Isolation and characterization of flavonoids from Tapirira guianensis leaves with vasodilatory and myeloperoxidase-inhibitory activities.

The aim of this study was to perform the isolation and characterization of vasodilatory flavonoids from Tapirira guianensis Aubl. (Annacardiaceae) leaves. In this context, ethyl acetate fraction (EA fraction) was obtained and subjected to fractionation batches by HSCCC affording: myricetin 3-O-α-L-rhamnopyranoside (myricitrin, 1); quercetin 3-O-(6"-O-galloyl)-β-D-galactopyranoside (2); quercetin 3-O-α-L-arabinofuranoside (avicularin, 3); and quercetin 3-O-α-L-rhamnopyranoside (quercitrin, 4). Myricitrin (1) induced a relaxation of 56.07 ± 13.04% at 300 μM (P < 0.05; n = 5), indicating that this flavonoid contributes to the vasodilatory activity of EA fraction. In addition, all EA fraction flavonoids were evaluated for their capacity of inhibiting myeloperoxidase activity and flavonoid (2) (IC50 1.0 ± 0.3 µM) was the strongest peroxidase inhibitor. In conclusion, it was possible to verify that myricitrin together with quercetin are mainly responsible for vasodilatory potential, besides flavonoid 2 for myeloperoxidase inhibition. Together these flavonoids seem to be responsible for Tapirira guianensis cardiovascular effects.