No abstract

The study was conducted to investigate the antibacterial effect of Andrographis paniculata against selected human pathogens using microbiological techniques. Different solvents were used to extract the active components from the leaves. The antibacterial activity was studied against selected human pathogens viz, Escherichia coli, Salmonella sp, Bacillus sp and Enterococccus sp. For E. coli, the range of minimum inhibition zone at 2.5 mg/ml, 5.0 mg/ml, 7.5 mg/ml and 10.0 mg/ml ethanol extract was 15 mm-25 mm while that of aqueous extract was 13 mm-17 mm with a nondetectable zone at 2.5 mg/ml concentration. Salmonella sp had inhibition zone range of 13 mm-22 mm for ethanol extract while the same organism showed minimum inhibitory zone range of 11 mm-21 mm for aqueous extract. The inhibition zone range of ethanol extract against Bacillus sp was 16.5 mm-25.5 mm while aqueous extract had 9.5 mm-19 mm. Finally for Enterococcus sp, the inhibition zone range of ethanol extract was 15 mm-25.5 mm while aqueous extract had 9 mm-25 mm. Among the two solvents, ethanol extract showed greater antibacterial activity against the test organisms when compared with the aqueous extract at 10.0 mg/ml concentration of the extracts. Preliminary screening of phytochemicals in the leaf extract of Andrographis paniculata revealed the presence of alkaloids (6.266±0.376 mg/100g), saponins (11.055±0.134 mg/100g), flavonoids (1.175±0.067 mg/100g), tannins (2.230±0.099 mg/100g) and cyannogenic glycosides (0.870±0.057 mg/100g). The results revealed that 10.0mg/ml concentration had effect on all the test bacteria.