3-Amino-5-hydroxybenzoic Acid in Antibiotic Biosynthesis. XI.
Biological Origins and Semisynthesis of Thionaphthomycins, and the Structures of Naphthomycins I and J
1998 年 51 巻 9 号 p. 845-851
詳細
1998 年 51 巻 9 号 p. 845-851
Fermentations of Streptomyces sp. E/784 produce low levels of the novel C-30 alkylthio-substituted ansamycin antibiotics naphthomycins J (9) and I (10), in addition to the more abundant C-30 hydroxylated analogues actamycin (1) and naphthomycin D (2) and C-30 chlorinated analogues naphthomycins H (3) and A (4). The addition of N-acetyl-L-cysteine to the fermentation medium substantially increases the production of the thionaphthomycins J and I at the expense of their chloro analogues H and A. Other thiols and thiol progenitors are similarly utilised, including N-acetyl-L-cysteine methyl ester which affords the known naphthomycin F (8) and its novel 2-demethyl homologue (7). The formation of thioansamycins from chloroansamycins and thiols in vivo is probably non-enzymic since similar conversions can be effected in vitro.
