Effect of Extraction Conditions on Polyphenol Content and Antioxidant Activity of the Extract from Gynura Procumbens (Lour) Merr. Leaves

Abstract

       Gynura procumbens (Lour.) Merr. is a well - known traditional herb in South East Asia and it is widely used to treat inflammation, high cholesterol level, high blood pressure and diabetes. In the present study, the effects of various extraction conditions were investigated: solvent, solvent concentration, material to solvent ratio, extraction temperature, extraction time and extraction techniques (maceration and ultrasonic - assisted) on total phenolic content (TPC) and antioxidant activity of the extract from leaves of Gynura procumbens (Lour) Merr. cultivated in Khánh Hoa province. Folin - Ciocalteu’s method was used for the determination of TPC, while the antioxidant activity was determined by 2,2’ - diphenyl - 1 - picrylhydrazyl (DPPH) radical scavenging activity and reducing power assays. The best extraction conditions were as follows: 50% aqueous methanol as the extraction solvent,1: 50 material to solvent ratio, the extraction temperature at 60^oC and the extraction time of 30 min, using ultrasonic – assisted extraction. The total phenolic content, DPPH radical scavenging activity (EC₅₀) and reducing power (EC₅₀) under suitable condition, were 48.49 mg GAE/g dry extract, 0.13 and 0.06 mg/ml, respectively. The present study suggested that the Gynura procumbens extract could be a promising source of natural antioxidants.