Antioxidants overview

The above scientific information on rice bran phytochemicals indicates that a multitude of mechanisms are operating at the cellular level to bring about specific health effects. Several health benefits of rice bran appear to be the result of the synergistic function of the many phytochemicals, antioxidants, vitamins and minerals which operates through a specific immune response. Their role in the biochemical mechanisms at the cellular level which result in major health effects is shown in Fig. 17.1. A short overview summarizing the effect of the various phytochemicals on major health issues such as cancer, immune function, cardiovascular disease, diabetes, altered liver function and gastrointestinal and colon disease will be given below. 

PACKER L (1995) Antioxidant defenses in biological systems an overview. In Proceedings of The International Symposium on Natural Antioxidants - Molecular Mechanisms and Health Effects. Eds Packer, L, Traber, M G, Xin, W, Champaign, IL, USA AOCS Press 9-23. 

Palozza, P. and Krinsky, N.I., Antioxidant effects of carotenoids in vivo and in vitro an overview, Meth. EnzymoL, 213, 403, 1992. 

Pfander, H., Carotenoids An overview, in Methods in Ezymology Carotenoids, Part A Chemistry, Separation, Quantitation, and Antioxidation, Packer, L., Ed., Academic Press, San Diego, 1992, 9. 

Lussier [71] has given an overview of Uniroyal Chemical s approach to the analysis of compounded elastomers (Scheme 2.2). Uncured compounds are first extracted with ethanol to remove oils for subsequent analysis, whereas cured compounds are best extracted with ETA (ethanol/toluene azeotrope). Uncured compounds are then dissolved in a low-boiling solvent (chloroform, toluene), and filler and CB are removed by filtration. When the compound is cured, extended treatment in o-dichlorobenzene (ODCB) (b.p. 180 °C) will usually suffice to dissolve enough polymer to allow its separation from filler and CB via hot filtration. Polymer identification was based on IR spectroscopy (key role), CB analysis followed ASTM D 297, filler analysis (after direct ashing at 550-600 °C in air) by means of IR, AAS and XRD. Antioxidant analysis proceeded by IR examination of the nonpolymer ethanol or ETA organic extracts. For unknown AO systems (preparative) TLC was used with IR, NMR or MS identification. Alternatively GC-MS was applied directly to the preparative TLC eluent. 

Applications Identification of polymer additives by TLC-IR is labour intensive and comprises extraction, concentration of extracts, component separation by TLC on silica, drying, removal of spots, preparation of KBr pellets and IR analysis. The method was illustrated with natural rubber formulations, where N-cyclohexyl-2-benzothiazyl sulfenamide, IPPD and 6PPD antioxidants, and a naphthenic plasticiser were readily quantified [765]. An overview of polymer/additive type compounds analysed by transfer TLC-FTIR is given in Table 7.80. 

In this contribution we want to provide a short overview addressing the current state-of-the-art of water-soluble fullerene derivatives and their potential applications as antioxidant or neuroprotective drug candidates. After summarizing the most prominent concepts of designing water-soluble fullerenes in the first chapter we will present some more recent achievements with respect to biological activities of antioxidant fullerenes, with emphasis on our own results. 

Singh S, Singh RP (2008) In vitro methods of assay of antioxidants an overview. Food Rev Int 24 392-415... 

S. Vermani, A. Angusti, S. Manfredini (2004). The antioxidants and pro-antioxidants network an overview. Curr. Pharm. Des. 10 1677-1694. 

Figure 6.5 shows the structures of tra 5-cinnamic acid and four cinnamic acid derivatives (phenolic compounds) reported to be present in potatoes. Because potatoes are one of our major food plants, we validated with the aid of HPLC and LC/MS the content and distribution of antioxidative phenolic compounds in parts of the potato plant, in potato tubers, in the peel and flesh of tubers, in potatoes sold commercially in Korea and the United States, and in home-processed potatoes. The following discussion, based on our own studies, is followed by a brief overview of analytical methods for potato phenolic compounds by other investigators. 

All decontaminations of radicals within the body are operated by means of structural changes of ascorbate, P-carotin, or tocopherol. Those reactive partners known as the antioxidative system are all regenerated by the glutathione system. Therefore, this system gives a good overview on the oxidative state of a tissue (Fig. 6.18). 

In the postgenome era, proteomics has attracted much more attention due to its potential in understanding biological functions and structures at the protein level. The increased possibility of screening using proteomic techniques provides more comprehensive overview of the interaction of proteins, the interplay among processes, and the context in which a specific molecule or pathway may be operating in the mechanism of action of different antioxidants. 

Simic, M.G. 1991. Antioxidant compounds an overview. In K.J.A. Davies, ed., Oxidative Damage Repair Chemical, Biological, and Medical Aspects, pp. 47-56. Pergamon, Oxford. 

Diplock, A.T. 1991. Antioxidant nutrients and disease prevention An overview. Am. J. Clin. Nutr. 53 189S-193S. 

Abstract Low molecular weight antioxidants are an important part of the antioxidative defense mechanisms of cells and organisms. This chapter gives a short overview of the actions of the main antioxidants, including uric acid, ubichinones,lipoic acid, vitamins C and E, carotenoids, and phenolic compounds. The antioxidative properties of these endogeous and nutritional compounds are discussed in this chapter. However, it is critically discussed whether the antioxidative properties of some of these compounds are really important in vivo. 

As this paper is prepared for a special volume on bioactive natural products, a brief overview on bioactivity of carotenoids is included, divided into known functions of carotenoids and to their actions on biological systems. Charged carotenoid species are involved in the function of carotenoids in photosynthesis and may turn out to be relevant unstable intermediates in other biological contexts, including antioxidant action. 

---