Antioxidants protective functions

The antioxidant property of ferulic acid and related compounds from rice bran was reported by Kikuzaki et al, (2002). Their results indicated that these compounds elicit their antioxidant function through radical scavenging activity and their affinity with lipid substrates. Another recent study reported by Butterfield et al, (2002) demonstrated that ferulic acid offers antioxidant protection against hydroxyl and peroxyl radical oxidation in synaptosomal and neuronal cell culture systems in vitro. The effect of ferulic acid on blood pressure (BP) was investigated in spontaneously hypertensive rats (SHR). After oral administration of ferulic acid the systolic blood pressure (SBP) decreased in a dose-dependent manner. There was a significant correlation between plasma ferulic acid and changes in the SBP of the tail artery, suggesting... 

Cross, C.E., Halliwell, B. and Allen, A. (1984). Antioxidant protection a function of tracheobronchial and gastrointestinal mucus. Lancet i, 1328-1330. 

Aspirin (acetylsalicylic acid) (Figure 29.21) is a widely applied drug for reducing ischemic cardiovascular events in patients with coronary artery disease, hypertension, or at cardiovascular risk. It is believed that the main protective function of aspirin is the inhibition of cyclooxygenase however, it has been recently proposed that aspirin may possess additional antioxidant activity [348]. It was found that long-term aspirin treatment of normotensive and hypertensive rats resulted in a decrease in vascular superoxide production by the inhibition of NADPH oxidase activity. 

Sies H (1991) Oxidative stress oxidants and antioxidants. Academic Press, San Diego Shick JM (2004) The continuity and intensity of ultraviolet irradiation affect the kinetics of biosynthesis, accumulation, and conversion of mycosporine-like amino acids (MAAs) in the coral Stylophora pistillata. Limnol Oceanogr49 223-262 Shick JM, Dunlap WC (2002) Mycosporine-like amino acids and related gadusols biosynthesis, accumulation, and UV-protective functions in aquatic organisms. Annu Rev Physiol 64 223-262... 

Selenium is a significant component of the enzymatic system of the glutafion for antioxidant protection. It is included in the composition of 200 enzymes engaged in different biochemical reactions, demonstrates the immune-tropic, antiteratogenic and anticancer properties, betters the functional state of muscles, especially myocarditis, and takes part in hormones synthesis of the thyroid gland. Selenium s deficit in soil is the cause of hearth deficiency in endemic zones. 

Some tissues obviously are able to accumulate micronutrients selectively and to use them predominantly for specific functions. It has, for instance, been known for a long time that the accumulation of p-carotene in the skin does not only provide a golden-yellow color but considerable antioxidative protection as well. Yet... 

It has been known for some time that vitamin E can act as an antioxidant within the body [21, 61] and that the biological potency of the tocopherols is proportional to their antioxidant activity [62], Synthetic antioxidants, which often have structures unrelated to that of the vitamin, are also capable of preventing the symptoms of vitamin E deficiency [23, 24, 63, 64]. The general proposal [63, 65], therefore, is that the function of vitamin E is one of an in vivo antioxidant, protecting membrane phospholipids from attack by free radicals generated within the cell. 

The trachea and bronchi likewise have a protective function. Mucous and serous cells secrete fluids that together comprise the mucus, which is moved toward the pharynx by the cilia of the ciliated cells. The movement of mucus serves to move entrapped particles toward the pharynx where they are eliminated by swallowing or expectoration. The mucus may also have other protective functions, protecting the epithelial cells by free radical scavenging and antioxidant properties. The Clara cells are known to contain high concentrations of xenobiotic metabolizing enzymes. 

Other compounds such as phlorotannins, sporopollenin, coumarins, tridentatols, polyphenolics, and several as yet unidentified substances (e.g., P380) have also been implicated as UV protectants that can increase UV tolerance.57-63 With the rapidly accelerating rate of research in the area of aquatic UV photobiology, it is highly likely that additional new types of UV-screening compounds will continue to be discovered. Many of these secondary metabolites probably have multiple protective functions. For example, tridentatols serve as allelopathic agents, antioxidants, and sunscreens.57,58,64... 

Selenium This metal is an essential trace element that functions as a component of enzymes involved in antioxidant protection and thyroid hormone metabolism. The existence of a number of selenoproteins has been demonstrated. In several intra- and extracellular glutathione peroxidases and iodothyronine... 

Reiter RJ. Functional pleiotropy of the neurohormone melatonin Antioxidant protection and neuroendocrine regulation. Front. Neu-roendocrinol. 1995 16 383-415. 

Native Ap is unstructured and its function is still uncertain. Several possible roles have been suggested, including cholesterol transport, antioxidative protection and TGF-P activity (5-7). Similarly, a definite function for APP is still unidentified. APP is a putative Notch-like receptor for an unknown ligand (8) and has been suggested to play a role in intercellular adhesion (9). 

Vitamin A is a fat soluble vitamin derived from carotene. The alcohol form of vitamin A, retinol, is the storage form in the body. The aldehyde form, retinal, has a role in vision. The acid form, retinoic acid, functions in embryonic development. Vitamin A acts to some extent in the body as an antioxidant, protecting against oxidative damage. 

Ascorbate is a major antioxidant, protecting cells and tissues from damage by free radicals, peroxides, and other metabolites of O2.P It is chemically suited to react with many biologically important radicals and is present in high enough concentrations to be effective. It probably functions in cooperation with glutathione (Box 11-B), a-tocopherol (Fig. 15-24), and lipoic acid. Ascorbate can react with radicals in one-election transfer reactions to give the monodehy-droascorbate radical ... 

Key Words Abiotic stress acquired tolerance antioxidant breeding crop plants cross protection functional genomics heat shock heat shock factors heat shock proteins hydrogen peroxide oxidative stress reactive oxygen species signaling pathways stress tolerance transgenic plants. 

The metalloid selenium is also essential for the growth of many marine phytoplankton. It occurs in glutathione peroxidase, an enzyme that degrades hydrogen peroxide, and thus is important in antioxidant protection. However, it is likely that selenium has other as-yet-unidentified metabolic functions. The potential for selenium limitation in the ocean is currently unknown. 

FIGURE 8.5 Antioxidant protection within the cell. (From Bendich, A. 1988. Antioxidant Nutrients and Immune Functions, Plenum Press, New York. With permission.)... 

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