Baicalein (BAL), a main flavonoid constituent of Scutellaria radix, was studied for its inhibitory effects on tert-butyl hydroperoxide (t-BHP)-induced hepatotoxicity and oxidative damage in primary cultures of rat hepatocytes. In a preliminary study, baicalein revealed effective antioxidant properties in a test of its capacity to quench the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH). Further investigations showed that baicalein, at the concentrations of 1, 5, and 10 microM, decreased the leakage of lactate dehydrogenase (LDH) and alanine aminotransferase (ALT) and the formation of malondialdehyde (MDA) induced by 30 min of pretreatment with t-BHP (1.5 mM) in primary cultures of rat hepatocytes. Baicalein also attenuated t-BHP-induced mitochondrial depolarization as determined by a retention test of rhodamine 123 and DNA repair synthesis as evidenced by unscheduled DNA synthesis (UDS). In addition, baicalein decreased the 8-hydroxy-2'-deoxyguanosine (8-OH-dG) content which acts as a DNA damage marker. The sum of the results suggests that the protective effect of baicalein against the cytotoxicity and genotoxicity of hepatocytes induced by t-BHP is due to its ability to quench free radicals.
