Oleuropein, an Antioxidant Polyphenol from Olive Oil, Is Poorly Absorbed from Isolated Perfused Rat Intestine

Abstract

Epidemiological studies have shown that the incidence of heart disease and certain cancers is lower in the Mediterranean region. This has been attributed to the high consumption of olive oil in the Mediterranean diet, which contains polyphenolic compounds with antioxidant activity. Although many in vitro studies have been performed to elucidate mechanisms by which these compounds may act, there are virtually no data relating to their fate after ingestion. Therefore, we decided to investigate the intestinal absorption of one of the major olive oil polyphenolics, oleuropein. To do this, a novel in situ intestinal perfusion technique was developed, and the absorption of oleuropein was studied under both iso-osmotic and hypotonic luminal conditions. Oleuropein was absorbed, with an apparent permeability coefficient (P:(app)) of 1.47 +/- 0.13 x 10(-6) cm/s (+/-SE) observed under iso-osmotic conditions. The mechanism of absorption is unclear but may involve transcellular transport (SGLT1) or paracellular movement. Under hypotonic conditions, the permeability of oleuropein was significantly greater (5.92 +/- 0.49 x 10(-6) cm/s, P: < 0.001). This increase is thought to be due to an increase in paracellular movement facilitated by the opening of paracellular junctions in response to hypotonicity. Overall, we determined that the olive oil polyphenolic oleuropein can be absorbed, albeit poorly, from isolated perfused rat intestine. Therefore, it is possible that it or its metabolites may confer a positive health benefit after the consumption of olive oil, most likely via an antioxidant mechanism.

The phenolic compounds of olive oil: structure, biological activity and beneficial effects on human health

“…Absorption of oleuropein in such circumstances occurs mainly by way of a transcellular pathway. Since oleuropein is to some extent polar, it is unlikely that it diffuses rapidly through the lipid bilayer of the epithelial cell membrane; a carrier therefore has to be used (Edgecombe et al 2000). As it is a glycoside, oleuropein can probably use a glucose carrier.…”

Potential Health Benefits of Olive Leaf

“…Barsaklarda oleuropeinin tamamen hidroksitirozole ve diğer alt ürünlere metabolize olduğu, insan plazması ve dışkısında bulunmadığı bildirilmiştir. 9 Hidroksitirozolün insan vücudunda hızlı bir şekilde emildiği ve hızlı bir şekilde vücuttan atıldığı, ayrıca doğal bileşen olarak bulunduğu besinlerin alımı ile biyolojik yararının daha yüksek olduğu da rapor edilmiştir. 10 Ancak bazı çalışmalarda oleuropein için, bir glikozid olduğundan dolayı barsak epitel hücrelerinden sodyum bağımlı glikoz transporter benzeri bir taşıma ile emilebildiği söy-lenmiştir.…”

“…10 Ancak bazı çalışmalarda oleuropein için, bir glikozid olduğundan dolayı barsak epitel hücrelerinden sodyum bağımlı glikoz transporter benzeri bir taşıma ile emilebildiği söy-lenmiştir. 9 Oleuropeinden hidroksitirozol ve elenoik asit oluşumu aşağıda gösterilmiştir (Şekil 1). 17 Yapılan başka bir çalışmada, zeytin yapraklarından elde edilen oleuropeinin oksidatif hasar, enzimatik ve non-enzimatik antioksidan bileşikler üzerine etkileri alloksan verilmiş diyabetik tavşanlarda araştırılmış ve oleuropeinin diyabet ile gelişen hiperglisemi ve oksidatif hasarı inhibe etme özelliği olduğunu ve oksidatif stres ile ilişkili komplikasyoların önlenmesinde yararlı olabileceğini gös-termiştir.…”

Obtention and Characterization of Rosemary and Ash Tree Seed Extracts and Study of Their Preventive Effects on Metabolic Disorders

“…The authors reported paracellular absorption and/or an active transport mechanism via SGLT1 (Edgecombe et al, 2000).…”

“…In order to exert insulin secretion, compounds found in Fraxinus excelsior L. seed extract or its metabolites must be bioavailable. There is no evidence in literature on the bioavailability of nuzhenide or GI3; but some studies suggested that secoiridoids with similar structures can be absorbed by the body (Edgecombe et al, 2000;Singh et al, 2008).…”