New inhibitors of melanogenesis, OH-3984 K1 and K2. II. Physico-chemical properties and structural elucidation.
New melanin synthesis inhibitors, OH-3984 K1 and K2, were isolated from the fermentation broth of Streptomyces sp. OH-3984, and their structures were elucidated by spectroscopic methods and by chemical transformations. OH-3984 K1 (M.W.: 306; C18H26O4) and K2 (M.W.: 308; C18H28O4) have unique gamma-lactone rings, both of which correspond to oxidative products derived from C1-O14 cleavage of the 14-membered lactone group.
Studies on an antibiotic, albocycline VII. Minor components of albocycline.
As an approach to the search for new potentially useful macrolide antibiotics, we explored the minor components of albocycline (ALB) from the culture broth of Streptomyces bruneogriseus. Eight minor components were isolated and their structures were confirmed as 1 approximately 8. Unexpectedly, they were not glycosidic compounds but only oxidation or reduction products of ALB. Three or four of them will serve as a useful intermediate to introduce amino sugar moiety into ALB skeleton.
Biological conversion of narbonolide to picromycin.
The macrolide antibiotic, picromycin, was found to be synthesized from narbonolide by the following two metabolic pathways: (A) Narbonolide (I) → narbomycin (II) → picromycin (III). (B) Narbonolide (I) → picronolide (IV) → picromycin (III). In path (A) glycosidation at C-5 with desosamine preceded hydroxylation at C-12, while in path (B) the reverse is true.