[¹⁴C]-Lycopene and [¹⁴C]-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 ¹⁴C-lycopene (specific activity, 1.83 μCi/mg) and ¹⁴C-labeled products after an oral dose of 22 μCi 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 (∼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; ∼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.