Microencapsulated ascorbic acid for milk fortification

The present study was designed to develop a microencapsulated L-ascorbic acid and iron that could be used to fortify milk and to determine the sensory properties of milk fortified with microencapuslation. Coating material was medium-chain triacylglycerol (MCT), and selected core material was ferric ammonium sulfate and L-ascorbic acid. The highest efficiency of microencapsulation was 95.0% in the ratio of 15:1 as coating to core material. Ascorbic acid release was increased sharply up to 5 d storage as 6.5%. TBA value was the lowest when both capsulated iron and ascorbic acid were added during 12 d storage, compared with other treatments. In sensory analysis, most aspects were not significantly different between control and capsulated ascorbic acid fortified milk at 5 d storage. The present study indicated that the use of microencapsulated ascorbic acid with MCT is effective for fortifying milk. In addition, these results suggest that acceptable milk products can be prepared with microencapsulated ascorbic acid and iron.     

Application of microencapsulated isoflavone into milk

This study was designed to develop a microencapsulated, water-soluble isoflavone for application into milk and to examine the hypocholesterolemic effect of such a milk product in a rat diet. The coating material was medium-chain triglyceride (MCT) and the core material was water-soluble isoflavone. The microencapsulation efficiency was 70.2% when the ratio (w/w) of coating material to core material was 15:1. The isoflavone release from the microcapsules was 8% after 3-day storage at 40 degrees C. In in vitro study, 4.0-9.3% of water-soluble isoflavone in simulated gastric fluid was released in the pH range of 2 to 5 after 60 min incubation; however, in simulated intestinal fluid at pH 8, 87.6% of isoflavone was released from the capsules after 40 min incubation time. In sensory analysis, the scores of bitterness, astringency, and off-taste in the encapsulated isoflavone-added milk were slightly, but not significantly, different from those in uncapsulated, isoflavone-added milk. In blood analysis, total cholesterol was significantly decreased in the isoflavone-added group compared with that in the control after 6-week feeding. Therefore, this study confirmed the acceptability of MCT as a coating material in the microencapsulation of water-soluble isoflavone for application into milk, although a slight adverse effect was found in terms of sensory attributes. In addition, blood total cholesterol was lowered in rats which had been fed a cholesterol-reduced and microencapsulated, isoflavone-added milk for 6 weeks.     

Microencapsulation of ascorbic acid: effect of process variables on product characteristics

This study deals with a comparative investigation of the characteristics of ascorbic acid microcapsules prepared by different methods, such as thermal phase separation, melt dispersion, solvent evaporation and spray drying. Scanning electron microscopy (SEM), release tests and size distribution were used for the evaluation of product characteristics. The results show that microencapsulated ascorbic acid could prevent the ascorbic acid colour change, retard its core release rate, and generally mask its acid taste. In the thermal phase separation, molecular weight (Mw) of ethyl cellulose (EC) and the addition of polyisobutylene (PIB) significantly influenced the aggregation and release rate of microcapsules. In the melt dispersion method, spherical particles were prepared by using carnauba. The ascorbic acid release rate was found to be slower in the case of carnauba-encapsulated ascorbic acid than that made by EC using other methods. In the solvent evaporation method, a higher Mw of EC and the addition of plastizer were also found to be important for good encapsulation. In the spray drying method, loss of ascorbic acid was found to be minimum during microencapsulation. Starch and beta-cyclodextrin encapsulated ascorbic acid delayed the degradation of ascorbic acid during storage at 38 degrees C and relative humidity 84.0%.     

Microencapsulation of ascorbic acid: effect of process variables on product characteristics

This study deals with a comparative investigation of the characteristics of ascorbic acid microcapsules prepared by different methods, such as thermal phase separation, melt dispersion, solvent evaporation and spray drying. Scanning electron microscopy (SEM), release tests and size distribution were used for the evaluation of product characteristics. The results show that microencapsulated ascorbic acid could prevent the ascorbic acid colour change, retard its core release rate, and generally mask its acid taste. In the thermal phase separation, molecular weight (M_w) of ethyl cellulose (EC) and the addition of polyisobutylene (PIB) significantly influenced the aggregation and release rate of microcapsules. In the melt dispersion method, spherical particles were prepared by using carnauba. The ascorbic acid release rate was found to be slower in the case of carnauba-encapsulated ascorbic acid than that made by EC using other methods. In the solvent evaporation method, a higher M_w of EC and the addition of plastizer were also found to be important for good encapsulation. In the spray drying method, loss of ascorbic acid was found to be minimum during microencapsulation. Starch and beta-cyclodextrin encapsulated ascorbic acid delayed the degradation of ascorbic acid during storage at 38°C and relative humidity 84.0%.     

The stability of ascorbic acid microencapsulated in granules of rice starch and in gum arabic

Ascorbic acid (AA) was microencapsulated by spray drying, using gum arabic and rice starch as covering materials. The AA was dissolved in solutions of the wall material prior to processing. For the rice starch, gelatin was used as a binding agent and recovery was effected with calcium pectate. The morphology of the materials was analysed by optical and scanning electron microscopy, it thus being possible to verify the formation and evaluate the structural characteristics of the microcapsules. The capsules produced with gum arabic were smaller (d50% = 8.0 microns) and with a multimode particle size distribution, whilst uncovered starch capsules containing 1-2% gelatin presented a distribution mainly in the range of 5-40 microns. The capsules recovered with calcium pectate had average diameters 10-15 times greater than those obtained only by spray drying. The stability of the encapsulated materials was studied at room temperature (RH 60-65%) and at 45 degrees C (RH 60-65% and 90.7%). AA microencapsulated in gum arabic was shown to be as stable as free crystalline AA under environmental conditions, whereas that encapsulated in rice starch was less stable. Increasing the amount of the binding agent gelatin increased the stability of the uncovered starch encapsulated AA. Recovery with calcium pectate notably increased the stability of the starch encapsulated AA, as compared to the uncovered samples.     

Ascorbic acid modifies the surface of asbestos: possible implications in the molecular mechanisms of toxicity

Ascorbic acid is one of the major components of the antioxidants defenses of the lung lining layer where inhaled asbestos fibers are deposited. Crocidolite fibers were incubated at 37 degrees C in a 0.01 M aqueous solution of ascorbic acid for 25 days in order to investigate modifications in surface reactivity. Iron (820 nmol/mg) and monomeric silica (470 nmol/mg) were released in the supernatant, while ascorbic acid was consumed. The amount of iron and silicon released, respectively, 17 and 6% (in atoms) of the total fiber content, exceeded what was expected at the surface, suggesting a partial disgregation of crocidolite promoted by ascorbic acid. In the absence of ascorbic acid but at the same pH, the release of iron and monomeric silica was minimal. At time intervals, aliquots of fibers were withdrawn to evidence chemical modifications progressively taking place. Three families of Fe(II) centers, differing in coordinative unsaturation and progressively removed during incubation, have been evidenced from the FTIR spectra of NO adsorbed onto the fibers. The most uncoordinated ones are removed first. New highly uncoordinated iron sites are exposed at the fiber surface as a consequence of the erosion of the outmost layers while hydration of silica tetrahedra yields new silanol groups. The activity in the Fenton-like reaction (*OH from H(2)O(2)) decreases following surface iron depauperation. Conversely, the homolytic cleavage of the C-H bond (CO(2)*-) from the formate ion) appears related to the small fraction of iron ions always present but easily quenched by the adsorption of ascorbic acid or its oxidation products.     

The stability of ascorbic acid microencapsulated in granules of rice starch and in gum arabic

Ascorbic acid (AA) was microencapsulated by spray drying, using gum arabic and rice starch as covering materials. The AA was dissolved in solutions of the wall material prior to processing. For the rice starch, gelatin was used as a binding agent and recovery was effected with calcium pectate. The morphology of the materials was analysed by optical and scanning electron microscopy, it thus being possible to verify the formation and evaluate the structural characteristics of the microcapsules. The capsules produced with gum arabic were smaller (d _50% = 8:0 mum) and with a multimode particle size distribution, whilst uncovered starch capsules containing 1-2%gelatin presented a distribution mainly in the range of 5-40 mum. The capsules recovered with calcium pectate had average diameters 10-15 times greater than those obtained only by spray drying. The stability of the encapsulated materials was studied at room temperature (RH 60-65%) and at 45C (RH 60-65%and 90.7%). AA microencapsulated in gum arabic was shown to be as stable as free crystalline AA under environmental conditions, whereas that encapsulated in rice starch was less stable. Increasing the amount of the binding agent gelatin increased the stability of the uncovered starch encapsulated AA. Recovery with calcium pectate notably increased the stability of the starch encapsulated AA, as compared to the uncovered samples.     

Microencapsulation of water-soluble isoflavone and physico-chemical property in milk

This study was carried out to investigate the addition of water-soluble isoflavone into milk by means of microencapsulation technique. The yield of microencapsulation, sensory attributes, and capsule stability of water-soluble isoflavone microcapsules in milk were measured. Coating materials used was polyglycerol monostearate (PGMS), and core material was water-soluble isoflavone. The encapsulation yield of water-soluble isoflavone with PGMS was 67.2% when the ratio of coating material to core material was 15:1. The rate of water-soluble isoflavone release from capsules was 18, 19, and 25% when stored at 4, 20, and 30 degrees C for 12 days in milk, respectively. In sensory evaluation, beany flavor and color of microencapsuled water-soluble isoflavone added milk were significantly different from uncapsuled water-soluble isoflavone added milk, however, bitterness was not significantly different. In vitro study, micro-capsules of water-soluble isoflavone in simulated gastric fluid with the range of 3 to 6 pHs were released 3.0-15.0%, however, the capsules in simulated intestinal fluid with pH 7 were released 95.7% for 40 min incubation time. In conclusion, this study provided that PGMS as coating materials was suitable for the microencapsulation of water-soluble isoflavone, and the capsule containing milk was almost not affected with sensory attribute.     

甘糖酯抗血栓作用及其机理研究

家兔iv甘糖酯6.25mg·kg~(-1)和25m g·kg~(-1)观察其对实验性血栓形成的影响.并与等抗凝效价藻酸双酯钠及肝素做比较,提示甘糖酯具有较好的抗血栓作用、为探讨其作用机理。本实验观察了甘糖酯对家兔抗凝血酶Ⅲ(AT—Ⅲ)及纤溶酶原活性的影响。发现甘糖酯可明显提高AT一Ⅲ功能活性,并使纤溶酶原活性升高;提示甘糖酯可通过抑制凝血系统和激活纤维蛋白溶解系统发挥其抗血栓作用。     

Relationships between ascorbic acid and alpha-tocopherol during diquat-induced redox cycling in isolated rat hepatocytes

The effects of diquat-induced redox cycling on the levels of cellular ascorbic acid and alpha-tocopherol were investigated in isolated rat hepatocytes. In untreated hepatocytes, the metabolism of 1 or 2 mM diquat resulted in the depletion of cellular ascorbic acid and glutathione, but not of alpha-tocopherol, in association with the induction of cell death during the experimental period. In 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) pretreated cells, 1 mM diquat induced cell death accompanied by glutathione was rapid (to 9% of controls by 15 min) and cell ascorbate was completely consumed by 2 hr of incubation. In contrast, cellular alpha-tocopherol levels were stable for the first 30 min, but were depleted in association with the onset of lipid peroxidation. Supplementation of 0.1 or 1.0 mM ascorbic acid in the incubation medium delayed the onset of diquat-induced alpha-tocopherol loss, lipid peroxidation and cytotoxicity. When the concentration of exogenous cellular ascorbic acid was consumed to below that of endogenous ascorbic acid, alpha-tocopherol loss and lipid peroxidation were initiated. The results indicate that untreated hepatocytes have an effective multicomponent antioxidant system against diquat-induced oxidative stress. However, when glutathione is depleted from hepatocytes by treatment with BCNU and diquat, ascorbic acid plays a vital role in maintaining cellular alpha-tocopherol levels and survival of the cell.     

Development of a microencapsulated form of cefuroxime axetil using pH-sensitive acrylic polymers

Abstract

Cefuroxime axetil (CA) was encapsulated in pH-sensitive acrylic micro spheresin order to formulate a suspension dosage form. Using this microencapsulated form it was expected to prevent leaching of the drug from the micro spheresinto the suspension medium and to assure the release of the drug in the first part of the intestinethus avoiding changes to its bioavailability. For this purpose CA was microencapsulated within several types of acrylic polymers by the solvent evaporation and the solvent extraction techniques., The acrylic polymers selected were: Eudragit E (positively charged and soluble at pH 5)Eudragit L-55 (negatively charged and soluble at pH >5.5) and Eudragit RL (neutralinsolublebut readily permeable)., The influence of the polymer electrical charge on the stability and in vitro release of CA was investigated., Though Eudragit E micro spherespresented good morphological characteristics and dissolution behaviourthe analysis of the stability of CA in the presence of Eudragit E by HPL Cindicated a negative interaction between both compounds., Howeverformulations made of Eudragit L-55 and RL in the ratios 100:0 and 90:10 were adequate in terms of the stability of the encapsulated CA., The dissolution studies showed a critical pH between 5.2 and 6.0which allowed the complete release of CA in a short period., Furthermorethese polymer micro sphereswere shown to be efficient in masking the taste of CA.     

PEG-I-dC16酸敏释药胶束的制备及体外释放研究

目的:构建酸敏释药胶束并考查其酸敏释药特性。方法:用亚胺键连接PEG和苯棕榈酸脂肪链,用透析法制备载阿霉素胶束,对其粒径,载药量和包封率进行考察,用紫外分光光度法测定载药胶束在不同pH值条件下的释放。结果:载药胶束粒径为60~70 nm,PEG相对分子质量为2000 Da的胶束载药量和包封率分别为(12.7±1.1)%和(49.8±2.2)%,PEG相对分子质量为5000 Da的胶束载药量和包封率分别为(10.7±0.3)%和(39.9±2.1)%。体外释放研究表明酸敏释药胶束在pH 6.5时的累积释放率比pH 7.4时大,但在pH 5.0条件下其累积释放较pH 7.4时还要小,可能原因是胶束解聚太快致药物与材料形成复合物沉淀所致。结论:以酸敏感亚胺键连接的两亲材料载药胶束具有一定的酸敏释药特性。     

Plasmid DNA damage caused by methylated arsenicals,ascorbic acid and human liver ferritin

Both dimethylarsinic acid (DMA(V)) and dimethylarsinous acid (DMA(III)) release iron from human liver ferritin (HLF) with or without the presence of ascorbic acid. With ascorbic acid the rate of iron release from HLF by DMA(V) was intermediate (3.37 nM/min, P<0.05) and by DMA(III) was much higher (16.3 nM/min, P<0.001). No pBR322 plasmid DNA damage was observed from in vitro exposure to arsenate (iAs(V)), arsenite (iAs(III)), monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)) or DMA(V) alone. DNA damage was observed following DMA(III) exposure; coexposure to DMA(III) and HLF caused more DNA damage; considerably higher amounts of DNA damage was caused by coexposure of DMA(III), HLF and ascorbic acid. Diethylenetriaminepentaacetic acid (an iron chelator), significantly inhibited DNA damage. Addition of catalase (which can increase Fe(2+) concentrations) further increased the plasmid DNA damage. Iron-dependent DNA damage could be a mechanism of action of human arsenic carcinogenesis.     

Effect of microencapsulation of Lactobacillus salivarus 29 into alginate/chitosan/alginate microcapsules on viability and cytokine induction

Harsh gastric condition causes low bioavailability of probiotics when supplied orally. Polymeric encapsulation has successfully protected bacteria from harsh gastric condition and ultimately increased persistency and multiplication at the targeted region. In this study, we encapsulated LS29 into ACA microcapsules and characterized them. The survivability and release of LS29 from LS29-loaded ACA microcapsules in SGF and SIF were studied. Encapsulation efficiency of LS29 in ACA microcapsules was 99.9%. Approximately 70% of bacteria survived at pH 2 by 120?min after encapsulation. Although not much difference of the survivability of LS29 encapsulated into ACA and FDACA was observed, freeze-drying improved the controlled-release of LS29 in SIF and also showed better storage survivability at 4°C for 8 weeks. Furthermore, investigation of in?vitro production of cytokines in RAW264.7 showed high level of induction of TNF-α and IL-10. These in?vitro results support that the LS29 might have a balanced immunomodulatory effect.     

Rhizobacteria microencapsulation: properties of microparticles obtained by spray-drying

Rhizobacteria Pseudomonas fluorescens-putida were microencapsulated in Eudragit by spray-drying. These microparticles are subsequently included in seed coating or pelleting material. The survival of the bacterial cell in microparticles were studied under different levels of relative humidity (RH): 0, 33, 55 and 100%. The protective effects of silica, present in certain formulations, were demonstrated at the relative humidities of 33 and 55%. The release of the encapsulated bacteria was also studied over time. The release was fast, the bacteria being observed at 15 min immersion of the Eudragit microparticles in an aqueous-buffer medium at 20 degrees C. This result, related to the physicochemical character of the coating polymer, showed that water was the triggering element for the release of rhizobacteria. Compatibility studies between two film-forming agents used for seed coatings and the encapsulated bacteria, as well as wettability measures of tableted microparticles, were carried out. The bacterial survival was good with the seed coating agent, Sepiret 1039G, and the wettability measurements of agglomerated microparticles were in accord with the rapid release of the microencapsulated bacteria. The application of microparticles containing rhizobacteria on seeds can now be considered for preliminary trials.     

Ascorbic acid and membrane ageing: critical determinants of the in-vitro binding of [3H]ADTN to rat striatal tissue

Tritiated (+/-)-2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene [( 3H]ADTN), binding (0.125-4.0 nM) to rat striatal membranes was investigated using Tris-HCl buffer containing Na2EDTA, nialamide and varying concentrations of ascorbic acid. In the absence of ascorbic acid [3H]ADTN exhibited a high affinity (KD 1.26 nM) saturable binding (Bmax 138 fmol mg-1 protein) (Scatchard analysis). This was not modified by 10(-6) or 10(-5) M ascorbic acid used immediately or 60 min after preparation. However, 10(-4) M ascorbic acid added (within) 15 min after its preparation reduced the number of bindings sites and added 60 min after it also reduced affinity. Ascorbic acid 5.7 mM reduced affinity whether used within 15 min or 60 min of its preparation. When ascorbic acid 10(-4) M was used within 15 min of preparation, and membranes were used immediately, the binding of 2 nM [3H]ADTN was specifically displaceable by nM or sub-nM concentrations of dopamine agonists and antagonists. However, when membranes were used 1-2 h after their preparation there was an increasing loss of the high affinity binding sites displaceable by sub-nM concentrations of (+/-)-ADTN. Thus. [3H]ADTN can be shown to exhibit high affinity stereoselective binding to rat striatal membranes when these are freshly prepared and the assay is performed using Tris-HCl buffer containing nialamide. Na2EDTA and 10(-4) M ascorbic acid prepared within 15 min of use. The characteristics of this binding can be markedly modified if the concentration of ascorbic acid is increased, if its preparation time is extended, or if the membranes are allowed to 'age'.     

Bioavailability of seocalcitol III. Administration of lipid-based formulations to minipigs in the fasted and fed state.

The bioavailability of seocalcitol from two lipid-based formulations and a propylene glycol (PG) solution was studied in minipigs in the fasted and fed state. The lipid-based formulations were a medium chain triglyceride (MCT) solution and a self-microemulsifying drug delivery system (MC-SMEDDS) having a composition of 25% MCT, 48% cremophor RH 40, 27% akoline MCM. An IV solution was administered in order to determine the absolute bioavailability. In the fasted state the absolute bioavailability of seocalcitol was 15, 21 and 28% for the PG, MCT and MC-SMEDDS, respectively. The bioavailability from the PG solution was affected by the presence of food (29%), whereas the bioavailability from the lipid-based formulations was less affected by the presence of food; MCT (22%) and MC-SMEDDS (33%). The increased bioavailability from the PG solution in the fed state is believed to be due to the presence of lipids in the food. The present study illustrates an often mentioned beneficial effect of dosing lipid-based formulations; the reduced food effect on bioavailability. Previously published solubility data in simulated intestinal media relates very well to the present in vivo findings as the solubility studies showed that addition of lipids to the formulation could reduce/eliminate the difference in solubility between the fasted and fed state. Previously the same formulations were dosed to rats, resulting in a lower bioavailability from the MC-SMEDDS compared to the MCT. This illustrates that the animal model used should be carefully considered when studying formulations that are dependent on the dynamic processes in the GIT.     

Effect of microencapsulation of Lactobacillus salivarus 29 into alginate/chitosan/alginate microcapsules on viability and cytokine induction

Harsh gastric condition causes low bioavailability of probiotics when supplied orally. Polymeric encapsulation has successfully protected bacteria from harsh gastric condition and ultimately increased persistency and multiplication at the targeted region. In this study, we encapsulated LS29 into ACA microcapsules and characterized them. The survivability and release of LS29 from LS29-loaded ACA microcapsules in SGF and SIF were studied. Encapsulation efficiency of LS29 in ACA microcapsules was 99.9%. Approximately 70% of bacteria survived at pH 2 by 120?min after encapsulation. Although not much difference of the survivability of LS29 encapsulated into ACA and FDACA was observed, freeze-drying improved the controlled-release of LS29 in SIF and also showed better storage survivability at 4°C for 8 weeks. Furthermore, investigation of in vitro production of cytokines in RAW264.7 showed high level of induction of TNF-α and IL-10. These in vitro results support that the LS29 might have a balanced immunomodulatory effect.     

Effect of formulation factors on the matrix pH of nylon microcapsules

The application of nylon microencapsulation as a drug delivery system inherently demands that the microencapsulated matrix should not cause degradation of the encapsulated drug. The presence of alkaline hexamethylenediamine (HMD) in the microcapsule core will affect the final pH of the microcapsules and may influence the stability of some drugs. To follow the pH within the microcapsule core during manufacture, pH indicators were encapsulated. The final pH was found to depend on the formulation used and could be controlled by the addition of acid. Several other variables affecting the nylon wall formation were examined to determine optimum processing conditions. Increased agitation produced a decrease in microcapsule size. This cause an increase in nylon weight recovered. The increased recovery of nylon was due in part to nylon formation over a larger surface area. Varying the amounts of HMD and sebacyl chloride (SC) used also affected the total weight of nylon formed. In general, more nylon is recovered as the level of each reactant increases. However, the molar ratio of HMD:SC determined the total amount of nylon formed when SC was present in excess.