Aldose reductase inhibitors from the leaves of Myrciaria dubia (H. B. & K.) McVaugh.

Abstract Ellagic acid (1) and its two derivatives, 4- O -methylellagic acid (2) and 4-( α -rhamnopyranosyl)ellagic acid (3) were isolated as inhibitors of aldose reductase (AR) from Myrciaria dubia (H. B. & K.) McVaugh. Compound 2 was the first isolated from the nature. Compound 3 showed the strongest inhibition against human recombinant AR (HRAR) and rat lens AR (RLAR). Inhibitory activity of compound 3 against HRAR (IC 50 value=4.1×10 −8  M) was 60 times more than that of quercetin (2.5×10 −6  M). The type of inhibition against HRAR was uncompetitive.