Aurilides B and C, cancer cell toxins from a Papua New Guinea collection of the marine cyanobacterium Lyngbya majuscula

Cytotoxicity-guided fractionation of a strain of the marine cyanobacterium Lyngbya majuscula collected from Papua New Guinea led to the isolation of aurilides B (1) and C (2). The planar structures of 1 and 2 were established by spectroscopic analysis, including HR-FABMS, 1D ¹H and ¹³C NMR, and 2D COSY, HSQC, HSQC-TOCSY, and HMBC spectra. The absolute configuration was determined by spectroscopic analysis and chiral HPLC analysis of acid hydrolysates of 1 and 2. Both aurilides B and C showed in vitro cytotoxicity toward NCI-H460 human lung tumor and the neuro-2a mouse neuroblastoma cell lines, with LC₅₀ values between 0.01 and 0.13 μM. Aurilide B (1) was evaluated in the NCI 60 cell line panel and found to exhibit a high level of cytotoxicity (the mean panel GI₅₀ concentration was less than 10 nM) and to be particularly active against leukemia, renal, and prostate cancer cell lines.