Four acarviosin-containing oligosaccharides identified from Streptomyces coelicoflavus ZG0656 are potent inhibitors of alpha-amylase

Four aminooligosaccharides were isolated and purified from the culture filtrate of Streptomyces coelicoflavus ZG0656. Their chemical structures were determined by electrospray ionization tandem mass spectrometry (ESI-MS/MS) and two-dimensional nuclear magnetic resonance (NMR) spectroscopy. The names acarviostatins I03, II03, III03, and IV03 were given to the oligomers due to their acarviosin core structures. Acarviostatins III03 and IV03, which contain three and four acarviosin-glucose moieties, respectively, were identified as novel compounds. The four acarviostatins were all mixed noncompetitive inhibitors of porcine pancreatic alpha-amylase (PPA). The inhibition constants (K(i)) for acarviostatins III03 and IV03 were 0.008 and 0.033muM, respectively. Acarviostatin III03 is the most effective alpha-amylase inhibitor known to date, with a K(i) value 260 times more potent than acarbose.