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Objective: To prepare the taxifolin and determine its apparent oil-water partition coefficient in different media, and to study the mechanism of absorption and transport of taxifolin in Caco-2 cell model. Methods: Taxifolin was prepared by enzymolysis. HPLC was used to determine the saturated solubility of taxifolin in 37 ℃, different pH buffer solution and water, apparent oil-water distribution coefficient of taxifolin obtained by calculation formula of oil-water distribution coefficient; CCK-8 experiment was used to investigate the safe concentration range of taxifolin in Caco-2 cells, and then the single-layer model of Caco-2 cells was used to study the mechanism of bilateral transmembrane absorption and transport. CCK-8 experiment was used to investigate the safe concentration range of taxifolin in HDMEC cells. The inflammatory model of HDMEC cells induced by lipopolysaccharide was established, and the activity of lactic dehydrogenase was detected by the intervention of floxacin. The activity of lactic dehydrogenase was detected by lactic dehydrogenase kit. Results: The lgP values of taxifolin in the following solvents were 0.29 (0.1 mol/L hydrochloric acid), 0.48 (pH 2.0), 0.46 (pH 5.8), 0.34 (pH 6.8), 0.26 (pH 7.4), and 0.38 (water), respectively; There was no significant toxic effect on Caco-2 cells in the range of 50-500 μg/mL; There was no significant difference in Papp value of bilateral transport between different concentrations of taxifolin in Caco-2 monolayer cell model, and it was less than 1 × 10-6 cm/s and ER was less than 2. There was no significant toxic effect on HDMEC cells in the range of 50-300 μg/mL; After treatment with taxifolin, compared with LPS stimulation group, the activity of LDH in each treatment group was decreased significantly (P < 0.05), and the activity of LDH was decreased significantly in the range of 50-100 μg/mL, and tended to be stable in the range of 100-250 μg/mL. Conclusion: Taxifolin is a kind of drug which is difficult to absorb in the intestine. The mechanism of transmembrane transport is passive transport. It can inhibit the inflammation of hdmec cells induced by LPS and has anti-inflammatory activity.
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Objective:To determine the equilibrium solubility and the apparent oil/water partition coefficients of nicotinate-curcu-min ester,so as to provide basis for the new formula design. Methods:Nicotinate-curcumin ester was dissolved in buffer solution with pH of 1.2-7.8. HPLC was used to detect the equilibrium solubility of nicotinate-curcumin ester in various solutions. The apparent oil/water partition coefficients in octanol-water and octanol-buffer solution system were measured by a shaking-flask method. Results:The solubility of nicotinate-curcumin ester in pH 6.8 was the highest. The apparent oil-water partition coefficients of nicotinate-curcumin ester in pH 1.2,5.8,6.5 and 7.8 were lgPapvalues within the range(lgPap=1.69-1.98) beneficial to the absorption in vivo. But in pH 2,5 and 6.8,the lgPapvalues were greater than 2 with strong lipophilicity. Conclusion:The equilibrium solubility as well as ap-parent oil/water partition coefficients of nicotinate-curcumin ester is greatly influenced by the pH value of media. In the pH value with relatively high solubility,lipophilicity is stronger,suggesting it is difficult to be absorbed by the body and needs to be further studied on dosage forms.
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Objective:To determine the equilibrium solubility and the apparent oil/water partition coefficient of nebivolol hydrochloride to provide experimental basis for the development of new preparations.Methods:The concentration of nebivolol hydrochloride was determined by an HPLC method,and a saturated solution method and a shake-flask method were respectively applied to determine the equilibrium solubility and the apparent oil/water partition coefficient of nebivolol hydrochloride in water,0.1 mol·L-1 HCl solution and phosphate buffer solution with different pH values(pH2.0,pH6.8,pH7.4 and pH8.0).Results:At (37±0.5)℃,the equilibrium solubility of nebivolol hydrochloride in water and in 0.1 mol·L-1 HCl solution was 722.53 μg·ml-1and 56.07μg·ml-1,respectively.The apparent oil/water partition coefficient (Log P) of nebivolol hydrochloride was 1.17 and 1.32,respectively.Within the pH range of 2.0-7.4,with the increase of pH value, the equilibrium solubility and the Log P decreased and increased,respectively,while pH value increased from 7.4 to 8.0,the equilibrium solubility of nebivolol hydrochloride increased and Log P decreased.Conclusion:The method is accurate and reliable.Nebivolol hydrochloride has poor water solubility,and the equilibrium solubility and the Log P are both influenced by pH values.
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Objective To determine equilibrium solubility and apparent oil/water partition coefficient of ephedra alkaloid in the compatibility Ephedrae Herba-Aconiti Lateralis Radix Praeparata; To provide a basis for transdermal delivery.Methods The extract was prepared by 70% ethyl alcohol and D101 macroporous absorbent resins. Dissolvability of its main effective components (ephedrine and pseudoephedrine) in the compatibility Ephedrae Herba-Aconiti Lateralis Radix Praeparata was determined by precipitation method and HPLC method; the oil/water partition coefficient of ephedrine and pseudoephedrine in n-octanol-water buffer solution system were determined by shaking flask method.Results The extract had optimum solubility in methyl alcohol and acetonitrile, and ephedrine and pseudoephedrine had optimum solubility in buffered solution of pH 7.4. Oil/water partition coefficient of ephedrine and pseudoephedrine in n-octanol-water system was 0.101 with lgP=-0.99 and 0.076 with lgP=-1.12. Oil-water partition coefficients of ephedrine and pseudoephedrine in the extract were affected by pH.Conclusion The extract has optimum solubility in high polar solvents. Ephedrine and pseudoephedrine have certain fatsoluble and water-soluble in suitable pH, which was beneficial for transdermal absorption.
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Objective To study the physical and chemical properties of silibinin; To lay foundation for optimal formulation design.Methods The high performance liquid chromatography method was used to detect the equilibrium solubility of silibininin in various solutions. The partition coefficients of silibinnin in the n-octalution-water and n-octalution-buffer solution systems were determined by shaking flask method. The destructive tests were carried out on silibinin.Results The equilibrium solubility of silibininin at 25℃ was 1.352 mg/L in water and the largest in acetonitrile, and increased in basic buffer solutions and after adding surfactants, of which sodium dodecyl benzene sulfonate was the strongest in solubilizing ability. The apparent oil-water partition coefficient of silibinnin was 61.39. Silibinnin was unstable in the acidic, basic, oxidizing and reducing solutions.Conclusion The experiment results can provide references for designing new preparations of silibinin.
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Objective: Taking luteolin-7-O-β-D-glucuronide, rosmarinic acid, and tilianin as indexes, the concentration of extracts from Dracocephalum moldavica (EDM) and their index components in various media, surfactant solution, and apparent oil/water partition coefficient (P) was detected in different pH values, then the stability of EDM in artificial gastrointestinal fluid was investigated. This research would give the reference for the selection and preparation of further novel formulation. Methods: Apparent solubility of EDM in various media and surfactant solution was determined by precipitation method and a shake flask method was used to determine the P of octanol-water/phosphate buffer salt, the stability of EDM in artificial gastrointestinal fluid was investigated. HPLC was adopted to determine the concentration of the index components with Shim-pack ODS column (250 mm×4.6 mm, 5 μm), mobile phase of acetonitrile (A)-0.5% formic acid aqueous solution (B) for gradient elution (0-30 min, 15% A; 30-55 min, 15%→25% A; 55-80 min, 25%→35% A) as the mobile phase at a flow rate of 1.0 mL/min. The detection wavelength was set at 324 nm and the column temperature was maintained at 35℃. Results: At 37℃, the equilibrium solubility of the three index components in acid buffer solution increased obviously in water, but in alkaline the buffer solution of the equilibrium solubility decreased with pH increasing. In 32 g/L sodium dodecyl sulfate solution, the equilibrium solubility of luteolin, rosmarinic acid, and tilianin increased to 1679.61, 1249.2, and 2765.27 μg/mL. The P of luteolin-7-O-β-D-glucuronide, rosmarinic acid, and tilianin were 0.1731 (lgP=-0.7618), 0.068 4 (lgP=-1.1650), and 1.0829 (lgP=0.0346), and increased as pH rising. EDM in artificial gastrointestinal fluid was stable (except luteolin). Conclusion: The methods can be used to determine the apparent solubility, the P value of the extracts and their index components; The EDM in artificial gastrointestinal fluid is stable. The research would give the reference for the selection and preparation of the further novel formulation.
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OBJECTIVE:To determine the equilibrium solubility of albendazole(ABZ)and its apparent oil-water partition coef-ficient. METHODS:The equilibrium solubility of ABZ in various solutions was determined at 37 ℃ by HPLC and saturation solu-bility method,including water,7 kinds of common organic solvents with different polarities(methanol,ethanol,etc.),organic ac-id(oleic acid,glacial acetic acid,lactic acid,formic acid),hydrochloric acid of pH 1.2,phosphate buffer solution(PBS)of dif-ferent pHs(2.0-7.8)and 6 kinds of common surfactants with mass concentrations of 10,50 and 100 mg/ml(polysorbate 80,polox-amer,etc.). The apparent oil-water partition coefficient(P)was calculated with the concentration ratio of ABZ in oil phase(N-oc-tyl alcohol)and water phase(water and PBS of different pHs)after partition equilibrium. RESULTS:The equilibrium solubility of ABZ reached(0.26±0.02)μg/ml in water,with the lgP of 3.66±0.01. The equilibrium solubility of ABZ in common organic sol-vents and organic acids was higher than in water. The higher the polarity of the organic solvent was and the weaker of organic acid was,the weaker of its ability to solubilize ABZ would be. The equilibrium solubility of ABZ was higher in the medium of pH 1.2-2.5 than in that of pH 5.0-7.8. The ability of the surfactant to solubilize ABZ was related to its type,and the higher of the mass concentration of the surfactant was,the stronger of its ability to solubilize ABZ became. lgP was less than 1.6 at pH 1.2-2.0 and changed little at pH 5.0-7.8 [(3.71 ± 0.26)-(3.68 ± 0.26)]. CONCLUSIONS:ABZ is insoluble in water. Its equilibrium solubility demonstrates a negative correlation with the polarity of the organic solvent and a positive correlation with the acidity of the organic acid and with the mass concentration of the surfactant. It has higher water solubility and lower lipid solubility in a strong acidic en-vironment,and higher lipid solubility and weaker water solubility in weak acidic,weak basic and neutral environments.
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Objective To establish a reversed-phase high performance liquid chromatograph ( RP-HPLC ) method for determination of equilibrium solubility and oil/water partition coeficient of phloridzin in different solvents. Methods A RP-HPLC method was established to detect the concentration of phloridzin in water and different organic solvents. The partition coefficients in the n-octanol-water/buffer solution systems of phloridzin were determined by shaking flask method. The Inertsil ODS-3 (4.6 mm×150 mm, 5μm) column was used and the detection wavelength was 284 nm.The flow rate was 1.0 mL??min-1, and acetonitrile-0.05% phosphoric acid(30??70)was used as mobile phase. Results The equilibrium solubility of phloridzin was 2.07 mg??mL-1 in water and 838.63 mg??mL-1 in methanol at 25 ℃.A good linear relationship of phloridzin was obtained within the range of 0.054 9-1.098 0 μg.The regression equation was Y=2 152.9X+7.26 (r=0.999 9).The solubility values of phloridzin were higher in ethanol and propylene glycol than in other solvents. Conclusion RP-HPLC method is simple, quick and accurate for the determination of phloridzin.Phloridzin was almost insoluble in petroleum ether and poorly soluble in water.The equilibrium solubility is higher in methanol than in other solvents. The apparent distribution coefficient of phloridzin varies significantly with pH under the alkaline conditions but less in the acidic solution.
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Objective To determine the solubility and apparent oil/ water partition coefficient of sitafloxacin in different solvents. Methods High performance liquid chromatography (HPLC) was used. The column was Dikma Diamonsil C18 (2) (4. 6 mmí250 mm,5 μm). The mobile phase was 0. 05 mol·L-1 KH2 PO4 solution (pH was adjusted with H3 PO4 to 2. 4)-acetonitrile (7030). The column temperature was set at room temperature. The flow rate was 1. 0 mL·min-1 . The detection wavelength was 295 nm and the injection volume was 10 μL. The solubility of sitafloxacin and the apparent oil/ water partition coefficient at pH 2. 0,4. 3,5. 8,6. 6,7. 4,8. 0,10. 0 and 11. 2 were determined. Results The equilibrium solubility of sitafloxacin in water was 0. 44 mg·mL-1 and the apparent oil/ water partition coefficient was 0. 23 (lgP= -0. 64) at (37±2) ℃ . Sitafloxacin has the lowest equilibrium solubility (0. 13 mg·mL-1 ) and the highest apparent oil/ water partition coefficient in pH7. 4 buffer solution system. At pH>10 and pH<5. 8,the solubility of sitafloxacin increased obviously and apparent oil/ water partition coefficient decreased. Conclusion Sitafloxacin is insoluble in water and also poorly soluble in oil,but its solubility could be improved significantly in acidic or alkaline solution.
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OBJECTIVE: To study the physical and chemical properties and transdermal delivery characteristics oi capsaicin. METHODS: Equilibrium solubility method, ultraviolet spectrophotometry, bottle-shaking method, differential scanning ealorimetry (DSC) and in vitro diffusion cell method were used to determine the apparent solubility, dissociation constant, apparent oil/water partition coefficient, melting point and percutaneous penetration of capsaicin, respectively. And the permeation characteristics were evaluated by lag time method. RESULTS: Capsaicin was slightly dissolved in water, and the apparent solubility was (22.85 ± 0.06) mg · L-1. It was a weak base with a dissociation constant of (10.25 ± 0.11). The apparent oil/water partition coefficient of capsaicin changed with the pH value, and increased when pH was greater than 8. Its melting point was 60.20°C. The residence time(ttag) was (2.437 ± 0.273) h, the permeability coefficient (P) (7.012 ± 0.341) × 10-2cm · h-1, and the percutaneous penetration rate (Js) (4.647 ± 0.226) μg · cm-2 · h-1. CONCLUSION: Capsaicin possesses appropriate physical and chemical properties for percutaneous penetration and exhibits excellent percutaneous penetration.
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Objective:To determine the equilibrium solubility of zolmitriptan in various media and its partition coefficients for the n-octanol-water/buffer solution systems.Methods:A high performance liquid chromatography was established and used to detect the concentration of zolmitriptan;the partition coefficients for the n-octanol-water/buffer solution systems of zolmitriptan were determined by shaking flask method.Results:The equilibrium solubility of zolmitriptan in water was 12.6 g/L at 37℃.The equilibrium solubility of zolmitriptan were 1 382.0,553.0,85.2,71.5,47.1,11.5 and 4.85 g/L in buffer solutions with pH values of 3.6,4.5,6.0,6.8,7.4,8.0 and 9.0 respectively.Papp of zolmitriptan was 0.013 in water and were 0.04,0.06,0.14,0.20,0.23,0.25 and 1.44 in buffer solutions with different pH values.Conclusion:In the range of pH3.6 to pH 9.0,the equilibrium solubility of zolmitriptan was decreased while the apparent oil/water partition coefficient was increased with the increasing of pH values.
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OBJECTIVE: To study the equilibrium solubility of aesculin and its apparent oil/water partition coefficient,and to provide basis for absorption mechanism study.METHODS: Equilibrium solubility of aesculin at the pH of 1.2～8.0 was determined by saturation method.The apparent oil/water partition coefficients of aesculin were determined by shaking flask method.RESULTS: The equilibrium solubility of aesculin at the pH of 1.2～6.8 was fluctuated slightly;it increased rapidly at the pH of 7.4;the maximum equilibrium solubility of aesculin was obtained at the pH of 8.0(10.58 g?L-1).The oil/water partition coefficient of aesculin changed slowly at the pH of 1.2～6.0;it decreased significantly at the pH of 6.0;the minimum oil/water partition coefficient was obtained at the pH of 8.0(0.03).CONCLUSIONS: The equilibrium solubility of aesculin and its apparent oil/water partition coefficient are associated with the pH of medium.The reason that aesculin has no effect on uric acid after oral administration is relevant to poor gastrointestinal tract absorption ability.