TMC-2A, -2B and -2C, novel dipeptidyl peptidase IV inhibitors produced by Aspergillus oryzae A374. I. Taxonomy of producing strain, fermentation, and biochemical properties.

TMC-2A(1), -2B (2) and -2C (3), novel dipeptidyl peptidase IV (DPIV) inhibitors, were isolated from the fermentation broth of Aspergillus oryzae A374. TMC-2A, -2B and -2C inhibited rat kidney DPIV with IC50 value of 8.1 microM, 17 microM, and 20 microM, respectively, as well as human DPIV prepared from mononuclear cells and adenocarcinoma cells. TMC-2 compounds inhibited only DPIV among the proteases tested, indicating their high selectivity for DPIV. The kinetic analyses revealed that TMC-2A was an uncompetitive inhibitor. Taxonomy and fermentation of the producing strain are also described.