Saliniquinone Derivatives, Saliniquinones G-I and Heraclemycin E, from the Marine Animal-Derived Nocardiopsis aegyptia HDN19-252.

Four new anthraquinone derivatives, namely saliniquinones G-I (1-3) and heraclemycin E (4), were obtained from the Antarctic marine-derived actinomycete Nocardiopsis aegyptia HDN19-252, guided by the Global Natural Products Social (GNPS) molecular networking platform. Their structures, including absolute configurations, were elucidated by extensive NMR, MS, and ECD analyses. Compounds 1 and 2 showed promising inhibitory activity against six tested bacterial strains, including methicillin-resistant coagulase-negative staphylococci (MRCNS), with MIC values ranging from 3.1 to 12.5 μM.