[C-14]-Lycopene and [C-14]-labeled polar products are differentially distributed in tissues of F344 rats prefed lycopene

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 C-14-lycopene (specific activity, 1.83 muCi/mg) and C-14-labeled products after an oral dose of 22 muCi of C-14-lycopene in male rats that had been prefed a lycopene-containing diet (0.25 g lycopene/kg diet) for 30 d. The percentage of C-14 excreted in feces and urine over the 168 h was 68%. Quantitatively, serum, levels were maintained between 3 and 24 h then decreased at 72 h (P < 0.05). At all time points the majority of tissue C-14 was in the liver (similar to72%), although total hepatic C-14 decreased after 24 h. In a comparison of the extrahepatic tissue at 168 h, the C-14 was greatest in adipose tissue followed by spleen and then adrenal; similar to80% of the C-14 in the liver was in the cis and all-trans configuration at all time points. At 3 h, the C-14 in seminal vesicles was primarily in the all-trans plus 5-cis forms (70%), but by 168 h, 55% of C-14 was present as C-14-polar products. Despite the presence of unlabeled lycopene in the prostate, the primary C-14 form was in C-14-polar products (67-92%), even at 3 h. The percentage and amount of C-14-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.