Isolation and structure determination of two new hydrophobic microcystins from Microcystis sp. (CAWBG11)

Two new hydrophobic microcystins, microcystin-FA ( 1 ) and microcystin-WA ( 2 ), were isolated from the cyanobacterium Microcystis sp. (CAWBG11). The structures were deduced using one- and two-dimensional nuclear magnetic resonance spectroscopy and tandem mass spectrometry. The absolute stereochemistry of the amino acid residues in 1 and 2 was determined using the Advanced Marfey's method.