Bioprospecção de atividades antiglicante e antioxidante de polpas de frutas industrializadas

Abstract

The Maillard reaction consists of the nucleophilic attack of the amino group of an amino acid to a carbonyl group of a reducing sugar, leading to the formation of glycation products and, in sequence, to reactive dicarbonyl compounds, which can attack free amino groups in proteins, forming the advanced glycation products (AGEs). AGEs, in conjunction with advanced lipoperoxidation products (ALEs), are related to various diseases. In this way, the interest for substances with antiglycation action, i.e. which prevent the reactions of glycation, by several mechanisms, has grown in the last years. In this context, the present work has as objectives to investigate the antiglycation and antioxidant capacities of pulps and fruit residues, commonly consumed by Brazilian population. For this, industrialized fruit pulps were extracted in two different ways: one simulates the in natura consumption of the fruits (only centrifugation and lyophilization), and the other, through ethanol extraction, for biotechnological purposes. The ethanolic extraction of genipap residues was carried out in Soxhlet apparatus, furnishing the extract seed + endocarpus (EJSE) and epicarpus + mesocarpus (EJEM). The extracts were submitted to antiglycation activity screening, in two systems: one for initial glycation from a glucose / fructose mixture and bovine serum albumin (BSA), and another, concerning intermediate glycation system, consisting of the mixture of BSA and methylglyoxal (MG). The antioxidant activity was determined by the radical DPPH scavenging activity (RSADPPH), iron reducing potential (FRAP), total phenol content (CTF) and inhibition of lipid peroxidation (IPL). The lyophilized extract of acerola (LAC) was shown to have RSADPPH of 86.4%, and the lyophilized extract of papaya (LMM) had the lowest value (9.9%). For the FRAP method, the acerola ethanolic extract (EAC) presented the best result, 147.2 mg equivalents of trolox (ET)/ g, respectively, and the ethanol extract of caja (ACE) presented the lowest result, 8.2 mg of ET/ g. For the CTF method, the lyophilized extract of acerola (LAC) presented the most promising result being 179.6 mg of equivalents of gallic acid (EGA)/g, whereas the ethanolic extract of papaya (EMM) showed the lowest result: 4.2 mg of EGA/ g of dry extract. In general, the ethanolic extracts of genipap residues presented low antioxidant activity. In the IPL test, the LAC extract was highlighted, once again, with about 95% inhibition, during 30 min. The ethanol extracts of graviola and caja (EGR, ECA) were the most promising for the antiglycation activity, in a BSA-glucose / fructose system, showing inhibition values of AGEs near 86.5% and 85.2%, respectively. The lyophilized mango extract (LMG) had the lowest inhibition value (17.1%) and the ethanolic extracts of acerola, guava and papaya and the freeze -dried papaya (EAC, EGO, EMM and LMM) showed no antiglycation activity. The two ethanolic extracts of genipap residues showed AGE inhibition values of 93% for the EJSE and 86% for the EJEM. For the BSA-MG system, the acerola lyophilized extract (LAC) did not exhibit activity and the ethanolic extract of caja (ECA) presented the most promising results (62.6%), whereas the ethanol extract of graviola (EGR) inhibited about 23%. EJSE inhibited about 82%, and EJEM inhibited 9%. This study confirms that fruits can be great sources of antioxidants and antiglycation compounds, being potential nutraceutics, responsible for the prevention of several diseases, and can serve for future projects on biotechnology.