Himastatin, a New Antitumor Antibiotic from Streptomyces hygroscopicus: III. Structural Elucidation

The structure of the antitumor antibiotic himastatin was determined using a combination of spectroscopic and chemical degradation techniques. Himastatin is a unique dimeric cyclohexadepsipeptide joined through a biphenyl linkage between two oxidized tryptophan units. The gross structure of the dimer was established through degradative ozonolysis. Himastatin consists of D-valine, D-threonine, L-leucine, L-α-hydroxyisovaleric acid, (3R, 5R)-5-hydroxypiperazic acid, and (2R, 3aR, 8aR)-3a-hydroxyhexahydropyrrolo[2, 3b]indole 2-carboxylic acid subunits.