α-Pyrones and Diketopiperazine Derivatives from the Marine-Derived Actinomycete Nocardiopsis dassonvillei HR10-5

Three new alpha-pyrones, nocapyrones E-G (1-3), and three new diketopiperazine derivatives, nocazines A-C (4-6), together with a new oxazoline compound, nocazoline A (7), were isolated from the marine-derived actinomycete Nocardiopsis dassonvillei HR10-5. The new structures of 1-7 were determined by spectroscopic analysis, X-ray single-crystal diffraction, CD spectra, and modified Mosher and Marfey methods. Compounds 1-3 showed modest antimicrobial activity against Bacillus subtilis with MIC values of 26, 14, and 12 mu M, respectively.