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 natural resources, seven tannins and related compounds were isolated from the aerial part of Euphorbia pekinensis and identified as gallic acid (1), methyl 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 compounds, (-)-quinic acid (8), (-)-shikimic acid (9), ellagic acid (10), kaempferol (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 II 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 inhibitor against chitin synthase 11 of Saccharomyces cerevisiae with an IC50 value of 18 muM. The inhibition appears to be selective for chitin synthase II, as they did not appreciably inhibit chitin synthase.