A New Naphthopyrone Derivative from Cassia quinquangulata and Structural Revision of Quinquangulin and Its Glycosides

• Published in: Journal of natural products (Washington, D.C.) D.C.), 2001-09, Vol.64 (9), p.1153-1156
• Main Authors: Li, Xing-Cong, Dunbar, D. Chuck, ElSohly, Hala N, Jacob, Melissa R, Nimrod, Alison C, Walker, Larry A, Clark, Alice M
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents; Anti-Infective Agents - chemistry; Anti-Infective Agents - isolation & purification; Anti-Infective Agents - pharmacology; Aspergillus fumigatus - drug effects; Biological and medical sciences; Candida albicans - drug effects; Cassia - chemistry; Cassia quinquangulata; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Cryptococcus neoformans - drug effects; Drug Resistance, Microbial; General pharmacology; Glucosides - chemistry; Glucosides - isolation & purification; Glucosides - pharmacology; Glycosides - chemistry; Glycosides - isolation & purification; Glycosides - pharmacology; Magnetic Resonance Spectroscopy; Medical sciences; Methicillin Resistance; Microbial Sensitivity Tests; Molecular Conformation; Molecular Structure; Mycobacterium avium Complex - drug effects; Naphthols - chemistry; Naphthols - isolation & purification; Naphthols - pharmacology; Peru; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Plant Roots - chemistry; Plants; Plants, Medicinal - chemistry; Pyrones - chemistry; Pyrones - isolation & purification; Pyrones - pharmacology; quinquangulone; Spectrometry, Mass, Electrospray Ionization; Spectrophotometry, Infrared; Spectrophotometry, Ultraviolet; Staphylococcus aureus; Staphylococcus aureus - drug effects
• ISSN: 0163-3864; 1520-6025
• DOI: 10.1021/np010173h

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 and 4), rubrofusarin (5) and its two glycosides (6 and 7), nor-rubrofusarin (8) and its 6-O-glucoside (9), and three stilbenes (10−12). The structure of quinquangulone 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 of the NMR spectra of quinquangulin led to revision of its structure as 5,6-dihydroxy-8-methoxy-2,9-dimethyl-4H-naphtho[2,3-b]pyran-4-one (2a). The structures of two quinguangulin glycosides, 3 and 4, were also revised accordingly. Compound 2a exhibited activity against Staphylococcus aureus and methicillin-resistant S. aureus (MIC, 3.125 and 6.25 μg/mL, respectively).