The effect of the antioxidant activity of beta-carotene and related carotenoids on the free radical-oxidation of methyl linoleate in solution was examined by measuring the production of methyl linoleate hydroperoxides. Canthaxanthin and astaxanthin which possess oxo groups at the 4 and 4'-positions in the beta-ionone ring retarded the hydroperoxide formation more efficiently than beta-carotene ...

That 13-carotene can serve as a precursor of vitamin A in mammals was demonstrated almost 40 years ago." 2 In spite of innumerable nutritional and chemical studies on this reaction, however, neither the pathway nor the mechanism of vitamin A formation has been clarified.3-5 With respect to the pathway of vitamin A formation, two major hypotheses have been suggested: (1) carotene is cleaved at t...

A high plasma carotenoid concentration could improve the immune response and result in decreased risk of infectious diseases. However, data on the relationship of plasma carotenoid concentration with acute respiratory infections, which occur frequently in elderly people, are scarce. We investigated, therefore, the relationship of plasma concentrations of six major carotenoids (beta-carotene, al...

BACKGROUND Nitrogen starvation and limitation are known to induce important physiological changes especially in lipid metabolism of microalgae (triglycerides, membrane lipids, beta-carotene, etc.). Although little information is available for Dunaliella salina, it is a promising microalga for biofuel production and biotechnological applications due to its ability to accumulate lipid together wi...

Recent interest in /3-carotene has been stimulated by reports that reproductive performance in cattle was improved with dietary supplementation of /3-carotene even when the diet was supplemented with vitamin A. Vitamin A requirements for cattle are based on studies with /3carotene as the vitamin A source and with studies with vitamin A in the ester or alcohol form. Most of the studies with catt...

To determine the effect of physical activity on serum beta-carotene, we analyzed data about life styles including 3-day food records and blood samples collected from 57 men and 74 women in a rural city of Japan. Physical activity was asked as mean frequency of hard physical activities per week last year. A declining trend in serum beta-carotene was observed with increasing frequency of hard phy...

BACKGROUND Oxidative stress contributes to brain aging. Antioxidant treatment, especially over the long term, might confer cognitive benefits. METHODS We added cognitive testing to the Physicians' Health Study II (PHSII), a randomized trial of beta carotene and other vitamin supplements for chronic disease prevention. The PHSII is a continuation of the Physicians' Health Study (PHS), which ha...

The demosponge Suberites domuncula has been described to contain high levels of a proteinaceous toxin, Suberitine, that displays haemolytic activityIn the present study this 7-8 kDa polypeptide has been isolated and was shown to exhibit also cytotoxic effects on cells of the same species. Addition of retinal, a recently identified metabolite of β-carotene that is abundantly present in S. domunc...

Experimental and epidemiological evidence supports the hypothesis that oxidation of low density lipoprotein (LDL) appears to be important in mediating the atherogenicity of LDL. To test this hypothesis in humans, it will be necessary to perform intervention studies in large populations. We performed two studies to assess the effectiveness of supplementation with beta-carotene and vitamin E, use...

Patients with the acquired immunodeficiency syndrome (AIDS) are characterized by a decrease in the number of T helper cells, a defect that is linked to the impaired immunologic competence. Vitamin A and its dietary precursor, beta-carotene, increase absolute T helper cell counts as well as indices of T cell function in both human and animal models. To determine if short-term beta-carotene treat...