Isolation and characterization of flavonoids from <i>Tapirira guianensis</i> leaves with vasodilatory and myeloperoxidase-inhibitory activities

Abstract

The aim of this study was to perform the isolation and characterization of vasodilatory flavonoids from <i>Tapirira guianensis</i> Aubl. (Annacardiaceae) leaves. In this context, ethyl acetate fraction (EA fraction) was obtained and subjected to fractionation batches by HSCCC affording: myricetin 3-<i>O</i>-<i>α</i>-L-rhamnopyranoside (myricitrin, <b>1</b>); quercetin 3-<i>O</i>-(6"-<i>O</i>-galloyl)-<i>β</i>-D-galactopyranoside (<b>2</b>); quercetin 3-<i>O</i>-<i>α</i>-L-arabinofuranoside (avicularin, <b>3</b>); and quercetin 3-<i>O</i>-<i>α</i>-L-rhamnopyranoside (quercitrin, <b>4</b>). Myricitrin (<b>1</b>) 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 (<b>2</b>) (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 <b>2</b> for myeloperoxidase inhibition. Together these flavonoids seem to be responsible for <i>Tapirira guianensis</i> cardiovascular effects.