Caracterização de frutos de araçá (Psidium cattleianum Sabine): composição fenólica, atividade antioxidante e inibição de alfa-amilase e alfa-glicosidase

Abstract

Among the wild fruits of the Atlantic forest, araçá stands out for presenting bioactive compounds with antiproliferative, antimicrobial, anti-aging and antidiabetic action (by the inhibition of alpha-amylase and alpha-glucosidase). However, the quantification and characterization of the compounds present in the araçá have not been sufficiently elucidated. Thus, phenolic compounds present in different pulp-peel and seed extracts of three araçá genotypes were identified and quantified. In addition, their antioxidant activities and alphaglucosidase and alpha-amylase inhibition potentials were evaluated. The obtained extracts were fractionated by solid phase extraction and the phenolic compounds were identified and quantified by chromatographic analysis. No significant differences were observed for the enzymatic inhibition between the three genotypes, nor even between pulp-peel and seed. Alpha-amylase and alpha-glucosidase enzymes were inhibited by the compounds present in araçá pulp-peel and seed extracts regardless of genotype. Phenolic compounds present in fraction III (flavonoids) were distinguished by the inhibition of both alpha-glucosidase and alpha-amylase enzymes. However, phenolic compounds present in fraction IV (polymeric anthocyanins) and in the unfractionated extract, were distinguished by the inhibition of alpha-glucosidase, with slight inhibition of alpha-amylase. Ellagic acid was the compound found in higher amounts in the fractions and non-fractionated extract, while quercetin cyanidin-3-glycoside, malvidin-3-glycoside, and vanillic, syringic p-coumaric and 4-hidroxybenzoic acids were present in lower amounts. In conclusion, araçá phenolic extracts inhibited alpha-amylase and alpha-glucosidase; the genotype and the fruit part did not influence the inhibition of these enzymes; the compounds present in the unfractionated extract and fractions III and IV resulted in higher inhibition of the enzymes studie.