Astaxanthin Delivery Systems for Skin Application: A Review.

Astaxanthin (AST) is a biomolecule known for its powerful antioxidant effect, which is considered of great importance in biochemical research and has great potential for application in cosmetics, as well as food products that are beneficial to human health and medicines. Unfortunately, its poor solubility in water, chemical instability, and low oral bioavailability make its applications in the cosmetic and pharmaceutical field a major challenge for the development of new products. To favor the search for alternatives to enhance and make possible the use of AST in formulations, this article aimed to review the scientific data on its application in delivery systems. The search was made in databases without time restriction, using keywords such as astaxanthin, delivery systems, skin, cosmetic, topical, and dermal. All delivery systems found, such as liposomes, particulate systems, inclusion complexes, emulsions, and films, presented peculiar advantages able to enhance AST properties, among which are stability, antioxidant potential, biological activities, and drug release. This survey showed that further studies are needed for the industrial development of new AST-containing cosmetics and topical formulations.

Adsorption of inorganic mercury from aqueous solutions onto dry biomass of Chlorella vulgaris: kinetic and isotherm study.

This study focused on kinetics and equilibrium isotherms of mercury biosorption from water using dry biomass of Chlorella vulgaris as biosorbent at pH 5.0. Biosorption tests were performed at 2.0 g/L biomass dosage varying initial Hg concentration from 11.0 to 90.6 mg/L. The Lagergren equation was found to best describe the process, with R2 of 0.984 and specific rate constant of 0.029 ± 0.004 min-1. Although equilibrium data were well fitted by the Dubinin and Radushkevich isotherm (R2 = 0.870; qDR = 16.6 mg/g), important insights on phenomenological events occurring at equilibrium were concurrently provided by the Lamgmuir one (R2 = 0.826; q0 = 32.6 mg/g; KL = 0.059 L/mg). FT-IR analysis confirmed that Hg biosorption took place via physisorption. Since C. vulgaris is a fresh-water microalga that can be easily cultivated anywhere, these promising results suggest its possible use as an effective, low-cost biosorbent to treat industrial effluents contaminated by this metal.

Effects of pH on chromate(VI) adsorption by Spirulina platensis biomass: batch tests and FT-IR studies.

Raw and methylated biomass of Spirulina platensis was employed in chromate batch adsorption tests at pH range 1-7. The acid conditions seemed to favour the removal of chromium (Cr) with a yield of 87.0 and 97.6% by using raw and methylated biomass, respectively. However, the chromate and total chromium determination, carried out in the same sample, evidenced that a fraction of the initial chromate present in solution was reduced to Cr(III). This was ascribed to the presence of reducing groups on the biomass surface, active in the acid medium. The data showed that the methylated biomass was able to operate an effective Cr(VI) removal only. In fact, the biomass treatment allowed a lowering of the amount of negative functional groups, making the biomass surface available to bind the anions. The real best efficiency of Cr(VI) removal (83.5%) was obtained by methylated biomass of S. platensis at pH about 7.0. The nature of the biomass/chromate interactions was investigated by Fourier transform infrared spectroscopy (FT-IR) analysis. The bands ascribing to the adsorbed Cr(VI) species were well evident in the spectra of the biomass after adsorption, confirming this experimental finding.

Effect of extracts from Spirulina platensis bioaccumulating cadmium and zinc on L929 cells.

The uptake of cadmium and zinc by Spirulina platensis was investigated using a laboratory culture of this cyanobacterium. The cells were treated with metal concentrations increasing from 0.5 to 2.0 mg L(-1), in order to evaluate their adsorption capacity and survival potential. Afterwards, the cytotoxicity of cell extracts bioaccumulating heavy metals was evaluated on cultured L929 mouse fibroblasts. Cadmium was removed with higher yield (84.0-88.7%) than zinc (54.5-68.0%) and the maximum specific removal of these metals was 1.82 and 2.60 mg g(-1), respectively. Cadmium bioaccumulating algal extracts caused higher cell mortality of L929 cells than zinc accumulating ones, with a clear dose-response trend. EC(50) estimated by Trimmed Spearman-Karber (TSK) method were 7.21 and 9.59cells mL(-1) for cadmium and zinc, respectively. The capability to accumulate heavy metals could have a remarkable importance for the utilization of algal species in human or animal feeding.

Removal of exhausted oils by adsorption on mixed Ca and Mg oxides.

Adsorption tests were performed on two different exhausted oils to reduce their polluting and health hazard potential: a "water-insoluble oil", utilised for automotive engine lubrication, and an "emulsified" oil, used as coolant for metal-cutting tools. Dolomite, a low-cost recovery material, was used to prepare two effective adsorbents: (a) a mixed Ca and Mg oxide obtained by thermal decomposition of dolomite at 1800 degrees C, and (b) an activated material obtained by submitting this product to chemical treatment with HCl. Preliminary tests carried out with an excess of the former material showed that the insoluble oil was adsorbed with lower yield (Y = 0.40) than the soluble (emulsified) oil (Y = 0.60). The material activation with HCl remarkably improved the adsorption of soluble oil organic fraction (Y > 0.90), while only a little increase in the removal yield was observed for the insoluble oil (Y = 0.44). The results presented and discussed in this work pointed out that the products of dolomite calcination can successfully replace the conventional adsorbing materials in the removal of organic pollutants, with particular concern to exhausted soluble oils, which cannot usually be recycled, thus reducing the operational costs of their treatment.