Complete ¹H and 13C NMR assignments and anti fungal 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.

RESUMO

Os flavonóis 8-hidroxi-3, 4', 5, 6, 7-pentametoxiflavona (1) e 8-hidroxi-3, 3', 4', 5, 6, 7-hexametoxiflavona (2) foram isolados em mistura a partir de uma amostra comercial de Citrus aurantifolia. A determinação estrutural e a inequívoca atribuição dos sinais de deslocamento químico dos átomos de hidrogênio e carbono destes compostos naturais foram realizadas através da análise dos espectros de RMN 1D e 2D, incluindo COSY, NOESY, HMQC e HMBC. Em adição, a atividade antifúngica destes compostos contra fungos patogênicos também foiinvestigada.