Placenta aldose reductase

Sawad H, Hamatake M, Hara A, Nakagawa M, Nakayama T. (1989) Inhibition of human placenta aldose reductase by tannic acid. Chem Pharma Bull 37 1662-1664. 

From the leaves of Comus officinalis a novel gallotannin, 1,7-di-O-galloyl-D-sedoheptulose, has been isolated. 1,2,3,4,6-Penta- and 1,2,3,4-tetra-O-galloyl- -D-glucose have been shown to be inhibitors of human placenta aldose reductase and of a mitochondrial oxidoreductase, respectively, and the ability of penta-0-galloyl-/J-D-glucose and twenty-four related, more complex, natural, hydrolysable tannins to scavenge radicals (e.g.. superoxide radicals) has been demonstrated. ... 

In these coupled reactions, the overall transformation of glucose to fructose is accompanied by a transfer of hydrogen from NADPH to NAD. Studies on the activity of aldose reductase and sorbitol dehydrogenase as well as the presence of sorbitol in seminal vesicles of several species and rat coagulating gland are consistent with the operation of the sorbitol pathway as a major determinant of seminal fructose biosynthesis (248, 252-260). Nonphosphorylative conversion of glucose to sorbitol has also been demonstrated in placenta (258, 261, 262), smooth muscle of the aorta (263), the lens of the eye (264, 265), erythrocytes (266) and hepatoma-derived (HTC) cells in culture (267), and possibly normal liver cells (267, 268). 

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