Polyphenolic compounds antioxidants

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. 

Wojdylo A, Oszmianski J and Laskowski P. 2008. Polyphenolic compounds and antioxidant activity of new and old apple varieties. J Agric Food Chem 56(15) 6520-6530. 

Vitamins (C and E), polyphenolic compounds, and carotenoids are the main groups of antioxidants present in fruits and vegetables. Vitamins are single molecules, but polyphenols and carotenoids are made up of hundreds of compounds with a wide range of structures and molecular masses. The intake of these antioxidants can lead to sustained reduction of the kind of oxidative damage to lipids, proteins, and DNA that is associated with the development of chronic diseases (Evans and Halliwell 2001). 

Cervellati R, Renzulli C, Guerra MC and Speroni E. 2002. Evaluation of antioxidant activity of some natural polyphenolic compounds using the Briggs-Rauscher reaction method. J Agric Food Chem 50(26) 7504-7509. 

There are numerous other polyphenolic compounds possessing in vitro and in vivo antioxidative activity. Several examples of these compounds are cited below. One of nonflavonoid polyphenols of particular interest is resveratrol (3,5,4 -trihydroxy-Znmv-stilbcne, Figure 29.8), which has been identified as a potential cancer chemopreventive agent and an antimutagen [182]. It has been found that resveratrol is the efficient inhibitor of cyclooxygenase and the inhibitor of free radical-mediated cellular processes. For example, resveratrol is a better free radical scavenger than a-tocopherol or ascorbic acid but has nearly the same activity as... 

In addition to their possible prooxidant activity (see above) polyphenols and flavonoids may influence cancer cells via their antioxidant properties. Recently, Jang et al. [219] studied cancer chemopreventive activity of resveratrol, a natural polyphenolic compound derived from grapes (Chapter 29). These authors showed that resveratrol inhibited the development of preneoplastic lesions in carcinogen-treated mouse mammary glands in culture and inhibited tumorigenesis in a mouse skin cancer model. Flavonoids silymarin and silibinin also exhibited antitumor-promoting effects at the stage I tumor promotion in mouse skin [220] and manifested antiproliferative effects in rat prostate cancer cells [221]. 

Yoshino, M. and Murakami, K., Interaction of iron with polyphenolic compounds application to antioxidant characterization. Anal Biochem., 251, 40, 1998. 

The contribution of lipophilic antioxidants is small. Escobar et al. (E5) found that the TAC of lipophilic antoxidants in blood plasma was 16.5 1.5 pM and corresponded almost exclusively to a-tocopherol the concentration of this compound in the blood plasma, analyzed independently, was 17.6 0.3 pM. Popov and Lewin (PI9) found TAC of lipid-soluble antioxidants in blood plasma to be 28.0 8.1 /u.M, a value comparable with the concentration of a-tocopherol (20.5 6.6 /U.M). These (and other) results confirm that a-tocopherol is the main lipid-soluble antioxidant of blood plasma (II) and indicates that the contribution of the lipid-soluble antioxidants to TAC of blood plasma is in fact negligible, taking into account that TAC of human blood plasma is of the order of 1 mM (see later). The contribution of ascorbic acid is also low. This situation may differ considerably in other biological fluids and tissue homogenates. In seminal plasma, the concentration ratio of ascorbate to urate is about 1 (G3). Ascorbate and urate contribute 29% of the fast TRAP of human seminal plasma the share of proteins and polyphenolic compounds is 57%, whereas tyrosine contributes 15% of the slow TRAP (R14) (Table 7). Ascorbate and uric acid account for about half of TAC of human tears (K3). TAC of urine is determined mainly by urate and proteins (K5). 

Hydroxytyrosol has been also referred to as a potent agent with anticarcinogenic activity. Grape pomace is rich in a large number of polyphenolic compounds with high antioxidant activity, with resveratrol being probably the most known and referred to in the scientific literature. 

The infusion of spices and herbs not only gives vermouth its unique flavor and aroma but also imparts medicinal properties. Some of the benefits ascribed to vermouth are given in Table 8.1. Feher and Lugasi (2004) compared the antioxidant characteristics of young vermouth with three red, three white, and one rose wine. Consumption of one unit (100 mL) of vermouth provided 220 mg polyphenolics, whereas wine in the same quantity was reported to have 35 mg. Polyphenolic compounds are reported to play a substantial role in protection against oxidative stress. 

Vaccinium myrtillus, commonly known as bilberry fruit, originates mainly from northern and central Europe (Bisset, 1994). This well known plant is rich in flavonoids, the polyphenolic compounds that promote anti-oxidant activity (Bisset, 1994). A study conducted on the antioxidative potential of V. myrtillus showed potent protective action on LDL particles during in vitro copper-mediated oxidation. The study concluded that this extract may be more potent than either ascorbic acid or butylated hydroxy-toluene in the protection of LDL particles from oxidative stress (Mitcheva, 1993 Bisset, 1994). 

Siddhuraju, P. (2007) Antioxidant activity of polyphenolic compounds extracted from defatted raw and dry heated Famarindus indica seed coat. Food Science and Technology 40(6), 982-990. 

Bioflavonoids Polyphenolic compounds with antioxidant action, at one time known as vitamin P... 

Other Phenolic Antioxidative Compounds from Plants Higher plants are rich in a myriad of phenolic compounds in their secondary metabolite pool. Among these, phenolic acids and polyphenolic derivatives are found to be the most important series of hydrophilic-hydrophobic antioxidative compounds naturally present. In foods, these polyphenolic compounds act as radical scavengers... 

Phenolic and polyphenolic compounds are the most active dietary antioxidants (14). The structural variation of phenolic antioxidants directly influences their physical properties, resulting in differences in their antioxidant activity. BHA and BHT are examples of phenols, in which the aromatic ring contains alkyl groups (hindered phenols), which are extremely effective as antioxidants (11). 

Leaf extracts exhibit antioxidant activity in the liver (5). Antioxidant activity of tamarind leaves reported by Perez et al (2003) and Ramos et al (2003), cited in 11), was similar to the antioxidant activity of tamarind flowers observed by Al-Fatimi et al 11). The latter mechanism is probably caused by polyphenolic compounds which have already been isolated from the seeds (Luengthanaphol et al, 2004 and Sudjaroen et al, 2005, both cited in 11)). 

The use of natural antioxidants in supplements can also exhibit pro-oxidant activity under certain conditions such as the concentration and nature of the polyphenolic compounds causing oxidative damage to important cellular components (48). Aqueous extracts and erode polyphenolic fractions of both traditional and green rooibos were evaluated for possible pro-oxidant activity using a Fenton reaction model system containing FeCb-EDTA and H2O2 for the generation of hydroxyl radicals. Pro-oxidant activity was shown for pure aspalathin while the dihydrochalcone and flavonoid contents of the enriched... 

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