A new naphthopyrone derivative from Cassia quinquangulata and structural revision of quinquangulin and its glycosides.

摘要: A novel naphthopyrone derivative, named quinquangulone (1), has been isolated from Cassia quinquangulata, along with the known compounds quinquangulin (2) and its two glycosides (3 4), rubrofusarin (5) (6 7), nor-rubrofusarin (8) 6-O-glucoside (9), three stilbenes (10−12). The structure of was established by spectral interpretation as 5,9-dihydroxy-8-methoxy-2,9-dimethyl-6-oxo-4H,6H,9H-naphtho-[2,3-b]pyran-4-one. Reinvestigation NMR spectra led to revision 5,6-dihydroxy-8-methoxy-2,9-dimethyl-4H-naphtho[2,3-b]pyran-4-one (2a). structures quinguangulin glycosides, 3 4, were also revised accordingly. Compound 2a exhibited activity against Staphylococcus aureus methicillin-resistant S. (MIC, 3.125 6.25 μg/mL, respectively).