In vitro study of DNA protective effect of DuZhong (Eucommia ulmoides Oliv.) using single cell gel electrophoresis

DuZhong (Eucommia ulmoides Oliv.) is a Chinese traditional medicinal herb with antioxidant actions toward oxidative damage which is well documented in different scientific researches. Comet assay (single cell gel electrophoresis) is a well-developed technique for the analysis on DNA damage in single cell level. The purpose of this study is to compare aqueous and alcoholic crude extract of DuZhong cortex for its potential in vitro DNA protective effect on human lymphocytes against oxidative stress environment. Venous blood was collected from three healthy adult volunteers followed by isolation of lymphocytes. DuZhong extract was obtained by boiling in water and ultrasound-assisted alcoholic extraction. Lymphocytes were incubated to different dilutions of DuZhong extract before oxidative challenge with hydrogen peroxide solution in standard and lysed cell comet assay. The nucleus of lymphocyte was stained and manually scored under fluorescent microscope. Significant reduction in length of comet was only found in 0.1mg/L of aqueous extract undergone lysed cell comet assay while alcoholic extract did not show significant reduction with same other experimental setting. No significant reduction in comet length and no obvious difference were seen among aqueous and alcoholic extracts in standard comet assay. The result demonstrated that DuZhong shows some DNA protection action against oxidant stress for specific experimental condition.