A novel amino-oligosaccharide isolated from the culture of Streptomyces strain PW638 is a potent inhibitor of α-amylase

A novel amino-oligosaccharide, named SF638-1, was isolated from the culture filtrate of the Streptomyces strain PW638. Its chemical structure was determined by electrospray ionization tandem mass spectrometry (ESI-MS/MS) and two-dimensional nuclear magnetic resonance spectroscopy. The novel compound was a mixed inhibitor of human pancreatic α-amylase, with a Ki value in the same order of magnitude as that of the α-amylase inhibitor, acarbose. SF638-1 inhibited starch hydrolysis and glucose transfer in vitro, and suppressed postprandial blood glucose elevation in vivo. These results suggest that SF638-1 may be a potent antidiabetic agent.