Antioxidants and the strange case of free radicals

By Guest Author 12/09/2014


EurekaSymposium-WEBSciBlogs is running guest posts from some of the Eureka! Sir Paul Callaghan Awards 2014 finalists. In this guest post,Te Aho o Te Kura Pounamu student Joel Falconer weighs up antioxidants and free radicals.

The use of antioxidants to combat free radicals is a controversial subject, particularly regarding the use of supplements to supply them, and over concern high dose antioxidant supplements could be hindering natural processes.

Free radicals are produced during oxidative phosphorylation, which involves a series of chemical pathways in inner walls of mitochondria. Electrons create an H+ ion gradient which produces ATP, a useable form of energy. O2 molecules and H+ ions combine to form H2O molecules. During this process free radicals are produced, but 3-4% of these ‘leak’ across the mitochondrial walls. Free radicals are very reactive, unstable and short lived molecules and are believed to cause the progression of certain diseases.

Free radical formation beyond normal levels can happen due to poor sleep, smoking, alcohol, stress, and environmental sources such as air pollution.  They will ‘search’ for an electron to stabilize themselves, and may start a chain reaction, as they ‘steal’ an electron from another molecule, thus the reaction continues.  If this happens to DNA, this can cause mutations that may lead to diseases like cancer (Morrisey, 1998).

Antioxidants are suggested as a method to counter the harmful effects of free radicals, by providing the extra electron needed to make the pair, or by breaking down the free radical molecule, thus stopping the chain reaction. However, free radicals also protect cells and re-establish redox homeostasis in biochemical reactions. It is questioned whether excessive free radical production is a cause, or a result, of other pathological processes?

There is debate as to whether consuming large amounts of antioxidants in supplement form actually benefits health, and concern that excessive doses may even be harmful. This is the Dr Jekyl and Mr Hyde debate– are free radicals ‘good guys’ or ‘bad guys’, and do we need antioxidants to contain them? It is suggested that oxidative stress is inevitable in a healthy human cell, and is necessary for vital metabolic processes to function properly, (Valko, 2007), in other words, “Is it better to keep the free radical balanced via redox homeostasis, rather than add excessive exogenous antioxidants?”

If natural antioxidants are proven helpful, then milk, a natural product, containing the vitamins E and C, and other anti-oxidative organic compounds, enzymes, and protein appears to be an answer as it not only has antioxidants, but has the customers’ acceptance, and is cheaply and readily available worldwide.

Could we use genetically modified cattle or goats to manufacture a balanced fresh supply of ‘natural’ antioxidants in milk? Ruakura are doing world leading research, using RNAi to knock-down specific genes via gene silencing.  They have developed a transgenic cow called Daisy who produces milk with reduced amounts of protein BLG, which is the leading cause of milk allergies in children. They also have developed transgenic cows to help people suffering from multiple sclerosis. Could similar process could be used to turn on genes that produce antioxidants, via milk, allowing large amounts of antioxidants to be produced?

The challenge is to get an equilibrium, not too many antioxidants, but enough to keep cells disease free. This will need to be researched, as to exactly how much antioxidants are needed to maintain this balance, and could this lead to world changing science?  NZ has a reputation worldwide for agricultural and technological innovation, and has the expertise to enhance this reputation by supplying the world with a solution to this debate.

Joel Falconer is completing L3 NCEA with Te Aho O Te Kura Pounamu.  He plans to study Veterinary Science at Massey University, and has completed his pre-vet experience.   He is very interested in research and has spent time at Ruakura.

References

BIOL101-13B Manual 2013, Alison Campbell, Molecular and Cellular Biology

Morrisey, P. O. (1998). Dietary Antioxidants in Health and Disease. Int. Dairy Journal 8, 463 – 472.

Reece, J.B.; Urry, L.A.; Cain, M.L.; Wasserman, S.A.; Minorsky, P.V.; Jackson, R.B. (2011). Campbell Biology Nineth Edition. San Fransisco: Pearson

Valko, M.,  Leibfritz, D., Moncol, J., Cronin, M. T.D. , Mazur,  M., Telsa, J. ,(2007). Free radicals and antioxidants in normal physiological functions and human disease. The International Journal of Biochemistry and Cell Biology Vol 39, 44 – 84.