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

Three new α-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 μM, respectively.