Structure-Related Cytotoxicity and Anti-Hepatofibric Effect of Asiatic Acid Derivatives in Rat Hepatic Stellate Cell-Line, HSC-T6

The structural relationship of 16 asiatic acid (AA) derivatives, including AA and asiaticoside (AS) to cytotoxicity and anti-hepatofibrotic activity in HSC-T6 cells, were investigated. Cytotoxicities of AA derivatives varied from 5.5 $\mu$M to over 2000 $\mu$M of $IC_{50}$/ depending on AA functional group modifications. Substituting the hydroxyl group at the C(2) to N≡C and substituting bulky groups for dihydroxyl groups at (3), (23) of the A-ring increased the cytotoxicity, but keto group at C(11) and benzoyl ester at C(2) were greatly reduced it. Modification of the carboxylic acid group at C28 also reduced the cytotoxicity. The collagen synthesis determined by hydroxyproline content in the cells was inhibited from a maximum of 48% (Zlx-i-85 and 87) to 15% (AS) by AA derivatives. The anti-hepatofibrotic effect of these compounds might be due to the reduced expression of prolyl 4-hydroxylase $\alpha$ and $\beta$ subunits and TIMP2. However, the inhibition of collagen by asiaticoside derivatives did not show any structural-activity relationship.