Antifungal Activity of Cyperus articulatus, Cyperus rotundus and Lippia alba Essential Oils against Aspergillus flavus Isolated from Peanut Seeds.

Aspergillus flavus is a cosmopolitan saprophytic fungus that infests several foodstuffs and is associated with adverse effects in humans. In Senegal, significant losses of groundnut production are mainly due to contamination caused by this species. This study evaluated in vitro antifungal activities of Cyperus articulatus, Cyperus rotundus and Lippia alba essential oils against A. flavus isolated from peanut seeds. Essential oils obtained by hydrodistillation of rhizomes of the two Cyperus species and leaves of L. alba were analyzed with GC-DIF and GC-MS. The essential oil yields from C. articulatus, C. rotundus and L. alba were 1.1%, 1.3% and 1.7%, respectively. These three samples had the following chemotypes: (i) mustakone (21.4%)/eudesma-4(15)-7-dien-1ß-ol (8.8%)/caryophyllene oxide (5.9%), (ii) caryophyllene oxide (25.2%)/humulene epoxyde 2 (35.0%) and (iii) geranial (46.6%)/neral (34.6%). The three oils tested inhibited the growth of A. flavus at concentrations between 100 and 1000 ppm. The L. alba oil was the most effective with total clearance of A. flavus on PDA. For the essential oils of C. rotundus (93.65%) and C. articulatus (78.11%), the highest inhibition rates were obtained with a 1000 ppm dose. Thus, L. alba oil could be used safely as an effective protector of groundnuts against A. flavus.

Larvicidal activity of Neem oil and three plant essential oils from Senegal against Chrysodeixis chalcites (Esper, 1789)

Objective:To evaluate the insecticide,larvicidal and repellent activity of the essential oils from Callistemon vimindis,Melaleuca leueadendron,and Hyptis suaveolens against Chrysodeixischalcites and to compare it with neem oil (Azadirachta indica).Methods:The essential oils of the leaves of these aromatiques plants were extracted by steam distillation and contacts tests were carried out.Results:Essential oils in ethanol from Callistemon viminalis showed a higher biological activity than the neem with 100％ larval mortality at the concentration of 2 μg/mL for 6 h,100％ and 90％ in ethanol from Melaleuca leucadendron and Hyptis suaveolens,respectively at the concentration of 4 μg/mL for 24 h.By inhalation,the essential oils from Melaleuca leucadendron and of Hyptis suaveolens were more effective with mortality rates of larvae 100％ and 50％ respectively at 2 μg/L air applied after 24 h.Nevertheless,the neem has shown to be a repulsive plant and anti-nutritional plant.A significant difference in the percentages of consumption between leaves treated with neem oil and the control samples was observed (Newman-Keuls test) except for Melaleucaleucadendron.Conclusions:The results of the study highlight remarkable biocide,properties of tested extracts,which provides important opportunities for the development of biopesticides.

Chemical characterization of essential oil from the leaves of Callistemon viminalis (D.R.) and Melaleuca leucadendron (Linn.)

Objective:To isolate and identify the compounds in the essential oils from the leaves of Callistemon viminalis (D.R.) and Melaleuca leucadendron (Linn.) collected in Dakar,Senegal.Methods:The essential oils from the leaves of these two myrtaceaes were extracted by steam distillation and analyzed by gas chromatograph and gas chromatography-mass spectrometer.Results:A total of 34 constituents were identified in the oil of Callistemon viminalis and the major compounds were 1.8-cineole (58.12％),limonene (9.72％),α-terpineol (9.56％),geranial (6.02％),δ-elemene (3.53％),myrcene (2.96％) and α-pinene (2.49％).For the essential oil of Melaleuca leucadendron,43 constituents were identified,and 1.8-cineole (28.87％),epiglobulol (23.06％),α-pinene (12.22％),limonene (11.65％) and α-terpineol (7.06％) were major compounds.Conclusions:Considering properties of the identified major compounds,essential oils of both studied myrtaceae could be used in the medicine field including the food,pharmaceutical and cosmetic industry.

Benchmarking the DFT methodology for assessing antioxidant-related properties: quercetin and edaravone as case studies.

The overall objective was to identify an accurate computational electronic method to virtually screen phenolic compounds through their antioxidant and free-radical scavenging activity. The impact of a key parameter of the density functional theory (DFT) approach was studied. Performances of the 21 most commonly used exchange-correlation functionals are thus detailed in the evaluation of the main energetic parameters related to the activities of two prototype antioxidants, namely quercetin and edaravone, is reported. These functionals have been chosen among those belonging to three different families of hybrid functionals, namely global, range separated, and double hybrids. Other computational parameters have also been considered, such as basis set and solvent effects. The selected parameters, namely bond dissociation enthalpy (BDE), ionization potential (IP), and proton dissociation enthalpy (PDE) allow a mechanistic evaluation of the antioxidant activities of free radical scavengers. Our results show that all the selected functionals provide a coherent picture of these properties, predicting the same order of BDEs and PDEs. However, with respect to the reference values, the errors found at CBS-Q3 level significantly vary with the functional. Although it is difficult to evidence a global trend from the reported data, it clearly appears that LC-ωPBE, M05-2X, and M06-2X are the most suitable approaches for the considered properties, giving the lowest cumulative mean absolute errors. These methods are therefore suggested for an accurate and fast evaluation of energetic parameters related to an antioxidant activity via free radical scavenging.

In vitro vasorelaxation mechanisms of bioactive compounds extracted from Hibiscus sabdariffa on rat thoracic aorta.

BACKGROUND: In this study, we suggested characterizing the vasodilator effects and the phytochemical characteristics of a plant with food usage also used in traditional treatment of arterial high blood pressure in Senegal. METHODS: Vascular effects of crude extract of dried and powdered calyces of Hibiscus sabdariffa were evaluated on isolated thoracic aorta of male Wistar rats on organ chambers. The crude extract was also enriched by liquid-liquid extraction. The various cyclohexane, dichloromethane, ethyl acetate, butanol extracts obtained as well as the residual marc were subjected to Sephadex LH-20 column chromatography. The different methanolic eluate fractions were then analyzed by Thin Layer (TLC) and High Performance Liquid Chromatography (HPLC) and their vascular effects also evaluated. RESULTS: The H. Sabdariffa crude extract induced mainly endothelium-dependent relaxant effects. The endothelium-dependent relaxations result from NOS activation and those who not dependent to endothelium from activation of smooth muscle potassium channels. The phytochemical analysis revealed the presence of phenolic acids in the ethyl acetate extract and anthocyans in the butanolic extract. The biological efficiency of the various studied extracts, in term of vasorelaxant capacity, showed that: Butanol extract > Crude extract > Residual marc > Ethyl acetate extract. These results suggest that the strong activity of the butanolic extract is essentially due to the presence of anthocyans found in its fractions 43-67. CONCLUSION: These results demonstrate the vasodilator potential of hibiscus sabdariffa and contribute to his valuation as therapeutic alternative.