Yutaka Kido

5838-DNI, A Deoxyribonuclease Inhibitor Produced by Streptomyces Sp. Strain No. A-5838

5838-DNI, an inhibitor of deoxyribonuclease (DNase) II from porcine spleen was produced by Streptomyces sp. strain No. A-5838. The structure of 5838-DNI was shown to be 1,4,4a,5,12,12a-hexahydro-4,4a,11,12a-tetrahydroxy-3,8-dimethoxy-9- methoxycarbonyl-10-methyl-1,5,12-trioxo naphthacene. Although similar in structure to tetracenomycin C, which is an antibiotic against Gram-positive bacteria, 5838-DNI has different antibacterial activity. 5838-DNI was distinguished from 5923-DNI, a previously reported DNase II inhibitor, in inhibitory activity against each enzyme. 5838-DNI showed dependency of inhibition on pH and temperature, and inhibited phosphodiesterase I in a competitive manner. These data suggest that 5838-DNI is the first reported example of an inhibitor of microbial origin which is able to inhibit DNase II and phosphodiesterase I.

Hyphal extension inhibitors I and II with similar inhibitory spectra to validamycin, isolated from hyphae of Rhizoctonia solani

A hyphal extract was obtained by methanol extraction of a hyphal cake of Rhizoctonia solani culture. The crude hyphal extension inhibitor (HE-inhibitor), which only inhibits hyphal extension, i.e., without growth inhibition, was extracted with ethyl acetate, at pH 9.5, from the aqueous hyphal extract. The HE-inhibitor was further purified by silica gel colunm chromatography with a solvent mixture of benzene and acetone, and then separated into HE-inhibitors I and II. HE-inhibitor I, which highly inhibited the hyphal extension, with characteristic curling of the hyphal tips, was isolated as a colorless syrup, whereas HE-inhibitor II, with weak activity, was isolated as colorless needles: mp 187°C; C, 80.38, 79.14; H, 4.36, 4.96; N, 16.10, 15.94%. HE-inhibitors I and II exhibt no antibiotic activity against various fungi, yeasts and bacteria, but inhibit the hyphal extension of Rhizoctonia solani R-44 at 0.1l μg/ml and 5.0 μg/ml, respectively. Their inhibitory spectra resemble that of validamycin, though bo...

A new amino acid antibiotic KT-151, produced by Streptomyces luteogriseus, strain No. KT-151.

From the results of taxonomic studies, Streptomyces sp. strain No. KT–151 isolated from a soil sample collected in Kumamoto City, was identified as a strain belonging to Streptomyces luteogriseus Schmitz, Deak, Crook and Hooper 1964. A new antibiotic, produced by this strain, was isolated as a leaflet crystal by ion-exchange chromatography and found to be an amino acid with the molecular formula, C5H12N2O2, and named antibiotic KT–151 (refered to as KT–151 hereinafter). The antibiotic showed antimicrobial activity against various Gram-positive and Gram-negative bacteria in a chemically defined medium but it was antagonized by several amino acids such as valine, leucine, isoleucine and threonine.