Horticulture and Crop Sciences, The Ohio State University, Columbus, OH.
Food Science and Technology, The Ohio State University, Columbus, OH.
Am J Clin Nutr. 2018 Oct 1;108(4):784-792. doi: 10.1093/ajcn/nqy177.
Nonvitamin A apocarotenoids occur in foods. Some function as retinoic acid receptor antagonists in vitro, though it is unclear if apocarotenoids are absorbed or accumulate to levels needed to elicit biological function.
The aim of this study was to quantify carotenoids and apocarotenoids (β-apo-8'-, -10'-, -12'-, and -14'-carotenal, apo-6'-, -8'-, -10'-, -12'-, and -14'-lycopenal, retinal, acycloretinal, β-apo-13-carotenone, and apo-13-lycopenone) in human plasma after controlled consumption of carotenoid-rich tomato juices.
Healthy subjects (n = 35) consumed a low-carotenoid diet for 2 wk, then consumed 360 mL of high-β-carotene tomato juice (30.4 mg of β-carotene, 34.5 μg total β-apocarotenoids/d), high-lycopene tomato juice (42.5 mg of lycopene, 119.2 μg total apolycopenoids/d), or a carotenoid-free control (cucumber juice) per day for 4 wk. Plasma was sampled at baseline (after washout) and after 2 and 4 wk, and analyzed for carotenoids and apocarotenoids using high-pressure liquid chromatography (HPLC) and HPLC-tandem mass spectrometry, respectively. The methods used to analyze the apocarotenoids had limits of detection of ∼ 100 pmol/L.
Apocarotenoids are present in tomato juices at 0.1-0.5% of the parent carotenoids. Plasma lycopene and β-carotene increased (P < 0.001) after consuming high-lycopene and β-carotene tomato juices, respectively, while retinol remained unchanged. β-Apo-13-carotenone was found in the blood of all subjects at every visit, although elevated (P < 0.001) after consuming β-carotene tomato juice for 4 wk (1.01 ± 0.27 nmol/L) compared with both baseline (0.37 ± 0.17 nmol/L) and control (0.46 ± 0.11 nmol/L). Apo-6'-lycopenal was detected or quantifiable in 29 subjects, while β-apo-10'- and 12'-carotenal were detected in 6 and 2 subjects, respectively. No other apolycopenoids or apocarotenoids were detected.
β-Apo-13-carotenone was the only apocarotenoid that was quantifiable in all subjects, and was elevated in those consuming high-β-carotene tomato juice. Levels were similar to previous reports of all-trans-retinoic acid. Other apocarotenoids are either poorly absorbed or rapidly metabolized or cleared, and so are absent or limited in blood. β-Apo-13-carotenone may form from vitamin A and its presence warrants further investigation. This trial was registered at clinicaltrials.gov as NCT02550483.
非维生素 A 类胡萝卜素存在于食物中。一些在体外作为视黄酸受体拮抗剂发挥作用，尽管尚不清楚类胡萝卜素是否被吸收并积累到足以引起生物学功能的水平。
本研究旨在定量检测人血浆中的类胡萝卜素和类胡萝卜素（β-apo-8'，-10'，-12'，-14'-胡萝卜醛，apo-6'，-8'，-10'，-12'，-14'-番茄红素醛，视黄醇，无环视黄醛，β-apo-13-胡萝卜酮和 apo-13-番茄红素酮），方法是在受控条件下摄入富含类胡萝卜素的番茄汁后。
健康受试者（n=35）首先食用低类胡萝卜素饮食 2 周，然后每天食用 360 毫升高β-胡萝卜素番茄汁（30.4mgβ-胡萝卜素，34.5μg总β-类胡萝卜素/ d），高番茄红素番茄汁（42.5mg 番茄红素，119.2μg 总 apo-类胡萝卜素/ d）或不含类胡萝卜素的对照（黄瓜汁）4 周。在基线（洗脱后）以及 2 周和 4 周后采集血浆样本，并使用高效液相色谱（HPLC）和 HPLC-串联质谱法分别分析类胡萝卜素和类胡萝卜素。用于分析类胡萝卜素的方法的检测限约为 100pmol/L。
类胡萝卜素在番茄汁中的含量为母体类胡萝卜素的 0.1-0.5%。食用高番茄红素和β-胡萝卜素番茄汁后，血浆番茄红素和β-胡萝卜素均增加（P<0.001），而视黄醇保持不变。β-apo-13-胡萝卜酮在所有受试者的每次就诊中均存在，尽管在食用β-胡萝卜素番茄汁 4 周后（1.01±0.27nmol/L）升高（P<0.001），与基线（0.37±0.17nmol/L）和对照（0.46±0.11nmol/L）相比。在 29 名受试者中检测到或可定量检测到 apo-6'-lycopenal，而在 6 名和 2 名受试者中分别检测到β-apo-10'-和 12'-carotenal。未检测到其他 apo-类胡萝卜素或类胡萝卜素。
β-apo-13-胡萝卜酮是所有受试者均可定量检测到的唯一类胡萝卜素，并且在食用高β-胡萝卜素番茄汁的受试者中升高。水平与先前报道的全反式视黄酸相似。其他类胡萝卜素要么吸收不良，要么代谢或清除迅速，因此在血液中不存在或含量有限。β-apo-13-胡萝卜酮可能由维生素 A 形成，其存在值得进一步研究。本试验在 clinicaltrials.gov 上注册为 NCT02550483。
