Allosamidin(1), a novel insect chitinase inhibitor, was isolated from the mycelium of Streptomyces sp. Allosamidin showed strong inhibitory activity against the chitinases of the silkworm, Bombyx mori, in vitro, and also prevented its larval ecdysis in vivo. The structure of allosamidin was elucidated as 1 by acid hydrolysis experiments and analysis of 2D-NMR spectra. 1 is a basic pseudotrisaccharide consisting of N-acetyl-D-allosamine and a novel aminocyclitol derivative(3), termed allosamizoline. Methylallosamidin(2) was isolated from the mycelium of the unidentified actinomycetes and characterized as 2 by spectral comparison with 1.
