ABSTRACT
ETHNOPHARMACOLOGICAL IMPORTANCE: The hemiparasitic species Psittacanthus plagiophyllus Eichl. (Loranthaceae), also known as erva de passarinho, is used in folk medicine in the Santarém region in the state of Pará, Brazil, to treat gastritis and a variety of inflammatory disorders. In view of the lack of pharmacological studies on this species in the literature and the fact that it is used constantly by the local population, this study sought to standardize the extract of the leaves of P. plagiophyllus (AEPp) and to assess its anti-inflammatory potential in in vivo tests. MATERIAL AND METHODS: Quality control and standardization of AEPp were performed following the 5th edition of the Brazilian Pharmacopeia. To assess the in vivo anti-inflammatory activity of AEPp, the carrageenan-induced and dextran-induced rat paw edema models were initially used. To investigate the effect of AEPp on carrageenan-induced leukocyte recruitment and exudate production, the air pouch inflammation model was used. In addition, the antioxidant activity of AEPp was assessed in vitro by the DPPH radical scavenging method. RESULTS: The chromatographic profile of AEPp indicated the presence of flavonoids, coumarins and hydrolyzable and condensed tannins. Measurement of phenolics revealed the following percentages in the extract: 12.62±0.18% total phenolics, 5.39±0.01% total tannins, 12.54±0.24% hydrolyzable tannins, 8.37±0.32% condensed tannins and 1.23±0.02% total flavonoids. In 500 and 1000mg/kg doses (p.o.) AEPp had significant edema-inhibiting activity (p<0.01) in both the models used, suggesting that the extract may act in vascular and cell events in the inflammatory response and exert an inhibitory effect on mediators responsible for edema. In all the doses tested [250, 500 and 1000mg/kg (p.o.)], AEPp inhibited total leukocyte and neutrophil migration and reduced the amount of exudate in the air pouch in a dose-dependent manner. Both effects were statistically significant (p<0.01). The extract also reduced the DPPH radical (maximum reduction 93.13±1.71% at a concentration of 75µg/mL), indicating that it has antioxidant activity. AEPp, therefore, exhibited considerable in vivo anti-inflammatory activity and in vitro antioxidant activity. This may be due to its high phenolics content. CONCLUSION: These findings provide evidence to support the use of P. plagiophyllus in folk medicine to treat inflammatory disorders.