Isolation and structures of biselyngbyasides B, C, and D from the marine cyanobacterium Lyngbya sp., and the biological activities of biselyngbyasides

Bioassay-guided fractionation of the marine cyanobacterium Lyngbya sp. led to the isolation of biselyngbyasides B (3), C (4), and D (5), novel analogs of biselyngbyaside (1) and biselyngbyolide A (2). The gross structures of 3–5 were determined by NMR spectral analyses, and their stereochemistries were established based on NOESY spectra and CD data. Biselyngbyasides (1–3) showed growth-inhibitory activity and apoptosis-inducing activity against both HeLa S3 cells and HL60 cells. The fura-2 method revealed that biselyngbyasides (1–3) increased the cytosolic Ca2+ concentration in HeLa S3 cells.