Determination of phenolic bioactive compounds and evaluation of the antioxidant and hemolytic activities in the methanolic extracts of Tradescantia zebrina

Abstract

Introduction: Tradescantia zebrina is a species used mainly in South America, with few reports about its chemical composition and bioactivity. Aim: To determine phenolic bioactive compounds, for the first time in the literature, and the antioxidant and hemolytic activities of extracts (dried and in natura) of this species. Methods: The extracts were obtained by maceration in methanol and the total phenolic and flavonoid contents were expressed in mg equivalent of gallic acid (EAG)/g and quercetin (EQ) of extract, respectively. The antioxidant potential was evaluated by DPPH• and ABTS•+ radical capture methods. The identification and quantification of phenolic bioactive compounds was performed by high performance liquid chromatography coupled to a diode detector (HPLC-DAD) and, the hemolytic activity assay was performed by diffusion in blood agar, using the disk antiobiogram technique. Results: The total phenolic and flavonoid contents in the extracts (in natura and dried) were 67.68 and 233.94 mg EAG/g and 29.70 and 10.99 mg EQ/g of concentrated extract, respectively. Phenolic acids (caffeic, ellagic, ferulic, ρ-coumaric and protocatechuic), flavonoids (chrysin and rutin) and a phenolic aldehyde (vanillin) were determined by high performance liquid chromatography-diodearray detector (HPLC-DAD). The antioxidant activities were confirmed by inhibition of DPPH• (44.08%) and ABTS•+ (46.99%) radicals for in natura samples, respectively. Conclusion: The tested methanolic extracts of Tradescantia zebrina did not present toxicities when tested for hemolytic activity after 72 hours. Therefore, Tradescantia zebrina is a potential source of bioactive substances