Potencial antioxidante, antiglicante e antidiabético de extrato etanólico de sementes de espécies de Passiflora e piceatanol in vitro

Abstract

This work investigated the in vitro antioxidant, antidiabetic, and antiglycation activities of ethanolic extract of seeds of Brazilian Passiflora edulis from Alagoas (EPED1), P. edulis from Bahia (EPED2), and P. cincinnata (EPCIN), a major by-product of the juice industry, along with one of its chemical constituent, piceatannol (PIC), which was characterized by HPLC-DAD-MS/MS. The extracts IC50 values for DPPH•, HOCl, and O2 •- scavenging assays showed an antioxidant potential of all extracts and PIC when compared to quercetin (QCT). Among all extracts, EPED1 exhibited the highest activity for α-amylase (IC50 of 32.1 ± 2.7 μg/mL) and DPP-4 human recombinant enzyme inhibition (IC50 of 71.1 ± 2.6 μg/mL), positive controls were acarbose (ACB, 0.40 ± 0.05 μg/mL) and sitagliptin (STG, 0.005 ± 0.001 μg/mL), respectively. PIC stood up for α-glucosidase inhibition with IC50 of 20.4 ± 7. 6 μg/mL, the positive control, ACB had 251,6 ± 4.5 μg/mL. The extracts and PIC inhibited the formation of advanced glycation end-products (AGE) in a dose-dependent manner through the method of glycation of bovine serum albumin (BSA) by reducing sugars or methylglyoxal (MGO). For 1 h of incubation of MGO with EPED1, EPED2, EPCIN, PIC, and aminoguanidine (AMG) the remaining % MGO values were 78.1%, 71.4%, 52.1%, 24.9% and 0,4%, respectively. Additionally, the formation of β-amyloid fibrils decreased as sample concentration increased achieving 100% of inhibition at a concentration higher than at least 300 μg/mL, except for EPCIN whose inhibition was not detected at concentrations up to 400 μg/mL. This suggests that EPED1, EPED2, and PIC may prevent glycation. Cell viability assay showed that EPED1 had no cytotoxic effect on alpha mouse liver (AML-12) and on the normal bronchial epithelium (BEAS-2B) cells up to 50 and 100 μg/mL, respectively. However, even, at lower concentrations (10 μg/mL), the extracts were cytotoxic to nonmalignant breast epithelial cells (MCF-10A). EPED1, EPED2, EPCIN, and PIC were found to be capable of protecting BEAS-2B cells from the oxidative stress caused by the carcinogen NNKOAc at 100 μM. This investigation collected some in vitro evidence for the potential use of P. edulis seeds as a complementary to the treatment of diabetes and its complications, although more research is still needed.