Gastrointestinal Release Research Articles

Synthesis and properties of core-shell thymol-loaded zein/shellac nanoparticles by coaxial electrospray as edible coatings

In this study, a coaxial electrospray process was used to produce nanoparticles, in which thymol was encapsulated in a core–shell of zein and shellac. We then investigated fluid velocity and solution concentrations on the electrospray. Scanning electron microscopy revealed that the thymol/zein/shellac particles prepared at a flow rate ratio of 0.6:0.3 mL/h were rounder with smaller diameters. The highest encapsulation efficiency of thymol was 81.34%, the average particle size was 606.53 nm, and the retention rate of thymol was 68.74% after 30 days. Moreover, we investigated the thermal stability, antimicrobial activity, and simulated gastrointestinal release curves of the nanoparticles. Finally, the nanoparticles were used as a coating for fresh-cut cantaloupe. Compared with the blank nanoparticle control group, the coating significantly extended the shelf life of cantaloupe to 16 days. Our results indicate that these nanoparticles have great potential for application in food preservation.

Protection and Controlled Gastrointestinal Release of Bromelain by Encapsulating in Pectin-Resistant Starch Based Hydrogel Beads.

Hybrid pectin and resistant starch–based hydrogel beads loaded with bromelain using the extrusion gelation method were prepared and evaluated to enhance the activity of bromelain during gastrointestinal passage and thermal processing. The solutions of pectin–resistant starch with bromelain were dropped into the gelation bath containing calcium chloride (0.2 M) solution to develop various types of hydrogel beads. The physicochemical characteristics of the synthesized hydrogel beads were evaluated. The ratio (4.5:1.5 w/w) of pectin and resistant starch concentration significantly (p < 0.05) enhanced the encapsulation efficiency (80.53%). The presence of resistant starch resulted in increased entrapment of bromelain, improved swelling properties with sustained release behavior, and improved gastric stability than pectin hydrogels alone. The swelling of hydrogel beads was higher at pH 7.4 than pH 1.2. Optimized batch of hybrid pectin/resistant starch exhibited a spherical shape. Optical and scanning electron microscopy showed a more packed and spherical shape from the pectin/resistant starch hydrogel bead network. Fourier transformation infrared spectroscopy was also used to confirm the presence of bromelain in the hydrogel beads. The encapsulated bromelain in the pectin/hi-maize starch beads produced at a pectin/hi-maize ratio of 4.5:1.5 (percent w/w; formulation P4) obtained the highest relative bromelain activity in all heat treatments including at 95°C, whereas the highest activity of free bromelain was found only at 30°C. Bromelain encapsulated in hydrogels released at a faster rate at simulated intestinal fluid (SIF, pH 7.4) than at simulated gastrointestinal fluid (SGF, pH 1.2).

Dual-modified starch nanospheres encapsulated with curcumin by self-assembly: Structure, physicochemical properties and anti-inflammatory activity

Pullulanase debranching and subsequent hydroxypropylation were applied to prepare a series of dual-modified starches (Hydroxypropylated debranched starch, HPDS) with different degrees of hydroxypropyl substitution. Their structural and physicochemical properties varied with the degree of hydroxypropyl substitution, and all HPDS exhibited the ability to self-assemble into well-shaped nanospheres (100–150 nm, PDI < 0.2). These HPDS nanospheres were attempted to encapsulate curcumin with the aim of improving the bioavailability, solubility and stability of curcumin. Their structural characteristics, thermal stability, iodine staining, morphology, safety, encapsulation efficiency, in vitro gastrointestinal release behavior, and anti-inflammatory activity were evaluated. The results showed that curcumin could be effectively encapsulated into the HPDS nanospheres, and the encapsulation efficiency, water solubility and physical stability were positively correlated with the degree of hydroxypropyl substitution. After encapsulation, the water solubility and physical stability of curcumin could be increased up to 226-fold and 6-fold, respectively. The HPDS nanospheres also exhibited good safety (including hemolysis and cytotoxicity) and sustainable release of curcumin. Evaluation of anti-inflammatory activity showed that the activity of curcumin-encapsulated HPDS was enhanced by 170% compared to unencapsulated curcumin. These suggest that HPDS nanospheres encapsulation may be a more suitable option for the development of functional foods containing bioactive compounds.

Influence of Cooking Methods on Onion Phenolic Compounds Bioaccessibility.

The impact of domestic cooking (baking, boiling, frying and grilling) and in vitro digestion on the stability and release of phenolic compounds from yellow-skinned (YSO) and red-skinned onions (RSO) have been evaluated. The mass spectrometry identification pointed out flavonols as the most representative phenolic class, led by quercetin-derivatives. RSO contained almost the double amount of phenolic compounds respect to YSO (50.12 and 27.42 mg/100 g, respectively). Baking, grilling and primarily frying resulted in an increased amount of total phenolic compounds, especially quercetin-derivatives, in both the onion varieties. Some treatments promoted the degradation of quercetin-3-O-hexoside-4′-O-hexoside, the main compound present in both the onion varieties, leading to the occurrence of quercetin-4′-O-hexoside and protocatechuic acid-4-O-hexoside. After in vitro digestion, the bioaccessibility index for total phenolic compounds ranged between 42.6% and 65.5% in grilled and baked YSO, respectively, and between 39.8% and 80.2% in boiled and baked RSO, respectively. Baking contributed to the highest amount of bioaccessible phenolic compounds for both the onion varieties after in vitro digestion. An in-depth design of the cooking process may be of paramount importance in modulating the gastro-intestinal release of onion phenolic compounds.

Curcumin-loaded core-shell biopolymer nanoparticles produced by the pH-driven method: Physicochemical and release properties

In this study, core-shell biopolymer nanoparticles were fabricated for the encapsulation and delivery of curcumin using a pH-driven method. The influences of the coating composition on the physicochemical properties and curcumin release characteristics of the core-shell nanoparticles were studied. Fourier transform infrared spectroscopy and X-ray diffraction analyses indicated that curcumin was encapsulated in an amorphous state inside the nanoparticles. Particle size and ζ-potential measurements indicated that the biopolymer nanoparticles were relatively stable under different environmental conditions: long term storage, heating, pH changes and salt. The DPPH radical scavenging activity of the curcumin was increased after encapsulation within the nanoparticles, whereas the gastrointestinal release of curcumin was prolonged. These results were attributed to the ability of alginate and NaCas to form a thick layer around the nanoparticles, which increased the steric and electrostatic repulsion between them, as well as inhibiting the release of curcumin.

Nanoencapsulation of vitamin D3 and fortification in an experimental jelly model of Acca sellowiana: Bioaccessibility in a simulated gastrointestinal system

In this study, Vitamin D3 (D3) was nanoencapsulated (NP-D3) in zein polymeric matrices to improve its physicochemical stability and availability. An experimental jelly model produced with Acca sellowiana was fortified with NP-D3 to demonstrate its suitability for food fortification. The nanocapsules presented a high encapsulation efficiency of D3 (97.21 ± 1.87%) with a particle size smaller than 200 nm. The morphological structure showed particles with homogeneous populations, spherical shape, and smooth surfaces. In addition, positive physicochemical stability was obtained under storage, with a low polydispersity index (<0.2) and electrophoretic stability of the zeta potential (24.5 ± 1.60 mV). DSC demonstrated that NP-D3 is thermally stable, which allows its application in processed foods. The jelly fortified with NP-D3 presented a high content of bioactive compounds (phenolic and flavonoids) with antioxidant capacity. The fortified jelly was microbiologically stable for 90 days, indicating a suitable shelf life. Under the gastrointestinal release simulations, NP-D3 demonstrated an 80% release, with similar behavior when incorporated into the jelly, showing peak release in the duodenum step. Therefore, zein nanoparticles can be a promising approach to prolong the residence time of Vitamin D3 when subjected to food processing and gastrointestinal conditions.

Comparing microfluidics and ultrasonication as formulation methods for developing hempseed oil nanoemulsions for oral delivery applications

Emerging formulation technologies aimed to produce nanoemulsions with improved characteristics, such as stability are attractive endeavors; however, comparisons between competing technologies are lacking. In this study, two formulation techniques that employed ultrasound and microfluidic approaches, respectively, were examined for relative capacity to produce serviceable oil in water nanoemulsions, based on hempseed oil (HSO). The ultrasound method reached > 99.5% entrapment efficiency with nanoemulsions that had an average droplet size (Z-Ave) < 180 nm and polydispersity index (PDI) of 0.15 ± 0.04. Surfactant concentration (% w/v) was found to be a significant factor (p < 0.05) controlling the Z-Ave, PDI and zeta potential of these nanoparticles. On the other hand, the microfluidic approach produced smaller particles compared to ultrasonication, with good stability observed during storage at room temperature. The Z-Ave of < 62.0 nm was achieved for microfluidic nanoemulsions by adjusting the aqueous : organic flow rate ratio and total flow rate at 4:1 and 12 mL/min, respectively. Further analyses including a morphology examination, a simulated gastrointestinal release behavior study, transepithelial transport evaluations and a toxicity test, using a Caco2-cell model, were performed to assess the functionality of the prepared formulations. The results of this study conclude that both approaches of ultrasound and microfluidics have the capability to prepare an HSO-nanoemulsion formulation, with acceptable characteristics and stability for oral delivery applications.

Impact of succinylation on pea protein-curcumin interaction, polyelectrolyte complexation with chitosan, and gastrointestinal release of curcumin in loaded-biopolymer nano-complexes

The influence of pea protein succinylation on the nature and strength of interaction with curcumin for a potential role in encapsulation and gastrointestinal delivery was investigated. Succinylation neutralized the positive charge on lysine residue and increased the effective negative charge on the protein from −34.4 ± 0.2 to −59.9 ± 0.9 mV with corresponding decrease in surface hydrophobicity and binding with curcumin. The binding constants (K) of 6.9 (± 0.21) × 104 M−1 and 4.2 (±0.05) × 104 M−1 were obtained for the native protein-curcumin (CUR/PPI) and succinylated protein-curcumin (CUR/SPPI) interactions, respectively. These values increased to 14.5 (± 0.64) × 104 M−1 and 187.9 (± 12.40) × 104 M−1 for curcumin-native pea protein-chitosan (CUR/PPI/CHI) and curcumin-succinylated protein-chitosan complexes (CUR/SPPI/CHI), respectively. Incorporation of chitosan to the protein-curcumin complex favoured static interaction. Transmission electron microscopy and dynamic light scattering confirmed the formation of spherical nano-complexes within the size range of 100–194.5 nm. FTIR showed that curcumin was stabilized more in the native protein complex than in the succinylated form. Polyelectrolyte complexation with chitosan by electrostatic interaction stabilized the succinylated protein-curcumin complex. The encapsulation efficiency decreased with a decrease in protein hydrophobicity and binding as a result of succinylation, from 34.65 ± 0.10% in CUR/PPI to 24.92 ± 0.03% in CUR/SPPI and from 85.01 ± 1.43 in CUR/PPI/CHI to 62.05 ± 2.95% in CUR/SPPI/CHI nano-complex. Although polyelectrolyte biopolymers enhance curcumin-loaded complex stability at the gastric phase, the release profile demonstrated that pea protein isolate effectively encapsulated and released curcumin without protein modification or incorporation of chitosan.

Application of whey protein isolate fibrils in encapsulation and protection of β-carotene

β-Carotene (BC) exhibits several bioactive properties, but its application is restrained due to the unstability and low biological availability. In this study, protein fibrils were prepared from whey protein isolate fibrils (WPIF), which were used as carriers to protect and deliver BC. With the extension of heating time, the molecular weight of WPI decreased gradually. WPI was hydrolyzed into peptides which self-assembled into WPIF, resulting in significant changes in secondary structure, zeta-potential, viscosity and, antioxidant capacity. The main interactions between WPIF and BC were hydrogen bonding and hydrophobic interaction. The encapsulation efficiency of WPIF24 was increased from 76.55% to 92.11% compared to that of untreated WPI. Moreover, the simulated gastrointestinal release showed that the cumulative release of BC encapsulated by WPIF24 reached the maximum in the simulated intestine. Therefore, WPIF could be a potential delivery system for water-insoluble bioactive compounds with enhanced encapsulation efficiency and protection effect.

Encapsulation of betacyanins from the peel of red dragon fruit (Hylocereus polyrhizus L.) in alginate microbeads

Red dragon fruit (Hylocereus polyrhizus L.) is a rich source of betalains compounds, natural pigments with desirable bioactive and antioxidant properties. In this paper, we focused on the use of mathematical models for prediction the properties of alginate microspheres loaded with betacyanins from the peel of red dragon fruit. Besides to assess their storage and heat stability, the prepared alginate-loaded microspheres were characterized by encapsulation efficiency (EE%), particle size, uniformity and morphology. Antioxidant properties, thermal degradation kinetics of betacyanins (half-life: T1/2) loaded in alginate and simulated gastro-intestinal (SGI) release behavior were mentioned as indices for microspheres stability. Based on the mathematical optimization, betacyanins extract was efficiently entrapped in alginate (EE% = 78. 62; mean particle size: 106.32 ± 6.77 μm and uniformity: 0.279 ± 0.05) in a ratio of 1:8.97 alginate: betacyanins. The investigation of SGI release behavior of alginate-loaded betacyanins extract showed the good potential of micro-capsules as a carrier for delivery of antioxidants. The half-life (T1/2), and total betacyanins retention (%) in microspheres during storage were also improved in comparison with non-capsulated extract and commercial betanin solution (control). Alginate microspheres loaded with betacyanins are effective models for food colourant additives and oral delivery purposes.

In vitro and in vivo evaluations on nanoparticle and phospholipid hybrid nanoparticles with absorption enhancers for oral insulin delivery

Oral delivery of peptide and proteins is challenging due to their poor physical and chemical stability which usually results in inadequate therapeutic efficacy. Nanoparticles encapsulating insulin was developed by the ionic gelation technique using sulfobutyl ether-β-cyclodextrin as an anionic linker. Phospholipid hybrid nanoparticles were formulated by utilizing ionic gelation and thin-film hydration methods using D-α-Tocopheryl polyethylene glycol 1000 succinate, sodium deoxycholate separately and in combination to take the advantage of liposomes and nanoparticles also various absorption enhancement mechanisms. All formulations were characterized and tested for in vitro gastrointestinal stability, in vitro drug release, and cytotoxicity. On the other hand, in vivo effects of developed formulations on reducing blood glucose levels were monitored for 8 hours. Phospholipid hybrid nanoparticles including D-α-Tocopheryl polyethylene glycol 1000 succinate and sodium deoxycholate in combination with 548.7 nm particle size, 0.332 polydispersity index, 22.0 mV zeta potential, and 61.9% encapsulation efficiency, exhibited desired gastrointestinal stability and insulin release in vitro. In addition, the formulation proved its safety with cytotoxicity studies on L929 cells. The subjected phospholipid hybrid nanoparticle formulation was found to be the most effective formulation by reducing and maintaining blood glucose levels with avoiding fluctuations.

Alginate-, Carboxymethyl Cellulose-, and κ-Carrageenan-Based Microparticles as Storage Vehicles for Cranberry Extract.

This study discusses the relationship between the structural properties of the selected polysaccharides (low (ALGLV) and medium viscosity (ALGMV) sodium alginate, 90 kDa (CMC90) and 250 kDa (CMC250) carboxymethyl cellulose, and κ-carrageenan (CARκ)) and their abilities to serve as protective materials of encapsulated large cranberry (Vaccinium macrocarpon Aiton) fruit extract (CE) from losing its health beneficial activities during long-term storage. The microparticles were characterized in terms of their encapsulation efficiency (UV-Vis and FTIR), morphology (SEM) and the physical stability in various environments (gravimetry). The microparticles’ size and encapsulation efficiency were 46–50 µm and 28–58%, respectively, and the microparticles were physically stable. CMC90 and ALGMV most efficiently protected the plant extract from losing its biological activity after 18 months, while the plant extract stored outside the particles had lost its activity. CE was intended for oral administration, thus CE release from the microparticles was monitored in vitro under gastrointestinal conditions. In vitro gastrointestinal release studies revealed that the ALGMV-, CMC90-, and CMC250-based particles exhibited the desired intestinal release pattern. This result supports the suitability of sodium alginate and carboxymethyl cellulose for the safe delivery of CE to the intestines while maintaining its biological properties and improving long-term storage stability.

Development of food-grade bigels based on κ-carrageenan hydrogel and monoglyceride oleogels as carriers for β-carotene: Roles of oleogel fraction

Bigels based on κ-carrageenan hydrogel and monoglyceride oleogels were developed as carriers for lipophilic bioactives. Bigels were prepared by mixing the hydrogel and oleogels under temperature control, and the roles of oleogel fraction in the structures of the bigels and the delivery of β-carotene were investigated. Microstructural observation indicated that the structures of bigels changed from oleogel-in-hydrogel type (25, 40, 50%) to bi-continuous type (60%) and to hydrogel-in-oleogel type (75%). Mechanical properties (storage modulus, stiffness, fracture stress) of the bigels were enhanced with higher content of oleogel, and the biggest enhancement was observed when the bigel was transformed into bi-continuous or hydrogel-in-oleogel structures. XRD analysis revealed the crystalline structures of monoglyceride and liquid state of the corn oil, and the highest crystallinity was found in the bigel with 50% oleogel. Thermal stability of the bigels was improved with the increase in oleogel fraction, as monoglyceride tended to melt at higher temperature with higher oleogel content. All the bigels had low swelling ratio except for the sample with 50% oleogel. When bigels were used to encapsulate β-carotene, oleogel fraction also influenced stability and in vitro gastrointestinal release of the bioactive. Both light stability and thermal stability of β-carotene were improved with the increase in oleogel fraction, and about 70% of the original β-carotene could be retained after 8 h of UV-light exposure in the bigel with 75% oleogel. All the bigels had minor release in simulated gastric juice, and the release ratios were greatly increased in the simulated intestinal juice, and higher content of oleogel could promote the release.

Storage Stability, Gastrointestinal Release and Sensory Properties of Cookies Incorporated with Protein-based Moringa oleifera Leaf Extract microcapsule

Storage Stability, Gastrointestinal Release and Sensory Properties of Cookies Incorporated with Protein-based Moringa oleifera Leaf Extract microcapsule

Chrysin-loaded bovine serum albumin particles as bioactive nanosupplements

Development of nanosupplements based on bioactive compound encapsulation and their incorporation into diet constitutes a field that is growing exponentially. Among flavonoids, chrysin (Chrys) shows high antitumor activity but its poor water solubility limits its applications. Bovine serum albumin nanoparticles (BSAnp) with sizes in the range of 13-28 nm were previously prepared by applying a heat-induced self-assembly method, and they were able to load Chrys. Hence, the aim of this study is to provide information about elaboration of Chrys nanosupplements considering the incidence of the freeze-drying process of Chrys-loaded and unloaded BSAnp systems on aqueous redispersibility and on the retention of their physicochemical properties as examined by DSC, turbidity and DLS measurements. In general, the physicochemical properties of Chrys-loaded BSAnp were retained after the freeze-drying process. The cytotoxic activity of the reconstituted powders was assayed on MCF-7 and MDA-MB-231 cell lines (as models of cancer cell lines) by using the MTT assay. Furthermore, the mechanism of cell death was researched by Annexin V-FITC flow cytometry. The apoptosis-mediated cytotoxicity was higher for Chrys-loaded BSAnp than for the BSAnp system. The greatest in vitro cytotoxic effect was observed for the smallest sized Chrys-loaded BSAnp, which was obtained at pH 11.0 and 70 °C. Finally, this system was subjected to static in vitro gastrointestinal digestion using the standardized protocol, and ∼14% Chrys was released from BSAnp after digestion. These results would provide a procedure to obtain bioactive nanosupplements in a soluble form, and they would suggest that smaller sized Chrys-loaded BSAnp could be a promising oral delivery system for potential cancer therapies.

Stability of Fish Oil in Calcium Alginate Microcapsules Cross-Linked by In Situ Internal Gelation During Spray Drying

Microencapsulating bioactive compounds, such as polyunsaturated fatty acids (PUFA), in dry cross-linked alginate serves to enhance their shelf life, mask unwanted flavors and odors, facilitate their incorporation into food products, and provide an intestinal release mechanism. Alginate microencapsulation is challenging to implement at industrial scale, but a recently developed process provides scalability by accomplishing alginate cross-linking in situ during spray drying. This study investigated how formulation variables affect the oxidative stability of fish oil in cross-linked alginate microcapsules (CLAMs) prepared via this industrially scalable process. Storage stability of PUFA from fish oil was prolonged by microencapsulation in CLAMs, relative to nonencapsulated fish oil. Neither the choice of emulsifier (Tween 80 or whey protein isolate) nor the extent of alginate cross-linking influenced the duration of storage stability of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, the retention of EPA and DHA during spray drying was significantly lower for CLAMs prepared with Tween 80. The addition of n-octenyl succinic anhydride (OSA) modified starch into spray-drying formulations improved the storage stability of microencapsulated fish oil. With increasing OSA-starch content in CLAMs, surface oil content decreased, particle size and powder yield increased, and PUFA storage stability increased. Despite OSA-starch being the majority component, OSA-starch CLAMs exhibited gastrointestinal release properties more akin to CLAMs than control OSA-starch microcapsules. OSA-starch CLAMs retained fish oil cargo in simulated gastric fluid and released it in simulated intestinal fluid, while OSA-starch microcapsules completely released cargo in either fluid. Overall, OSA-starch CLAMs show promise as an industrial-scale system for stabilizing PUFA while providing an enteric delivery mechanism.

In vitro digestion of polysaccharide including whey protein isolate hydrogels.

Hydrogels are great systems for bioactive agent encapsulation and delivery. In this study, polysaccharide blended whey protein isolate (WPI) based hydrogels were loaded with black carrot (Daucus carota) concentrate (BC) and in vitro gastrointestinal release measurements were performed. Prior to 6 h digestion in simulated intestinal fluid (SIF), all hydrogels were exposed to simulated gastric fluid (SGF) for 2 h. Pectin (PC), gum tragacanth (GT) and xanthan gum (XG) were the polysaccharides used with WPI to manipulate the release behavior. Physico-chemical changes of the hydrogels throughout the digestion were evaluated by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) relaxometry measurements. Each polysaccharide induced different physico-chemical interactions within the hydrogels due to their distinct structural characteristics. Polysaccharide blending to hydrogels also retarded the release rates in all samples in SIF (p < 0.05). Moreover, microstructural differences between hydrogels were evaluated by scanning electron microscope (SEM) images.

Biodegradable biopolymer network structures to create delayed burst digestive release of encapsulated lipids

This study sought to investigate whether encapsulation of lipids in core-shell hydrogel structures of tailored shell porosity could create a delayed burst release of encapsulated lipids, and examined the underpinning mechanisms. We demonstrated that gastrointestinal digestion of core-shell structures resulted in a delay in the onset of lipid digestion, without affecting lipid digestion kinetics. Systematic increase in hydrogel protein content above 65 g/L lead to an exponential increase in digestive delay (250 min). Whilst an increase in xanthan content between 5 and 9 g/L lead to a modest decrease in digestive delay (40 min). Rheological investigations revealed a linear relationship between hydrogel storage modulus G′ and digestive breakdown delay (T1/2). Given that G’ is directly related to hydrogel mesh size, this result suggests that the main factor controlling the timing of digestive release is the average mesh size of the outer protein hydrogel. A kinetic model was created to describe the delayed burst release behaviour of encapsulated lipids and successfully predicted the influence of shell thickness, shell protein density on the timing of gastro-intestinal release (in vitro). By combining microstructural/rheological experiments with in vitro digestive studies we have understood the main factors controlling the digestive breakdown of hierarchical biopolymer hydrogels. We could successfully miniaturise these core-shell structures so they would easily empty from the stomach whilst maintaining programmable delayed burst release. We have created a novel family of core-shell hydrogel oral dosage forms for the delivery of poorly soluble drugs and the programmed delivery of lipids within the gut.

Fabrication of Enteric Release Tablet without Coating Process by Using Bleached Shellac

The purpose of this study was to design an enteric release tablet by a simple method of tableting and avoiding the coating process. Polymers which had a protection ability against acid were required for tablet formulation. Bleached shellac was selected as an excipient due to colorless property, a protection ability against acid in upper gastrointestinal tract and release ability in lower gastrointestinal tract. Bleached shellacs in salt and acid forms were dissolved in 12 ml of 95% ethanol and used as a binding agent to get a concentration of 5, 7.5, 10, 12.5, 15, 17.5 and 20 %w/w of total formulation. 60% lactose, 30% Avicel pH 102 and 10% paracetamol (model drug) were mixed and tablets were prepared by wet granulation method with the weight of 550 mg and hardness of 8-10 kg. The tablets were evaluated for their disintegration and drug release at pH 1.2 and 6.8 and kept at 40 °C, 75%RH for 6 months. The findings showed that the disintegration and amount of release were dependent on type and concentration of bleached shellac. Only the bleached shellac in salt form could protect the release of drug at pH 1.2 for 2 h and could release completely at pH 6.8 but not in acid form. After 6 months of storage, 15% bleached shellac in salt form could still protect against acid and complete release at pH 6.8 for 4 h. Although the bleached shellac showed protection ability against acid, it could not comply with the required criteria of enteric release tablet. Further study is hence required. However, the stability test of tablets prepared with bleached shellacs in salt form could show protection against acid and complete release at pH 6.8 after 6 months of storage. Bleached shellacs in salt form as a binding agent showed a good approach for the fabrication of enteric release tablets without coating process by using a proper concentration of bleached shellac. Therefore, the attempt to design an enteric tablet by a simple method and avoiding the coating process is achieved.

SUN-303 DIETARY MANIPULATION OF THE GUT MICROBIOTA REDUCES DIABETIC KIDNEY INJURY IN MICE

Diabetic nephropathy (DN) is the leading cause of chronic kidney disease (CKD) globally. High dietary fibre intake has been associated with decreased inflammation and mortality in CKD. Short-chain fatty acids (SCFA) derived from gut microbial fermentation of dietary fibre are thought to regulate gut and systemic inflammation. Here we evaluated the effect of dietary modification, or supplementation with the three main SCFAs (acetate, propionate, butyrate) on the development of DN in a mouse model of streptozotocin (STZ) induced diabetes. Diabetes was induced using a low dose STZ protocol in C57BL/6 mice. Three weeks after STZ injection, diabetic mice were switched to a zero-fibre (ZF) or high-fibre (HF) diet, whilst control diabetic mice remained on the normal diet. For mechanistic studies, two-weeks after STZ, groups of diabetic mice received daily intra-peritoneal injections of either sodium acetate (SA), propionate (SP), butyrate (SB) 200mg/kg or saline for 2 weeks, then switched to oral SCFAs (SA 150mM, SP 100mM, SB 50mM, or pH and sodium-matched water) in their drinking water for the duration of the study. Blood, urine and kidneys were collected after 12 weeks. All STZ-treated mice developed diabetes within two weeks. Diet altered the gut microbiome in diabetic mice, with significant preservation of diversity evident in HF compared to ZF mice. As compared to ZF and normal diets, HF fed mice had higher faecal SCFA levels (>2-fold, p<0.05) and serum acetate concentrations (>3-fold, p<0.001). HF fed mice were protected from DN, with a reduction in albuminuria of 50% (p<0.01), reduced kidney to body weight ratio (1.33 vs 2.4, p<0.0001), glomerular hypertrophy (22±17.5 vs 35.5±15.3 (x104 μm3), p<0.0001), glomerular cellularity (24.9±1.7 vs 36.6±1.7, p<0.0001), interstitial fibrosis (p<0.0001) and podocyte injury (p<0.0001) compared to diabetic controls on normal or ZF diets. Treatment of diabetic mice with SA, SP or SB achieved similar degrees of protection to the HF-diet, with less glomerular hypertrophy (p<0.01), podocyte injury (p<0.05), interstitial fibrosis (p<0.001) and interstitial macrophage accumulation (p<0.01), as compared to diabetic controls. Albuminuria was also reduced by over 50% (p<0.05). mRNA expression of cytokines (IL6, TGF-β), chemokine (CCL2) and pro-fibrotic (fibronectin) genes in the kidney were attenuated in SA treated diabetic mice versus controls (p<0.05). Treatment with dietary fibre supplementation provides protection against development of DN through modulation of the gut microbiota with increased gastrointestinal release and systemic distribution of SCFAs. SCFA treatment was similarly protective, supporting SCFAs as a key mediator of the beneficial effects of the HF diet. Manipulation of the gastrointestinal microbiota through diet may be a novel strategy in prevention and management of diabetic nephropathy.