A series of 2,4-dioxo-5-(2-naphthylmethylene)-3-thiazolidineacetic acids and 2-thioxo analogues have been prepared as aldose reductase inhibitors. In vitro inhibitory activities of bovine lens aldose reductase were determined by a conventional method. 1-Naphthyl-substituted derivatives of the 2-thioxo series were the more potent inhibitors (IC50 congruent with 10 nM) with similar activity to that of Epalrestat. Structural analysis, especially by X-ray crystallography of two selected compounds, and molecular modeling comparisons with Zopolrestat were performed. These results provide explanations of the good activity of the inhibitor, the preference for 1-naphthyl-substituted compounds, and the nature of molecular interactions in these systems.

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In the course of the chemical investigation of extracts of the trunk bark and root bark of Trema orientalis, three new compounds were isolated, namely, (9S*,10S*)-3-[7-(3,10-dihydroxy-9-hydroxymethyl-2,5-dimethoxy)-9,10-dihydrophenanthrenyl]propenal (1), (9S*,10S*)-3-[7-(5-O-beta-glucopyranosyl-10-hydroxy-9-hydroxymethyl-2,6-dimethoxy)-9,10-dihydrophenanthrenyl]propenal (2), and (3R*,3aR*,4R*,5S*)-6-O-alpha-arabinopyranosyl-8-hydroxy-3-(4-hydroxyphenyl)-4-(4-hydroxyphenyl)-5-(3,5-dihydroxyphenyl)-3,3a-dihydrocyclopenta[1,2,3-de]isobenzopyran-1-one (3, orientoside A). The structures of 1-3 were determined by spectral methods.