Dengue vector control strategies are mostly based on chemicals use against Aedes aegypti populations. The current study aimed at investigating the insecticidal effects of essential oils (EOs) obtained from five plant species, Cymbopogon citrates (D. C.) Stapf. (Poaceae), Cymbopogon nardus (Linn.) Rendle (Poaceae), Eucalyptus camaldulensis Linn. (Myrtaceae), Lippia multiflora Moldenke (Verbenaceae), and Ocimum americanum Linn. Lamiaceae, and combinations of Cymbopogon nardus and Ocimum americanum on Ae. aegypti populations from Bobo-Dioulasso. For this purpose, adults of the susceptible and field strains of Ae. aegypti were tested in WHO tubes with EO alone and binary combinations of O. americanum (OA) and C. nardus (CN; scored from C1 to C9). The extraction of the essential oils was done by hydrodistillation, and their components were determined by GC/MS. Among the 5 EOs tested, L. multiflora essential oil was the most efficient, with KDT50 values below 60 min on all Ae. aegypti strains tested, and also with a rate of mortality up to 100 and 85% for Bora Bora and Bobo-Dioulasso strains, respectively. This efficacy may be due to its major compounds which are with major compounds as β-caryophyllene, p-cymene, thymol acetate, and 1.8 cineol. Interestingly, on all strains, C8 combination showed a synergistic effect, while C2 showed an additive effect. These combinations exhibit a rate of mortality varying from 80 to 100%. Their toxicity would be due to the major compounds and the putative combined effects of some major and minor compounds. More importanly, L. multiflora EO and combinations of C. nardus and O. americanum EO, may be used as alternatives against pyrethroid resistant of Ae. aegypti.
The antifungal and antiaflatoxinogenic activities of the essential oils (EOs) from the leaves of Cymbopogon schoenanthus, Cymbopogon citratus, Cymbopogon nardus, and their pair combinations were investigated. Antifungal susceptibility and the efficacy of paired combinations of EOs were assessed using agar microdilution and checkerboard methods, respectively. Identification and quantification of chemical components of the EOs were carried out by gas chromatography-mass spectrometry and gas chromatography-flame ionization detector (GC-MS and GC-FID), respectively. Aflatoxins were separated and identified by High-Performance Liquid Chromatography (HPLC) and then quantified by spectrofluorescence. The EO of C. nardus exhibited the highest inhibitory activity against Aspergillus flavus and Aspergillus parasiticus. The combination of C. citratus and C. nardus and that of C. nardus and C. schoenanthus exhibited a synergistic effect against Aspergillus flavus and Aspergillus, respectively. Both C. citratus and C. schoenanthus EOs totally inhibited the synthesis of aflatoxin B1 at 1 µL/mL. C. citratus blocked the production of aflatoxins B2 and G2 at 0.5 µL/mL. Both C. citratus and C. schoenanthus totally hampered the production of the aflatoxin G1 at 0.75 µL/mL. The combination of C. citratus and C. schoenanthus completely inhibited the production of the four aflatoxins. The study shows that the combinations can be used to improve their antifungal and antiaflatoxinogenic activities.
The persistence of malaria and the increasing of resistance of Anopheles gambiae species to chemicals remain major public health concerns in sub-Saharan Africa. Faced to these concerns, the search for alternative vector control strategies as use of essential oils need to be implemented. Here, the five essential oils (EOs) from Cymbopogon citratus, Cymbopogon nardus, Eucalyptus camaldulensis, Lippia multiflora, Ocimum americanum obtained by hydro distillation were tested according to WHO procedures on Anopheles gambiae “Kisumu” and field strains collected in “Vallée du Kou”. Also, the binary combinations of C. nardus and O. americanum were examined. As results, among the EOs tested, L. multiflora was the most efficient regarding KDT50 and KDT95 and rate of morality values. Our current study showed that C8 (C.n 80% : O.a 20%) and C9 (C.n 90% : O.a 10%), were more toxic to Anopheles gambiae strain VK with the mortality rates reaching 80.7 and 100% at the 1% concentration, respectively. These two binary combinations shown a synergistic effect on the susceptible population. However, only C9 showed a synergistic effect on VK population. The bioactivity of the two EOs, Cymbopogon nardus and Ocimum americanum, was improved by the combinations at certain proportions and may constitute an alternative to pyrethroid resistance.
The frequency of occurrence and four principal kinds of aflatoxin concentration in maize seeds grown in Burkina Faso was investigated. Ten (10) samples collected, were analyzed by high performance liquid chromatography (HPLC) with post-column derivatisation after immunoaffinity column cleanup. Eight strains of Aspergillus section Flavi were previously isolated from these samples and cultivated on "Aspergillus flavus and parasiticus agar (AFPA)" to ascertain if they belong to A. flavus or A. parasiticus species. The qualitative ability of aflatoxin production was also previously performed by fluorescence emission under ultra violet light at 365 nm after four (4) days of incubation at 30 °C on Coconut Agar Medium (CAM). Results showed that 70% of samples were contaminated by aflatoxins. The levels ranged from 0.93 to 58.94 µg/kg. Samples M1 and M10 had high concentrations, 58.94 µg/kg and 70.73 µg/kg; whereas M4 and M5 had low concentrations from 1.68 to 0.93 µg/kg, respectively. In these samples, four were contaminated with aflatoxin B1 (AFB1) and aflatoxin G1 (AFG1), two with AFB1 and aflatoxin B2 (AFB2) and one (01) with AFB1 only. We notice that AFB1 was the most prevalent member of aflatoxins, and AFG2 was absent in all samples.
Fungi and their toxins have an impact on the hygienic standards and market value of corn (Zea Mayas L.) in Burkina Faso. Though effective, other pesticides have been shown to be harmful. This study aims to aid in the management of corn diseases by assessing the effectiveness of bio-fungicide formulations. In this study, the blotter method was used to assess the antifungal activity at doses of 0.5% (5 g/kg) and 1% (10 g/kg) of powdered formulations of Cymbopogon giganteus (F1) and Eucalyptus camaldulensis (F2) essential oils on the fungal flora of a corn sample. Untreated controls were also observed. The results of this study demonstrated that Aspergillus flavus and Aspergillus parasiticus, which could produce aflatoxin, were more susceptible to the 0.5% dose at F1 than at F2. Though Aspergillus niger and Rhizopus sp. were resistant to 0.5% of F1 and 0.5% of F2, while Fusarium sp. was resistant to 0.5% of F1. All of the above fungi were vulnerable to 1% of F1 and F2. Therefore, these two formulations could be utilized successfully to combat the decline in the hygienic, nutritional, and market value of corn in Burkina Faso caused by aflatoxin contamination and other toxins produced by these fungi. However, it would be important to evaluate the synergistic effect of these biofungicide formulations in situ and on a large scale.
The side effects prediction is a regulatory requirement prior the effective use of a new product as drug or pesticide constituent is allowed. The handling hazards of Cymbopogon schoenanthus essential oils (CSEO) were determined by investigating their acute and subacute toxicities as well as irritancy potential for eye and skin in compliance with the Organization for Economic Cooperation and Development guidelines. In mice, the essential oils did not induce mortality at the limit single dose of 2000 mg/kg b.w., meaning that the test product estimated LD 50 is 5000 mg/kg b.w. In the 28 days subacute oral toxicity study in rats, there was no mortality observed for all tested doses in both sex. Furthermore, besides body weight gain that slightly dropped, there was no significant difference observed in food and water consumption, relative organs weight, and blood biochemical profile in test animals, compared to the control. No eye irritant reaction was shown in the rabbits exposed to CSEO. To assess dermal irritation, rabbits were dermally exposed to CSEO for 4 h. The results showed that no adverse reactions such as erythema and edema were observed throughout the test. Based on these findings, CSEO do not cause either oral toxicity up to 28 days in repeated administration, nor dermal and eye irritation, and seems to be safe for animal in the study conditions. These results constitute a new scientific support for the safe use of C. scheonanthus essential oils as alternatives to synthetic pesticides. However, for further clinical relevance of the results and complete toxicological profile elucidation, toxicity studies must be extended to long term toxicity test as subchronic and chronic toxicities, reprotoxicity, carcinogenicity, teratogenicity, and mutagenicity investigations.
The persistence of malaria and the increasing of resistance of Anopheles gambiae species to chemicals remain major public health concerns in sub-Saharan Africa. Faced to these concerns, the search for alternative vector control strategies as use of essential oils (EOs) need to be implemented. Here, the five EOs from Cymbopogon citratus, Cymbopogon nardus, Eucalyptus camaldulensis, Lippia multiflora, Ocimum americanum obtained by hydro distillation were tested according to World Health Organization procedures on An. gambiae “Kisumu” and field strains collected in “Vallée du Kou”. Also, the binary combinations of C. nardus (Cn) and O. americanum (Oa) were examined. As results, among the EOs tested, L. multiflora was the most efficient on both An. gambiae strains regarding KDT50 (50% of mosquitoes knock down time) and KDT95 and rate of morality values. Our current study showed that C8 (Cn 80%: Oa 20%) and C9 (Cn 90%: Oa 10%), were the most toxic to An. gambiae strain “Vallée de Kou” (VK) with the mortality rates reaching 80.7 and 100% at 1% concentration, respectively. These two binary combinations shown a synergistic effect on the susceptible population. However, only C9 gave a synergistic effect on VK population. The bioactivity of the two EOs, C. nardus and O. americanum, was improved by the combinations at certain proportions. The resistance ratios of all EOs and of the combinations were low (< 5). The combinations of C. nardus and O. americanum EOs at 90: 10 ratio and to a lesser extent L. multiflora EO, could be used as alternative bio-insecticides against malaria vectors resistant to pyrethroids in vector control programmes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.