Preparation and characterization of astaxanthin-loaded microcapsules stabilized by lecithin-chitosan-alginate interfaces with layer-by-layer assembly method

Astaxanthin is a kind of keto-carotenes with various health benefits. However, its solubility and chemical stability are poor, which leads to low bio-availability. Microcapsules have been reported to improve the solubility, chemical stability, and bio-availability of lipophilic bioactives. Freeze-dried astaxanthin-loaded microcapsules were prepared by layer-by-layer assembly of tertiary emulsions with maltodextrin as the filling matrix. Tertiary emulsions were fabricated by performing chitosan and sodium alginate electrostatic deposition onto soybean lecithin stabilized emulsions. 0.9 wt% of chitosan solution, 0.3 wt% of sodium alginate solution and 20 wt% of maltodextrin were optimized as the suitable concentrations. The prepared microcapsules were powders with irregular blocky structures. The astaxanthin loading was 0.56 ± 0.05 % and the encapsulation efficiency was >90 %. A slow release of astaxanthin could be observed in microcapsules promoted by the modulating of chitosan, alginate and maltodextrin. In vitro simulated digestion displayed that the microcapsules increased the bio-accessibility of astaxanthin to 69 ± 1 %. Chitosan, alginate and maltodextrin can control the digestion of microcapsules. The coating of chitosan and sodium alginate, and the filling of maltodextrin in microcapsules improved the chemical stability of astaxanthin. The constructed microcapsules were valuable to enrich scientific knowledge about improving the application of functional ingredients.

Supersaturable Solid Self-microemulsifying Delivery Systems of Astaxanthin via Spray Drying: Effects of Polymers and Solid Carriers

This study aimed to develop the solid astaxanthin-encapsulated self-microemulsifying delivery system (S-AST SMEDS) spray-dried particles and investigate the effect of materials in formulations on product characteristics. The optimized liquid AST SMEDS incorporated with a polymeric precipitation inhibitor (PI) was solidified with a solid carrier by spray drying. Physicochemical properties of S-AST SMEDS spray-dried powders including morphology, particle size and distribution, flowability, solid-state characters, moisture content, yield, loading capacity of AST, and reconstitution properties were examined. Polymeric PIs seemed to have an impact on particles' size, surface smoothness, and flowability while solid carriers had an effect on the particles' moisture content and droplet size of microemulsions obtained after reconstitution. The amount of AST encapsulated in S-SMEDS powder was influenced by both polymer and solid carriers. Dissolution and short-term stability of S-AST SMEDS were also studied. Our developed spray-dried solid SMEDS particles helped enhance AST dissolution rate.

Production, physicochemical investigations, antioxidant effect, and cellular uptake in Caco-2 cells of the supersaturable astaxanthin self-microemulsifying tablets

The purpose of this study was to develop astaxanthin (AST)-loaded self-microemulsifying drug delivery system (SMEDDS) tablets and evaluate their physicochemical and biological properties. The optimized liquid (L)-AST SMEDDS formulation was composed of rice bran oil (33.67%), Kolliphor® RH 40 (34.70%), and Span® 20 (31.63%). Two types of hydrophilic polymers (hydroxypropyl methylcellulose, HPMC, and polyvinyl alcohol, PVA) solutions were selected as a precipitation inhibitor for AST and incorporated into L-AST SMEDDS to obtain supersaturation and enhance dissolution of AST. The formulation was then mixed with microcrystalline cellulose and subsequently transformed to solid S-AST SMEDDS particles using a spray dryer prior to direct compression into tablets. The HPMC AST SMEDDS tablet and PVA AST SMEDDS tablet were characterized for their physicochemical properties, dissolution, AST release, and stabilities. Moreover, the cellular uptake and antioxidant effect of AST SMEDDS tablets were evaluated in Caco-2 cells. With good tablet characters, both HPMC AST SMEDDS tablet and PVA AST SMEDDS tablet dissolution profiles were improved compared to that of raw AST. While initially less than 50% of AST released from HPMC AST SMEDDS tablet and PVA AST SMEDDS tablet in pH 1.2 medium, after 6 h more than 98% of AST releases in pH 6.8 were achieved which was similar to L-AST SMEDDS profile. Cellular antioxidant activities of L-AST SMEDDS and HPMC AST SMEDDS tablet & PVA AST SMEDDS tablet were significantly greater than pure AST powder. HPMC AST SMEDDS tablet showed better uptake and deeper penetration through Caco-2 cells than that in PVA AST SMEDDS tablet and pure powder. Our successfully developed AST SMEDDS tablets were demonstrated to be a potential platform to deliver highly lipophilic AST and improve permeation and bioavailability.

Comparison of bioaccessibility of astaxanthin encapsulated in starch-based double emulsion with different structures

In this study, different types of starch-based double emulsion (SDE) structures were developed to improve the bioavailability of astaxanthin (AST). Droplet size, microstructure, zeta potential of the AST-loaded SDEs were measured during in vitro digestion model. Compared with the C-type SDEs prepared with high amylose starch (HAS), the AST-loaded SDEs prepared using native corn starch of 5 wt% (B-type structure) and 7 wt% (A-type structure) presented small mean droplet diameters (MA = 11.18 ± 0.40 μm and 8.23 ± 0.37 μm, respectively) and were more stable after simulated gastric digestion. Furthermore, the lipid digestion products (free fatty acids) were studied after simulated intestinal digestion. Interestingly, the bioaccessibility (57.54 ± 1.88%) of AST-loaded SDEs prepared by HAS was six times higher than that of digested unencapsulated AST. Thus, SDEs were found to be suitable carriers for liposoluble nutrient delivery and bioavailability in foods, beverages, and nutraceuticals.

Calcitriol tablets with hybrid lipid-based solid dispersions with enhanced stability and content uniformity

Calcitriol, as the biologically active form of vitamin D3, is essential for patients with renal osteopathy. The solubilization, stabilization, and content uniformity are key issues in its formulation development. In our previous study, the incomplete release of calcitriol was solved by using the hybrid lipid-based solid dispersion (SD) for calcitriol. However, good stability and content uniformity are still urgently needed. In this study, solid lipid with antioxidant properties and liquid lipid compatible with calcitriol were employed as hybrid lipid carrier (HLC) to establish a solid dispersion. Moreover, the content uniformity of tablets with hybrid lipid carrier based SDs (HLCTs) was further guaranteed due to the multi-dispersion of calcitriol in HLC, solidification, and blank granules. Additionally, the compression of the blank granules was adjusted by the water content. The mixing method of calcitriol-containing and blank granules was also optimized. The obtained HLCTs were evaluated for hardness, disintegration time, in vitro drug dissolution, content uniformity, and stability. Satisfactory HLCTs were developed successfully in this study with superior content uniformity and better stability than the commercial soft capsule (Rocaltrol®). It was proved to be a promising formulation for drugs with poor water-solubility, instability to oxygen and heat, and dose-related toxicity.

Optimization and characterization of poly(lactic-co-glycolic acid) nanoparticles loaded with astaxanthin and evaluation of anti-photodamage effect in vitro

Astaxanthin is a xanthophyll carotenoid with high beneficial biological activities, such as antioxidant function and scavenging oxygen free radicals, but its application is limited because of poor water solubility and low bioavailability. Here, we prepared and optimized poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with astaxanthin using the emulsion solvent evaporation technique and investigated the anti-photodamage effect in HaCaT cells. The four-factor three-stage Box-Behnken design was used to optimize the nanoparticle formulation. The experimental determination of the optimal nanoparticle size was 154.4 ± 0.35 nm, the zeta potential was 22.07 ± 0.93 mV, encapsulation efficiency was 96.42 ± 0.73% and drug loading capacity was 7.19 ± 0.12%. The physico-chemical properties of the optimized nanoparticles were characterized by dynamic light scattering, scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and thermo-gravimetric analyser. In vitro study exhibited the excellent cell viability and cellular uptake of optimized nanoparticles on HaCaT cells. The anti-photodamage studies (cytotoxicity assay, reactive oxygen species content and JC-1 assessment) demonstrated that the optimized nanoparticles were more effective and safer than pure astaxanthin in HaCaT cells. These results suggest that our PLGA-coated astaxanthin nanoparticles synthesis method was highly feasible and can be used in cosmetics or the treatment of skin diseases.