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).
Opextan® and improvement of oxidative status in healthy volunteers from within
In a biological system, whenever an imbalance occurs between the natural production of reactive oxygen species and the capacity to detoxify them or repair the damage they induce, “oxidative stress” results. This condition can be harmful, since it leads to the production of reactive oxygen species that can cause extensive cellular damage, affecting all cell components, including protein, lipids and DNA.
Oxidative stress might underlay the onset of chronic degenerative diseases like Parkinson’s- and Alzheimer’s diseases and cancer. It has been linked to cardiovascular disease, and is certainly important in the ageing process. An increased lipid peroxidation is one of the results of oxidative stress, and has been correlated to the incidence of a host of diseases that affect the cardiovascular system(5). There are few suitable biomarkers for lipid peroxidation and oxidative stress, but an increase in both plasma levels and urinary excretion of F2 isoprostanes is believed to be directly related to an enhanced oxidative stress. F2 isoprostanes are a family of prostaglandin-like compounds formed in vivo by the free-radical catalyzed peroxidation of arachidonic acid, in a way independent from the action of cycloxygenase enzymes(6). Numerous studies have validated isoprostanes as accurate markers of lipid peroxidation in vivo.
Epidemiological studies suggest that a high intake of dietary antioxidants can reduce oxidative stress, and the effect of Opextan® on isoprostane excretion has been carried on in human volunteers, quantitating the excretion of 8-isoprostane (8-iso-prostaglandin F2a).
Nineteen healthy subjects received Opextan® at a daily dosage of 400 mg for 4 weeks. The urinary excretion of 8-isoprostane was evaluated in the urine before the beginning of the study and at the end of the four weeks treatment. The oral administration of olive fruit extract significantly decreased the formation of the oxidative stress marker 8-isoprostane (by 47%, mean data, p<0.05, fig. 1). The administration of Opextan® can therefore be recommended in order to control the organism’s oxidative stress. Although there is still no evidence that the beneficial impact of antioxidants may have a favorable impact on maximal life span, current data indicate that their biological activity on age-related degenerative diseases may produce an improvement in life span and enhance quality of life.
- 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
- Girotti AW, “Lipid peroxide generation, turnover and effector action in biological systems”, J. Lipid Research 39, (1998), 1529-1542
- Maramaldi G, Artaria C, Ikemoto T, Haratake A, “Estratto standardizzato di frutti di Olea europaea”, L’ integratore Nutrizionale 9 (3), (2006), 23-29
- 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
- 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
- Morrow JD, Roberts LJ 2nd, “The isoprostanes. Current knowledge and directions for future research”, Biochem Pharmacol, 1996 Jan 12; 51 (1): 1-9