Abstract
Five tannin-related compounds – gallic acid, flavogallonic acid dilactone, valoneic acid dilactone, gallagyldilactone, ellagic acid – were isolated from the heartwood of Shorea laeviforia, and the inhibitory activity of each against rat liver 5Α-reductase was evaluated. Valoneic acid dilactone and gallagyldilactone exhibited positive inhibitory activity, but gallic acid and ellagic acid did not. Flavogallonic acid dilactone stimulated 5Α-reductase activity, even though this compound is structurally similar to valoneic acid dilactone. The kinetic study of valoneic acid dilactone and gallagyldilactone indicated that the inhibitory behavior of 5Α-reductase were not competitive against the substrate (testosterone) and were partially competitive against the cofactor (NADPH). Additionally, double inhibition analysis of valoneic acid dilactone and NADP+ showed synergetic inhibition. These results suggested that neither valoneic acid dilactone nor gallagyldilactone can affect the binding of testosterone but that either compound could interact with an enzyme–NADP+ complex to inhibit 5Α-reductase.
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Hirano, Y., Kondo, R. & Sakai, K. 5Α-Reductase inhibitory tannin-related compounds isolated from Shorea laeviforia . J Wood Sci 49, 339–343 (2003). https://doi.org/10.1007/s10086-002-0481-y
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DOI: https://doi.org/10.1007/s10086-002-0481-y