Larvicidal activity, phytochemical composition, and antioxidant properties of different parts of five populations of Ricinus communis L.

This study was conducted to evaluate, the phytochemical composition of leaves and roots of five Tunisian populations of castor (Ricinus communis L.). Levels of total phenolic contents, total flavonoids, and condensed tannins of methanolic extracts were determined by UV-spectrophotometer. Phenolic compounds were identified and quantified by RP-HPLC (reverse phase HPLC). Gentisic acid, catechin, rutin, vanillic acid, vitexin, and gallic acid were detected. GC–MS analysis that uses the FAME (fatty acid methyl ester) method in castor oils revealed the existence of palmitic, stearic, oleic, gondoic, linoleic, and ricinoleic acids. The antioxidant properties of leaves, roots, and oils of castor using the DPPH radical scavenging capacity assays. The study showed a high antioxidant capacity which was expressed by a very low IC50 values for the leaves extracts: Hammamet (0.65 μg/ml), Aouled Amer (2.42 μg/ml), Riadh Andalous (2.34 μg/ml), Nefza (3.91 μg/ml), and Khanguet Hajej (2.39 μg/ml).Besides, we investigated the larvicidal activity of aqueous extracts of leaves and seeds against Culex pipiens L. larvae. Toxicity tests showed a mortality of 100% after 24 h of exposure. The LC50 values for the seed extracts were low: Aouled Amer (570 mg/l), Nefza (603 mg/l), Khanguet Hajej (1260 mg/l), Riadh Andalous (1225 mg/l), and Hammamet (2140 mg/l).This study permits to exhibit two positive correlation relationships: the first one between the total phenolic compounds, total flavonoid compounds, and the antioxidant activities of leaves and roots extracts, and the second one between the antioxidant activity and the larvicidal activity of the leaves extracts.