The protective activity of alpha-hederine against H2O2 genotoxicity in HepG2 cells by alkaline comet assay

This study was designed to evaluate the protective effect of alpha-hederine (alpha-hed) against H2O2-mediated DNA damage on HepG2 cell line by the alk aline comet assay. For the protective effect of alpha-hed study, cells were treated according to three protocols: pre-treatment, simultaneous treatmen t and post-treatment. The effect of oc-hed on catalase activity was evaluat ed after treating the cells with 3.36 mg/ml of 3-amino-1,2,4-triazole (AMT) singly or in combination with alpha-hed (1.5 or 3 IJ mu g/ml) and H2O2 (8. 8 mu M) during 1 h. The catalase activity was also biochemically measured a fter treating cells with a-hed at 1.5, 3, or 15 mu g/ml during 1 h. Additio nally, the influence of a-hed on membrane RedOx potential, pool of reduced glutathione and total protein content was evaluated by Row cytometry. In th e pre-treatment, the two concentrations of ol-hed (1.5 and 3 mu g/ml) decre ased the lesions induced by H2O2 (8.8 IJ mu M) significantly. This decrease was about 57.2% and 66.1%, respectively. Similar results were observed whe n cells were treated with oc-hed and H2O2 simultaneously. The decrease of H 2O2 induced lesions was about 78.2% and 83.2% (oc-hed 1.5 and 3 mu g/ml, re spectively). In the post-treatment protocol, this decrease was not signific ant. The combination of AMT and H2O2 induced more DNA damage than H2O2 alon e (tail moment (TM) means was 31.4% and 21.8%, respectively). When alpha-he d was added to this mixture, TM means were reduced significantly (17.4% for alpha-hed 1.5 mu g/ml and 15.5% for alpha-hed 3 mu g/ml). Up to 6.9 mu g/m l, alpha-hed enhanced catalase activity (60.5%), followed by a decrease of the activity. Total protein content and membrane RedOx potential were sligh tly increased up to 11 mu g/ml (14% and 3.6%, respectively) followed by a d rop and a plateau. Pool of reduced glutathione remained unchanged up to 10 mu g/ml then dropped and reached a plateau. In conclusion, alpha-hed could exert its protective effect against H2O2-mediated DNA damage by scavenging free radicals or by enhancing the catalase activity. (C)1999 Elsevier Scien ce B.V. All rights reserved.