Abstract
The purpose of this work was to study the distribution of oleacein (OLEA) and its metabolites in rat plasma and different tissues, namely brain, heart, kidney, liver, lung, small intestine, spleen, stomach, skin, and thyroid, following the acute intake of a refined olive oil containing 0.3 mg/mL of OLEA. For this purpose, a distribution kinetics study was carried out. The plasma and tissues were collected at 1, 2, and 4.5 h after the intervention, and analyzed by LC-ESI-LTQ-Orbitrap-MS. Unmetabolized OLEA was detected in the stomach, small intestine, liver, plasma and, most notably, the heart. This finding may be useful for the development of new applications of OLEA for cardiovascular disease prevention. Noteworthy are also the high levels of hydroxytyrosol (OH-TY) and OLEA + CH3 found in the small intestine, liver, and plasma, and the detection of nine OLEA metabolites, five of them arising from conjugation reactions. Liver, heart, spleen, and lungs were the target tissues where the metabolites were most distributed. However, it is important to note that OH-TY, in our experimental conditions, was not detected in any target tissue (heart, spleen, thyroids, lungs, brain, and skin). These results shed further light on the metabolism and tissue distribution of OLEA and contribute to understanding the mechanisms underlying its effect in human health.
Highlights
Oleacein (OLEA), termed 3,4-DHPEA-EDA, plays a significant role in the organoleptic qualities of extra virgin olive oil (EVOO), and its antioxidant properties improve the oil’s shelf life [1,2]
16% at 2 h and by 34% at 4.5 h (p < 0.05). One explanation for this reduction is gastric emptying, as OLEA was observed in the small intestine at 1 h post-ingestion. Another possible cause is the acidic environment of the stomach and/or the presence of nonlipolytic carboxylester hydrolases, which can contribute to a hydrolysis of OLEA, resulting in OHTY and elenolic acid (EA) [26]
In a recent in vivo study with rats by Pinto et al [18], OLEA was found to undergo a complete degradation in the gastric region, and only a partial hydrolysis after incubation at pH 2.0, with about 67% of OLEA remaining after 4 h
Summary
Oleacein (OLEA), termed 3,4-DHPEA-EDA, plays a significant role in the organoleptic qualities of extra virgin olive oil (EVOO), and its antioxidant properties improve the oil’s shelf life [1,2]. It is one of the most abundant compounds in EVOO and the concentrations of this secoiridoid can reach up to 1834 ± 110 mg/kg [3,4]. Anti-cancer effects have been reported, including antiproliferative and apoptosis-inducing activity in leukemia cells [11] and reduction of viability and migration of non-melanoma skin cancer cells [12]
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