A new tetracycline antibiotic from a Dactylosporangium species. Fermentation, isolation and structure elucidation

An actinomycete identified as a Dactylosporangium sp. produces a new tetracycline, 4a-hydroxy-8-methoxychlortetracycline (Sch 34164). The addition of magnesium ions to complex fermentation media increased the antibiotic titers. Sch 34164 was isolated by solvent extraction and Sephadex G-25 column chromatography. The novel structure was proposed based on spectroscopic analysis. The shift of C-4a (35 to 77 ppm) and C-8 (140 to 163 ppm) in the 13C NMR as compared to chlortetracycline was indicative of the novel hydroxyl and methoxy substituents, respectively.