, nutritional and industrial applications. Most of the differentially accumulated metabolites between organs were enriched in flavone and flavonol biosynthesis, phenylpropanoid biosynthesis, arginine and proline metabolism, arginine biosynthesis, tyrosine metabolism and 2-oxocarboxylic acid metabolism pathways. In addition, several important organ-specific metabolites were detected in K. coccinea. In conclusion, we provide extensive metabolic information to stimulate black tiger leaf and stem valorization in human healthcare and food.

The application of essential oils as a next-generation of pesticides: recent developments and future perspectives

The overuse of synthetic pesticide, a consequence of the rush to increase crop production, led to tremendous adverse effects, as they constitute a major pollutant for both soils and water, with a high toxicity towards humans and animals and, at the same time, led to development of pest resistance. In the last period, the researches were directed towards finding new solutions with a lower toxicity, less damaging behaviour towards the environment, and a better specificity of action. In this context, the use of essential oils, a complex and unique mixture of compounds, can be considered for the next-generation pesticides. This review aims to present the main applications of the essential oils as insecticides, herbicides, acaricides, and nematicides, as they emerged from the scientific literature published in the last 5 years (2015 to present). From the identified articles within the time period, only those dealing with essential oils obtained by the authors (not commercially available) were selected to be inserted in the review, characterized using established analytical techniques and employed for the envisaged applications. The review is concluded with a chapter containing the main conclusions of the literature study and the future perspectives, regarding the application of essential oils as next-generation pesticides.

Behavioral Responses of the Common Bed Bug to Essential Oil Constituents

Simple Summary

Bed bugs (Cimex lectularius L.) are blood-sucking insects that have emerged worldwide in the last two decades causing serious public health and economic impact. Today, control of bed bug infestations relies on the use of synthetic insecticides, but their frequent use has led to the development of resistance in bed bug populations. Therefore, there is a growing demand for the development of safer, green, and more effective tools for bed bug control. Plant-derived pesticides are part of the proposed “green” methods for bed bug control. We evaluated behavioral responses of bed bugs to essential oil constituents (EOCs) and detected that bed bugs did not rest on areas treated with geraniol, eugenol, citronellic acid, and carvacrol. Barriers of these constituents did not deter bed bugs from reaching warmed blood meal and feeding. Our results show that novel formulations of natural product insecticides that include geraniol, eugenol, carvacrol, or citronellic acid have potential to repel bed bugs. However, little benefit of protection against bed bug bites can be expected when EOC-based products are applied to items present in close proximity to a sleeping host such as mattress covers, liners, or around the bed.

Abstract

Botanical-derived pesticides have arisen as an attractive alternative to synthetic insecticides to effectively manage infestations of bed bugs (Cimex lectularius L.). While information on contact, residual, and fumigant toxicity of plant-essential oils against bed bugs have been recently published, there is a gap of information regarding the repellent activity of these products and their constituents. Identification of essential oil constituents (EOCs) with repellent activity will help develop potentially efficacious essential oil-based formulations for use in bed bug management programs. In this study, we first screened fresh and 24 h-aged residues of geraniol, eugenol, carvacrol, thymol, citronellic acid, linalool, menthone, trans-cinnamaldehyde, α-pinene, β-pinene, and limonene for avoidance behavior from individual bed bugs with a video-tracking system. Six EOCs, geraniol, eugenol, citronellic acid, thymol, carvacrol, and linalool were further evaluated overnight in choice tests to determine whether 24-h aged residues were still avoided by groups of bed bugs. While bed bugs avoided resting on filter papers treated with 24-h aged residues of geraniol, eugenol, citronellic acid, and carvacrol, bed bugs aggregated in areas treated with linalool-aged residues. Barriers of EOCs did not prevent bed bugs from reaching a warmed blood source and acquiring blood meals. Our results show that novel formulations of natural product insecticides that include geraniol, eugenol, carvacrol, or citronellic acid have potential to repel bed bugs. The presence of host-associated cues might interfere with these responses.

Plant Natural Sources of the Endocannabinoid (E)-β-Caryophyllene: A Systematic Quantitative Analysis of Published Literature

(E)-β-caryophyllene (BCP) is a natural sesquiterpene hydrocarbon present in hundreds of plant species. BCP possesses several important pharmacological activities, ranging from pain treatment to neurological and metabolic disorders. These are mainly due to its ability to interact with the cannabinoid receptor 2 (CB2) and the complete lack of interaction with the brain CB1. A systematic analysis of plant species with essential oils containing a BCP percentage > 10% provided almost 300 entries with species belonging to 51 families. The essential oils were found to be extracted from 13 plant parts and samples originated from 56 countries worldwide. Statistical analyses included the evaluation of variability in BCP% and yield% as well as the statistical linkage between families, plant parts and countries of origin by cluster analysis. Identified species were also grouped according to their presence in the Belfrit list. The survey evidences the importance of essential oil yield evaluation in support of the chemical analysis. The results provide a comprehensive picture of the species with the highest BCP and yield percentages.