Complete 1H and13C NMR assignments and antifungal activity of two 8-hydroxy flavonoids in mixture

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.