Complete ¹H and 13C NMR assignments and anti fungal activity of two 8-hydroxy flavonoids in mixture

Susana Johann,Raimundo Braz-Filho,Artur Smânia-Jr,Moacir G Pizzolatti,Jan Schripsema,Alexsandro Branco

doi:10.1590/s0001-37652007000200004

Abstract

A mixture of the two new flavonols 8-hydroxy-3, 4', 5, 6, 7-pentamethoxyflavone (1) and 8-hydroxy-3, 3', 4', 5, 6, 7-hexamethoxyflavone (2) was isolated from a commercial sample of Citrus aurantifolia. An array of one- (1HNMR, {1H}-13C NMR, and APT-13C NMR) and two-dimensional NMR techniques (COSY, NOESY, HMQC and HMBC) was used to achieve the structural elucidation and the complete 1H and 13C chemical shift assignments of these natural compounds. In addition, the antifungal activity of these compounds against phytopathogenic and human pathogenic fungi was investigated.

Highlights

Flavonoids constitute one of the most important classes of naturally occurring phenols with interesting properties, to the plants as protective agents and human health (Ezeonu et al 2001, Del Río et al 1998, Bohm 1998, Chen et al 1997, Harborne et al 1975, Mayer 1998)
Many analytical procedures have been developed for flavonoids analysis in mixture, the most successful are based on chromatographic techniques such as high-performance liquid chromatography (HPLC) and Gas Chromatography (GC) (Oliveira et al 2001, Robards et al 1997, Robards K. and Antolovich 1997, Branco et al 1998, 2001, Stremple 1998)
We report the structural elucidation of two new 8-hydroxypolymethoxyflavonols (1 and 2) isolated from a commercial sample of Citrus auranti

Summary

INTRODUCTION

Flavonoids constitute one of the most important classes of naturally occurring phenols with interesting properties, to the plants as protective agents and human health (Ezeonu et al 2001, Del Río et al 1998, Bohm 1998, Chen et al 1997, Harborne et al 1975, Mayer 1998). Many analytical procedures have been developed for flavonoids analysis in mixture, the most successful are based on chromatographic techniques such as high-performance liquid chromatography (HPLC) and Gas Chromatography (GC) (Oliveira et al 2001, Robards et al 1997, Robards K. and Antolovich 1997, Branco et al 1998, 2001, Stremple 1998). The structural determination of these compounds, as components of a mixture, was based on spectral data, including 2D NMR techniques, such as heteronuclear correlation 1H-13C-COSY-n J CH (n = 1, HMQC = 1Hdetected Heteronuclear Multiple Quantum Coherence; n = 2 and 3, HMBC = 1H-detected Heteronuclear Multiple Bond Connectivity) and gas chromatography mass spectrometry, together with chemical transformation and comparative analysis of chemical shifts described in the literature. The antifungal activity of these compounds against phytopathogenic and human pathogenic fungi was investigated

MATERIALS AND METHODS

BIOAUTOGRAPHY METHOD

AND DISCUSSION