title: Rat lens aldose reductase inhibitory constituents of Nelumbo nucifera stamens.
abstract: Aldose reductase, the principal enzyme of the polyol pathway, has been shown to play an important role in the complications associated with diabetes. A methanol extract of the stamens of Nelumbo nucifera Gaertn. was shown to exert an inhibitory effect on rat lens aldose reductase (RLAR), and thus was fractionated using several organic solvents, including dichloromethane, ethyl acetate and n-butanol. The ethyl acetate-soluble fraction, which manifested potent RLAR-inhibitory properties, was then purified further via repeated measures of silica gel and Sephadex LH-20 column chromatography. Thirteen flavonoids: kaempferol (1) and seven of its glycosides (2-9), myricetin 3',5'-dimethylether 3-O-beta-d-glucopyranoside (10), quercetin 3-O-beta-d-glucopyranoside (11) and two isorhamnetin glycosides (12, 13) were isolated from N. nucifera, as well as four non-flavonoid compounds: adenine (14), myo-inositol (15), arbutin (16) and beta-sitosterol glucopyranoside (17). These compounds were all assessed with regard to their RLAR-inhibitory properties. Among the isolated flavonoids, those harboring 3-O-alpha-l-rhamnopyranosyl-(1-->6)-beta-d-glucopyranoside groups in their C rings, including kaempferol 3-O-alpha-l-rhamnopyranosyl-(1-->6)-beta-d-glucopyranoside (5) and isorhamnetin 3-O-alpha-l-rhamnopyranosyl-(1-->6)-beta-d-glucopyranoside (13), were determined to exhibit the highest degree of rat lens aldose reductase inhibitory activity in vitro, evidencing IC(50) values (concentration required for a 50% inhibition of enzyme activity) of 5.6 and 9.0 microm, respectively.
authors.affiliation: Silver Biotechnology Research Center, Hallym University, Chuncheon 200-702, Korea.
authors.forename: Soon Sung
authors.initials: SS
authors.lastname: Lim
authors.forename: Yu Jung
authors.initials: YJ
authors.lastname: Jung
authors.forename: Sook Kyung
authors.initials: SK
authors.lastname: Hyun
authors.forename: Yeon Sil
authors.initials: YS
authors.lastname: Lee
authors.forename: Jae Sue
authors.initials: JS
authors.lastname: Choi
mesh_terms: D000449:Aldehyde Reductase / Q000037:antagonists & inhibitors*; D000818:Animals; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D035264:Flowers / Q000737:chemistry; D007908:Lens, Crystalline / Q000187:drug effects / Q000201:enzymology*; D031653:Nelumbo / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D005419:Flavonoids; D010936:Plant Extracts; D000449:Aldehyde Reductase