In vivo and in vitro effects of beta-carotene and algae extracts in murine tumor models

[Spirulina, exercise and serum glucose control in diabetic rats]

OBJECTIVE

The objective of this study was to analyze the effect of Spirulina and/or exercise training in the control of serum glucose homeostasis in diabetic rats.

MATERIALS AND METHODS

Young Wistar rats were induced to diabetes by intravenous alloxan administration and separated into four groups: diabetic control (DC), diabetic Spirulina (DS), diabetic exercise (DE) and diabetic exercise Spirulina (DES).

RESULTS

There were no differences between groups with respect to: body weight, food intake, glucose tolerance, insulin tolerance and blood lactate concentrations during a swimming effort test. DS group showed lower insulin concentrations when compared with DC (pancreas) and DE and DES (serum).

CONCLUSION

The protocols of exercise and supplementation with Spirulina used in the present study were not able to improve serum glucose homeostasis in diabetic rats.

Synergistic effects of some pairs of antioxidants and related agents on mouse leukaemia L5178Y cell growth in-vitro

The effects of simultaneous administration of some dyadic combinations of antioxidants or vitamins and related agents on cellular proliferation of mouse leukaemia L5178Y cells in-vitro have been examined experimentally. The data were analysed on the basis of the concept of independence for evaluation of interactions between biologically active agents. An approach for evaluation of the synergism or antagonism of the action of two agents is proposed in which the types and extents of interactions are described by response-surface diagrams. The combinations phytol with trans-retinol, abscisic acid with trans-retinol, and menadione with sodium L-ascorbate were synergistic, whereas menadione with trans-retinol, and plumbagin with trans-retinol were antagonistic in the dose-range tested. These results reveal that the interactions between two agents depend not only on the combinations of agents but also on the dose ranges or the ratios of agents under the experimental domain studied.

Studies of immunomodulating actions of carotenoids. I. Effects of beta-carotene and astaxanthin on murine lymphocyte functions and cell surface marker expression in in vitro culture system

The immunomodulating effects of carotenoids (beta-carotene and astaxanthin) on mouse lymphocytes were studied in in vitro culture system by use of assay for mitogen responses of spleen cells, thymocyte proliferation, interleukin 2 production, and antibody (Ab) production in vitro in response to sheep red blood cells. Changes of cell surface markers on spleen lymphocytes including Ia antigen (Ag), surface immunoglobulin, B220, and Thy-1 Ag were also examined. At a concentration of 10(-8) M, carotenoids did not show any significant effect on mitogen responses (phytohemagglutinin P and concanavalin A) on murine spleen cells, irrespective of the concentrations of mitogens used. Interleukin 2 production by murine spleen cells was not significantly altered by carotenoids in the culture media (10(-7) to 10(-9) M). [3H]thymidine incorporation by B6 thymocytes was somewhat enhanced in the presence of astaxanthin or beta-carotene when cultured in the concentration of 10(6)/ml. At higher concentrations of cells (5 x 10(6)/ml), such an effect was not observed. In assays of in vitro Ab production in response to sheep red blood cells, B6 spleen cells produced significantly more Ab-forming cells (plaque-forming cells, immunoglobulins M and G) in the presence of astaxanthin (greater than 10(-8) M) but not beta-carotene. Expression of Ia Ag seemed to be moderately enhanced on both Thy-1+ and Thy-1- spleen cells in the presence of astaxanthin (greater than 10(-9) M) but not beta-carotene. The expression of Thy-1 and surface immunoglobulin seemed unchanged with the treatment of these carotenoids. These results indicate that immunomodulating actions of carotenoids are not necessarily related to provitamin A activity, because astaxanthin, which does not have provitamin A activity, showed more significant effects in these bioassays and also indicate that such actions of carotenoid demonstrated in this study may be difficult to explain only by its oxygen-quenching capacity.

Microalgae as food and supplement

The microalgae Chlorella spp., Dunaliella spp., and Scenedesmus spp., and the cyanobacteria Spirulina spp., and Aphanizomenon flos-aquae, are being used as nutrient-dense foods and sources of fine chemicals. They have significant amounts of lipid, protein, chlorophyll, carotenoids, vitamins, minerals, and unique pigments. They may also have potent probiotic compounds that enhance health. Their historical and current use are reviewed in this article.