Prodigiosin R2, a new prodigiosin from the roseophilin producer Streptomyces griseoviridis 2464-S5.

Roseophilin (2) is a unique prodigiosin-related compound produced by Streptomyces griseoviridis 2464-S5, and is characterized by a central furan ring and a bicyclic alkyl chain. During a search for biosynthetic intermediates of 2, a new metabolite designated prodigiosin R2 (1) was isolated from the culture of the roseophilin producer. The molecular formula of 1 was established as CHNO by high-resolution FAB-MS. The structure of 1 was determined by NMR spectroscopic analyses as a prodigiosin derivative with the same bicyclic alkyl chain as 2. Prodigiosin R2 (1) showed potent cytotoxicity against HeLa human cervical carcinoma cells and HT1080 human fibrosarcoma cells with ICs of 0.41 and 0.82 μM, respectively.