SUMMARY
In vitro antibacterial activity of 21 plant methanolic extracts were investigated by disc diffusion method against gram-negative bacteria Escherichia coli. Amongst the extracts tested, the Datura stramonium L. and Ocimum basilicum L. showed significant antibacterial activity against the bacterial pathogen. D. stramonium showed the highest antibacterial activity followed by O. basilicum extract. Phytochemical analysis of extracts showed the presence of alkaloids, tannins, saponins, flavonoids, and phenols. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ABTS analysis of potent extract D. stramonium showed appreciable antioxidant activity. For DPPH and ABTS assay the highest antioxidant activity was observed at 60 mg ml-1 concentration with a percent inhibition of 71.66 and 77.19 with IC50 value 9.71 and 22.16 µg ml-1 respectively. Moreover, the radical scavenging activity of the extract was lower than that observed for the synthetic antioxidants butylated hydroxyanisole (BHA )and butylated hydroxytoluene (BHT). The total phenolic content of D. stramonium extract was found to be 0.592 mg GAE/gm which was assayed using Folin ciocalteau reagent. The results provide evidence that the extract of D. stramonium and O. basilicum can be further recommended in the treatment of the infections caused by E. coli; further D. stramonium is also a potential source of natural antioxidants.