Olive leaf extract concentrated in hydroxytyrosol attenuates protein carbonylation and the formation of advanced glycation end products in a hepatic cell line (HepG2)

Abstract

Glycation takes place both at the cellular level and at the extracellular matrix level and generates, consequently, advanced glycation end-products (AGEs) associated with chronic diseases and the aging process. Two olive leaf extracts concentrated in (i) oleuropein (OLE-A; 93.9 mg oleuropein g) and (ii) hydroxytyrosol (OLE-B; 54.5 mg hydroxytyrosol g) were evaluated according to their antiglycative and antioxidant capacity in vitro. OLE-B exerted the highest anti-AGE effect in different glycation models (IC: 0.25-0.29 mg mL). OLE-B showed the highest antioxidant capacity and methylglyoxal-trapping capacity (IC 0.16 mg mL). OLE-B showed a significant inhibitory effect against protein carbonylation (21%) and generation of argpyrimidine (26%) in a hepatocyte cellular carbonyl stress model evoked by methylglyoxal (MGO). OLE-B was further fractionated by solid phase-extraction, and the protective effect against protein carbonylation was only exerted by the fraction containing hydroxytyrosol. However, hydroxytyrosol standard, at the same concentration in the extract, inhibited the protein carbonylation below 10% but not significantly. The results indicate that the antiglycative activity of OLE in cells could be due to a synergic effect of hydroxytyrosol and other minor compounds with similar polarity. The research of the antiglycative activity in vivo could confirm these promising results and to propose OLE as a natural anti-AGE agent.

Redox Signaling and Advanced Glycation Endproducts (AGEs) in Diet-Related Diseases

“…Catechins act as a free radical scavenger and prevent lipid peroxidation [177,196]. Authors have also shown a protective role against the oxidation-induced damage in erythrocytes in type 2 diabetes patients [197].…”

β-Glucosidase Discovery and Design for the Degradation of Oleuropein

“…Additionally, previous research showed that the olive leaf extract concentrated in hydroxytyrosol had higher antiglycative and antioxidant activity than the olive leaf extract concentrated in oleuropein. 38 Therefore, increasing the hydroxytyrosol content of olive leaf tea could potentially increase its health benefits. Briante et al 39 explored using recombinant β-glucosidase immobilized in a chitosan support to produce hydroxytyrosol from olive leaf extract on an industrial scale.…”

Common Protective Strategies in Neurodegenerative Disease: Focusing on Risk Factors to Target the Cellular Redox System

“…Moreover, sulforaphane was able to counteract oxidative stress and to increase intracellular GSH levels and the expression, and activity, of glyoxalase 1 [ 236 , 237 ]. Bioactive substances from Olea europaea, such as oleocanthal and hydroxytyrosol, are able to counteract the glycation processes [ 238 , 239 ]; moreover, oleocanthal treatment improves GSH intracellular content and counteracts oxidative stress in neuron-like cell culture [ 240 ]. Recently, Angeloni et al analysed the relationship between oleocanthal and AD suggesting that, besides its effects to interfere with tau protein hyperphosphorylation and aggregation and its ability to induce A β efflux and clearance, it might counteract AD's progression by reducing glycation in the brain, thanks to its positive effect on the GSH level, and to its ability to decrease oxidative stress [ 241 ].…”