Antioxidants cryptoxanthin

Most carotenoids have no pro-vitamin A activity with the notable exceptions of P-carotene, and to a lesser extent a-carotene and P-cryptoxanthin. They act as macular pigments (lutein and zeaxanthin) and they have antioxidant and biochemical properties other than pro-vitamin A activity. 

It has been established that carotenoid structure has a great influence in its antioxidant activity for example, canthaxanthin and astaxanthin show better antioxidant activities than 3-carotene or zeaxanthin. 3- 3 3-Carotene also showed prooxidant activity in oil-in-water emulsions evaluated by the formation of lipid hydroperoxides, hexanal, or 2-heptenal the activity was reverted with a- and y-tocopherol. Carotenoid antioxidant activity against radicals has been established. In order of decreasing activity, the results are lycopene > 3-cryptoxanthin > lutein = zeaxanthin > a-carotene > echineone > canthaxanthin = astaxanthin. ... 

The lag-phase measurement at 234 nm of the development of conjugated dienes on copper-stimulated LDL oxidation is used to define the oxidation resistance of different LDL samples (Esterbauer et al., 1992). During the lag phase, the antioxidants in LDL (vitamin E, carotenoids, ubiquinol-10) are consumed in a distinct sequence with a-tocopherol as the first followed by 7-tocopherol, thereafter the carotenoids cryptoxanthin, lycopene and finally /3-carotene. a-Tocopherol is the most prominent antioxidant of LDL (6.4 1.8 mol/mol LDL), whereas the concentration of the others 7-tocopherol, /3-carotene, lycopene, cryptoxanthin, zea-xanthin, lutein and phytofluene is only 1/10 to 1/300 of a-tocopherol. Since the tocopherols reside in the outer layer of the LDL molecule, protecting the monolayer of phospholipids and the carotenoids are in the inner core protecting the cholesterylesters, and the progression of oxidation is likely to occur from the aqueous interface inwards, it seems reasonable to assign to a-tocopherol the rank of the front-line antioxidant. In vivo, the LDL will also interact with the plasma water-soluble antioxidants in the circulation, not in the artery wall, as mentioned above. 

Fresh peppers are excellent sources of vitamins A and C, as well as neutral and acidic phenolic compounds (Howard and others 2000). Levels of these can vary by genotype and maturity and are influenced by growing conditions and processing (Mejia and others 1988 Howard and others 1994 Lee and others 1995 Daood and others 1996 Simmone and others 1997 Osuna-Garcia and others 1998 Markus and others 1999 Howard and others 2000). Peppers have been reported to be rich in the provitamin A carotenoids (3-carotene, a-carotene, and (3-cryptoxanthin (Minguez-Mosquera and Hornero-Mendez 1994 Markus and others 1999), as well as xanthophylls (Davies and others 1970 Markus and others 1999). Bell peppers have been shown to exert low antioxidant activity (Al-Saikhan and others 1995 Cao and others 1996 Vinson and others 1998) or may even act as pro-oxidants (Gazzani and others 1998). 

Carotenoids are isoprenoid compounds that are biosynthesized only by plants and microorganisms. Some carotenoids (a- and p-carotene, p-cryptoxanthine) can be cleaved into vitamin A (retinol) by an enzyme in the small intestine. Carotenoids have been reported to present some effects in the prevention of cardiovascular diseases [410] and in the prevention of some kind of cancers [411]. Furthermore, antioxidant activity has been widely reported [411-414] but a switch to pro-oxidant activity can occur as a function of oxygen concentration [415,416]. 

Kimura et al. (74) recommended a procedure in which the carotenoids are dissolved in petroleum ether, an equal volume of 10% methanolic KOH is added, and the mixture is left standing overnight (about 16 h) in the dark at room temperature. This treatment caused no loss or isomerization of /3-carotene, while completely hydrolyzing /3-cryptoxanthin ester. Losses of xanthophylls could be reduced to insignificant levels by using an atmosphere of nitrogen or an antioxidant. 

Carotenoids are plant pigments which constitute more than 600 compounds, most of them being lipid-soluble and which contribute significantly to the nutritional benefits of fruit and vegetable consumption. f)-carotene is the most common form of the vitamin and is the precursor of vitamin A. f)-cryptoxanthine is another precursor of vitamin A. The latter is a powerful lipid-soluble antioxidant which protects cellular membranes from oxidative stress. Vitamin A is carried into the plasma by retinal binding protein which is synthesized in the liver. 

Nutrient Content high in protein, prebiotic fiber, antioxidant vitamins A and C, B vitamins, dietary minerals Phytochemical Content high in carotenoids (alpha- and beta-carotene, beta-cryptoxanthin, lutein, violaxanthin), polyphenols (quercetin, gallic acid, gallotannins, rhamnetin, cyanidin and xanthone glycosides, including mangiferin, mainly in skin)... 

High Nutrient Content protein, prebiotic fiber, antioxidant A-C-E vitamins (diminished by heating), B vitamins, dietary minerals High Phytochemical Content carotenoids (beta-cryptoxanthin, beta-carotene) polyphenols (anthocyanins, particularly delphinidin and cyanidin glycosides and rutinosides, catechins, proanthocyanidins, chlorogenic acid, quercetin, hydroxycinnamic acid)... 

High Nutrient Content antioxidant A-C-E vitamins High Phytochemical Content carotenoids (beta-cryptoxanthin, beta-c rotene, lycopene) polyphenols (anthocyanins, tannins)... 

In an excellent review of variables influencing the analysis of carotenoids by HPLC, Scott [768] noted that some parameters had adverse effects on the system, First, stainless steel frits seemed to lead to lowered responses for 8-cryptoxanthin and a- and / -carotene. Replacement of the frits with metal-free frits increased responses, but the replacement of stainless steel column tubing and injector tubing did not increase response. This is most likely a result of the large disparity in contact surface areas between the frits and the tubing. Storage of lycopene samples in 0.1% BHT (antioxidant)-preserved chloroform vs. chloroform without BHT showed considerably less degradation with time. The same results were found for BHT-preserved THF vs. unpreserved THF. Optimization of extraction procedures is also addressed in this paper. 

In 2007, a group of Department of Epidemiology and Preventive Medicine, Monash University, Central and Eastern Clinical School, Alfred Hospital, Melbourne, VIC 3004, Australia examined their effect of dietary antioxidants such as ascorbic acid (49), vitamin E (50), and 6 carotenoids such as a-carotene (1), P-carotene (2), P-cryptoxanthin (5), lutein (6), zeaxanthin (9) and lycopene (3) on the knee structure in a cohort of 293 healthy, middle aged subjects of mean age 58 ys with no their clinical knee osteoarthritis (Figme 13). 

In 2001, Buratti et al. [50] described an electrochemical method to evaluate the antioxidant power of lipophilic food extracts. The method was based on the association between FIA and amperometric detection and a working potential of +0.50 V (vs. Ag/AgCl) was used in the experiments. When applied to pure compounds, it was possible to observe that lycopene presented the greatest antioxidant power of all the lipophilic compounds (lycopene, )5-carotene, zeaxanthin, a-carotene, )5-cryptoxanthin, lutein, a-tocopherol, capsaicin, chlorophyll, astaxanthin, and canthaxanthin) used in this smdy. This result was... 

Some carotenoids are precursors (provitamins) of vitamin A. Other carotenoids, such as cryptoxanthin, zeaxanthin and lutein, exhibit, by contrast, about half of the activity of provitamins A. Some carotenoids, such as lycopene, astaxanthin and canthaxanthin, are more effective in quenching singlet oxygen than P-carotene. Carotenoids also react with free radicals such as P-carotene. Because of their antioxidative properties, they are used in the prevention of degenerative processes and as anticancer agents. 

The relative antioxidant activities of carotenoids in multilamellar liposomes, as assayed by inhibition of the formation of thiobarbituric acid-reactive substances (TBARs), were lycopene>a-carotene>p-cryptoxanthin >zeaxanthin= P-carotene>lutein (Stahl et al, 1998). Mixtures of carotenoids were more effective than the single compounds, and this synergistic effect was most pronounced when lycopene or lutein was present. The superior antioxidant activity of mixtures of carotenoids may be related to the specific positioning of different carotenoids within cell membranes. 

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