title: Antioxidant, Iron Chelating and Tyrosinase Inhibitory Activities of Extracts from Talinum triangulare Leach Stem.
abstract: The aim of this work is to evaluate the antioxidant activity against the radical species DPPH, the reducing capacity against Fe II ions, and the inhibitory activity on the tyrosinase enzyme of the T. triangulare. Hydromethanolic crude extract provided two fractions after the liquid/liquid partition with chloroform. The Folin-Ciocalteu method determined the total phenolic content of the crude extract (CE) and the hydromethanolic fraction (Fraction 1), resulting in a concentration of 0.5853 g/100 g for Fraction 1, and 0.1400 g/100 g for the CE. Taking into account the results of the DPPH, the free radical scavenging capacity was confirmed. The formation of complexes with Fe II ions was evaluated by UV/visible spectrometry; results showed that CE has complexing power similar to the positive control (Gingko biloba extract).The inhibitory capacity of samples against the tyrosinase enzyme was determined by the oxidation of L-DOPA, providing IC50 values of 13.3 μg·mL(-1) (CE) and 6.6 μg·mL(-1) (Fraction 1). The values indicate that Fraction 1 was more active and showed a higher inhibitory power on the tyrosinase enzyme than the ascorbic acid, used as positive control. The hydromethanolic extract of T. triangulare proved to have powerful antioxidant activity and to inhibit the tyrosinase enzyme; its potential is increased after the partition with chloroform.
authors.affiliation: Department of Chemistry, Institute of Exact Sciences, Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro 23890-000, Brazil. amorim@ufrrj.br.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Oliveira Amorim
authors.affiliation: Department of Chemistry, Institute of Exact Sciences, Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro 23890-000, Brazil. mccdeo@ufrrj.br.
authors.forename: Márcia Cristina
authors.initials: MC
authors.lastname: Campos de Oliveira
authors.affiliation: Department of Botanic, Institute of Biology, Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro 23890-000, Brazil. thiagodb@ufrrj.br.
authors.forename: Thiago
authors.initials: T
authors.lastname: de Azevedo Amorim
authors.affiliation: Department of Chemistry, Institute of Exact Sciences, Universidade Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro 23890-000, Brazil. echevarria@ufrrj.br.
authors.forename: Aurea
authors.initials: A
authors.lastname: Echevarria
keywords: DPPH; Fe II ions; oxidase; portulacaceae; tyrosinase