Inhibitory activity for chitin synthase II from Saccharomyces cerevisiae by tannins and related compounds

In the course of search for potent inhibitors of chitin synthase II from na tural resources, seven tannins and related compounds were isolated from the aerial part of Euphorbia pekinensis and identified as gallic acid (1), met hyl gallate (2), 3-O-galloyl-(-)-shikimic acid (3), corilagin (4), geraniin (5), quercetin-3-O-(2 "- O-galloyl)-beta -D-glucoside (6), and kaempferol- 3-O-(2 "- O-galloyl)-beta -D-glucoside (7). These and nine related compound s, (-)-quinic acid (8), (-)-shikimic acid (9), ellagic acid (10), kaempfero l (11), quercetin (12), quercitrin (13), rutin (14), quercetin-3-O-(2 " -0- galloyl)-beta -D-rutinoside (15) and 1,3,4,6-tetra-O-gallyl-beta -D-glucose (16), were evaluated for the inhibitory activity against chitin synthase I I and III. They inhibited chitin synthase II with IC50 values of 18-206 muM , except for two organic acids, (-)-quinic acid (8) and (-)-shikimic acid ( 9). Among them, 3-O-galloyl-(-)-shikimic acid (3) was the most potent inhib itor against chitin synthase 11 of Saccharomyces cerevisiae with an IC50 va lue of 18 muM. The inhibition appears to be selective for chitin synthase I I, as they did not appreciably inhibit chitin synthase.