Abstract

Objective: To evaluate antioxidant activity and quantify total content of polyphenols and flavonoids in two Cucurbitaceae plant extracts, Citrullus colocynthis (C. colocynthis) fruits and Bryonia dioica (B. dioica) roots. Methods: Qualitative and quantitative analysis of aqueous and butanolic extracts, prepared from C. colocynthis fruits and B. dioica roots was carried out using standard methods. Estimation of their antioxidant activity was determined by free radical scavenging activity assay using 2,2-diphenyl-l-picrylhydrazyl and ferric reducing antioxidant power assay. Results: Preliminary phytochemical screening of the aqueous and organic extracts showed the presence of tannins, flavanoids, terpenoids, saponins and quinones. The content of phenolic compounds varies among the two species of cucurbits and even in the different extracts of the same species. The most important amount of total polyphenols and flavanoids expressed respectively as gallic acid and catechin equivalent per gram extract, was determined in butanolic extract of B. dioica roots (541.78 mg/g, 120.60 mg/g). The lowest values were noted in C. colocynthis fruit aqueous extract (219.58 mg/g, 46.13 mg/g). Butanolic extract of B. dioica roots exhibited an interesting free radical scavenging activity with IC50 = 2.25 µg/mL compared to IC50 = 1.5 µg/mL of ascorbic acid, followed by B. dioica roots aqueous extract (IC50 = 47.25 µg/mL), butanolic C. colocynthis fruit extract (IC50 = 61 µg/mL) and C. colocynthis fruit aqueous extract (IC50 = 241.25 µg/mL). A highest reducing power was observed in B. dioica roots butanolic extract compared to other extracts (C. colocynthis fruit aqueous and butanolic extracts and B. dioica roots aqueous extract). Conclusions: The results indicate that the wealth of B. dioica roots extracts on polyphenols and flavonoids is more than C. colocynthis fruit extracts. These phytoconstituents ensure an interesting free radical scavenging activity and reducing power for the B. dioica roots extracts especially butanolic extract.

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