Crystal structure, spectroscopic properties and antimicrobial activity of 4H-1-Benzopyran-4-one, 5-hydroxy-2-(4-hydroxyphenyl)-7-methoxy-6,8-dimethyl from Miconia ioneura (M.i.) Melastomataceae

M. I. TRACANA; S. M. AMANI; E. ROMANO; A. B. RASCHI; L. R. HERNÁNDEZ MOLINA; O. E. PIRO; E. E. CASTELLANO; A. M. BENAVENTE

Molecular Medicinal Chemistry

INSTITUTO DE INVESTIGACIÓN DE LAS CIENCIAS EXACTAS FÍSICAS Y NATURALES

Año: 2010 vol. 21 p. 94 - 104

1666-888X

From the bioactive ethyl acetate extract of leaves of Miconia ioneura Griseb (Melastomataceae) we isolated a flavone as a microcrystalline solid. This substance was identified as 4H-1-Benzopyran-4-one,5-hydroxy-2-(4-hydroxyphenyl)-7-methoxy-6,8-dimethyl (sideroxylin) by melting point and IR of the solid and by NMR and UV spectroscopic techniques in solution. Furthermore, we succeeded in growing single crystals adequate for structural studies. The molecular structure of sideroxylin, C18H16O5, has been determined by X-ray diffraction methods at 150K. The substance crystallizes as a monohydrate in the monoclinic P21/c space group with a=7.322(1), b=17.014(2), c=12.210(1) Å, beta=93.73(1)º, and Z=4 molecules per unit cell. The fused phenyl and hetero-cycle rings are coplanar to each other and the phenyl group which is sigma-bonded to the latter ring belongs closely to that plane. Observed intra-molecular distances and angles complain with the bonding structure expected from the Organic Chemistry rules. The molecule presents a strong intra-molecular O-H…O bond. As a result of antimicrobial tests with ethyl acetate extracts and sideroxylin we found antifungal activity of both substances against several Candida strains.