Isolation of two peptaibols with potent antimicrobial and cytotoxic activities from the mangrove endophytic fungus ML-P8-2.

Trichorzin PA is a family of 18-residue peptaibols with linear and flexible peptide chains. The three-dimensional structures and biological activities of trichorzin PA peptaibols are largely uncharacterised. In this work, two previously identified peptaibols, trichorzin PA VI () and II (), were isolated from ML-P8-2. While for the first time, we report here the X-ray crystallographic structure of , antimicrobial activities against a panel of common pathogenic bacteria and fungi, and cytotoxicities of and . In bioassays, and exhibited strong antimicrobial activities against the seven tested microbes, with MIC values in the range of 0.19-6.25 μM. Additionally, and displayed potent cytotoxicities against five human cancer cell lines, with IC values in the range of 0.01 ± 0.02-2.75 ± 0.17 μM. The bioassay results were generally better than those reported for other 18-residue peptaibols, including other trichorzin PA members.