Oxidative stress is one of the main causes for the onset of various degenerative disorders. Lipid peroxidation is a well known example of oxidative damage in lipid-containing structures
(1,2), and epidemiological studies suggest that a high intake of antioxidants is protective in this context.
Olive polyphenols are free radical scavengers with a direct impact on skin health, since they can prevent the oxidative damage involved in the formation of wrinkles and in skin hyperproliferation and dryness. In vitro studies have been carried out under the assumption that the antioxidant activity of the olive fruit extract, as its radical scavenging properties, are responsible for the major part of the biological effect attributed to olive polyphenols.
The stable radical DPPH (1,1 diphenyl-2 picrylhydrazyl) method has been used to determine the antioxidant activity of the extract, and of its single polyphenolic constituents (3). This method measures the hydrogen donating capacity of a test material. The antioxidant capacity of purified olive polyphenolics (verbascoside, hydroxytyrosol, caffeic acid), has been compared with two references (ascorbic acid and oleuropein), qualifying verbascoside as a very potent antioxidant, 5 fold more active than oleuropein (a polyphenolic iridoid typical of olive leaves).
Another very common test for in vitro antioxidant activity is based on superoxide anion O2-. This model mimics the in vivo situation, employing a physiological oxidant. Thus, the harmful effect of skin exposure to UV rays has been linked to the formation of reactive oxygen species (ROS), including the superoxide radical. Verbascoside, the major polyphenolic compound present in Opextan, was found in this test to be able to inhibit anion superoxide formation by 68% (3).
In an other independent study verbascoside has been shown to be the most potent SOR and H2O2 scavenging agent compared to the major poliphenols found in olives (ex. caffeic acid or hydroxytyrosol) evaluated individually or in equimolar mixtures. Furthermore, verbascoside could protect DNA from oxidative damage in a dose-independent manner (4).
Figure 1: Effect of Opextan®, orally administered, on lipid peroxidation.
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1. Sakurai H, Yasui H, Yamada Y, Nishimura H, Shigemoto M, "Detection of ROS in the skin of live mice and rats exposed to UV light: a research review on chemiluminescence and trials protection" Photochem Photobiol Sci, 4 (9), (2005), 715-720
2. Girotti AW, "Lipid peroxide generation, turnover and effector action in biological systems", J. Lipid Research 39, (1998), 1529-1542
3. Maramaldi G, Artaria C, Ikemoto T, Haratake A, "Estratto standardizzato di frutti di Olea europaea", L' integratore Nutrizionale 9 (3), (2006), 23-29
4. Obied, H. K., Prenzlere, P. D., Konczak, I., Rehman, A.-u., Robards, K. 2009. Chemistry and bioactivity of olive biopenols in some antioxidant and antiproliferative bioassays. Chem. Res. Toxicol
5. Visioli F, Galli C, Plasmati E, Viappiani S, Hernandez A, Colombo C, Sala A, "Olive Phenol Hydroxytyrosol prevents passive smoking-induced oxidative stress", Circulation, 2000 (102) 2169-2170
6. Morrow JD, Roberts LJ 2nd, "The isoprostanes. Current knowledge and directions for future research", Biochem Pharmacol, 1996 Jan 12; 51 (1): 1-9