Extraction of phenolic compounds from Pfaffia glomerata leaves and evaluation of composition, antioxidant and antibacterial properties.

Abstract

This work aimed to evaluate the extraction conditions of total phenolic compounds (TPC) from Pfaffia glomerata leaves (PGLs) and characterize the extract obtained in the best conditions. Aqueous extraction was performed in a Shaker, varying the levels of rotation (100, 150, 200 rpm), temperature (30, 45, 60° C) and mass to volume (w v-1) ratio (1:10, 1:20, 1:30 g ml-1). The variables w v-1 ratio and temperature, and their combination, showed a positive effect (p<0.05) in TPC extraction. The time of extraction increased TPC extraction until 30 min, thereafter, the values decreased. The extraction performed at 60o C, 1:30 g ml-1, 125 rpm and 30 min allowed to reach the maximum TPC content (11.94 mg g-1). This extract contains β-ecdysone (4.64 g 100g-1), a chemical marker of P. glomerata, and, phenolic compounds, as gallic acid (28.51 mg 100g-1) and catechin (24.82 mg 100g-1). PGLs extract exhibits antioxidant activity by the in vitro methods evaluated (iron reduction powder and radical scavenging ability). Antibacterial activity was also detected, being found the minimum inhibitory concentration of 20 mg mL-1 for Escherichia coli and Pseudomonas aeruginosa. Therefore, PGL extract had a potential application as natural antioxidant and antimicrobial in food or pharmaceutical products.