Biological properties of olive leaf extract

The concept of using olive tree leaves arose from the observation that the olive trees not only are among the most ancient plants in the world but are also resistant to a variety of diseases. More specifically, when a leaf falls from the tree it will remain green for a long time, revealing the presence of highly potent and protective anti-oxidant activity. EurolBT is a water-based extract that contains bio-polyphenol and bioflavonoid compounds that synergistically operate to provide a biological action. Oleuropein is the predominant active molecule found in the new active. It consists of a glycosidic form of the ester formed by elenolic acid and dihydroxyphenylethanol and its two OH groups, placed in position 3 and 4 towards the ethoxylic chain. The position of the two hydroxyls determines particular resonance conditions that stabilise the intermediate radical, through an intra-molecular hydrogen bond.2,3 In this structure we can observe two parts performing different activities: the diphenolic part (A) is responsible for the radical scavenging action, while the glucosidic part (B) ensures the water solubility. Oleuropein may be defined as a chemical exception in nature. In fact, the glucosidic bond is usually a very feeble one, impossible to keep safe in the extraction process, while in this case we are able to maintain exactly the same structure that we find in nature. The benefits of EurolBT (from now on referred to as ‘the new active’) as an active cosmetic ingredient are described below. Other advantages of the product as an active ingredient come from its excellent safety profile (LD50 not detectable) and its complete water solubility. The new active is endowed with numerous applications and we will focus here on its antioxidant and antiinflammatory properties.

 Protection against the oxidation of polyunsaturated fatty acids

The aim of this test is to evaluate the antioxidant action of the new active towards plasma lipoproteins by dosing the peroxidation of polyunsaturated fatty acids (PUFA) submitted to an oxidative stress induced by copper salts. Briefly, samples of plasma lipoproteins were incubated in the presence of 6 mM CuSO4 to trigger the oxidation reaction.4 The rate of PUFA oxidation was assessed for samples preincubated in the presence, or the absence, of the new active at a final concentration of 0.01% and 0.1%. The antioxidant action of the new active was verified for linolenic acid (C18:3), arachidonic (C20:4), eicosapentaenoic acid (EPA) (C20:5) and docohexaenoic acid (DHA) (C22:6). At the end of incubation, samples were immediately submitted to extraction of fatty acids from proteins and the former analysed by HPLC (PECOSPHERE column CR C18 8.3 cm x 4.6 mm, using a linear gradient with solvents: methanol and solution acetonitrile/water 50/50). Results showing the extent of the CuSO4 oxidation and the protection in the presence of the new active are shown in Figures 2 and 3. The biological activity of the new active was quantified as per the amount of the PUFA oxidation. The addition of the copper salt caused a 79.2% reduction of the components DHA (C22:6), EPA (C20:5) and linolenic acid (2.93% for control vs. 0.61% for CuSO4) and a 51.6% reduction in the amount of arachidonic acid (9.59% for control vs. 4.64% for CuSO4). The presence of the new active (0.01% and 0.1%) led to a complete protection of all the PUFA tested against the oxidative chemical stress.