A Method of Solubilizing and Concentrating Astaxanthin and Other Carotenoids

Anticancer Activity of Astaxanthin-Incorporated Chitosan Nanoparticles

Astaxanthin (AST)-encapsulated nanoparticles were fabricated using glycol chitosan (Chito) through electrostatic interaction (abbreviated as ChitoAST) to solve the aqueous solubility of astaxanthin and improve its biological activity. AST was dissolved in organic solvents and then mixed with chitosan solution, followed by a dialysis procedure. All formulations of ChitoAST nanoparticles showed small diameters (less than 400 nm) with monomodal distributions. Analysis with Fourier transform infrared (FT-IR) spectroscopy confirmed the specific peaks of AST and Chito. Furthermore, ChitoAST nanoparticles were formed through electrostatic interactions between Chito and AST. In addition, ChitoAST nanoparticles showed superior antioxidant activity, as good as AST itself; the half maximal radical scavenging concentrations (RC50) of AST and ChitoAST nanoparticles were 11.8 and 29.3 µg/mL, respectively. In vitro, AST and ChitoAST nanoparticles at 10 and 20 µg/mL properly inhibited the production of intracellular reactive oxygen species (ROSs), nitric oxide (NO), and inducible nitric oxide synthase (iNOS). ChitoAST nanoparticles had no significant cytotoxicity against RAW264.7 cells or B16F10 melanoma cells, whereas AST and ChitoAST nanoparticles inhibited the growth of cancer cells. Furthermore, AST itself and ChitoAST nanoparticles (20 µg/mL) efficiently inhibited the migration of cancer cells in a wound healing assay. An in vivo study using mice and a pulmonary metastasis model showed that ChitoAST nanoparticles were efficiently delivered to a lung with B16F10 cell metastasis; i.e., fluorescence intensity in the lung was significantly higher than in other organs. We suggest that ChitoAST nanoparticles are promising candidates for antioxidative and anticancer therapies of B16F10 cells.

Effects of including of Japanese Pumpkin Seeds and Pomace in the Diets of Pacific White Shrimp (Penaeus vannamei)

A 60-day feeding trial was conducted to evaluate the effects of including pumpkin seeds and pomace in the diets of Pacific white shrimp Penaeus vannamei, and the effects of these supplements on growth performance, body composition, and total polyphenol, flavonoid and carotenoid contents, as well as on total antioxidant activity, and body color parameters. Five diets were evaluated: pumpkin seeds (PS) at 50 and 100 g·kg-1, pumpkin pomace (PP) at 50 and 100 g·kg-1, and a control treatment. Pacific white shrimp (P. vannamei) juveniles (0.60 ± 0.01 g) were stocked in 15 tanks (310 L), containing 30 shrimps per tank, and the treatments were randomly distributed in triplicate. At the end of the experiment, shrimps were euthanized, weighed, and dissected for further analyses. The inclusion of PS in the diets impaired growth performance, reduced the total flavonoid content and had a pro-oxidative effect on muscle. The inclusion of PP in the diets did not affect growth performance, improved the feed conversion ratio, increased the total flavonoid content in the diets and hepatopancreas, and improved the antioxidant activity of the feeds and shrimp muscle. The total carotenoid content of the feeds increased with the inclusion of PS or PP in the diets; however, the total carotenoid content of shrimp increased only in those fed PP diets. Shrimp fed with PS diets showed a yellowish color and higher saturation when fresh and a reddish color and yellow hue angle after cooking. Shrimp fed PP diets turned reddish and yellowish, both when fresh and after cooking. The inclusion of PS in P. vannamei diets is not recommended; however, PP can be included at 100 g·kg-1 without affecting the growth parameters. Further studies evaluating the inclusion of higher PP levels in shrimp diets are recommended.

Silkworm carotenoprotein as an efficient carotenoid extractor, solubilizer and transporter

Found in many organisms, water-soluble carotenoproteins are prospective antioxidant nanocarriers for biomedical applications. Yet, the toolkit of characterized carotenoproteins is rather limited: such proteins are either too specific binders of only few different carotenoids, or their ability to transfer carotenoids to various acceptor systems is unknown. Here, by focusing on a recently characterized recombinant ~27-kDa Carotenoid-Binding Protein from Bombyx mori (BmCBP) [Slonimskiy et al., International Journal of Biological Macromolecules 214 (2022): 664-671], we analyze its carotenoid-binding repertoire and potential as a carotenoid delivery module. We show that BmCBP forms productive complexes with both hydroxyl- and ketocarotenoids - lutein, zeaxanthin, astaxanthin, canthaxanthin and a smaller antioxidant, aporhodoxanthinone, but not with β-carotene or retinal, which defines its broad ligand specificity toward xanthophylls valuable to human health. Moreover, the His-tagged BmCBP apoform is capable of cost-efficient and scalable enrichment of xanthophylls from various crude methanolic herbal extracts. Upon carotenoid binding, BmCBP remains monomeric and shows a remarkable ability to dynamically shuttle carotenoids to biological membrane models and to unrelated carotenoproteins, which in particular makes from the cyanobacterial Orange Carotenoid Protein a blue-light controlled photoswitch. Furthermore, administration of BmCBP loaded by zeaxanthin stimulates fibroblast growth, which is attractive for cell- and tissue-based assays.

1Progress, applications, challenges and prospects of protein purification technology

Protein is one of the most important biological macromolecules in life, which plays a vital role in cell growth, development, movement, heredity, reproduction and other life activities. High quality isolation and purification is an essential step in the study of the structure and function of target proteins. Therefore, the development of protein purification technologies has great theoretical and practical significance in exploring the laws of life activities and guiding production practice. Up to now, there is no forthcoming method to extract any proteins from a complex system, and the field of protein purification still faces significant opportunities and challenges. Conventional protein purification generally includes three steps: pretreatment, rough fractionation, and fine fractionation. Each of the steps will significantly affect the purity, yield and the activity of target proteins. The present review focuses on the principle and process of protein purification, recent advances, and the applications of these technologies in the life and health industry as well as their far-reaching impact, so as to promote the research of protein structure and function, drug development and precision medicine, and bring new insights to researchers in related fields.