Kynapcin-13 and -28, new benzofuran prolyl endopeptidase inhibitors from Polyozellus multiplex

Two new benzofurans, 5,6-dihydroxybenzofuran-2,3-dicarboxylic acid dimethyl ester (kynapcin-13) and 5,6,5',6'-tetrahydroxy[3,3']bibenzofuranyl-2,2'-dicarboxylic acid 2'-methyl ester (kynapcin-28) were isolated from Polyozellus multiplex, and shown to non-competitively inhibit prolyl endopeptidase (PEP), with the IC50 values of 76.80 and 0.98 muM, respectively. Kynapcin-13 and -28 were less inhibitory to other serine proteases such as chymotrypsin, trypsin, and elastase.