Olive Leaf Extracts Are a Natural Source of Advanced Glycation End Product Inhibitors

Abstract

Advanced glycation end products (AGEs), which are readily formed and accumulated with sustained hyperglycemia, contribute to the development of diabetic complications. As a consequence, inhibition of AGE formation constitutes an attractive therapeutic/preventive target. In the current study, we explored the phytochemical composition and the in vitro effect of two different olive leaf extracts (an aqueous and a methanolic) on AGE formation. The methanolic olive leaf extract inhibited fluorescent AGE formation in a bovine serum albumin (BSA)-ribose system, whereas the aqueous extract had no effect in both BSA-fructose and BSA-ribose systems. The phytochemical profile was investigated with liquid chromatographyultraviolet-visible (UV-Vis) diode array coupled to electrospray ionization multistage mass spectrometry (LC/DAD/ESI-MS n ). Quantification of the major phenolic compounds was performed with high performance liquid chromatography with UV-Vis diode array detection and nuclear magnetic resonance spectroscopy. Among the major phenolic components (luteolin, hydroxytyrosol, luteolin-

A review: benefit and bioactive properties of olive (Olea europaea L.) leaves

“…Hydroxytyrosol, a degradation product of oleuropein, also shares some of the latter biological properties such as antimicrobial, hypoglycemic, hypolipidemic, hypocholesterolic, antioxidant and free radical-scaveging [76,99,100]. In the olive leaf phenol extract, the hydroxytyrosol amount was 0.2 g/100 g of fresh olive (Ortice variety) leaves [3].…”

The Olive Tree, a Source of Antioxidant Compounds

“…The concentration and type of polyphenols in the leaves is influenced by many factors, such as geographical location, cultivar and age of plant [33]. The main phenol encountered in olive leaves is the secoiridoid oleuropein, whereas its analogues oleuropein aglycone and ligstroside aglycone occur in variable concentrations (Table 3) [34][35][36][37]. The second most abundant compound in olive leaves is the phenolic alcohol hydroxytyrosol, whereas tyrosol is only found in small concentrations in leaves.…”

Iridoids are natural glycation inhibitors

“…In an in vitro bovine serum antiglycation assay, oleuropein displayed little activity up to a concentration of 100 μM when ribose or fructose were used as the glycating agents [99]. However, hydroxytyrosol, a major metabolite of oleuropein, binds methylglyoxal under physiological conditions, thereby limiting the formation of AGEs via carbonyl scavenging [100].…”