Chemical composition and in vitro antioxidant activity of hydro-ethanolic extracts from Bauhinia forficata subsp. pruinosa and B. variegata.

Bauhinia species are known to have hypoglycemiant and antioxidant activities. Here, hydro-ethanolic leaf extracts from Bauhinia forficata subsp. pruinosa and Bauhinia variegata, collected in a Pampa biome region of Brazil, were investigated to characterize their chromatographic profile, flavonoid content and in vitro antioxidant activity (TBARS and DPH assays). The extracts were obtained from dried and fresh leaves. The total flavonoid content was assessed by spectrophotometric determination, and the results ranged between 572.08 and 1,102.99 μg mL-1. Moreover, flavonoids were more predominant in B. variegata than in B. forficata subsp. pruinosa. HPLC analysis detected a complex profile of phenolic compounds, being the flavonoid kaempferitrin founded B. forficata subsp. pruinosa; in addition, other kaempferol and quercetin derivatives were present. In vitro antioxidant assays demonstrated a different behavior depending on the species, leaf treatment and extract concentration. In general, B. variegata extracts obtained from fresh material presented higher antioxidant potential, which can be attributed to the predominance of flavonoids in their chemical composition.