Studies in the biochemistry of micro-organisms. 93. Cyclopenin, a nitrogen-containing metabolic product of Penicillium cyclopium Westling

Abstract

A hitherto undescribed mold metabolic product, cyclopenin, was isolated from culture filtrates of laboratory cultures of a strain of Penicillium cyclopium Westling. Cyclopenin, C17H14O3N2, forms colorless tablets, m.p. 207[degree], [image] in ethanol. Cyclopenin is readily decomposed by dilute mineral acids giving one mole each of CO2, methylamine and viridicatin, C15H11O2N, which is optically inactive. Viridicatin, previously isolated from P. viridicatum Westling. by Cunningham and Freeman, has now been prepared from 5 different strains of P. cyclopium but appears to be absent from the strain of this sp. which gives cyclopenin. It is oxidized in alkaline solution by gaseous O2 to one mole each of o-aminobenzophenone and oxalic acid. Viridicatin was synthesized and was shown to be 2:3-dihydroxy-4-phenylquinoline or its keto tautomer. The 5 strains of P. cyclopium which gave viridicatin also gave good yields of palitantin and 2 of them gave the anti-fungal substance, frequentin. Two possible, closely related, structures are suggested for cyclopenin.