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Study flags up oxidative stress reduction benefits of cocoa

By Jane Byrne , 09-Feb-2011

New research from Spain finds that polyphenol-enriched cocoa powder could be used as a functional ingredient to reduce oxidative stress in the elderly.

The Spain based authors, who published their findings in the Journal of Agriculture and Food Chemistry, also report the use of models that demonstrate evidence of the metabolic target of cocoa to ensure compliance with EU health claim regulation requirements.

Damage to DNA, protein and lipids increases with age, note the researchers, citing the contribution of oxygen radicals in age-related disease.

They argue that nutritional intervention using functional foods may be an effective way to improve quality of life of elderly people and, furthermore, that studies into the effects of food ingredients with antioxidant properties are thus of great interest.

“Searching for and validating ingredients with in vivo antioxidant effects is one of the key steps in developing this kind of food,” explained the team.

The research group reveals that they have recently developed a cocoa powder with high flavonoid content by improving seed-processing methods: “This cocoa powder has been obtained from nonfermented cocoa beans without roasting and submitted to a short heat treatment to rapidly inactivate polyphenol oxidase (PPO).”

The study

However, the team aimed to establish which metabolic target this flavonoid-rich cocoa powder acts upon – its antioxidative capacity. The authors said they employed the yeast Saccharomyces cerevisiae and the worm Caenorhabditis elegans as model organisms to determine this.

“Companies that want to market functional foods should have reliable, rapid and inexpensive models for identification of these metabolic targets,” observe the Valencia based researchers.

Two different cocoa powders were analysed in the study: a natural (conventional) cocoa powder and the flavonoid-enriched cocoa powder, which they said had an increased total polyphenol content (12 per cent) compared with conventional cocoa powder (4 per cent).

The team reported that they developed a protocol using S. cerevisiae to study the antioxidant effect of the cocoa powder both quantitatively and qualitatively, and that they performed several experiments with C. elegans to analyze the effect of cocoa antioxidants on lifespan extension.

A genomic approach was performed with mutant strains in both organisms to elucidate the metabolic targets of the cocoa powder, added the Spanish scientists.

Findings

The researchers concluded that their findings provides evidence that a flavonoid-enriched cocoa powder exerts resistance to oxidative stress in two in vivo models, the yeast S. cerevisiae and the worm C. elegans, after hydrogen peroxide induced oxidative damage.

They said that the protection upon oxidative stress provided by the cocoa powder is due to its high polyphenol content, as increased survival was observed in yeast cultures after an oxidative stress when compared with a conventional cocoa powder.

“There was a marked resistance to oxidative stress in both organisms using 4 mg/mL of the cocoa powder, representing a supplementation of 8 μg/mL of catechin and 12 μg/mL of epicatechin.”

And they found that the cocoa powder’s protection against such stress is mediated by sirtuin proteins through the insulin/IGF-1 signaling pathway.

“We found that polyphenol-enriched cocoa powder activates the sirtuin protein Hst3p in the budding yeast S. cerevisiae. Sirtuins encompass a family of proteins that are present in the cell nucleus and exhibit deacetylase activity, promoting longevity in diverse organisms,” commented the team.

The findings of the research also showed that the polyphenol-enriched cocoa powder produces lifespan extension in C. elegans, said the Spanish scientists, and they added that the lifespan extension of the worms was dependent on SIR-2.1 and DAF-16 proteins.

Further studies should be done in order to identify the exact polyphenol that is responsible for these beneficial effects, and to determine the amount of effective daily dose of polyphenol-enriched cocoa powder, concluded the team.

Source: Journal of Agriculture and Food Chemistry
Published online ahead of print: dx.doi.org/10.1021/jf104217g
Title: Use of Saccharomyces cerevisiae and Caenorhabditis elegans as Model Organisms To Study the Effect of Cocoa Polyphenols in the Resistance to Oxidative Stress
Authors: P. Martorell, J V Forment, R de Llanos, F Montón, S Llopis, N González, S Genovés, E Cienfuegos, Ho Monzó, D Ramón,

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