[14C]-Lycopene and [14C]-Labeled Polar Products Are Differentially Distributed in Tissues of F344 Rats Prefed Lycopene

Abstract

Epidemiologic evidence suggests a possible role for lycopene-rich foods in the prevention of prostate cancer and cardiovascular disease. Despite active research in disease reduction, there is a paucity of information on the absorption, biodistribution and metabolism of lycopene. The aim of this study was to evaluate the biodistribution of 14C-lycopene (specific activity, 1.83 microCi/mg) and 14C-labeled products after an oral dose of 22 microCi of 14C-lycopene in male rats that had been prefed a lycopene-containing diet (0.25 g lycopene/ kg diet) for 30 d. The percentage of 14C excreted in feces and urine over the 168 h was 68%. Quantitatively, serum 14C levels were maintained between 3 and 24 h then decreased at 72 h (P < 0.05). At all time points the majority of tissue 14C was in the liver (approximately 72%), although total hepatic 14C decreased after 24 h. In a comparison of the extrahepatic tissue at 168 h, the 14C was greatest in adipose tissue followed by spleen and then adrenal; approximately 80% of the 14C in the liver was in the cis and all-trans configuration at all time points. At 3 h, the 14C in seminal vesicles was primarily in the all-trans plus 5-cis forms (70%), but by 168 h, 55% of 14C was present as 14C-polar products. Despite the presence of unlabeled lycopene in the prostate, the primary 14C form was in 14C-polar products (67-92%), even at 3 h. The percentage and amount of 14C-polar products in the dorsolateral prostate lobe increased from 3 to 24 h and then reached a plateau. The data suggest that lycopene may be metabolized differently among tissues in rats prefed lycopene.

Phytoene, phytofluene, and lycopene from tomato powder differentially accumulate in tissues of male Fisher 344 rats

“…Differences among treatment groups were analyzed by one-way ANOVA, and group mean comparisons were further analyzed by the post-hoc Tukey's studentized range test with α=0.05 and 0.01 [20]. This statistical analysis has been previously utilized in prior studies [16,18]. All statistical analyses were conducted with SAS (version 8.1; SAS Institute, Cary, NC, USA).…”

“…Therefore, continued mechanistic evaluation of PE and PF in prostate cancer prevention, as compared to LYC, is warranted due to these detectable PE and PF prostate concentrations. Future studies should focus on the in vivo metabolism of PE and PF in a similar manner to studies that have been accomplished for LYC metabolism [16,46]. As 14 C-PE and 14 C-PF sources are not available, biosynthesis of these and other carotenoids through in vitro plant cell culture methodologies is necessary [17].…”

“…As 14 C-PE and 14 C-PF sources are not available, biosynthesis of these and other carotenoids through in vitro plant cell culture methodologies is necessary [17]. Precise qualitative and quantitative identification of 14 Ccarotenoid metabolites throughout the body, with an emphasis on the prostate [16,46], are essential to evaluate potential mechanisms of actions by which tomato carotenoids may act in prostate cancer prevention. Results from this work provide a better understanding of relative PE and PF tissue accumulation, compared to LYC (information not previously known).…”

“…Tissue and serum extraction and analysis was performed as previously described [16]. Briefly, tissue or serum samples were combined with a KOH/ethanol solution (1:5) containing 0.1% BHT.…”

“…Carotenoid concentrations in tissue and serum samples were quantified by a previously described HPLC-PDA system [16][17][18], and the HPLC mobile phases and gradient procedure utilized in this study have been previously described [19]. In brief, samples from each carotenoid-enriched tissue extract were dissolved in 32-40 µL methyl-tert-butyl ether (MTBE) and injected onto a C30, 4.6 × 150 mm analytical column (YMC, Wilmington, NC, USA) maintained at 25 °C.…”