Phosmidosine C

An antifungal antibiotic, phosmidosine (1) was previously isolated (J. Antibiotics 44: 375 approximately 381, 1991). Phosmidosine derivatives, phosmidosines B (2) and C (3) were newly isolated as detransforming compounds from the fermentation broth of Streptomyces sp. strain RK-16 which is a producer strain of phosmidosine (1). The structures of 2 and 3 were established by spectroscopic methods, including UV, HRFAB-MS, and NMR. 1 and 2 showed the inhibitory activity of the cell cycle progression and the morphological reversion activity on srcts-NRK cells. On the other hand, 3 had no activity. These results indicate that the prolyl group in phosmidosine derivatives plays an important role in the inhibitory activity against the cell cycle progression and the morphological reversion activity on srcts-NRK cells.