The Sources of Natural Antioxidants

About author
Abhilash A*, Prabhu Raj KJ, Hemalatha M, Gopi Krishna B, Dr. Hindustan Abdul Ahad
B. Pharmacy, Balaji College of Pharmacy, Anantapur, AP, India.
* E-mail: [email protected]

Abstract
Intensive oxidative processes occurring in human organism lead to formation ofoxygen reactive forms, which can damage systemic cells and tissues. It is shown, thatbody endogenous protective system can be supported in that case by natural antioxidantcompounds provided from food. The assessment of food products as the potential sourcesof antioxidants was performed, taking into consideration the kinds of compounds supplied,and their significance in the diet of different nations.
Key words: antioxidants, polyphenols, source of antioxidants in diet
Introduction
The importance of the antioxidants contained in foods is well appreciated for both preserving the foods themselves and supplying essential antioxidants in vivo.With increasing experimental, clinical and epidemiological data which show the beneficial effects of antioxidants against oxidative stress-induced degenerative and age-related diseases, cancer and ageing, the importance and role of antioxidants have received renewed attention. We are protected from oxidative stress by various antioxidants which have different functions. Some are enzymes and proteins and others are small molecule antioxidants. Foods are important as an essential source of such antioxidants, components and trace elements. In addition, numerous synthetic antioxidants have been developed and some of them have been used in practice as, for example, food additives,supplements and drugs. The phenolic compounds such as vitamin E andflavonoids are typical antioxidants. Numerous phenolic compoundshave been also synthesized: 2,6-di-tert-butyl-4-methylphenol known asBHT is one of the most popular synthetic antioxidants. It is generallyaccepted, however, that natural antioxidants are more potent, efficientand safer than synthetic antioxidants. For example, a-tocopherol is themost active form of vitamin E and natural 2R,4’R,8’R-a-tocopherol ismore potent than synthetic racemic a-tocopherol primarily becausea-tocopherol transfer protein selectively recognizes natural a-tocopherol.As such, natural antioxidants are more favorably accepted than syntheticantioxidants.
Discussion
The Kinds of Natural Antioxidants in Diet
The results of epidemiological and scientific studies show that nutritional factor plays important role in prevention of the consequences of free radicals activity in theorganism. A diet rich in natural antioxidants can significantly influence the increaseof reactive antioxidant potential of the organism, and ipso facto decrease the risk ofsome diseases of free radicals origin. It is considered that adequate level of antioxidantssupplied with diet induces immunological processes and increases defensive abilitiesof cell in proper way.There are mentioned: tocopherols (vitamin E), vitamin C, vitamin A, and also itsprovitamin β-carotene as well as selenium and phenolic compounds among antioxidants.Properties and significance of vitamins A, C and E are quite well known beinga subject (as a nutritional compound) of numerous studies for a long time^[2]. Recently, the attention has been paid to antioxidativeproperties of other compounds belonging to carotenoids, particularly to lycopene andlutein. It has been shown that lycopene is the most effective compound removing singletoxygen, and its high consumption is negatively correlated with some types of cancer. First of all, lutein playssome role in protection of retina against harmful action of free radicals and in preventionof atherosclerosis
Antioxidative Properties of Fruits
Fruits belong to food products appreciated by dieteticians and nutritionists. They contain several vitamins and mineral salts deciding about their nutritional value, andalso dietary fiber. Majority of fruits are rich source of vitamin C, carotenoids and polyphenoliccompounds^[3]. Especially berry fruits are precious in this regard. Among berryfruits, the content of particular substances with antioxidant activity is rather diversified– some of them are especially rich source of vitamin C, the other contain huge amountsof phenolic compounds. Fruits of blackcurrant have a high content of antioxidants. Theycontain huge amounts of vitamin C, in range of 120-215 mg/100 gand also significant amounts of carotenoids, mainly lutein andb-carotene . In blackcurrant fruits phenolic compounds are alsopresent, on the level of about 25 mg/g d.m, with anthocyanins consisting1/3. Except anthocyanins, blackcurrant fruits contain phenolic  acids, among which derivatives of hydroxycinnamic acid dominate, especiallym-coumaric acid.
Aroniamalanocarpa fruits are considered as the richest polyphenols source. Theirtotal content is 40-70 mg/g d.m., with over 50% share for anthocyanins. The latter,contain group ofpolyphenols are the derivatives of hydroxycinnamic acid, representedmainly by chlorogenic andneochlorogenic acids. These compounds, together with epicatechins, decide about very tart taste of Aroniamalanocarpa fruits, which causes thatthey are rarely consumed in raw state. Phenolic compounds presentin grapes, mainly in seeds and peel, are mainly anthocyanins and derivatives of hydroxycinnamicacid, flavonols and stilbenoids. The richest source are pomace receivedduring vine production.
Crowberry fruits are valuable source of vitamin C, with its amount about 18 mg/100 g.They contain also carotenoides – lutein (about 3.6 μg/g d.m.) and β-carotene (2 μg/g d.m.)and also phenolic compounds (26-46 mg/g d.m.). Among them, flavanols and procyanidins, cinnamicacid, trans-resveratrol and p-coumaric acid dominate. They decide about organolepticfeatures and healing properties of products made from these fruits.
Citrus fruits – grapefruits, lemons, oranges – are a rich source of antioxidants, becauseof big content of vitamin C (40-50 mg/100 g) and phenolic compounds, amongwhich flavanones (hesperitin, naringenin, eriodictyol) dominate. Pink grapefruits showrelatively high content of lycopene, too.
Five-Important Natural Antioxidants
1. Red Kidney Beans or Rajma: Dried red kidney beans, locally referred to as Rajma are a great source of proteins and also antioxidants. Their function is mainly disease fighting. On this earth plagued by pollution and contamination it is all the more important to incorporate these beans in your diet. Almost all types of beans; red, black, pinto, have antioxidant properties but red kidney beans are the best antioxidant of the lot.
2. Cloves or Loung: This is a spice widely used in Indian cuisine for its flavor. In India, cloves are a component of the ‘garam masala’ which is a familiar spice in our kitchens. Cloves are natural antioxidants that are very effective for lipid oxidation. Cloves need to be used specifically to spice meat dishes as meat contains fats and bad cholesterol that clogs arteries.
3. Bell Peppers: We are specifically talking about the red and yellow bell peppers here for their immense role as deterrents of the killer disease cancer. Colored bell peppers are the best antioxidants for fighting malignancy. As a matter of fact, many Herbal healing therapies put cancer patients on a diet of bell peppers for cure.
4. Anti-aging Vitamins: When myth-makers talked about the ‘fountain of youth’ they probably meant antioxidants. Vitamin C, found in citrus fruits and Vitamin E, found in dry fruits like almonds, prunes etc. are excellent for the cell renewal process of the skin to keep it youthful. Smoke, pollution and exposure to the sun eat way these anti-oxidizing vitamins from your skin and you need to keep the supply on if you are to avoid wrinkles, dark spots and flaky skin.
5. Tea: Surprising but true, our favorite energy beverage tea is a great natural antioxidant. Drinking tea conclusively lessens the threat of heart attacks and cancer^[6]. However, this has to be either black tea or green tea as adding milk may reduce the body’s capacity of absorb the antioxidants brewed in the liquor tea. So switch to black tea to reduce your calorie intake or green tea for the advantage of extra vitamin C.
Antioxidative Properties of Animal-Derived Food
Important group of natural antioxidants in animal-derived food products are aminocompounds:aminoacids, peptides and proteins. Antioxidant activity of these compounds is connected mainly with aminoacids which possess thiol groups (metionine,cysteine). Proteins, acting as antioxidants, scavenging of free radicals formed in biochemicalprocesses of cells. Antioxidantactivity of proteins from animal-derived products can be also connected with addition(in food technology) of concentrates and isolates gained from high-protein plants origin(legumes seeds) and animal origin (milk, eggs) raw materials. Isolated soybean proteins,because of their good functional properties, are wide used in meat industry and they caninhibit reaction of lipid oxidation. Huge antioxidant activity have also preparationsof albumin and globulin derived from seeds of legumes cultivated in Poland – bean, peas, and broad bean. In several studies, the ability of casein and whey proteins ofmilk to inhibit autooxidation of lipids was confirmed. Casein inhibits enzymatic, as wellas non-enzymatic oxidation of lipids.Main non-protein thiol compound of animal tissues is glutathione (GSH). Its basicfunction in organism is protection of thiol protein groups from oxidation. Reduced formof glutathione is a scavenger of RFT. It is worth to add, that glutathione and other reducedthiol compounds can regenerate oxidized α-tocopherol radical to vitamin E.
Over 20 compounds of quercetin and kaempferol were found in cabbage. In red pepper, two derivatives of quercetin, tree – luteolin and one – apigeninwere found. Anthocyanin pigments are found only in afew vegetables. They give characteristic colour of red cabbage, onion and lettuce withred leaves. They can also be found in peel of radish, aubergine and coloured potatoes.As regarding potatoes, varieties with pink or violet coloured pulp are also cultivated.
Conclusion
Antioxidants protect cells from damage caused by unstable molecules known as free radicals.Laboratory and animal research has shown antioxidants help prevent the free radical damage that is associated with cancer. However, results from recent studies in people (clinical trials) are not consistent.Antioxidants are provided by a healthy diet that includes a variety of fruits and vegetables.

References

1. Ghiselli et al. 2000, Prior 2003, Gałek and Targonski 2003, Grajek2004.
2. Wartanowiczand Ziemlanski 1992, 1999
3. Amin I., Marjan Z.M., Foong C.W., 2004. Total antioxidant activity and phenolic content inselected vegetables. Food Chem. 87, 4, 581-586.
4. Anttonen M.J., Karjalainen R.O., 2005. Environmental and genetic variation of phenolic compoundsin red raspberry. J. Food Comp. Anal. 18, 759-769.
5. Bahorun T., Luximon-Ramma A., Crozier A., Aruoma O., 2004. Total phenol, flavonoid, proanthocyanidin and vitamin C levels and antioxidant activities of Mauritian vegetables. J. Sci.Food Agric. 84, 1553-1561.
6. Cao G., Sofic E., Prior R.L., 1996. Antioxidant capacity of tea and common vegetables. J. Agric.Food Chem. 44, 3426-3431.
7. Kim O.-D., Padilla-Zakour Griffiths P.D., 2004. Flavonoids and antioxidant capacity of variouscabbage genotypes at juvenile stage. J. Food Sci. 69, 9, C685-C689.
8. Kim J.-S., Kwon C.-S., 2001. Estimated dietary isoflavone intake of Korean population based onNational Nutrition Survey. Nutr. Res. 21, 947-953.
9. Klopotek Y., Otto K., Böhm V., 2005. Processing strawberries to different products alters contents of vitamin C, total phenolics, total anthocyanins, and antioxidant capacity. J. Agric.Food Chem. 53, 5640-5646.
10. Kopsell D.A., Kopsell D.E., 2006. Accumulation and bioavailability of dietary carotenoids invegetable crops. Trends in Plant Science, 11, 10, 499-507.
11. Kopsell D.A., Kopsell D.E., Lefsrud M.G., Curran-Celentano J., Dukach L.E., 2004. Variation in lutein, b-carotene, and chlorophyll concentrations among Brassica oleracea cultigens andseasons. HortScience 39, 2, 361-364.
12. Remberg SF (2006) Studies of antioxidant activity in fruits and berries. Effects of cultivars and postharvest condition. PhDDissertation. Norwegian University of Life Science, p. 11.
13. Wang SY, Lin HS (2000) Antioxidant activity in fruits and leaves of blackberry, raspberry and strawberry varies with cultivar and developmental stage. J Agric Food Chem 48: 140-146.
14. Eyduran SP, Eyduran E, Agaoglu YS (2008) Estimation of fruit weight by cane traits for various raspberries (Rubusidaeus L.)cultivars. Afr J Biotechnol 7: 3044-3052.
15. Gercekcioglu R (2008) Cane characteristics of ‘Cola II’ red raspberry as affected by application of nitrogen fertilizers and organicmanure. J ApplBiolSci 2: 81-83.