Blasticidin A (C51-52H99-101O23N1/2Ca, m. p. 165.5-166.5°C, λmax 246 mμ and 298mμ in 50 % methanol, [α]24D-31° in pyridine) was isolated in crystal form as calcium-chelated compound. The antibiotic shows activity against a variety of microorganisms with relatively less toxicity to mice orally. It seems to have some relationship to polyene macrolide antibiotics, but has marked differences in its properties. The isolation, purification and physicochemical properties of the antibiotic are described.
A new antibiotic, tsushimycin, was isolated from cultures of a Streptomyces strain. The antibiotic is an acidic acylpeptide related to the amphomycinglumamycin group of antibiotics. However, fatty acid analysis by means of gas-liquid chromatography revealed that the antibiotic contains isotetradecenoic acid which has not been found in known antibiotics. The constituent fatty acids as well as the amino acid composition were compared with those of the above group of antibiotics.
An antibiotic weakly active against Candida was isolated as a colorless crystalline hydrochloride from a culture of a streptomyces which showed some resemblances with Streptomyces eurythermits. This antibiotic was unstable to acid and alkali, but was recovered in good yield by elution with 0.5M ammoniumchloride solution from the ion-exchange resin, Amberlite IRC-50 (Na+ type). It was determined to be acrylamidine by spectroscopic data, degradation and direct comparison with a synthetic sample. The LD50 (mice) of acrylamidine was 44 mg/kg intravenously.
The biosynthetic preparation of an anti-fungal agent assumed to be 4'-fluoropyrrolnitrin from 6-fluorotryptophan by Pseudomonas aureofaciens has been previously reported1, 2). We undertook the determination of the structure by X-ray crystallographic analysis in order to prove the position of the fluorine and to obtain information regarding the relative conformation of the two rings and the effect of substituent crowding in this unusual molecule.
Kalafungin is a new antibiotic extracted from the fermentation broth of Streptomyces tanashiensis strain Kala, and purified by chromatography on silica gel followed by crystallization. It is a weakly acidic, orange colored compound, pKa=10.0, with a molecular formula C16H12O6 and a molecular weight of 300. It is dextrorotatory in chloroform, [α]25D+159, and exhibits ultraviolet and visible absorption maxima at 212, 256, and 425 mμ in methanol. Kalafungin melts at 163-166°C and is readily soluble in ethyl acetate, chloroform, and acetone but only slightly soluble in water.