Benzoxacystol, a benzoxazine-type enzyme inhibitor from the deep-sea strain Streptomyces sp. NTK 935

Benzoxacystol, a new 1,4-benzoxazine-type metabolite, was produced by strain NTK 935, a marine member of the Streptomyces griseus 16S rRNA clade, isolated from deep-sea sediment collected from the Canary Basin. The structure of benzoxacystol was determined by mass spectrometry, NMR experiments and X-ray analysis. The compound showed an inhibitory activity against the enzyme glycogen synthase kinase 3β and a weak antiproliferative activity against mouse fibroblast cells.