Differential Bioavailability, Clearance, and Tissue Distribution of the Acyclic Tomato Carotenoids Lycopene and Phytoene in Mongolian Gerbils

Abstract

Lycopene (LYC) is the major tomato carotenoid and is the focus of substantial research. Phytoene (PE), a minor tomato carotenoid, is found in human blood and tissues in similar concentrations to LYC. To determine which metabolic differences underlie this phenomenon, Mongolian gerbils (Meriones unguiculatus, n = 56) were fed control or tomato powder (TP)-containing diets (to establish steady-state serum and tissue carotenoid concentrations similar to tomato-fed humans) for 26 d. The TP-fed gerbils were then provided either a single, oral, cottonseed oil (CO) vehicle dose and tissues were collected at 6 h or they were provided unlabeled PE or LYC in CO and tissues were evaluated at 6, 12, or 24 h. In vehicle-dosed, TP-fed gerbils, LYC was the major carotenoid (≥ 55% carotenoids) in liver, spleen, testes, and the prostate-seminal vesicle complex, whereas PE was the major serum and adipose carotenoid (≥ 37% total carotenoid) and phytofluene was the major carotenoid (≥ 38%) in adrenals and lungs. PE dosing increased hepatic, splenic, and serum PE concentrations compared with vehicle dosing (P < 0.05) from 6 to 24 h, whereas LYC dosing increased only serum LYC at 6 and 12 h (P < 0.05) compared with vehicle dosing. This suggested PE was more bioavailable and cleared more slowly than LYC. To precisely track absorptive and distributive differences, (14)C-PE or (14)C-LYC (n = 2/group) was provided to TP-fed gerbils. Bioavailability assessed by carcass (14)C-content was 23% for PE and 8% for LYC. Nearly every extra-hepatic tissue accumulated greater dose radioactivity after (14)C-PE than (14)C-LYC dosing. Thus, LYC and PE, which structurally differ only by saturation, pharmacokinetically differ in bioavailability, tissue deposition, and clearance.

A comprehensive review on the colorless carotenoids phytoene and phytofluene

“…Interestingly, it was observed that almost all extra-hepatic tissue accumulated more radioactivity after labeled-phytoene than labeled-lycopene dosing. Altogether, the data from this interesting study confirmed that there are important differences between these two carotenoids in bioavailability, tissue accumulation and clearance [124].…”

“…On the other hand, the tomato supplementation significantly decreased the multiplicity of inflammatory and altered hepatic foci in the liver of HFD-fed rats [123]. Contrastingly, no changes in inflammatory markers were observed in a study referred to before where gerbils were fed tomato powder plus lycopene or phytoene [124].…”

Tomatoes protect against development of UV-induced keratinocyte carcinoma via metabolomic alterations

“…This provides rationale to feeding tangerine tomatoes when increasing tissue lycopene is desirable, and contrary to others who have found that phytoene is more bioavailable than lycopene 25, 26 .…”

β-Carotene 9′,10′ Oxygenase Modulates the Anticancer Activity of Dietary Tomato or Lycopene on Prostate Carcinogenesis in the TRAMP Model

“…Serum and diet samples were analyzed by HPLC using a photodiode array detector (HPLC-PDA) (PDA 2996, Waters, Milford, MA). The HPLC system and carotenoid standard preparation have been previously described (49). The analytical lab participates semi-annually in the National Institute for Standards and Technology’s Fat Soluble Vitamin and Carotenoid Round Robin activity to monitor protocol accuracy with respect to other analytical labs.…”