Investigação química e atividades farmacológicas de Vernonia polyanthes Less

Abstract

Vernonia polyanthes Less, known as assa-peixe, is used in traditional medicine as anti-inflammatory, healing and antimicrobial. The aim of the present study was to investigate the chemical and pharmacological potential of V. polyanthes. Dried and powdered leaves were exhaustively extracted with ethanol by static maceration. The ethanol extract was fractionated by partition, obtaining the hexane fraction, dichloromethane, in ethyl acetate, butanol and residual fractions. The phytochemical screening was performed by identification reactions and of total phenols and flavonoids contents were determined by spectrophotometry. Antioxidant activity was measured by DPPH (2,2-diphenyl-1-picryl-hydrazyl), power reduction and TBA methods. The antimicrobial activity by the diffusion method and minimum inhibitory concentration. The acute toxicity was determined by 50% lethal dose (LD50). The antinociceptive activity was evaluated by writhing, formalin and hot plate tests, while the anti-inflammatory activity by paw edema and pleurisy methods. Data are expressed as mean  standard error and analysis of variance followed by Newman-Keuls test or Tukey was used to measure the significance level (p < 0.05). Tannins, flavonoids, coumarins, saponins, alkaloids and terpenes and steroids were detected in the samples. The total phenolic content ranged from 0.76 to 18.63 g/100 g, while flavonoids were 0.26 to 7.73 g/100 g. Extract and fractions showed antioxidant activity using the applied methods. The LD50 of the ethanolic extract was 2.78 g/kg. The extract reduced the writhing, licking time induced by formalin and increased latency on the hot plate, showing antinociceptive activity. The ethanol extract also reduced the paw edema and the volume and number of leukocytes in carrageenan-induced pleural exudate, demonstrating anti-inflammatory activity. The results indicated that V. polyanthes is a source of bioactive substances withe antioxidant activity, antimicrobial, antinociceptive and anti-inflammatory activities and this plant may constitute an alternative for therapeutic applications.