Inhibition of aldose reductase in vitro by constituents of Ganoderma lucidum.

CHCl(3) extract of the fruiting body of Ganoderma lucidum was found to show inhibitory activity on human aldose reductase in vitro. From the acidic fraction, potent human aldose reductase inhibitors, ganoderic acid C2 (1) and ganoderenic acid A (2), were isolated together with three related compounds. It was found that the free carboxyl group of ganoderic acid C2 and ganoderenic acid A is essential in eliciting the inhibitory activity considering the much lower activity of their methyl esters.