Structurally Diverse New Metabolites from Three Hadal Trench-Derived Microorganisms.

Two new tetraene lactone derivatives ( and ), two new α-pyrone derivatives ( and ), three compounds reported as natural products for the first time [an α-pyrone derivative (), an indole-diketopiperazine alkaloid (), and a β-amino acid derivative ()], and 11 known compounds (, -), were obtained from microorganisms isolated from hadal trench sediments in the Pacific Ocean. Their structures were determined using NMR, HRESIMS, optical rotatory dispersion (ORD) spectra, NMR calculations followed by DP4+ analysis, electronic circular dichroism (ECD) calculations, X-ray crystallography analysis, and advanced Marfey's and modified Mosher eater methods. Microbial broth dilution assay suggested that compounds - and had weak antibacterial effects.