Absorption and storage of [14C]beta-carotene in control and beta-carotene-fed (BC-fed) rats were determined. Pre-feeding with beta-carotene for 2 weeks caused a 1.9-fold stimulation of its own absorption as well as its conversion to retinyl esters, whereas the absorption of [3H]retinyl acetate was unaffected. The liver and the lungs accounted for 60% and 30%, respectively, of the total recovere...

Does beta-carotene increase, rather than decrease, human lung cancer rates? A large body of observational epidemiologic study has demonstrated that individuals who eat more fruits and vegetables rich in carotenoids and/or who have higher levels of serum betacarotene have a lower risk of cancer, particularly lung cancer. This inverse relationship has been particularly strong in lung cancer patie...

A new HPLC/DAD (Diode Array Detector) method is proposed for the identification of some carotene isomers. The operating conditions adopted permit the resolution of α-carotene, all-trans-β-carotene, 9-cis-β-carotene, 13-cis-β-carotene and 15-cis-β-carotene. Moreover, the chromatographic conditions reported are simplified in respect of those reported up to now. The method is applied to the determ...

Patients undergoing carotid endarterectomy were pretreated with low-dose, oral beta carotene to determine whether the carotenoid content of plaque could be increased in vivo. Beta carotene-treated patients had a 50-fold increase in their plaque beta carotene level from 0.066 to 3.3 micrograms beta carotene/g plaque. Microscopy and microspectrophotometry demonstrated that plaque from beta carote...

BACKGROUND Intervention studies have shown an increased mortality in patients who received beta-carotene. However, the mechanisms involved in this phenomenon are still unknown. OBJECTIVE Evaluate the influence of beta-carotene on oxidative stress and the expression of connexin 43 in rat hearts. METHODS Wistar rats, weighing approximately 100 g, were allocated in two groups: CONTROL GROUP (n...

2-Oxo-carotenoids, 2-Hydroxy-carotenoids, [uC]/?-Carotene, Metabolism, Stick Insects The carotenoids of the stick insect, Ectatosoma tiaratum, were studied by spectroscopic and chemical methods. The /?,/?-type pigments are /?,/?-carotene, /?,/?-caroten-2-one, /?,/?-caroten-2-ol, /?,/?-carotene-2,2'-dione, 2'-hydroxy-/?,/?-caroten-2-one, ß,^-carotene-2,2'-diol, 3,4-didehydro-/?,/?carotene-2,2'-d...

The three beta-carotene intervention trials: the Beta Carotene and Retinol Efficacy Trial (CARET), Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC), and Physician's Health Study (PHS) have all pointed to a lack of effect of synthetic beta-carotene in decreasing cardiovascular disease or cancer risk in well-nourished populations. The potential contribution of beta-carotene suppleme...

The composition of carotenoids, along with anthocyanins and chlorophyll, accounts for the distinctive range of colour found in the Actinidia (kiwifruit) species. Lutein and beta-carotene are the most abundant carotenoids found during fruit development, with beta-carotene concentration increasing rapidly during fruit maturation and ripening. In addition, the accumulation of beta-carotene and lut...

Lutein, a dihydroxy derivative of alpha-carotene (beta,epsilon-carotene), is the most abundant carotenoid in photosynthetic plant tissues where it plays important roles in light-harvesting complex-II structure and function. The synthesis of lutein from lycopene requires at least four distinct enzymatic reactions: beta- and epsilon-ring cyclizations and hydroxylation of each ring at the C-3 posi...

Because animals are not able to synthesize retinoids de novo, ultimately they must derive them from dietary provitamin A carotenoids through a process known as carotene cleavage. The enzyme responsible for catalyzing carotene cleavage ( -carotene 15,15 -dioxygenase) has been characterized primarily in rat intestinal scrapings. Using a recently reported cDNA sequence for a carotene cleavage enzy...