Abstract: AIM:To investigate the effect of different types of flavonoids, galangin (flavonol), hesperetin (flavonone) and hydroxysafflor yellow A (HYSA, chalcone), on cardiomyocytic injury induced by H₂O₂, and explore the possible signal pathways involved.METHODS:The cytotoxicity of different flavonoids was determined by MTT assay. Apoptosis rate was determined by flow cytometry (FCM) and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). Immunohistochemistry was used for detection of Bcl-2, Bax and Caspase-3 protein.RESULTS:It showed that each flavonoid did not have noticeable cytotoxicity at a concentration of 5 μmol/L by MTT assay. Flavonoids at concentrations of 5, 15 and 30 μmol/L significantly increased cell viability compared to model group induced by H₂O₂ (100 μmol/L). Flavonoids also increased apoptosis rate and neorobiosis rate determined by FCM compared to model group. Galangin and hesperetin significantly decreased the apoptotic rate determined by TUNEL and the expression of Caspase-3 and increased the ratio of Bcl-2 Bax (P<0. 05) compared with model group.CONCLUSION:The results suggest that galangin and hesperetin inhibit the apoptosis induced by H₂O₂ in neonatal rat cardiomyocytes and that there was not noticeable difference between galangin and hesperetin in TUNEL test when H₂O₂ was used at a concentration of 100 μmol/L. They regulate the expression of Bcl-2, Bax and Caspase-3 proteins. HYSA may have stronger effect on neorobiosis than on apoptosis.

Key words: flavonoids, apoptosis of cardiomyocytes, antioxidant