Alahopcin

An actinomycete strain No. B-52653 was found to produce an antibiotic selectively active against the in vitro antibiotic resistant mutant of Staphylococcus aureus. Based on taxonomic studies, the name Streptomyces albulus subsp. ochragerus subsp. nov. is proposed for the strain. The microorganism produced two kinds of antibiotics; one identical with gougerotin, the other an amphoteric water soluble dipeptide containing L-alanine. The latter has the molecular formula C9H15N3O6 and is named alahopcin. It has a broad antibacterial spectrum and a synergistic effect with some other antibiotics against some antibiotic resistant staphylococci. Alahopcin has a low toxicity and was effective against experimental infections in mice caused by Staphylococcus aureus.

The structure of alahopcin (nourseimycin) (1), a new dipeptide antibiotic isolated from Streptomyces, has been established to be (2S, 3R)-2-[(L-alanyl)amino]-4-formyl-3-(hydroxy-aminocarbonyl)butyric acid. 1 exists in two cyclic hemiacetal type tautomers formed by intramolecular ring closure between the hydroxyamino group and the formyl group in aqueous solution. The structure of the new weakly acidic amino acid (2), a constituent of 1, is revealed to be (2S, 3R)-2-amino-4-formyl-3-(hydroxyaminocarbonyl)butyric acid, and 2 also exists in two cyclic hemiacetal type tautomers in aqueous solution.

A new amino acid, dealanylalahopcin, was isolated from a culture filtrate of Streptomyces albulus subsp. ochragerus; it was also formed by the enzymatic hydrolysis of alahopcin using microbial alpha-amino acid ester hydrolase. The amino acid was obtained as colorless needles and its molecular formula is C6H10N2O5. It showed very weak antibacterial activity against Gram-positive and Gram-negative bacteria, and weak inhibitory activity against the collagen prolylhydroxylase.