13 C‐phytoene from tomato cell suspension cultures for pharmacokinetic studies in healthy adults (645.15)

Phytoene (C 40 H 64 ) is a colorless carotenoid found in tomatoes and other plant foods and is enriched in tomato consumers’ plasma and tissues. Yet, little is known about its absorption, distribution, and clearance. To study phytoene pharmacokinetics, phytoene was 13 C‐biolabeled using tomato cell suspension cultures grown with uniformly‐labeled 13 C‐glucose (30 g/L media) for a 7‐d 13 C‐loading and 18‐d 13 C‐labeling cycle to yield 290 g cells/L culture. Uniformly labeled 13 C‐phytoene was the predominant isotopomer ( 13 C 40 H 56 ; ~47%), and 蠅85% carbon was 13 C across the major isotopomers. 13 C‐phytoene was isolated from 2.53 kg of cells by hexane/ethanol/water biphasic extraction and purified by semi‐preparatory C18 HPLC‐PDA. Two wk before test meal consumption, 4 healthy adults (2 females, 2 males, 27.7 ± 2.3 yr, BMI 22 ± 1) began a controlled phytoene diet (1‐5 mg/d) to achieve steady‐state conditions and continued this diet for 4 wk, after 13 C‐phytoene consumption. On day 0, subjects consumed 3.2 mg 13 C‐phytoene in 10 mL carotenoid‐free olive oil with a low‐carotenoid breakfast. Plasma samples were collected at baseline, hourly from 1‐15 h, at 17, 19, 21, and 24 h, and 2, 3, 4, 7, 10, 14, 17, 21, and 28 d after dosing. Mean dietary phytoene intake was 2.5 ± 0.6 mg/d over 6 wk, with major dietary sources being tomato‐containing products, sweet bell peppers, and winter squash. Plasma 13 C‐phytoene concentrations will be measured by HPLC‐MS/MS for pharmacokinetic analyses. Pharmacokinetic investigation of tomato phytochemicals elucidates their biological relevance and promotes development of rational dietary interventions for clinical trial investigations. NIH/NCCAM‐ R21AT005166 Grant Funding Source : NIH/NCCAM‐R21AT005166