Structurally DiverseNew Metabolites from Three HadalTrench-Derived Microorganisms

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