The influence of serratula coronata and trigonella foenum-graecum extracts on resistance of bacteria Escherichia coli to peroxide stress

The influence of Serratula coronata and Trigonella foenum-graecum extracts and ecdisteroid-containing substance Serpisten on stress gene expression and resistance of bacteria E. coli to action of hydrogen peroxide was investigated. All the substances studied were shown to increase expression of antioxidant genes katG and sodA, encoding catalase-hydroperoxidase I and Mn-superoxidedismutase, respectively. The extracts of S. coronata and T. foenum-graecum protected bacteria against bacteriostatic doses of hydrogen peroxide, while Serpisten did not affect bacterial resistance to peroxide stress. Apparently, the observed protection was due to the extracts' content of polyphenols which demonstrated radical-scavenging, metal-chelating and prooxidant activities.