Inhibitors of Aldose Reductase and Formation of Advanced Glycation End-Products in Moutan Cortex (Paeonia suffruticosa)

The methanol extract of Moutan cortex (Paeonia suffruticosa) afforded two new compounds, 8-O-benzoylpaeonidanin (1) and 5-hydroxy-3S-hydroxymethyl-6-methyl-2,3-dihydrobenzofuran (2), in addition to 4-O-butylpaeoniflorin (3) as an artifact of the separation, seven monoterpene glycosides (4-10), two monoterpenes (11, 12), four acetophenones (13-16), and two triterpenes (17, 18). The structures of the compounds were determined by spectroscopic methods, and the compounds were evaluated for inhibitory effects against rat lens aldose reductase (RLAR) and advanced glycation end-product (AGEs) formation. Compounds 17 and 18 showed the most potent inhibitory activity against RLAR, with IC50 values of 11.4 and 28.8 mu M, respectively. Compounds 3 and 6 also inhibited RLAR with IC50 values of 36.2 and 44.6 mu M, respectively. The positive control, 3,3-tetramethyleneglutamic acid, had an IC50 value of 31.8 mu M. Compounds 3 and 6 inhibited AGE formation with IC50 values of 10.8 and 11.3 mu M, respectively. Compound 2 had an IC50 value of 177.0 mu M, whereas the positive control, aminoguanidine, had an IC50 value of 1026.8 mu M.