Isolation of (-)-14-O-malonylindolactam-V as a possible precursor of (-)-indolactam-V and (-)-14-O-acetylindolactam-V from Streptomyces blastmyceticum

(-)-Indolactam-V (1) has the fundamental structure of potent tumor-promoting teleocidins. A new teleocidin-related metabolite, (-)-14-O-malonylindolactam-V (2), was isolated from the culture broth of Streptomyces blastmyceticum NA34-17 which produced a large quantity of 1 along with a small amount of (-)-14-O-acetylindolactam-V (3). Heat treatment of 2 in methanol readily produced 1 and 3, suggesting that S. blastmyceticum NA34-17 excreted 1 as a malonic acid conjugate to accumulate 1 and 3 in