A study using brain cells ( in vitro ) and another using live mice ( ex vivo ) showed that the olive extract, rich in hydroxytyrosol, could reduce the damaging effects of iron- and nitric oxide-induced cytotoxicity, report researchers in the Journal of Agricultural and Food Chemistry .
"Although the first study of its kind, our data provide an informative basis for subsequent in vivo experiments exploring the neuroprotective potential of long-term hydroxytyrosol intake," wrote lead author Sebastian Schaffer from University of Frankfurt.
Hydroxytyrosol is thought to be the main antioxidant compound in olives, and believed to play a signficant role in the many health benefits attributed to olive oil.
Previous research by a team from the University of Barcelona found that LDL or 'bad' cholesterol levels could be cut substantially after consuming just 25 millilitres of virgin olive oil daily for one week.
Other studies have suggested that it could also protect against cancer.
Schaffer and co-workers used the hydroxytyrosol-rich ingredient OlivActiv (Glanbia Nutritionals, provided by Spanish company Genosa I+D), to investigate the potential of the olive extract to protect against oxidative stress in the brain cells of mice.
The in vitro study added oxidative stressors (iron ions or SNP, a nitric oxide donor) to mice brain cells with or without the hydroxytyrosol-rich extract.
The researchers report that, in the absence of the olive extract, the oxidative stressors resulted in a 40 per cent loss of adenosince triphosphate (ATP), the body's co-called 'energy currency'.
In the presence of the extract however ATP loss was only 15 per cent.
Moreover, the neuroprotective activity of hydroxytyrosol became apparent from concentrations as low as 0.01 mg/mL. In two ex vivo studies, the first report of the effects of hydroxytyrosol on brain cell survival, Schaffer and co-workers examined the bioavailability of hydroxytyrosol (including that isolated from olive mill wastewater), and penetration of hydroxytyrosol into brain cells.
The researchers report that a 45.5 per cent hydroxytyrosol extract increased resistance to oxidative stress in dissociated brain cells (DBC).
Indeed, levels of malondialdehyde (MDA), a reactive carbonyl compound and a major end product of lipid oxidation, was 25 per cent lower when the oxidative stressors were administered in the presence of the extract.
"This study indicates that hydroxytyrosol and extra-virgin olive oil afford neuroprotection and might contribute to the lower incidence of neurodegenerative diseases, as observed in the Mediterranean area.
Moreover, we corroborate that olive mill wastewater can be exploited for obtaining hydroxytyrosol -rich extracts with promising biological effects," concluded the researchers.
The results were welcomed by Mr. Pablo Baena, responsible for research and development at Genosa.
"Polyphenols are being associated to exerting neuronal biological activities and brain biomarkers reflecting antioxidant response," he said.
"Hydroxytyrosol is a low weight molecule with a significant antioxidant potential by acting as a free radical scavenger and non-toxic to DBC under the current experimental design."
Source: Journal of Agricultural and Food Chemistry Volume 55, Number 13, Pages 5043 -5049 "Hydroxytyrosol-Rich Olive Mill Wastewater Extract Protects Brain Cells in Vitro and ex Vivo" Authors: S. Schaffer, M. Podstawa, F. Visioli, P. Bogani, W.E. Müller, and G.P. Eckert