Carotenoids antioxidant effects

To nnderstand the mechanism of antioxidant activity of the carotenoids it is also important to analyze the oxidation prodncts that are formed during their action as antioxidants. A relationship between prodnct-forming oxidation reactions to carotenoid antioxidant effects has been additionally... 

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

Baker, D. L. et al. (1999). Reactions of beta-carotene with cigarette smoke oxidants. Identification of carotenoid oxidation products and evaluation of the prooxidant antioxidant effect. Chem. Res. Toxicol. 12(6) 535-543. Bonnie, T. Y. P. and Y. M. Choo (1999). Oxidation and thermal degradation of carotenoids. J. Oil Palm Res. 11(1) 62-78. 

As mentioned previously, the ability of carotenoids to inhibit oxidative stress was tested in vitro in many different cell types. In the retina only lutein and zeaxanthin accumulate in sufficient concentrations to exert direct antioxidant effects, therefore our further discussion of these antioxidant effects will be focused mainly on those two xanthophylls. 

In most assays designed to study antioxidant action of carotenoids, the effects of carotenoids were followed for a relatively short periods of time, while carotenoids were still present at substantial concentrations. Carotenoids, such as [1-carotene, lutein, and zeaxanthin, undergo rapid degradation upon exposure to oxidants or irradiation with ultraviolet and visible light (Ojima et al 1993 Siems et al 1999, 2005). 

Tomato was reported to exert antioxidant activity in some studies (Vinson and others 1998 Kahkonen and others 1999), whereas it showed no antioxidant activity or even acted as a pro-oxidant in others (Gazzani and others 1998). The antioxidant effect of tomato is most probably due to synergism between several compounds and not due to lycopene content alone, as pure lycopene and several other carotenoids act as pro-oxidants in a lipid environment (Al-Saikhan and others 1995 Haila and others 1996). 

This method is also used to measure ex vivo low-density lipoprotein (LDL) oxidation. LDL is isolated fresh from blood samples, oxidation is initiated by Cu(II) or AAPH, and peroxidation of the lipid components is followed at 234 nm for conjugated dienes (Prior and others 2005). In this specific case the procedure can be used to assess the interaction of certain antioxidant compounds, such as vitamin E, carotenoids, and retinyl stearate, exerting a protective effect on LDL (Esterbauer and others 1989). Hence, Viana and others (1996) studied the in vitro antioxidative effects of an extract rich in flavonoids. Similarly, Pearson and others (1999) assessed the ability of compounds in apple juices and extracts from fresh apple to protect LDL. Wang and Goodman (1999) examined the antioxidant properties of 26 common dietary phenolic agents in an ex vivo LDL oxidation model. Salleh and others (2002) screened 12 edible plant extracts rich in polyphenols for their potential to inhibit oxidation of LDL in vitro. Gongalves and others (2004) observed that phenolic extracts from cherry inhibited LDL oxidation in vitro in a dose-dependent manner. Yildirin and others (2007) demonstrated that grapes inhibited oxidation of human LDL at a level comparable to wine. Coinu and others (2007) studied the antioxidant properties of extracts obtained from artichoke leaves and outer bracts measured on human oxidized LDL. Milde and others (2007) showed that many phenolics, as well as carotenoids, enhance resistance to LDL oxidation. 

Biflavanoids in vegetables and fruits play a vital role in the storage of ascorbic acid in leukocytes, in the core of adrenal glands and in other organs. It also causes more effective expenses under ascorbic acid s deficiency in the organism. Phenolic compounds present in the organism, activate detoxication processes in the liver. The flavanoids exceed the tocopherols and carotenoids in terms of antioxidant effect. 

Oxidative stress is now recognized as an important etiological factor in the causation of several chronic diseases including cancer, cardiovascular diseases, osteoporosis, and diabetes. Antioxidants play an important role in mitigating the damaging effects of oxidative stress on cells. Lycopene, a carotenoid antioxidant, has received considerable scientific interest in recent years. Epidemiological, tissue culture, and animal studies provide... 

Many medicinal and food plants contain large amounts of antioxidants other than vitamin C, vitamin E, and carotenoids. The antioxidative effects are mainly due to phenolic compounds phenolic acids, flavonoids, and phenolic diterpenes. These namral antioxidants can exert considerable protection, in humans, against aging and cancer caused by free radicals, and can replace synthetic antioxidants such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), which are suspected to have toxic and carcinogenic effects on humans. 

Crocin is a carotenoid from the stigma of the saffron flower with many medicinal properties, including antioxidant effects. Crocin has the ability to prevent amyloid formation. The antiamy-loidogenic effect of crocin may be exerted not only by the inhibition of Ap amyloid formation but also by the disruption of amyloid aggregate [384],... 

It was observed that people with low carotenoid intake or low blood levels have an increased risk of degenerative diseases. In a number of these diseases free radical damage plays a role in the pathophysiology of the disease. Earlier studies were focused mainly on p-carotene and the lycopene protective effect against prostate and lung cancer, but there is as yet no definitive proof for a causal relationship or for a beneficial antioxidant effect of carotenoids. 

Since carotenoids and several of their enzymatic and non-enzymatic breakdown products exert a multitude of biological effects, including the regulation of gene expression, it is very often difficult to discriminate between antioxidant effects and other mechanisms of carotenoid action. 

Capsanthin (Figure 1) is the most abundant carotenoid in the paprika spice. The concentration of capsanthin is about IS90 mg per kg of dry matter and 41 54% of total carotenoids in paprika 18,19). The antiphotooxidative effect and kintics study of capsanthin on soybean oil has not been well studied. In addition, the study of the antiphotooxidative effect of carotenoids mostly focused on lipid or fatty acids. The antioxidative effect of carotenoids on the photooxidation of flavor compounds has not been well studied, either. 

Torbergsen AC, Collins AR. Recovery of human lymphocytes from oxidative DNA damage the apparent enhancement of DNA repair by carotenoids is probably simply an antioxidant effect. Fur J... 

The antioxidant behavior of astaxanthin has been demonstrated in vivo as well. In Haematococcus algae, astaxanthin is accumulated as part of a stress response, and it is believed to protect cellular DNA from photodynamic damage. This carotenoid also protects lipids from peroxidation in trout and salmon. In chicks, astaxanthin supplementation suppressed the formation of lipid peroxides in the plasma. Significant biological antioxidant effects have been observed in vitamin E-deficient rats fed an astaxanthin-rich diet these include protection of mitochondrial function and inhibition of peroxidation of erythrocyte membranes. In two independent studies, lipid peroxidation in the seram and liver of astaxanthin-fed rats treated with carbon tetrachloride was... 

Haila et al. examined the effect of solvent polarity on the antioxidant effect of different carotenoids. It was found that in acetone in air, all carotenoids except P-carotene reduced the number of spin adducts formed by about 20%, whereas in the less polar solvent toluene most carotenoids lowered the number of spin adducts to a lesser extent than in acetone. 

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