ISOLATION, STRUCTURE DETERMINATION AND BIOLOGICAL-ACTIVITIES OF A NOVEL ANTIFUNGAL ANTIBIOTIC, S-632-C, CLOSELY-RELATED TO GLUTARIMIDE ANTIBIOTICS

A new antifungal antibiotic, S-632-C, was extracted with ethyl acetate from the culture filtrate of Streptomyces ky,hygroscopicus S-632 and isolated through a combination of column and preparative thin-layer ch romatographies on silica gel. The structure of S-632-C was determined by analysis of H-1 and C-13-NMR, MS, UV and IR spectra in comparison w ith those of S-632-A(2), (9-methylstreptimidone). The signals were ass igned on the basis of 2D NMR experiments, which involved H-1-H-1 DQF C OSY, HMQC and HMBC spectral analysis. From these results, the chemical structure of S-632-C was elucidated as yl)-4-carbamoylmethyl-3,4,5,6- tetrahydro-2-pyrone. The antibiotic exhibited exclusively weak in vitr o antifungal activity against Saccharomyces spp. and similar cytotoxic activity against KB carcinoma cells, as compared with the glutarimide antibiotic S-632-A(2). In addition, this antibiotic had the ability t o change the morphology of ras(ts)-transformed NRK cells to that of no rmal cells, also a characteristic S-632-A(2) and B-1.