Carotenoids, in plasma

Khachik, F, de Moura, FF, Zhao, DY, Aebischer, CP, and Bernstein, PS, 2002. Transformations of selected carotenoids in plasma, liver, and ocular tissues of humans and in nonprimate animal models. Invest Ophthalmol Vis Sci 43, 3383-3392. 

Fresh tomato fruit contains about 0.72 to 20 mg of lycopene per 100 g of fresh weight, which accounts for about 30% of the total carotenoids in plasma (Stahl and Sies 1996). In contrast to other pigments such as (3-carotene, lutein, violaxanthin, auroxanthin, neoxanthin, and chlorophylls a and b, which accumulate in inner pulp and in the outer region of the pericarp, lycopene appears only at the end of the maturation period and almost exclusively in the external part of the fruit (Laval-Martin and others 1975). Other tomato components that can contribute to health include flavonoids, folic acid, and vitamin E (Dorais and others 2001a,b). 

Zaman Z, Fielden P, Frost PG. Simultaneous determination of vitamins A and E and carotenoids in plasma by reversed-phase HPLC in elderly and younger subjects. Clin Chem 1993 39 2229-34,... 

Lin S, Quaroni L, White WS, Cotton T, Chumanov G. Localization of carotenoids in plasma low-density lipoproteins studied by surface-enhanced resonance Raman spectroscopy. Biopolymers 2000 57 249-256. 

Serum. Many of the current HPLC procedures used for the analysis of carotenoids in plasma or serum are based on the RP isocratic procedure reported by Nelis and De Leenheer (190). When acetonitrile is used as a component of the mobile phase, it is necessary to include ammonium acetate as otherwise there... 

Gomez-Aracena, J., Rogers, R., Van t Veer, P. et al (2003) Vq etable consumption and carotenoids in plasma and adipose tissue in Malaga, Spain. Int. J. Vitam. Nutr. Res., 73, 24-31. 

More specific methods involve chromatographic separation of the retinoids and carotenoids followed by an appropriate detection method. This subject has been reviewed (57). Typically, hplc techniques are used and are coupled with detection by uv. For the retinoids, fluorescent detection is possible and picogram quantities of retinol in plasma have been measured (58—62). These techniques are particularly powerful for the separation of isomers. Owing to the thermal lability of these compounds, gc methods have also been used but to a lesser extent. Recently, the utiUty of cool-on-column injection methods for these materials has been demonstrated (63). 

The mechanisms of the metabolism and excretion of P-carotene are not clear, other than the identification of a number of partially oxidised intermediates found in plasma (Khachik et al., 1992). It is assumed that the carotenoids are metabolised in a manner analogous to the P-oxidation of fatty acids although there is no evidence for this. 

FAULKS R M, HART D J, SCOTT K J and SOUTHON s (1998) Changes in plasma carotenoid and vitamin E profile during supplementation with oil palm fruit carotenoids. J Lab Clin Med 132(6) 507-11. 

Carotenoid and tocopherol concentrations in plasma, peripheral blood mononuclear cells and red blood cells after long-term beta-carotene supplementation in men. Am J Clin Nutr 63(4) 553-8. 

VAN HET HOF K H, DE BOER B C, TIJBURG L B, LUCIUS B R, ZIJP I, WEST C E, HAUTVAST J G and WESTRATE J A (2000) Carotenoid bioavailability in humans from tomatoes processed in different ways determined from the carotenoid response in the triglyceride-rich lipoprotein fraction of plasma after a single consumption and in plasma after 4 days of consumption. JNutr 130(5) 1189-96. 

With investigations of phytochemicals and functional foods, the outcome measure is generally going to be a biomarker of disease, such as serum cholesterol level as a marker of heart disease risk, or indicators of bone turnover as markers of osteoporosis risk. Alternatively, markers of exposure may also indicate the benefit from a functional food by demonstrating bioavailability, such as increased serum levels of vitamins or carotenoids. Some components will be measurable in both ways. For instance, effects of a folic acid-fortified food could be measured via decrease in plasma homocysteine levels, or increase in red blood cell folate. 

Carotenoids and breast cancer — Among seven case-control studies investigating the correlation between different carotenoid plasma levels or dietary intakes and breast cancer risk, five showed significant inverse associations with some carotenoids. - In most cases, this protective effect was due to 3-carotene and lutein. However, one (the Canadian National Breast Screening Study ) showed no association for all studied carotenoids including (I-carotene and lutein. More recently, another study even demonstrated a positive correlation between breast cancer risk and tissue and serum levels of P-carotenes and total carotenes. Nevertheless, these observational results must be confirmed by intervention studies to prove consistent. 

Al-Delaimy, W.K. et al., Plasma levels of six carotenoids in nine European countries report from the European Prospective Investigation into Cancer and Nutrition (EPIC), Public Health Nutr., 1, 713, 2004. 

Lindqvist, A. and Andersson, S., Biochemical properties of purified recombinant human beta-carotene 15,15-monooxygenase, J. Biol. Chem., 277, 23942, 2002. Krinsky, N.I., Cornwell, D.G., and Oncley, J.I., The transport of vitamin A and carotenoids in human plasma. Arch. Biochem. Biophys., 73, 233, 1958. 

Experimental evidence in humans is based upon intervention studies with diets enriched in carotenoids or carotenoid-contaiifing foods. Oxidative stress biomarkers are measured in plasma or urine. The inhibition of low density lipoprotein (LDL) oxidation has been posmlated as one mechanism by which antioxidants may prevent the development of atherosclerosis. Since carotenoids are transported mainly via LDL in blood, testing the susceptibility of carotenoid-loaded LDL to oxidation is a common method of evaluating the antioxidant activities of carotenoids in vivo. This type of smdy is more precisely of the ex vivo type because LDLs are extracted from plasma in order to be tested in vitro for oxidative sensitivity after the subjects are given a special diet. 

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). 

The presence of only two dietary carotenoids in the retina, lutein and zeaxanthin, out of about 14 normally present in the plasma indicates their highly specific uptake and retention (Bernstein et al., 2001 Bone and Landrum, 1992 Bone et al., 1988,1997,1993 Davies and Morland, 2004 Khachik et al., 1997, 2002). The retina-blood barrier is formed by the tight zonulae occludentes of the endothelial cells in the inner retina and of the RPE, a monolayer of cells which separates the outer retina from its choroidal blood supply (Strauss, 2005). 

Lidebjer, C, Leanderson, P, Ernerudh, J, and Jonasson, L, 2007. Low plasma levels of oxygenated carotenoids in patients with coronary artery disease. Nutr Metab Cardiovasc Dis 17,448 156. 

Ojima, F, Sakamoto, H, Ishiguro, Y, and Terao, J, 1993. Consumption of carotenoids in photosensitized oxidation of human plasma and plasma low-density-lipoprotein. Free Radic Biol Med 15, 377-384. 

V. Tyssandier, N. Cardinault, C. Caris-Veyrat, M.-J. Amiot, R Grolier, C. Bouteloup, V. Azais-Braesco, and R Borel, Vegetable-home lutein, lycopene, and beta-carotene compete for incorporation into cylomi-crons, with no adverse effect on the medium term (3-wk) plasma status of carotenoids in humans, Am. J. Clin. Nutr. 75 (2002) 526-534. 

Khachik, F., G. R. Beecher, M. B. Goli, W. R. Lusby, and C. E. Daitch. 1992a. Separation and quantification of carotenoids in human plasma. Methods Enzymol 213 205-219. 

Isaksson, C., McLaughlin, P., Monaghan, P., and Andersson, S. 2007. Carotenoid pigmentation does not reflect total non-enzymatic antioxidant activity in plasma of adult and nestling great tits, Parus major. Fund. Ecol. 21 1123-1129. 

Khachik F, Beecher GR and Goli MG. 1991. Separation, identification, and quantification of carotenoids in fruits, vegetables and human plasma by high performance liquid chromatography. Pure Appl Chem... 

Wise JA, Morin RJ, Sanderson R and Blum K. (1996). Changes in plasma carotenoid, alpha-tocopherol, and lipid peroxide levels in response to supplementation with concentrated fruit and vegetable extracts a pilot study. Curr Ther Res 57(6) 445 t61. 

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