In vitro antibacterial effect of Withania somnifera root extract on Escherichia coli

The aim was to investigate antibacterial activity of Withania somnifera (Ashwagandha), an Indian traditional medicinal plant against Escherichia coli O78, a pathogenic strain.

Two-fold serial dilutions of 20% aqueous W. somnifera root (WSR) extract were inoculated with E. coli O78 @ 1*10(7) colony forming units grown in nutrient broth. Following inoculation, turbidity optical density was measured by spectrophotometer at 600 nm in all the tubes at 0, 2, 4, 6 and 8 h of incubation at 37°C.

The results revealed that the maximum inhibition of bacterial growth was observed at 1:8 dilution of WSR extract. The highest dilution of the extract that showed inhibited growth of the test organism when compared with control was 1:16. Therefore, the minimum inhibitory concentration of aqueous extract of WSR is 1:16.

It is concluded that WSR possessed good antibacterial activity, confirming the great potential of bioactive compounds and its rationalizing use in health care.