New quinic acid derivatives from hepatoprotective Inula crithmoides root extract

Fractionation directed by hepatoprotective activity of Inula crithmoides L. root resulted in the isolation of two new quinic acid derivatives, 3,5-di-O-caffeoylquinic acid 1-methyl ether (I; caffeoyl=(E)-3-(3,4- dihydroxyphenyl)prop-2-enoyl; quinic acid=1,3,4,5- tetrahydroxycyclohexanecarboxylic acid) and 4,5-di-O-caffeoylquinic acid 1-methyl ether (II), in addition to the well-known hepatoprotective compound, 1,5-di-O-caffeoylquinic acid (III). The hepatoprotective effect was indicated by the significant decrease in the level of four measured serum biochemical parameters (SGOT, SGPT, ALP, and bilirubin) in experimental rats. The structures of the isolated compounds were determined by analyses of 1D- and 2D-NMR spectroscopic data.