Antioxidant potential and polyphenols analysis of medicinal herb Ocimum tenuiflorum (Shyama Tulsi)

Abstract

Ocimum tenuiflorum considered the queen of herbs, is a clinically proven medicinal plant. O.tenuiflorum has two varients: Shyama Tulsi and Rama Tulsi. Yet, no clear record of polyphenols in Shyama Tulsi is available in the literature. So, the present study aimed to analyse the antioxidant potential and polyphenolic content of O.tenuiflorum (Shyama Tulsi). The leaves were procured from the Department of Genetics and Plant Breeding, College of Agriculture at Chaudhary Charan Singh Haryana Agriculture University (CCS HAU), Hisar, India and extracted with 50 % methanol (OtM) and sequentially fractionated with n-hexane (OtH), ethyl acetate (OtE) and n-butanol (OtB). Total phenolic and flavonoid content was determined using the Folin-Ciocalteu Colorimetric method; and the aluminum chloride using the Colorimetric method. The antioxidant potential was evaluated through DPPH (2,2-Diphenyl-1-picrylhydrazyl), ABTS (2,2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) and FRAP (Ferric reducing antioxidant power) assay, using ascorbic acid as a positive control. The study revealed that total phenolic and flavonoid content were highest in methanol extract, i.e. 863.63±0.17 mg GAE/g, 310.16±0.25 mg QE /g, followed by n-butanol, ethyl acetate and n-hexane. The antioxidant potential was highest in the n-butanol fraction compared to all other fractions. HR-LCMS profiling of OtB and OtE showed the presence of different polyphenols like 6-C-Galactosylluteolin, quercitrin, apigenin 4’-O-glucoside, caffeic acid, myricitrin, kaempferol and their derivatives. The presence of different polyphenols and the higher antioxidant activity of this medicinal herb make it an alternative source for treating various ailments and human health problems.