Carotenoids cryptoxanthin

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. 

Zeaxanthin (135) was synthesized from the salt (133) and the dialdehyde (134) in 1,2-epoxybutane, a reagent superior to ethylene oxide particularly for polyenedialdehydes. The same salt was also used to prepare /3-cryptoxanthin and zeinoxanthin. Phenolic carotenoids from Strep-tomyces mediolani and 1,2-dihydro- and l,2,r,2 -tetrahydro-lycopene have also been obtained by conventional olefin synthesis. 

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. 

BREITHAUPT D E and BAMEDIA (2001) Carotenoid esters in vegetables and fruits A screening with emphasis on P-cryptoxanthin esters. JAgric Food Chem 49(4) 2064-70. 

There are basically two types of carotenoids those that contain one or more oxygen atoms are known as xanthophylls those that contain hydrocarbons are known as carotenes. Common oxygen substituents are the hydroxy (as in p-cryptoxanthin), keto (as in canthaxanthin), epoxy (as in violaxanthin), and aldehyde (as in p-citraurin) groups. Both types of carotenoids may be acyclic (no ring, e.g., lycopene), monocyclic (one ring, e.g., y-carotene), or dicyclic (two rings, e.g., a- and p-carotene). In nature, carotenoids exist primarily in the more stable all-trans (or all-E) forms, but small amounts of cis (or Z) isomers do occur. - ... 

Typically several different carotenoids occur in plant tissues containing this class of pigments. Carotenoids are accumulated in chloroplasts of all green plants as mixtures of a- and P-carotene, P-cryptoxanthin, lutein, zeaxanthin, violaxanthin, and neoxanthin. These pigments are found as complexes formed by noncovalent bonding with proteins. In green leaves, carotenoids are free, nonesterified, and their compositions depend on the plant and developmental conditions. In reproductive... 

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. ... 

Carotenoids and prostate cancer — Numerous epidemiological studies including prospective cohort and case-control studies have demonstrated the protective roles of lycopene, tomatoes, and tomato-derived products on prostate cancer risk other carotenoids showed no effects. " In two studies based on correlations between plasma levels or dietary intake of various carotenoids and prostate cancer risk, lycopene appeared inversely associated with prostate cancer but no association was reported for a-carotene, P-carotene, lutein, zeaxanthin, or p-cryptoxanthin. - Nevertheless, a protective role of all these carotenoids (provided by tomatoes, pumpkin, spinach, watermelon, and citrus fruits) against prostate cancer was recently reported by Jian et al. ... 

Some prospective and case-control studies also investigated the relationship of carotenoids and the evolution of CCA-IMT. Although the EVA study showed no association between total carotenoids and IMT, others like the ARIC study, the Los Angeles Atherosclerosis Study, " and the Kuopio Ischaemic Heart Disease Risk Factor Study demonstrated the protective role of isolated carotenoids such as lycopene, lutein, zeaxanthin, and P-cryptoxanthin on IMT. Thus, findings from prospective and case-control studies have suggested that some carotenoids such as lycopene and P-carotene may present protective effects against CVD and particularly myocardial infarcts and intima media thickness, a marker of atherosclerosis. 

More than 600 carotenoids have been isolated from natural sources, but only about 60 have been detected in the human diet — about 20 in human blood and tissues. P-Carotene, a-carotene, lycopene, lutein, and P-cryptoxanthin are the five most prominent carotenoids present in the human body. 

In order to exhibit provitamin A activity, the carotenoid molecule must have at least one unsubstituted p-ionone ring and the correct number and position of methyl groups in the polyene chain. Compared to aU-trans P-carotene (100% provitamin A activity), a-carotene, P-cryptoxanthin, and y-carotene show 30 to 50% activity and cis isomers of P-carotene less than 10%. Vitamin A equivalence values of carotenoids from foods have been recently revised to higher ratio numbers (see Table 3.2.2) due to poorer bioavailability of provitamin A carotenoids from foods than previously thought when assessed with more recent and appropriate methods. 

The speed of autoxidation was compared for different carotenoids in an aqueous model system in which the carotenoids were adsorbed onto a C-18 solid phase and exposed to a continnons flow of water saturated with oxygen at 30°C. Major products of P-carotene were identified as (Z)-isomers, 13-(Z), 9-(Z), and a di-(Z) isomer cleavage prodncts were P-apo-13-carotenone and p-apo-14 -carotenal, and also P-carotene 5,8-epoxide and P-carotene 5,8-endoperoxide. The degradation of all the carotenoids followed zero-order reaction kinetics with the following relative rates lycopene > P-cryptoxanthin > (E)-P-carotene > 9-(Z)-p-carotene. 

Many countries have food composition databases but only a few present the compositions of some carotenoids. The U.S. Department of Agriculture s NCC Carotenoid Database covers 215 foods and cites levels of a-carotene, P-carotene, lycopene, P-cryptoxanthin, lutein plus zeaxanthin, and also zeaxanthin in a more limited number of foods. An electronic version of this database is available at http //www.ars.usda.gov/nutrientdata. 

Tables 4.2.1 and 4.2.2 show, respectively, major sources of P-carotene and other provitamin A carotenoids, especially a-carotene and P-cryptoxanthin. Since cis isomers have different biological and physical-chemical properties than their corresponding dll-trans carotenoids, whenever available, their distribution was included in the tables. The structures of P-carotene cis isomers are shown in Figure 4.2.1, whereas the structures of the other provitamin A carotenoids are presented in Figure...

In processed products of the tropical fruit caja and in some cultivars of persimmons, all-tran P-cryptoxanthin was found to be the major carotenoid, contributing to 31 to 38% of the total carotenoid contents in both fruits (Table... 

Although p-cryptoxanthin was not the major carotenoid in three cultivars of sea buckthorn berries, their contents were higher than those found in other fruits (Table 4.2.2). 

Dunaliella natural P-carotene is distributed widely in many different markets under three categories p-carotene extracts, Dunaliella powder for human use, dried Dunaliella for feed use. Extracted purified P-carotene is sold mostly in vegetable oil in bulk concentrations from 1 to 20% to color various food products and for personal use in soft gels usually containing 5 mg P-carotene per gel. Purified natural p-carotene is generally accompanied by the other Dunaliella carotenoids, primarily lutein, neoxanthin, zeaxan-thin, violaxanthin, cryptoxanthin, and a-carotene for a total of approximately 15% of carotene concentration. This compound is marketed as carotenoids mix. ... 

The most common mobile phase is a gradient of petroleum ether or hexane with increasing concentrations of acetone or diethyl ether. Development of the column should be optimized for each sample to afford a quick and effective separation to avoid band broadening. The separation can be followed visually. The most non-polar a- and 3-carotenes are eluted first as a yellow band followed by the chlorophylls and other more polar carotenoids like cryptoxanthin, lutein, and zeaxanthin that frequently fuse together and appear as a single band. ... 

Independently of the reversed phase column, the addition of TEA to the mobile phase increases carotenoid recovery from the column." Increased recoveries of 18% lutein, 33% zeaxanthin, 33% P-cryptoxanthin, 53% lycopene, 30% a-carotene, and 42% P-carotene in a Vydac column were observed after the addition of 0.1% TEA to the mobile phase. Recovery on a C30 column was also enhanced by the addition of 0.1% TEA to the mobile phase, with the peak area of lutein increasing by 26%, that of zeaxanthin by 42%, that of P-cryptoxanthin by 55%, that of lycopene by 21%, and those of a-carotene and P-carotene by 47 and 64%, respectively. ... 

Mercadante, A.Z. and Rodriguez-Amaya, D.B., Confirmation of the identity of a-cryptoxanthin and incidence of minor provitamin A carotenoids in green leafy vegetables, Cienc. Tecnol. Alim., 21, 216, 2001. 

The phase-transition temperature, 7 , and the width of transition, A7j/2, were operationally defined based on EPR data, as shown in Figure 10.6a. As a rule, in the presence of polar carotenoids the phase transition broadens and shifts to lower temperatures (Subczynski et al. 1993, Wisniewska et al. 2006). The effects on Tm are the strongest for dipolar carotenoids, significantly weaker for monopolar carotenoids, and negligible for nonpolar carotenoids. The effects decrease with the increase of membrane thickness. Additionally, the difference between dipolar and monopolar carotenoids decreases for thicker membranes (Subczynski and Wisniewska 1998, Wisniewska et al. 2006). These effects for lutein, P-cryptoxanthin, and P-carotene are illustrated in Figure 10.6b... 

FIGURE 10.12 The mole ratio of carotenoid/phospholipid and carotenoid/total lipid (phospholipid + cholesterol) in raft domain (detergent-resistant membrane, DRM) and bulk domain (detergent-soluble membrane, DSM) isolated from membranes made of raft-forming mixture (equimolar ternary mixture of dioleoyl-PC (DOPC)/sphingomyelin/cholesterol) with 1 mol% lutein (LUT), zeaxanthin (ZEA), P-cryptoxanthin (P-CXT), or P-carotene (P-CAR). 

Interestingly, carotenoids more abundant in the blood plasma than zeaxanthin, such as lycopene, P-carotene, and P-cryptoxanthin, do not accumulate in the retina. RPE cells express p,p-carotene 15,15 -monooxygenase (BCO), formerly known as P-carotene 15,l5 -dioxygcnase, an enzyme that catalyzes the oxidative cleavage of P-carotene into two molecules of all-trans-retinal (Aleman et al., 2001 Bhatti et al., 2003 Chichili et al., 2005 Leuenberger et al., 2001 Lindqvist and Andersson, 2002). Therefore it may be suggested that p -carotene transported into RPE-cells is efficiently cleaved into retinal molecules. BCO cleaves also P-cryptoxanthin (Lindqvist and Andersson, 2002), and its absence in the retina may also be explained by its efficient cleavage to retinoids. However, lycopene, often the most abundant carotenoid in human plasma, cannot serve as a substrate for BCO, and yet it is not detectable in the neural retina (Khachik et al., 2002). 

---