Structurally Diverse New Metabolites from Three Hadal Trench-Derived Microorganisms

Two new tetraene lactone derivatives (1 and 2), two new α-pyrone derivatives (3 and 4), three compounds reported as natural products for the first time [an α-pyrone derivative (5), an indole-diketopiperazine alkaloid (6), and a β-amino acid derivative (8)], and 11 known compounds (7, 9–18), 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 6–11 and 15 had weak antibacterial effects.