Caracterização de frutos de genótipos de cajá-umbuzeiras : teor de fitoquímicos bioativos e potencial antioxidante

Abstract

The aim this work was to characterize "cajá-umbu" fruits coming from the germplasm's collection IPA (Instituto Agronômico de Pernambuco). Fruits of the 4 genotypes (G 2.2, G 2.3, G 3.1, G 3.2) were used to quantify the phytochemicals bioactive and evaluate the antioxidant potential. The polyphenols were quantified by spectrophotometric method, the ascorbic acid by titulometric method and carotenoids by chromatographic and spectrophotometric techniques. Hydroacetone, hydromethanolic and aqueous extracts were obtained using 3 extraction systems: a) sequential extraction: acetone 80%, methanol 80% and water, b) sequential extraction: water, methanol 80% and acetone 80% c) non¬sequential extraction. The isolated and combined extracts were submitted to the determination of total phenolic content, screened for their free DPPH- (1,1¬diphenyl-2-picrilhidrazil) and ABTS-+) (2,2'-azino-bis-(3-etilbenzotiazoline 6¬sulfonic acid) scavenging activity, and their effect on the linoleic acid peroxidation by the system of co-oxidation r3-carotene/acid linoleic and ferric thiocyanate method. The fruits showed significant content of polyphenols, low levels of ascorbic acid and carotenoids. The I3-carotene 5-6, 5'6'-diepoxide was the major component of genotypes G 2.2, G 2.3, G 3.1, and 5-6 epoxide lutein for G 3.2. The extraction procedure which employed acetone 80% as first solvent could extract a larger amount of total phenolic. Ali genotypes exhibited good DPPH- scavenging activity (ECSD value of 0.30 to 0.43, TEcSD value of 8.98 to 15.24 minutes, and EA value of 0.18 to 0.40), significant ABTS-+ scavenging capacity (55.56 a 120.08 IJMol TEAC.g-1) and high percentage of inhibition of peroxidation of linoleic acid (88.45 to 92.89%). In co-oxidation of linoleic acid/r3-carotene system exhibited moderate activity (56.91 to 69.41 % inhibition), showing that they are effective in blocking the onset of oxidation reaction (F1 <1), but the propagation phase, G 3.2 genotype showed higher efficiency (F2 <1). Therefore, fruits of "cajá-umbuzeiro" have bioactive compounds and good antioxidant potential that can contribute te the dietary intake of antioxidant.