RESUMEN
Assay-guided fractionation of the ethanol extract of the twigs and leaves of Miconia myriantha yielded two new compounds, mattucinol-7-O-[4' ',6' '-O-(S)-hexahydroxydiphenoyl]-beta-D-glucopyranoside (1) and mattucinol-7-O-[4' ',6' '-di-O-galloyl]-beta-D-glucopyranoside (2), along with mattucinol-7-O-beta-D-glucopyranoside (3), ellagic acid (4), 3,3'-di-O-methyl ellagic acid-4-O-beta-D-xylopyranoside, and gallic acid. Complete (1)H and (13)C NMR assignments of compound 1, which possesses a hexahydroxydiphenoyl unit, were achieved using the HMBC technique optimized for small couplings to enhance the four-bond and two-bond H/C correlations. Compounds 1 and 4 showed inhibitory effects against Candida albicans secreted aspartic proteases, with IC(50) of 8.4 and 10.5 microM, respectively.
Asunto(s)
Glucósidos/aislamiento & purificación , Magnoliopsida/química , Plantas Medicinales/química , Inhibidores de Proteasas/aislamiento & purificación , Ácido Aspártico Endopeptidasas/antagonistas & inhibidores , Candida albicans/efectos de los fármacos , Candida albicans/enzimología , Candida albicans/metabolismo , Cromatografía en Capa Delgada , Dicroismo Circular , Ácido Elágico/química , Ácido Elágico/farmacología , Ácido Gálico/química , Ácido Gálico/farmacología , Glucósidos/química , Glucósidos/farmacología , Concentración 50 Inhibidora , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Conformación Molecular , Estructura Molecular , Pepsina A/antagonistas & inhibidores , Perú , Hojas de la Planta/química , Inhibidores de Proteasas/química , Inhibidores de Proteasas/farmacología , Espectrofotometría Infrarroja , Espectroscopía Infrarroja por Transformada de Fourier , Relación Estructura-ActividadRESUMEN
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 microg/mL, respectively).