Bioactive Bafilomycins and a New N-Arylpyrazinone Derivative from Marine-derived Streptomyces sp. HZP-2216E

A MeOH extract prepared from culture of an actinomycete Streptomyces sp. HZP-2216E isolated from marine green algae Ulva pertusa was found to significantly inhibit proliferation of human glioma cells. Two different media were applied to culture this marine actinomycete, which produced two new compounds of 23-O-butyrylbafilomycin D and streptoarylpyrazinone A, together with known bafilomycin D, 9-hydroxybafilomycin D, and bafilomycin A₁. Structures of new compounds were determined by extensive NMR spectroscopic analyses and HRESIMS data. Bioactive assay indicated that all isolated bafilomycins significantly inhibited the proliferation of different glioma cell lines and the growth of methicillin-resistant Staphylococcus aureus with 23-O-butyrylbafilomycin D as the most active compound. Streptoarylpyrazinone A is a new N-arylpyrazinone derivative existing as a zwitterion, and this type of compounds was rarely found from natural resources.