Avaliação da atividade antioxidante e quantificação do teor de fenóis, flavonóides e taninos condensados de Psychotria carthagenensis e P. leiocarpa

Abstract

In folk medicine Psychotria species are employed in the treatment of various diseases such as diarrhea and intestinal parasites, viral, bacterial and other infections. "Cafeeiro-do-mato" and "Pimenteira" is the popular name given to two species of the family Rubiaceae being respectively Psychotria carthagenensis and Psychotria leiocarpa. Chemistry study related the presence of alkaloids, as constituents main. Therefore, the objective of the study was to evaluate the in vitro antioxidant activity and phenolic content, flavonoids and tannins of the methanolic extract of the leaves of P. carthagenensis and P. leiocarpa. The antioxidant activity was performed by in vitro fotocolorimetric with free radical 2,2-diphenyl-1-picryl hidrazila (DPPH) and β-carotene/ácid linoleic bleaching. The total phenolic content was determined by Folin-Ciocalteu's, the flavonoids for aluminum chloride reagent and condensed tannins using acidified vanillin reagent. The results showed that both the methanolics extracts of P. carthagenensis and P. leiocarpa, have significant antioxidant in the DPPH assay, with value of IC50 3.0 mg / mL for P. carthagenensis and IC50 of 15.20 mg/mL for P. leiocarpa, whith compared with to the control BHT (IC50 of 16.8 mg/mL). The method β-Carotene/ácido linoleic bleaching, P. leiocarpa was the most promising (AA = 82.1%). The P. leiocarpa CT showed a high value of 304.68 mg/g sample and TF of the 83.04 mg of quercetin/g of sample. The PT content in both species was not representative. It was concluded that P. leiocarpa can be considered a promising plant species for further studies.