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PubMed1998

Enthalpy-entropy compensation for the solubility of drugs in solvent mixtures: paracetamol, acetanilide, and nalidixic acid in dioxane-water.

In earlier work, a nonlinear enthalpy-entropy compensation was observed for the solubility of phenacetin in dioxane-water mixtures. This effect had not been earlier reported for the solubility of drugs in solvent mixtures. To gain insight into the compensation effect, the behavior of the apparent thermodynamic magnitudes for the solubility of paracetamol, acetanilide, and nalidixic acid is studied in this work. The solubility of these drugs was measured at several temperatures in dioxane-water mixtures. DSC analysis was performed on the original powders and on the solid phases after equilibration with the solvent mixture. The thermal properties of the solid phases did not show significant changes. The three drugs display a solubility maximum against the cosolvent ratio. The solubility peaks of acetanilide and nalidixic acid shift to a more polar region at the higher temperatures. Nonlinear van't Hoff plots were observed for nalidixic acid whereas acetanilide and paracetamol show linear behavior at the temperature range studied. The apparent enthalpies of solution are endothermic going through a maximum at 50% dioxane. Two different mechanisms, entropy and enthalpy, are suggested to be the driving forces that increase the solubility of the three drugs. Solubility is entropy controlled at the water-rich region (0-50% dioxane) and enthalpy controlled at the dioxane-rich region (50-100% dioxane). The enthalpy-entropy compensation analysis also suggests that two different mechanisms, dependent on cosolvent ratio, are involved in the solubility enhancement of the three drugs. The plots of deltaH versus deltaG are nonlinear, and the slope changes from positive to negative above 50% dioxane. The compensation effect for the thermodynamic magnitudes of transfer from water to the aqueous mixtures can be described by a common empirical nonlinear relationship, with the exception of paracetamol, which follows a separate linear relationship at dioxane ratios above 50%. The results corroborate earlier findings with phenacetin. The similar pattern shown by the drugs studied suggests that the nonlinear enthalpy-entropy compensation effect may be characteristic of the solubility of semipolar drugs in dioxane-water mixtures.

Acetaminophen↗

PubMed1981

Independent biosynthesis of soluble and membrane-bound alkaline phosphatases in the suckling rat ileum.

Enzymically active intestinal alkaline phosphatase exists in both soluble and membrane-bound forms in the suckling rat. Antiserum prepared against purified soluble alkaline phosphatase (anti-AlP) was shown to be monospecific when assessed by Ouchterlony double-diffusion analysis and immunoelectrophoresis. The two forms of alkaline phosphatase were antigenically identical and possessed similar affinities for anti-AlP. To study the biosynthesis of the two forms, 14-day-old rats were injected intraperitoneally with [(3)H]leucine. The labelling kinetics of alkaline phosphatase, extracted from supernatant and brush-border membrane fractions with anti-AlP, was followed over 20h. Incorporation of [(3)H]leucine into membrane-bound alkaline phosphatase was rapid, reaching a plateau at 6h. The soluble enzyme showed slower incorporation of label and maximal radioactivity was not reached until 12h after labelling, a lag of 6h behind the membrane-bound enzyme. Soluble alkaline phosphatase could not have been a precursor of the membrane form, as there was no early peak of radioactivity in the soluble form. To determine if the soluble enzyme was irreversibly derived from the membrane enzyme, a newly developed technique of labelling brush-border membrane proteins in vivo by intraluminal injection of diazotized [(125)I]iodosulphanilic acid was used. The appearance of (125)I in soluble and membrane alkaline phosphatase was then monitored over a 7h period, encompassing the lag between maximal leucine labelling of the two forms. The results failed to show either a proportional transfer of radioactivity from membrane to soluble alkaline phosphatase or an absolute increase in radioactivity of the soluble form during degradation of brush-border alkaline phosphatase. Therefore there does not appear to be a serial precursor/product relationship between the soluble and membrane-bound forms of suckling-rat intestinal alkaline phosphatase.

Alkaline Phosphatase↗

PubMed1995

Soluble thrombomodulin increases in patients with disseminated intravascular coagulation and in those with multiple organ dysfunction syndrome after trauma: role of neutrophil elastase.

OBJECTIVE: Our goal was to investigate the role of soluble thrombomodulin (TM) and neutrophil elastase in patients with trauma. DESIGN: This study is a prospective case-control study. MATERIALS AND METHODS: Forty-seven trauma victims, 14 with disseminated intravascular coagulation (DIC), 5 with multiple organ dysfunction syndrome (MODS), and 28 control patients without DIC or MODS were the participants. Soluble TM and neutrophil elastase (elastase-alpha1-proteinase inhibitor complex) were measured on the day of the injury, and on the first, third, and fifth days after admission. The results of these measurements and demographic data were compared among the groups, and correlations between the soluble TM and the neutrophil elastase were examined. The DIC patients were classified into subgroups of survivors (n = 5) and nonsurvivors (n = 9), and the changes of the soluble TM between the subgroups were then studied. MEASUREMENTS AND MAIN RESULTS: A high incidence of DIC patients encountered MODS complications (12 of 14, 86%). The DIC patients had higher Injury Severity Scores (ISSs) than the other patients. The levels of soluble TM and neutrophil elastase significantly increased on the day of admission in the patients with DIC and also in those with MODS (p < 0.05 vs. control patients) and continued to show markedly high values until the fifth day of admission in the patients with DIC. In the DIC patients, the levels of soluble TM were higher in the nonsurvivors than in the survivors (p < 0.05 on the third and the fifth days of admission). In all patients, there was weak but statistically significant correlation between peak levels of soluble TM and ISS (r2 = 0.125, p < 0.025). Comparison of the levels of soluble TM and neutrophil elastase in the patients with DIC or MODS demonstrated an excellent correlation (r2 = 0.718 and r2 = 0.714, respectively). CONCLUSIONS: Soluble TM as a novel endothelial cell injury marker increases in patients with DIC and also in those with MODS after trauma. Neutrophil elastase may be involved in the pathogenesis of the injury. Soluble TM is a marker of the severity of injury and is a good predictor of MODS.

Adult↗

PubMed2006

A form of circulating interleukin-6 receptor component soluble gp130 as a potential interleukin-6 inhibitor in inflammatory bowel disease.

The presence and the role of soluble gp130, the soluble form of a component of the interleukin (IL)-6 receptor complex, were investigated in inflammatory bowel disease. The serum concentrations of soluble gp130 were increased in ulcerative colitis (active disease, median, 93.5 ng/ml; interquartile range, 26-125 ng/ml; inactive disease, 81 ng/ml, 24.8-137.3 ng/ml) and to a lesser extent in Crohn's disease (active disease, 66 ng/ml, 44.4-87.6 ng/ml; inactive disease, 63 ng/ml, 43.5-82.5 ng/ml) compared to normal controls (43 ng/ml, 27-59 ng/ml). Paired analysis of serum samples showed a decrease of IL-6 and soluble IL-6 receptor concentrations in both diseases and an increase of soluble gp130 concentrations, especially in ulcerative colitis, just after the resolution of disease exacerbation. Size fractionation of the serum revealed that a part of the IL-6 co-eluted with soluble gp130 and soluble IL-6 receptor. The IL-6-induced proliferation of murine B9 hybridoma was enhanced by recombinant soluble IL-6 receptor, whereas the proliferation was inhibited by recombinant soluble gp130. These results indicate that soluble gp130 may function as a natural inhibitor of the IL-6 actions in inflammatory bowel disease.

Acute Disease↗

PubMed2004

[Soluble sugar content of clonal plant Neosinocalamus affinis at module and ramet levels].

In this paper, soluble sugar content of Neosinocalamus affinis was measured by anthrone colorimetry at two levels of module and ramet in order to reveal its ecological and physiological adaptability. The results showed that soluble sugar content decreased in the order of leaf > branch > culm. As for soluble sugar content, different modules responded to ramet age and position in different ways. The branch and culm of 1-year-old ramets contented more soluble sugar than those of other four ages, but soluble sugar content in leaf was independent to ramet age. For leaf and culm, lower parts of ramet contented more soluble sugar than middle and upper parts. Under high irradiance, the soluble sugar content of Neosinocalamus affinis leaf was more than that under low irradiance. Seasonal change had significant effect on soluble sugar content. The soluble sugar content of leaf presented a monthly change, with a bottom and upper value in January and in April, respectively, but there was no obvious difference between 2-year-old and 3-year-old ramets. The soluble sugar content of parent ramet leaves was positively correlative to that of daughter ramet in upper and middle parts of ramets. There was no significant difference between ramet ages at ramet level. Hierarchical response of physiological character to environmental changes existed at the module and ramet levels of Neosinocalamus affinis.

Glucose↗

PubMed2005

Soluble CTLA-4 in sera of patients with bronchial asthma.

Cytotoxic lymphocyte associated antigen-4 (CTLA-4) is a homologue of CD28, which plays a critical role in the down-regulation of antigen-activated immune response. The aim of the present study was to investigate the concentrations of soluble CTLA-4 in sera of patients with bronchial asthma and the correlation between soluble CTLA-4 concentrations and some clinical measures of asthma. The concentrations of serum soluble CTLA-4 in 31 atopic asthmatics, 20 non-atopic asthmatics, and 28 non-atopic normal control volunteers were determined by ELISA technique, and the relationship between serum soluble CTLA-4 concentrations in asthmatics and airway responsiveness, pulmonary function, blood white cell counts and differentials, respectively, were analyzed. Serum soluble CTLA-4 concentrations in both atopic asthmatics (20.2 +/- 5.4 microg/L) and non-atopic asthmatics (19.2 +/- 6.2 microg/L) were all higher than that in normal controls (1.8 +/- 0.8 microg/L, p = 0.04 and 0.014, respectively). There was no difference in serum soluble CTLA-4 concentrations between atopic and non-atopic asthmatics (p = 0.877). The serum soluble CTLA-4 concentrations in the asthmatics statistically correlated with forced expiratory volume in one second (r = -0.410, p = 0.027), percentage of predicted peak expiratory flow (r = -0.449, p = 0.015), and PaCO2 (r = 0.555, p = 0.002), respectively. Our data also showed that the concentration of soluble CTLA-4 was significantly related to blood lymphocyte numbers. The serum soluble CTLA-4 protein level was significantly elevated in patients with asthma. This level correlated with the severity of asthma. Our data also showed that the concentration of soluble CTLA-4 was significantly related to blood lymphocyte numbers.

Adult↗

PubMed1991

The relationship between soluble interleukin 2 receptor levels and antidouble stranded DNA antibody levels in patients with systemic lupus erythematosus.

Levels of soluble interleukin 2 receptors (IL-2R) have been found to be elevated in the serum of patients with systemic lupus erythematosus (SLE) and are considered an indication of immune system activation in this disease. To assess the relationship between soluble IL-2R levels and other serological markers, we compared levels of soluble IL-2R and anti-double stranded DNA (anti-dsDNA) antibodies in SLE sera. In a cross sectional study of 34 patients with SLE, soluble IL-2R levels were elevated compared with healthy individuals (1126 U/ml vs 235 U/ml, p less than 0.0001), and a significant correlation between levels of soluble IL-2R and anti-dsDNA antibodies was present (r = 0.543, p = 0.0009). In a longitudinal study of 10 additional patients, the time courses of soluble IL-2R levels and anti-dsDNA antibody measurements were similar in 3 patients. In 7 patients, substantial differences in the levels of soluble IL-2R and anti-dsDNA antibodies over time were observed, including marked changes in anti-dsDNA antibody levels that were accompanied by only minor changes in soluble IL-2R levels, and soluble IL-2R measurements that were persistently elevated despite generally low anti-dsDNA antibody levels. Our results indicate that soluble IL-2R levels may not always parallel other serological markers of SLE, suggesting measurement of different facets of immune system activation by various assays.

Adult↗

PubMed1975

Characterization of particulate and soluble guanylate cyclases from rat lung.

Rat lung homogenates contained significant amounts of guanylate cyclase activity in both 100,000 times g (60 min) particulate and supernatant fractions. In the presence of detergent, the particulate fraction contained 40% as much activity as did the supernatant fraction. Detergent-dispersed particulate and partially purified soluble guanylate cyclase preparations were characterized with respect to divalent cation requirements, divalent cation interactions, kinetic behavior, and gel filtration profiles. Both soluble and particulate guanylate cyclases required divalent cation for activity. The soluble preparation was 10 times more active in the presence of Mn-2plus than in the presence of Mg-2plus or Ca-2plus and no detectable activity was seen with Ba-2plus or Sr-2plus. Particulate guanylate cyclase activity was detectable only in the presence of Mn-2plus. Both enzyme preparations required Mn-2plus in excess of GTP for optimal activity at subsaturating amounts of GTP. At near-saturating GTP, the soluble enzyme required excess Mn-2plus, but the particulate enzyme did not. For kinetic analyses the enzymes were considered to require two substrates: metal-GTP and Me-2plus. Apparent negative cooperative behavior was seen with the soluble enzyme when excess Mn-2plus (in excess of GTP) was varied from 0.01 to 0.2 mM; above 0.2 mM excess Mn-2plus classical kinetic behavior was seen with an apparent KMn-2plus of 0.2 mM at near-saturating MnGTP. Similar studies using the particulate preparation yielded only classical kinetic behavior, but the apparent KMn-2plus decreased to near zero when MnGTP was near-saturating. Kinetic patterns for the particulate and soluble enzymes also differed when reciprocal initial velocities were plotted as a function of reciprocal MnGTP concentrations; classical kinetic behavior was seen with the soluble enzyme with an apparent KMnGTP of about 12 muM (at near-saturating excess Mn-2plus), whereas apparent positive cooperative behavior was seen with the particulate preparation (Hill coefficient equals 1.6, S0.5 EQUALS 70 MUM. Ca-2plus "activation" of soluble guanylate cyclase was related to the Mn-2plus:GTP ratio. Activation was most apparent when saturating amounts of Mn-2plus and MnGTP. At relatively high concentrations of Ca-2plus (0.1 to 4 mM), the addition of 10 muM Mn-2plus resulted in a 3- to 5-fold increase in soluble guanylate cyclase activity. In contrast, Ca-2plus sharply inhibited particulate guanylate cyclase activity. Gel filtration profiles of particulate and soluble preparations indicated differences in physical properties of the enzymes. As estimated by gel filtration, particulate (detergent-dispersed)evels. Here, removal of renal tissue is contraindicated. In all renal hy

Animals↗

PubMed1996

Dynamics of soluble adhesion molecule levels in patients with pollinosis.

OBJECTIVES: To define the dynamics of systemic and local soluble adhesion molecule levels and to discuss the role of these molecules in the pathogenesis of allergic rhinitis. DESIGN: Randomized control trial. SUBJECTS: Twelve volunteers with Japanese cedar pollinosis and 7 healthy volunteers. INTERVENTIONS: The levels of soluble intercellular adhesion molecule 1 (sICAM-1), soluble vascular cell adhesion molecule 1 (sVCAM-1), soluble E-selectin, and soluble L-selectin in serum samples and nasal epithelial lining fluids (ELF) from 12 patients with pollinosis were measured 5 times throughout the allergy preseason to postseason, and the results were compared with those from 7 healthy subjects. RESULTS: The levels of sICAM-1 (P < .05) and sVCAM-1 (P < .05) in sera were up-regulated, and the levels of soluble L-selectin (P < .01) in sera were down-regulated during the early stage of the season in the allergic subjects. The difference between the levels of sICAM-1 and sVCAM-1 in sera in the early and mid-season was statistically significant in the allergic subjects (P < .05). The levels of sICAM-1 in ELF were up-regulated during the early and mid-season. The levels of sVCAM-1, soluble E-selectin, and soluble L-selectin in ELF were undetectably low throughout the preseason to postseason. CONCLUSION: There is evidence of the unique stage-dependent differential contributions of various soluble adhesion molecules in the pathogenesis of seasonal allergic rhinitis with a small amount of natural allergen provocation.

Adult↗

PubMed2007

Mutational analysis of protein solubility enhancement using short peptide tags.

Protein aggregation is a common phenomenon. The preparation of highly concentrated protein samples, typically required for biophysical measurements, often involves a time consuming and tedious testing of solvent conditions for improving protein solubility. Here, in a systematic analysis, we have determined the increase in solubility upon the addition of SEP-tags (solubility enhancement peptide tags) containing, one, three, and five lysines or arginines (or six arginines) to either the N or C terminus of our low solubility model protein, bovine pancreatic trypsin inhibitor variant, BPTI-22 (a BPTI variant containing 22 alanines). As anticipated, the BPTI-22 solubility increased in direct relation to the number of charged residues contained in the SEP-tag, and without altering either the activity or the structure of the protein. The largest solubility increases were of 4.2-, 4.8-, and 6.2-folds produced by the addition, at the C terminus, of five lysine (BPTI-22-C5K), five and six arginine residues (BPTI-22-C5R and BPTI-22-C6R), respectively. The increased solubility of the tagged BPTI-22 yielded higher quality NMR spectra (hetero single quantum correlation HSQC spectra; with respect of the signal-to-noise and line shapes) in a much shorter time than for the untagged BPTI-22. Furthermore, tagged samples remained soluble for over ten days, as observed by their HSQC spectra. We believe that lysine- and arginine-based SEP-tags may provide an effective and versatile method for enhancing protein solubility.

Amino Acid Sequence↗

PubMed2006

Equilibrium versus kinetic measurements of aqueous solubility, and the ability of compounds to supersaturate in solution--a validation study.

A novel potentiometric procedure has recently been described for rapid measurement of equilibrium aqueous solubility values of organic acids, bases, and ampholytes that form supersaturated solutions. In this procedure, the equilibrium solubility is actively sought by changing the concentration of the neutral form by adding HCl or KOH titrants and monitoring the rate of change of pH due to precipitation or dissolution in a process called Chasing Equilibrium. In this article, we seek to validate the procedure against a shake-flask protocol for solubility determination. A set of 16 small organic compounds, covering a wide range of solubilities was chosen for the study. Interestingly, while 10 compounds in the study were found to chase equilibrium, the others did not. Kinetic solubility data was also collected. It was noted that kinetic solubility was consistently higher than equilibrium solubility for chasers, but correlated well with equilibrium solubility for nonchasers. The ratio of kinetic to equilibrium solubility indicated a compound's ability to form supersaturated solutions.

Buffers↗

PubMed1980

Solubility of polar organic solutes in nonaqueous systems: role of specific interactions.

The changes in solubility of several polar organic solutes when polar organic solvents are added to a relatively inert solvent such as isooctane were determined. The relative changes in solubility predicted from regular solution theory using solubility parameters often did not agree with the observed results. However, the solubilities could be rationalized mathematically by assuming the formation of specific solute-solvent complexes. Agreement of the thermodynamic data reported here with such models provides further evidence that specific interactions, when they occur, are more important than the bulk properties of the pure components in determining drug solubilities in nonaqueous systems. Specific examples demonstrate the relationship between the solubility and molecular structure of the solute and solvent. For example, solubility can be related to the hydrogen-donating and hydrogen-accepting abilities of the solute and solvent. Steric factors also appear to play a role in solubility, while structural modifications in a solute or solvent molecule far removed from the interactive functional group have little influence on molar solubility changes with the added polar cosolvent.

Anthraquinones↗

PubMed1983

Solubility of hydrocortisone in organic and aqueous media: evidence for regular solution behavior in apolar solvents.

The solubility of hydrocortisone was determined experimentally in a wide variety of solvents. Groups of solvents were selected to emphasize different solute-solvent interactions which can influence the solubility profile of such a large, polyfunctional solute. Regular solution theory for a crystalline solute was shown to be applicable to the solubility behavior of hydrocortisone in solvents that lack strong dipoles and the ability to hydrogen bond. A best-fit solubility parameter of 12.4 (cal/ml)1/2 for hydrocortisone was determined from the latter solubilities and the ideal solubility of hydrocortisone. This solubility parameter estimate was significantly higher than estimates calculated from molar-attraction constants. Even though molar volume ratios between hydrocortisone and the solvents ranged from 2.25 to 3.28, the associated Flory-Huggins entropy term did not seem to be a significant solubility-determining factor. In all cases, the solubility of hydrocortisone in solvents capable of dipole-dipole interactions and hydrogen bonding was shown to be higher by logarithmic orders when compared with regular solution theory predictions. Thus, for this solute, regular solution theory was shown to be appropriate only for solvents where London dispersion forces dominate the interactions between solute and solvent molecules.

Crystallization↗

PubMed1985

Predictive relationships in the water solubility of salts of a nonsteroidal anti-inflammatory drug.

A number of metal and amine salts of the nonsteroidal anti-inflammatory drug 2-(2-fluoro-4-biphenylyl)propionic acid (flurbiprofen) (1) were synthesized, and the water solubilities of these materials were investigated. The solubility of flurbiprofen versus pH is in excellent agreement with the theoretical profile which assumes an intrinsic solubility of 5.0 X 10(-5) M for the free acid and a pKa of 4.22. The solubility determination of 1:1 amine salts of slightly soluble carboxylic acids is complicated by possible precipitation of the free acid when the salt is dissolved in water. The lower than expected apparent salt solubility seen when this phenomenon occurs is referred to as the "stoichiometric solubility." A theoretical treatment delineating three distinct regions in the phase solubility diagram for the tromethamine salt of flurbiprofen illustrates the care which must be taken in characterizing the system for salt solubility determinations. A multiple linear regression analysis was carried out to determine the relationship between the log Ksp of six amine salts and their melting points and cation hydrophilicities. While a strong dependence of Ksp on melting point was found, there was not a significant correlation between Ksp and amine cation hydrophilicity.

Anti-Inflammatory Agents↗

PubMed1992

Evaluation of soluble CD 14 and neopterin as serum parameters of the inflammatory activity of pulmonary sarcoidosis.

CD14 represents the most specific marker for monocytes/macrophages. It has been demonstrated in vitro that monocytes/macrophages lose this antigen upon activation. Results of studies investigating the expression of membrane-bound CD14 on the surface of monocytes/macrophages in sarcoidosis patients are controversial. To investigate whether the soluble form of CD14 reflects monocyte/macrophage activation in sarcoidosis, serum levels of soluble CD14 were determined concurrently with other serum markers of monocyte/macrophage activation (neopterin, angiotensin-converting enzyme) in 50 consecutive patients with bioptically confirmed sarcoidosis. The patients were allocated to three groups according to disease activity and therapy. The soluble interleukin-2 receptor in serum and the CD4/CD8 ratio in lavage fluid were used to monitor T-lymphocyte activation. No significant differences in serum or bronchoalveolar lavage levels of soluble CD14 were observed in patients with active or inactive sarcoidosis. Despite the presence of normal soluble CD14 serum concentrations a correlation with serum neopterin and angiotensin-converting enzyme was found in active sarcoidosis (soluble CD14 versus neopterin, rs = 0.61 and 0.65, P < 0.05 and 0.01, respectively; soluble CD14 versus angiotensin-converting enzyme, rs = 0.6 and 0.72, P < 0.02 and 0.003, respectively). A correlation between soluble CD14 and parameters of T-cell activity was not demonstrated. We therefore conclude that soluble CD14 in serum is not a useful clinical parameter in establishing disease activity in sarcoidosis. Neopterin and angiotensin-converting enzyme serum concentrations are parameters with higher sensitivity, although specificity remains very low. The exact role of CD14 antigen in sarcoidosis requires further investigation.

Antigens, CD↗

PubMed1990

Are soluble and membrane-bound rat brain acetylcholinesterase different?

Salt-soluble and detergent-soluble acetylcholinesterases (AChE) from adult rat brain were purified to homogeneity and studied with the aim to establish the differences existing between these two forms. It was found that the enzymatic activities of the purified salt-soluble AChE as well as the detergent-soluble AChE were dependent on the Triton X-100 concentration. Moreover, the interaction of salt-soluble AChE with liposomes suggests amphiphilic behaviour of this enzyme. Serum cholinesterase (ChE) did not bind to liposomes but its activity was also detergent-dependent. Detergent-soluble AChE remained in solution below critical micellar concentrations of Triton X-100. SDS polyacrylamide gel electrophoresis of purified, Biobeads-treated and iodinated detergent-soluble 11 S AChE showed, under non reducing conditions, bands of 69 kD, 130 kD and greater than 250 kD corresponding, respectively, to monomers, dimers and probably tetramers of the same polypeptide chain. Under reducing conditions, only a 69 kD band was detected. It is proposed that an amphiphilic environment stabilizes the salt-soluble forms of AChE in the brain in vivo and that detergent-soluble Biobeads-treated 11 S AChE possess hydrophobic domain(s) different from the 20 kD peptide already described.

Acetylcholinesterase↗

PubMed2003

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.

Absorption↗

PubMed1986

Effect of pH on the speciation and solubility of divalent metals in human and bovine milks.

Computer models estimated the ligand speciation and solubility of calcium, magnesium, zinc, and copper over a pH range for low molecular weight fractions characteristic of either human or bovine milks. Above pH 4 calcium is the only metal predicted to precipitate. Most of the remaining soluble calcium, magnesium, and zinc should be complexed with citrate. The solubility of calcium, magnesium, and zinc in human and bovine milks was measured experimentally from pH 2 to 7. The solubility of all three metals decreased as the pH increased. Calcium and zinc were soluble over a narrower pH range in bovine milk than in human milk. Increasing the levels of either calcium or inorganic phosphate alone in decaseinated human milk did not affect the solubility of zinc, but when both calcium and inorganic phosphate were added at levels comparable to bovine milk the solubility of zinc decreased at the higher pH's. The decreased solubility of zinc in skimmed milks in pH's characteristic of the small intestine is likely due to coprecipitation of zinc with calcium phosphate--a reaction not predicted for milk systems from known chemical solubility product data.

Animals↗