Trichormamides A and B from the Cultured Freshwater Cyanobacterium trichormus SP. (UIC 10339)

Cyanobacteria, also known as blue-green algae, have provided a variety of structurally diverse and bioactive natural products. As part of our ongoing natural product drug discovery project, we evaluated organic extracts of cultured cyanobacteria for cytotoxicity against the MDA-MB-435 human melanoma cancer cell line. The organic extract of Trichormus sp. (UIC 10339) displayed significant activity in this assay. LC-MS-NMR dereplication indicated the activity to be associated with potentially new peptides. Bioassay guided fractionation led to the isolation of two cyclic lipopeptides, Trichormamides A and B. The structures were determined by a combination of 1D/2D NMR spectroscopic techniques and HRESIMS as dodeca and endeca lipopeptides with non-standard amino acids including β-amino acid residues. The structure elucidation and biological activities of the compound will be presented.