Two new 2-arylbenzofuran derivatives from hypoglycemic activity-bearing fractions of Morus insignis.

Ethyl acetate- and n-butanol-soluble fractions of the leaves of Morus insignis showed a significant hypoglycemic activity on streptozotocin (STZ)-induced hyperglycemic rats. From these hypoglycemic activity-showing fractions, two new compounds, mulberrofuran U (2) and moracin M-3-O-beta-D-glucopyranoside (3) were isolated, along with six known compounds [beta-sitosterol, beta-sitosterol-3-O-beta-glucopyranoside, ursolic acid, moracin M (1), kaempferol-3-O-beta-glucopyranoside and quercetin-3-O-beta-glucopyranoside] and the structures of the new compounds were determined by spectroscopic and chemical methods.

Palbinone, a novel terpenoid from Paeonia albiflora; potent inhibitory activity on 3 alpha-hydroxysteroid dehydrogenase.

Palbinone, a novel terpenoid isolated from the roots of Paeonia albiflora, showed a strong inhibitory activity on the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH)-linked 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD) of rat liver cytosol. The structures of palbinone and a known compound, paeonilactone-B isolated from the active fraction of this plant were determined by the use of 2D NMR techniques (1H-1H COSY, 1H-13C COSY, 1H-13C long-range COSY, and HMBC).

Studies on aldose reductase inhibitors from natural products. IV. Constituents and aldose reductase inhibitory effect of Chrysanthemum morifolium, Bixa orellana and Ipomoea batatas.

The hot water extracts of Chrysanthemum morifolium, Bixa orellana and Ipomoea batatas, were found to have potent inhibitory activity towards lens aldose reductase (AR). Ellagic acid (4) was isolated from C. morifolium and I. batatas, isoscutellarein (7) from B. orellana and 3,5-dicaffeoylquinic acid (10) from I. batatas, respectively, as potent inhibitors.

Studies on aldose reductase inhibitors from medicinal plant of "sinfito," Potentilla candicans, and further synthesis of their related compounds.

For several years we have screened natural products having aldose reductase (AR) inhibitory activity. 3,3',4-Tri-O-methylellagic acid 4'-sulfate potassium salt (2) was isolated from a Mexican herb "Sinfito" (Potentilla candicans) as a potent AR inhibitory active constituent. 2 was more potent (IC50 = 8.0 x 10(-8)M) than ellagic acid, which is one of the natural inhibitors of AR. So we examined the synthesis of ellagic acid derivatives and found that the sulfate group is one of the important function.

Studies on aldose reductase inhibitors from natural products. II. Active components of a Paraguayan crude drug "Para-parai mí," Phyllanthus niruri.

Aldose reductase (AR) inhibitory activity-directed fractionation of the 70% ethanolic extract of Para-parai mí, Phyllanthus niruri, has led to the isolation of three active components, ellagic acid (1), brevifolin carboxylic acid (4) and ethyl brevifolin carboxylate (5). Among them, 1 showed the highest inhibitory activity, being about 6 times more potent than quercitrin, which is a known natural inhibitor of AR.