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Self-nanoemulsifying drug delivery systems (SNEDDS) represent an interesting platform for improving the oral bioavailability of poorly soluble lipophilic drugs. While Liquid-SNEDDS (L-SNEDDS) effectively solubilize the drug in vivo, they have several drawbacks, including poor storage stability. Solid-SNEDDS (S-SNEDDS) combine the advantages of L-SNEDDS with those of solid dosage forms, particularly stability. The aim of the present study was to convert celecoxib L-SNEDDS into S-SNEDDS without altering their release behavior. Various commercially available adsorptive carrier materials were investigated, as well as novel cellulose-based microparticles prepared by spray drying from an aqueous dispersion containing Diacel® 10 and methyl cellulose or gum arabic as a binder prior to their use. Particle size and morphology of the carrier materials were screened by scanning electron microscopy and their effects on the loading capacity for L-SNEDDS were investigated, and comparative in vitro dissolution studies of celecoxib L-SNEDDS and the different S-SNEDDS were performed immediately after preparation and after 3 months of storage. Among the adsorptive carrier materials, the novel cellulose-based microparticles were found to be the most suitable for the preparation of celecoxib S-SNEDDS from L-SNEDDS, enabling the preparation of a solid, stable formulation while preserving the in vitro release performance of the L-SNEDDS formulation.
Target proteins in biotechnological applications are highly diverse. Therefore, versatile flexible expression systems for their functional overproduction are required. In order to find the right heterologous gene expression strategy, suitable host-vector systems, which combine different genetic circuits, are useful. In this study, we designed a novel Bacillus subtilis expression toolbox, which allows the overproduction and secretion of potentially toxic enzymes. This toolbox comprises a set of 60 expression vectors, which combine two promoter variants, four strong secretion signals, a translation-enhancing downstream box, and three plasmid backbones. This B. subtilis toolbox is based on a tailor-made, clean deletion mutant strain, which is protease and sporulation deficient and exhibits reduced autolysis and secondary metabolism. The appropriateness of this alternative expression platform was tested for the overproduction of two difficult-to-produce eukaryotic model proteins. These included the sulfhydryl oxidase Sox from Saccharomyces cerevisiae, which forms reactive hydrogen peroxide and undesired cross-linking of functional proteins, and the human interleukin-1β, a pro-inflammatory cytokine. For the best performing Sox and interleukin, overproducing and secreting variants of these new B. subtilis toolbox fermentation strategies were developed and tested. This study demonstrates the suitability of the prokaryotic B. subtilis host-vector system for the extracellular production of two eukaryotic proteins with biotechnological relevance.
Purpose
Mixing with liquids or soft foods is a common procedure to improve acceptability of oral medicines in children but may affect drug stability and the in vivo performance of the administered drug product. The aim of the present study was to obtain an overview of the variability of critical attributes of commonly used vehicles and to identify which vehicle characteristics need to be considered when developing in vitro methods for evaluating product quality.
Methods
One product of each vehicle listed in the FDA draft guidance “Use of Liquids and/or Soft Foods as Vehicles for Drug Administration” was analyzed with regard to composition, calorific content and physicochemical properties.
Results
The studied vehicles show wide variability, both in composition and physicochemical properties. No correlation was observed between vehicle composition and physicochemical properties. Comparison of results of the present study with previously published data also provided variability in physicochemical properties within individual vehicle types.
Conclusions
To identify acceptable (qualified) vehicles for global drug product labeling, it is important that the vehicles selected for in vitro compatibility screening reflect the variability in composition and essential physicochemical properties of the vehicles recommended on the product label, rather than relying on results obtained with a single vehicle of each type. Future activities will focus on the development of standardized dosing vehicles that can represent key vehicle characteristics in all their variability to ensure reliable risk assessment.
The polysaccharide β-mannan, which is common in terrestrial plants but unknown in microalgae, was recently detected during diatom blooms. We identified a β-mannan polysaccharide utilization locus (PUL) in the genome of the marine flavobacterium Muricauda sp. MAR_2010_75. Proteomics showed β-mannan induced translation of 22 proteins encoded within the PUL. Biochemical and structural analyses deduced the enzymatic cascade for β-mannan utilization. A conserved GH26 β-mannanase with endo-activity depolymerized the β-mannan. Consistent with the biochemistry, X-ray crystallography showed the typical TIM-barrel fold of related enzymes found in terrestrial β-mannan degraders. Structural and biochemical analyses of a second GH26 allowed the prediction of an exo-activity on shorter manno-gluco oligosaccharides. Further analysis demonstrated exo-α-1,6-galactosidase- and endo-β-1,4-glucanase activity of the PUL-encoded GH27 and GH5_26, respectively, indicating the target substrate is a galactoglucomannan. Epitope deletion assays with mannanases as analytic tools indicate the presence of β-mannan in the diatoms Coscinodiscus wailesii and Chaetoceros affinis. Mannanases from the PUL were active on diatom β-mannan and polysaccharide extracts sampled during a microalgal bloom at the North Sea. Together these results demonstrate that marine microorganisms use a conserved enzymatic cascade to degrade β-mannans of marine and terrestrial origin and that this metabolic pathway plays a role in marine carbon cycling.