Liver lycopene

GRADELET S, ASTORG P, LECLERC J, CHEVALIER J, VERNEVAUT M F and SIESS M H (1996) Effects of canthaxanthin, lycopene and lutein on liver xenobiotic metabolising enzymes in the Tat. Xenobiotica 26(1) 49-63. 

Stndies of the antoxidation of carotenoids in liposomal suspensions have also been performed since liposomes can mimic the environment of carotenoids in vivo. Kim et al. stndied the antoxidation of lycopene," P-carotene," and phytofluene" " in liposomal snspensions and identified oxidative cleavage compounds. Stabilities to oxidation at room temperature of various carotenoids incorporated in pig liver microsomes have also been studied." The model took into account membrane dynamics. After 3 hr of reactions, P-carotene and lycopene had completely degraded, whereas xanthophylls tested were shown to be more stable. 

Gajic, M. et al., Apo-8-lycopenal and apo-12-lycopenal are metabolic products of lycopene in rat liver, J. Nutr. Biochem., 136, 1552, 2006. 

Other carotenoids, such as canthaxanthin and astaxanthin have been recognized as potent inducers of CYP1A1 and 1A2 in rat liver (Gradelet et al., 1998). The administration of lycopene to rats was shown to induce liver CYP types 1 Al/2, 2B1/2, and 3A in a dose-dependent manner (Breinholt et al., 2000). The observation that these enzymatic activities were induced at very low lycopene plasma levels suggests that modulation of drug metabolising enzymes by carotenoids may be relevant to humans (Breinholt et al., 2000). 

In the enterocyte, provitamin A carotenoids are immediately converted to vitamin A esters. Carotenoids, vitamin A esters, and other lipophilic compounds are packaged into chylomicrons, which are secreted into lymph and then into the bloodstream. Chylomicrons are attacked by endothelial lipoprotein lipases in the bloodstream, leading to chylomicron remnants, which are taken up by the liver (van den Berg and others 2000). Carotenoids are exported from liver to various tissues by lipoproteins. Carotenes (such as (3-carotene and lycopene) are transported by low-density lipoproteins (LDL) and very low-density lipoproteins (VLDL), whereas xanthophylls (such as lutein, zeax-anthin, and (3-cryptoxanthin) are transported by high-density lipoproteins (HDL) and LDL (Furr and Clark 1997). 

In systems where several carotenoids are involved, the absorption of each carotenoid is governed by interactions among them carotenoids compete for absorption (Furr and Clark 1997). For example, (3-carotene supplementation reduced absorption of dietary lutein and lycopene in humans (Micozzi and others 1992). Tyssandier and others (2002) found that the absorption of dietary lycopene was reduced when a portion of spinach or pills of lutein were additionally administered to the volunteers. Similarly, the absorption of dietary lutein was reduced by consumption of tomato puree or lycopene pills (Tyssandier and others 2002). Furusho and others (2000) demonstrated that liver retinol accumulation in Wistar rats was significantly reduced when a fixed amount of (3-carotene was replaced by a mixture of (3- and a-carotene, suggesting that each one of these carotenoids mutually inhibits the utilization of the other. The proportion of (3-and a-carotene in the mixture used in that study (Furusho and others 2000) simulated that of carrots. 

Most of the organs (thyroid, spleen, kidney, liver, pancreas, and heart) investigated appear similar in that lycopene and P-carotene are the predominant carotenoids found in these organs, with an approximately equal percentage distribution between them. Selectively, the cellular uptake of individual carotenoids may be based upon the selective transport of the individual carotenoids. 

Following the absorption of lycopene, it is transported to various organs and accumulates in tissues. Tissue distribution of lycopene varies considerably suggesting unique biological effects on some tissues and not on others. The highest concentrations of lycopene are in the testes, adrenal glands, liver, and prostate. Table VI shows the lycopene levels in human tissues (Rao and Agarwal, 1999). 

In another study (Moriel et al., 2002), 11 patients with mild essential hypertension were compared with 11 healthy subjects for water- and lipid-soluble antioxidants and the concentrations of nitric oxide derivatives in the plasma. A significant reduction in plasma lycopene was observed in the hypertensive patients compared to the normal subjects. Similar reductions in ascorbate, urate, and (3-carotene were also observed in this study. However, there were no differences in the nitrous oxide derivatives between the two groups. Hypertension and lymphatic circulation impairment are associated with liver cirrhosis. When patients with liver cirrhosis were compared to healthy matched controls, a significant reduction in serum lycopene, other carotenoid antioxidants, retinol, and oc-tocopherol were observed in the cirrhotic patients. Based on these observations, the authors recommend thorough screening for the antioxidants and improved diet in the... 

Astrog, P., Gradelet, S., Berges, R., and Suschetet, M. 1997. Dietary lycopene decreases initiation of liver preneoplastic foci by diethylnitrosamine in rat. Nutr. Cancer 29, 60-68. 

No carotenoids were detected in tissues of animals sacrificed after 6 weeks. However, as shown in Table 10.4, after 24 weeks, nearly all carotenoids (lutein, zeaxanthin, lycopene, y-carotene, -carotene, a-carotene, P-carotene, phytofluene, phytoene) were bioavailable in colon and liver of the animals that received MCM. A typical HPLC profile of carotenoids in a pooled extract from mouse liver is shown in Figure 10.2. The major carotenoids in brain were lycopene, lutein, and P-carotene. Carotene predominated in the breast tissues, while lutein, lycopene, y-carotene, and a-carotene were detected in low concentrations. Carotenoids were not detected in tissues of the mice on WD without MCM. 

Problem 9.19 The yellow plant pigments / -, and y-caronne, and the red pigment of tomatoes, lycopene, aie converted into Vitamin A in the liver. All four have the molecular formula Upon catalytic hydrogenation, - and -carotene... 

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