KALKIPYRONE, A TOXIC GAMMA-PYRONE FROM AN ASSEMBLAGE OF THE MARINE CYANOBACTERIA LYNGBYA-MAJUSCULA AND TOLYPOTHRIX SP

Kalkipyrone, a novel alpha-methoxy-beta,beta'-dimethyl-gamma-pyrone po ssessing an alkyl side chain, was isolated from an assemblage of the m arine cyanobacteria Lyngbya majuscula and Tolypothrix sp. Its structur e, including stereochemistry, was determined by NMR, UV, and IR analys is and by GC-MS of the natural product and key derivatives. Kalkipyron e is toxic to brine shrimp (LD50 1 mu g/mL) and gold fish (LD50 2 mu g /mL) and is structurally related to the actinopyrones that were previo usly isolated from Streptomyces spp.