Cyclic Peptides from the Opportunistic Pathogen Basidiobolus meristosporus .

Three new cyclic peptides, meristosporins A, B, and C ( 1 - 3 ), one of which features an unusual amino acid, were isolated from the opportunistic pathogen Basidiobolus meristosporus and identified by 1D, 2D NMR, MS/MS, and Marfey's analysis. The biosynthetic pathway of the hexapeptide meristosporin A ( 1 ) was deduced based on nonribosomal peptide synthetase gene clusters analysis. Compounds 1 and 2 showed cytotoxicity to RAW264.7 and 293T cells, respectively. These compounds may be involved in the fungal injury caused to human cells.