Novel glycosidase inhibitors, nojirimycin B and D-mannonic-delta-lactam. Isolation, structure determination and biological property.

A new aminosugar named nojirimycin B (1) has been isolated as its bisulfite adduct from the culture broth of Streptomyces lavendulae SF-425, together with nojirimycin. Microbiological oxidation of 1 with Gluconobacter suboxydans IAM 1829 gave a delta-lactam (2). The structures of 1 and 2 were determined to be 5-amino-5-deoxy-D-mannopyranose and D-mannonic-delta-lactam, respectively, on the basis of 1H NMR spectroscopy and X-ray structural analysis. Both 1 and 2 exhibited powerful inhibitory activity against rat epididymal alpha-mannosidase and apricot beta-glucosidase.