Protective role of litchi (Litchi chinensis Sonn.) flower extract against cadmium- and lead-induced cytotoxicity and transforming growth factor β1-stimulated expression of smooth muscle α-actin estimated with rat liver cell lines

The protective potential of litchi flower acetone extract (LFAE) against cadmium (Cd)- and lead (Pb)-induced hepatocytotoxicity, and transforming growth factor β1 (TGF-β1)-mediated activation of hepatic stellate cells (HSCs) were evaluated. Phenolic compounds were plentiful in LFAE (429. mg/g of dried extract); epicatechin (122.1. mg/g of dried extract), gentisic acid (60.2. mg/g of dried extract) and proanthocyanidin A2 (163.3. mg/g of dried extract) were the major flavanoid, phenolic acid and proanthocyanidin, respectively. Cd and Pb treatments significantly promoted lipid peroxidation and DNA damage in rat liver cells (Clone 9), and caused viabilities of the cells down. However, LFAE addition could dose-dependently decrease the Cd- and Pb-induced lipid peroxidation and DNA fragmentation, and increase the cell viabilities. LFAE could also suppress TGF-β1-induced activation of HSCs concluded from down-regulating expression of smooth muscle α-actin (αSMA). These effects should be attributed to the antioxidant action of phenolic compounds in LFAE.