Natural sources of antioxidants

Food and herbs are main natural sources of antioxidants. In this connection, antioxidant activity (AOA) of these products is essential for planning right diet as well as for sound therapy. Screen-printed platinum sensor and potentiometric method of measuring AOA of food and herbal extracts are presented below. 

With the increasing interest in the food industry for natural sources of antioxidants for their beneficial effects on health, new potential sources have been screened among edible aromatic plants and microalgae. The cc-tocopherol content (a potent antioxidant) in parsley was reported to be 3.45mg/100g of fresh leaves obtained through supercritical fluid extraction (Diego et al., 2004). 

The regulatory climate and growing consumer preference for natural products caused the U.S. and European food industries to search for natural sources of antioxidants rather than invest in synthetic antioxidants. 

Noda, Y., Anzai, K., Mori, A., Kohno, M., Shinmei, M., and Packer, L., Hydroxyl and superoxide anion radical scavenging activities of natural source of antioxidants using the computerized JES-FR30 ESR spectrometer system, Biochem. Mol. Biol. Int, 42, 35 4, 1997. 

As a natural source of antioxidants, almond may be of great value in preventing the onset and/ or occurrence of oxidative stress and its related diseases [68]. Almond appears to have beneficial effects on blood cholesterol level and lipoprotein profile in humans [69]. Diets containing almond meal or oil were shown to reduce plasma triacylglycerols (TAG) and total and LDL cholesterol concentrations, increase the resistance of LDL to oxidation, and increase the concentration of HDL... 

SRB contains high-quality protein, oil, dietary fiber, polysaccharides, fat-soluble phytochemicals (plant derived bioactive compounds) and other bran nutrients. Rice bran and germ are the richest natural sources of B complex vitamins as well as E vitamins, polyphenols, several antioxidants and minerals. It is now available in the commercial food ingredient market as a safe and effective functional food and dietary supplement. 

There exists a list of permitted additives. This list is concerned only with chemical synthetics (substances obtained by a chemical reaction other than degradation). It means that the substances on the list are those which either do not occur naturally or are not obtained from natural sources. Of the substances which are not on the list it is not always possible to decide whether these may be used in food. The antioxidants and foodstuffs in which a limited amount of antioxidant is permitted are given in Table 12.11. Only the above-mentioned foods may contain antioxidants, except -tocopherol which may be generally used in foods as an antioxidant. 

Covipherol. [Henkel/Cospha] Toco-ph ls natural source of vitamin E antioxidant in food and cosmetic prods. 

Covitol. [Henkel] Tocopherol and derivs. antioxidant for pharmaceuticals natural source of vitamin E. 

The need to prepare lipids and lipid-containing products that are stable with respect to the effect of atmospheric oxygen has increased the interest in finding suitable natural sources of harmless antioxidants. The high biological activity of extracts from such sources is often due to the presence of phenolic compounds, many of them exercising a pronounced antioxidative effect on lipids [42,43]. 

Arthrospira production is realized in China and India (Kato and Suzuki, 1971 Morris et ah, 2007). Therefore, new interest has been developed to search natural and safe bioactive peptides from natural sources. Furthermore, antioxidant peptides have been isolated from hydrolysates of various proteinaceous food materials and recently the possible roles of food-derived bioactive peptides in reducing the risk of diseases have been reported (Kim and Wijesekara, 2010). In addition, two peptides were identified from the enzyme hydrolysis of N. incerta. Table 25.2 shows some microalgae-derived peptides. 

Zhang and coworkers reported the isolation of 20 and 22 from bee-coUected pollen of B. campestris In China, this pollen is considered to be a health food and herbal medicine. It is also considered as an antioxidant and may have antitumor properties. In an attempt to understand the biogenesis of 20 and 22, the biosynthesis from 5-(hydroxymethyl)-l//-pyrrole-2-carbaldehyde (23) and 3-deoxy-D-fructose (24) was proposed. The authors do acknowledge that this biosynthesis is problematic, as there are no known natural sources of 3-deoxy-D-fructose 24 and there are only a few known syntheses (Scheme 9) ... 

Lichens are proven to be good source of antioxidants, and a plenty of literatures have supported the antioxidant action of these organisms. Few reports concerning the antioxidative nature of pure lichen metabolites are available in the literamre most of the publications describe the antioxidant activities of crude lichen extracts. 

Rutin and several other flavonoid glycosides exhibit antioxidant properties and affect the flexibility and permeability of blood capillaries. Rutin (formerly vitamin P) is thus used in pharmaceutical preparations and food supplements. Together with other substances called bioflavonoids (see Section 5.15), rutin increases levels of ascorbic acid in various animal organs, either by protection against oxidation catalysed by metal ions, or by increased ascorbic acid utilisation in the body. Natural sources of ascorbic acid containing flavonoids (such as rosehips with a considerable amount of rutin) are thus more effective than synthetic vitamin C. A complex of rutin with iron causes dark discoloration of asparagus in tins, and the stannous complex of rutin is yeUow. 

Typically, soHd stabilizers utilize natural saturated fatty acid ligands with chain lengths of Cg—C g. Ziac stearate [557-05-1/, ziac neodecanoate [27253-29-8] calcium stearate [1592-23-0] barium stearate [6865-35-6] and cadmium laurate [2605-44-9] are some examples. To complete the package, the soHd products also contain other soHd additives such as polyols, antioxidants, and lubricants. Liquid stabilizers can make use of metal soaps of oleic acid, tall oil acids, 2-ethyl-hexanoic acid, octylphenol, and nonylphenol. Barium bis(nonylphenate) [41157-58-8] ziac 2-ethyIhexanoate [136-53-8], cadmium 2-ethyIhexanoate [2420-98-6], and overbased barium tallate [68855-79-8] are normally used ia the Hquid formulations along with solubilizers such as plasticizers, phosphites, and/or epoxidized oils. The majority of the Hquid barium—cadmium formulations rely on barium nonylphenate as the source of that metal. There are even some mixed metal stabilizers suppHed as pastes. The U.S. FDA approved calcium—zinc stabilizers are good examples because they contain a mixture of calcium stearate and ziac stearate suspended ia epoxidized soya oil. Table 4 shows examples of typical mixed metal stabilizers. 

One excellent UV protector for foods is PABA, a B vitamin. Likewise, many of the same antioxidants we ingest as health supplements—such as vitamin C and a similar chemical, erythorbic acid vitamin E and lecithin, a source of the important nutrients choline and inositol—occur naturally in food. 

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