Free Radicals and Antioxidants against Cancer

In the beginning,the earth's atmosphere had no O₂.Anaerobic organisms,which can live without O₂,thrived.About 2.5 million years ago blue-green algae in the ocean acquired the ability to split water(H₂O)into Hydrogen(H) and  Oxygen(O₂) .This chemical reaction initiated the release of oxygen into the atmosphere.The increased levels of atmospheric oxygen led to the extinction of many anaerobic organisms,owing to oxygen's toxicity.

This important biological event also lead to the evolution of multicellular organisms, including humans,who utilize oxygen for survival.Today the amount of O₂ in dry air is about 21% and water it is about 34%.To understand the role of free radicals and antioxidants in the human body,it is important to grasp the relationship between oxidation and reduction processed which are currently taking place in the body.

Oxidation and reduction

Oxidation is a process in which an atom or molecule gains oxygen,loses hydrogen,or loses an electron.
For example:- carbon gains O₂ during Oxidation and becomes CO₂.An oxidizing agent is a molecule or atom that changes another chemical by adding O₂ to it or by removing an electron or hydrogen from it.
Examples of oxidizing agents or processes are free radicals,Ozone and irradiation.
Reduction is a process in which an atom or molecule loses O₂,gains Hydrogen or gains an electron.
For example:- CO₂ loses O₂ and becomes carbon monoxide,Carbon gains Hydrogen and becomes methane and O₂ gains ana electron and becomes Superoxide anion.Thus a reducing agent is a molecule or atom that changes another chemical by removing O₂ from it or by adding H₂ or an electron to it.All antioxidants can be considered reducing agents.
A process that generates free radicals.Free radicals are created during the intake of oxygen,in the course of infection,and during the oxidative metabolism of certain compounds.
Mitochondria are elongated membranous structures in the cells that are responsible for producing energy,while generating energy,mitochondria utilize oxygen and produce superoxide anions,hydroxy radicals and hydrogen peroxide as by products.About 2% of unused O₂ leaks out of mitochondria and makes about twenty billion molecules of superoxide anions and hydrogen peroxide per cell per day.
During bacterial or viral infection,phagocyte cells generate high levels of nitric oxide,superoxide anions and hydrogen peroxide,in order to kill infectious agents however,they also can damage to normal cells.
In order course of the metabolism of fatty acids and other molecules in the body,free radicals are also produced.Certain factors and agents,such as smoking,free iron,copper and manganese can increase the rate of production of free radicals.Thus ,the human body is exposed constantly to varying levels of the free radicals.

Antioxidants against cancer

The term "Antioxidant" was coined in the the 1920's to denote any substance that fought rust or other forms of oxidation.Oxygen-containing compounds give rise to molecules called "free radicals" in that wreak havoc.
Scientific work over the last decades has shown that  free radicals can also damage genetic material,lipids(fats) or proteins.

 Free Radicals

Free radicals are atoms or molecules which unpaired electrons(reactive O₂ or reactive nitrogen)that  are highly damaging.Most free radicals are very short lived(10 seconds) Free radicals commonly mediate the actions of a diverse group of toxins that can enhance the incidence of many human chronic diseases including cancer.They can damage DNA,RNA,Protein Membrane,fat and other cell components.Free radicals are derived from either oxygen or nitrogen.Most free radicals  derived from oxygen are called reactive oxygen species,and those derived from nitrogen are called reactive
nitrogen species.
Eg:
Super Oxide anion
Hydooperoxy radical
Organic radical
Organic radical
Nitric Oxide
Nitric Dioxide
Hydrogen poeroxide
Thus,the human body is exposed to several types of free radicals.Fortunately,we have  Antioxidant defense system that  protects the body against free radical damage.

Antioxidant Defense

when oxygen appeared in the atmosphere of the earth,only those organisms that had developed antioxidant systems for protecting  themselves against free radical damage survived and evolved.
The antioxidant defense system in humans can be divided into 3 groups.
1.Antioxidant enzymes made in the body such as Super Oxide Dismutase(SOD) catalase and glutathione peroxides.
2.Antioxidants not made in the body and consumed principally through the diet including vitamin A,C and E,carotenoides,flavonoids and other polyphenols and other antioxidants present in plants)
3.Antioxidants primarily made in the body  but also consumed through the diet(Primarily in the meat and eggs)and in the form of  supplements including glutathione, coenzyme.Q 10 Nicotinamide adenine dinucleotide-lipoic acid,and melatonin.
The antioxidant enzyme SOD requires manganese,copper or Zinc for its biological activity.Manganese-SOD is present in Zinc for its biological activity. Manganese-SOD is present in mitochondria where as copper SOD and Zinc SOD are present in the cytoplasm and in the nucleus of the cell.They can destroy free radicals and hydrogen peroxide.
Human tissue also contains glutathione peroxide,which requires selenium for its biological activity and it's responsible for removing hydrogen peroxide.Although iron,copper and manganese are essential for the activities of antioxidant enzymes.

Foods and Antioxidants

Foods contain many antioxidant,some of which may not even be known to science yet.There are hundreds of carotenoids alone.Fresh,deeply coloured,organic produce. Colorful fruits and vegetables are a fantastic source of potent antioxidant.
Cancer - dietary        Self - defense
More cancer fighters in plant foods.selenium,beta-carotene and Vit.C, vit.E are antioxidant.

Colours	Foods Substances and Possible Actions	Colourful Protective
Red	Tomatoes and Products,Beet Root	Lycopene antioxidanet cuts Prostate cancer risk
Orange	Carrots,Sweet potatoes,Mangoes	Beta carotene supports immune system and powerful antioxidant
Yellow Orange	Citrus fruit,Oranges,Lemons,Grape fruits,Papaya	Vit C-Flavonoide inhibit tumour cell growth detoxify harmful substances
Green	Spinach and other greens	Folate,builds healthy cells and genetic material
Green or White cruciferous vegetables	Broccoli,Cabbage,Cauliflower,Brussels sprouts,Brocolo	indoles,lutein eliminates excess oestrogen and carconogen
Green or white onion family	Garlic,Onion and Asparagous	Allyl sulfides destroy cancer cells
Blue	Grapes,Plums	Reservatrol many decrease oestrogen production
Red Apple	Grapes,egg plant	Reservatrol many decrease oestrogen production
Brown	Whole grains,Legumes Soya	Fibre-carcinogen removel Phyto oestrogen