Chemical investigation of methanol extract leaves from Annona dioica (Annonaceae) resulted in the identification of flavonoids kaempferol (1), 3-O-[3",6"-di-O-p-hydroxycinnamoyl]-beta-galactopyranosyl-kaempferol (2), 6"-O-p-hydroxycinnamoyl-beta-galactopyranosyl-kaempferol (3) and 3-O-beta-galactopyranosyl-kaempferol (4). The structures were unequivocally characterized by ¹H and 13C NMR spectroscopic analyses using 1D and 2D experiments. The cytotoxic effects of the flavonoids and flavonoid fraction (FF) were evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay against Ehrlich carcinoma cells. The results indicated that 1, 2, 3 and FF exhibit significant antiproliferative action when compared to quercetin. The inhibitory action on DNA-topoisomerase I and II of all the flavonoids was evaluated by relaxation assays on pBR322 plasmid DNA. The results indicated the inhibitory and non-selective effects of the flavonoids on DNA-topoisomerase I and II.
Annona dioica; Annonaceae; cytotoxic activity; flavonoids; DNA-topoisomerase
