Insight into Screening of Secondary Metabolites, Phenolic and Flavonoid Contents and Antioxidant Activity of Raphanus sativus L. Cultivated in Eastern Province of Saudi Arabia

Medicinal plants and vegetables are promising source of antioxidant products. The purpose of this study is to evaluate the phytochemicals and antioxidant activity of leaves and roots of Raphanus sativus of Saudi origin. Various phytochemicals were screened in n-hexane, chloroform, ethyl acetate and aqueous fractions of leaves and roots of Raphanus sativus using standard protocols and IR screening method. Total phenolic (TPC) and flavonoid (TFC) contents were assessed by Folin-Ciocalteau and aluminium chloride methods respectively. The antioxidant activity was evaluated by DPPH antioxidant protocol, using trolox as standard. Results demonstrated that Raphanus sativus chemically characterized by the availability of various constituents such as flavonoids, steroids, saponins, tannins and carbohydrates at different levels in fractions of leaves and roots of Raphanus sativus and the absence of cardiac glycosides, anthraquinones and alkaloids which was further confirmed using FTIR analysis. TPC was ranged from (8.92±1.01) and (211.80±1.57) mg GAE/g extract and TFC was ranged from (0.036±0.03) and (11.57±0.60) mg QE/g extract for leaves and roots extracts respectively. Due to the high phenolic and flavonoid content in aqueous and ethyl acetate fractions of leaves and roots extracts , results demonstrated high antioxidant activity with IC₅₀: (56.3±1.3) and (69.7±1.8) for aqueous fractions and (47.2±1.5) and (58.7±0.7) for ethyl acetate fractions of leaves and roots extracts respectively Study revealed that ethyl acetate and aqueous fractions of leaves and roots of Raphanus sativus could develop a potential natural antioxidant herbal remedy. The study recommends future investigation to isolate and identify the bioactive secondary metabolites in Raphanus sativus.