Oligostatins, new antibiotics with amylase inhibitory activity, II. Structures of oligostatins C, D, and E.

Structure of Oligostatin C Oligostatin C (Ic), a basic, water-soluble, amorphous substance; m.p. 183'C (dec.), [a]21+154' (c 1, H,O), shows strong IR absorption maxima at 31003600 and 9801180 cm-1 indicative of its oligosaccharide nature. PMR spectrum of Ic in D2O shows a methyl signal at 1.38 ppm (d, J=6 Hz), a methine proton at 2.76 ppm (t, J=9 Hz) and complex signals at 5.2 5.5 ppm assignable to anomeric protons (J=4 Hz). Neither olefinic proton in PMR, nor sp'carbon in CMR is observed. Acid hydrolysis of Ic gave 3 moles of D-glucose and a basic product found identical with tricyclic