Flavonoids and Antioxidant Potential from the Leaves of Bauhinia longifolia (Bong.) Steud

Abstract

In this study the chemical composition of Bauhinia longifolia leaves was evaluated. The phytochemical study of the methanolic extract from the leaves of B. longifolia led to the isolation and structural elucidation of aglycone quercetin and its 3-O-monoglycoside derivatives: quercetin-3-O-α-Arabinofuranoside, quercetin-3-O-α-rhamnopyranoside, quercetin-3-O-β-glucopyranoside and quercetin-3-O-β-galactopyranoside. Flavonoid structures were determined using a combination of techniques, including HPLC-UV, ESI-MS and NMR, in addition to the literature data. The antioxidant activity of the hexane, dichloromethane, ethyl acetate (EtOAc) and butanol (BuOH) fractions from the partition of the methanolic extract from the leaves of B. longifolia was evaluated by the DPPH radical reduction method and expressed in terms of its CE50. The highest antioxidant activity was observed for EtOAc fractions (CE50 =.μg/L ad BuOH CE50=.μg /L fractions. They were also evaluated for total phenol content by the Folin-Ciocalteau spectrophotometric method, which revealed high oetratios of pheoli opouds i EtOA . μg EAG/g ad BuOH . μg EAG/mg) and low total pheoli otet i hexae . μg EAG/g ad dihloroethae . μg EAG / gfratios. For the first tie the antioxidant activity of B. longifolia leaves is reported, as well as the presence of the monoglycosides avicularin, hyperin and isoquercitrin, flavonoid commun on Bauhinia genus, but never described for B. longifolia. Thus the present study contributes with the chemical and pharmacological knowledge of B. longifolia, a great medicinal importance specie.