Evaluation of antioxidant and antibacterial activities of methanolic flower extract of Wedelia trilobata (L.) Hitch

Abstract

Wedelia trilobata (L.) Hitch is a member of the family Asteraceae, with attractive yellow flowers borne singly at the end of each stem. The work was conducted to investigate the antioxidant, antimicrobial and DNA protecting ability of the methanol extract of W. trilobata flower. Antioxidant properties were assessed by 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2'-azino-bis 3- thylbenzthiazoline-6-sulphonic acid (ABTS) assay. The methanol extract and standard ascorbic acid showed antioxidant activity with IC₅₀ value of 90 μg/ml and 60 μg/ml respectively in DPPH radical scavenging assay. The in vitro antibacterial screening was evaluated by disc diffusion method against three Gram-positive and three Gram-negative human pathogenic bacteria. The extract showed zones of inhibition of 10-16 mm against different strains. The phenolic content of the extract was 250 gallic acid equivalence (GAE in μg) which was measured by Folin-Ciocalteu method. The extract was tested for pTZ57R/T plasmid DNA protection against hydroxyl radicals as evidenced by DNA fragmentation assay.

Key words: Asteraceae plant species, methanol extract, antioxidant, antimicrobial, DNA protection assay.