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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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The components of traditional Chinese medicine(TCMCs) are the basic unit of raw materials for Chinese medicines, and their physical and chemical properties directly affect the choice of dosage forms and the optimization of prescriptions. However, most of TCMCs are multi-component complex systems, and the characterization of their overall properties is still in the exploration stage. On the basis of biological activity, the representative components are determined, and then the individual characteristics are fitted with the weight coefficient of efficacy contribution rate, which may provide reference for characterizing the overall properties of TCMCs. In this study, with the pharmacological effects of isoproterenol(ISO)-induced myocardial ischemia in rats as the indicators, the pharmacodynamic contribution rates of three representative components of chishao terpene glucoside components(CSTGCs) were evaluated by the normalization weighting method. The contribution rates of paeoniflorin, paeoniflorin and benzoylpaeoniflorin were 54.87%, 32.46% and 12.67%, respectively. The oil-water partition coefficients of paeoniflorin, albiflorin, benzoylpaeoniflorin in water and buffer solutions with different pH values were measured, and the oil-water partition coefficients of CSTGCs were characterized by the weight of their pharmacodynamics contribution rate. The results showed that the apparent oil-water partition coefficient(log P) of CSTGCs in the phosphate buffer system such as n-octanol-water(pH 2.0, 2.5, 5.0, 5.8, 6.8) were 0.18-0.22, indicating that CSTGCs have common absorption and low permeability, providing basis for the preparation of CSTGCs.
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Animals , Rats , Coronary Artery Disease , Glucosides , Medicine, Chinese Traditional , Myocardial Ischemia , Terpenes , WaterABSTRACT
To study the biopharmaceutics characteristics of paris saponin VII (PSVII). The solubility of PSVII was evaluated by measurement of the equilibrium solubility in different solvents and media. The permeability of PSVII was evaluated by measuring the oil/water partition coefficient (lgP) and determining the apparent permeability coefficient (PC) on a mono-layer Caco-2 cell model. The effects of p-glycoprotein and multidrug resistance related protein 2 on PSVII transport in mono-layer Caco-2 cell model were further investigated. Finally, the small intestinal absorption of PSVII was investigated in rat. In solvents of different pH, the equilibrium solubility of PSVII was quite low, and the dose number of PSVII was larger than 1. The lgP of PSVII was less than 0. The apparent permeability coefficient [PC] of PSVII in mono-layer Caco-2 cell model was less than 14.96 × 10 cm·s, and the efflux ratio of PSVII in mono-layer Caco-2 cell model was less than 1. The transport rate of PSVII in mono-layer Caco-2 cell model was not affected by the inhibitors of p-glycoprotein and multidrug resistance related protein 2. After oral administration, PSVII could be detected in rat intestinal contents, but could not be detected in the small intestinal mucosa. PSVII showed low solubility and permeability, which would result in low oral bioavailability in clinic. PSVII belonged to Class IV compound in biopharmaceutics classification system.
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Objective: To study on the physical and chemical properties of dichroa alkali hydrochloride and to establish a method for the determination of entrapment efficiency of dichroa alkali hydrochloride liposomes. Method: HPLC was used to determine the content of dichroa alkali hydrochloride with mobile phase of acetonitrile-water-triethylamine-glacial acetic acid(9:91:0.35:0.75) and detection wavelength at 265 nm.The oil-water partition coefficient of this compound in different pH range was measured by shake flask method.The stability of the dichroa alkali hydrochloride in phosphate buffer solution with different pH after sterilization at 125℃ for 30 min was investigated.Ammonium sulfate gradient method was used to prepare dichroa alkali hydrochloride liposomes.The microcolumn was prepared by dextran gel and cation exchange resin,respectively.Then the free drug and liposome were separated by centrifugation,the drug content was measured,and the encapsulation efficiency was calculated.The t-test was performed using SPSS 20.0 software,the differences between these two methods were compared. Result: In the pH 6-9,the oil-water partition coefficient of dichroa alkali hydrochloride increased with increasing of pH,which was between 0.016 and 1.44;the recovery rate of dichroa alkali hydrochloride after sterilization was 37.16%-57.91%.Between the dextran gel microcolumn centrifugation and the cation exchange resin microcolumn centrifugation,there was no significant difference in the entrapment efficiency of the liposomes. Conclusion: Dichroa alkali hydrochloride is suitable for preparation of liposomes.However,its stability is not ideal,so the experimental temperature should be strictly controlled in the preparation process.Dextran gel microcolumn centrifugation and cation exchange resin microcolumn centrifugation can be used to determine the entrapment efficiency of dichroa alkali hydrochloride liposomes,and the cation exchange resin microcolumn centrifugation is suggested after comparison.
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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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Nuciferin is the main active ingredients in Nelumbinis Folium， which was proved to have good hypolipidemic， antioxidative and anti-inflammatory bioactivities. Currently， pharmacokinetic studies of nuciferin showed different results based on different animal models. evaluation experiments were low-cost， stable and controllable. Biopharmaceutical classification system(BCS) was an effective and reliable simulation method to evaluate the bioavailability of oral drugs. It was a scientific framework for classifying drugs or active pharmaceutical ingredients(API) according to their solubility and impermeability . In the study， BCS was applied in an active ingredient in traditional Chinese medicine(TCM)， which was consisted of numerous chemical components. To study the equilibrium solubility of nuciferine， ideal solution model， Ape blat model and polynomial model were adopted. The permeability was measured based on partition coefficient(logP) and distribution coefficient(logD). Besides， apparent permeabilities of Caco-2 cells and murine intestine tissues were evaluated. Nuciferine was classified as BCSⅠ， since it had a good solubility and permeability in all methods under acidic conditions. However， in neutral and alkaline environments， nuciferine was classified as BCSⅣ by using everted intestinal sac. It indicated that the species of experimental animals has a significant influence on the absorption of nuciferine. This experiment can provide data support to the prediction in a complex environment(medicinal materials and absorbed parts). The application of BCS on TCM ingredients provided a new method to evaluate and screen out the druggability of TCM ingredients.
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Animals , Humans , Mice , Aporphines , Chemistry , Biological Availability , Biological Products , Classification , Biopharmaceutics , Caco-2 Cells , Intestinal Absorption , Nelumbo , Chemistry , Permeability , Plant Leaves , Chemistry , SolubilityABSTRACT
Objective To perform a preformulation study for a new antirheumatic drug DK-507 so as to provide theoretical basis for its preparation research.Methods The appearance,crystal form and solubility of DK-507 were investigated.A high perfor-mance liquid chromatography(HPLC)method for the quantitative determination of DK-507 was established.The apparent oil/water (O/W)partition coefficient of DK-507 and the equilibrium solubility of the drug under different pH conditions were determined. Re-sults DK-507 is a white crystalline powder,which is odorless,tasteless and insoluble in water.The quantitative HPLC method for the DK-507 determination showed a good linearity in the range of 10-80 μg/ml(R=0.9998).The apparent O/W partition coefficient of DK-507 was determined to be 1.80.In the different pH solutions,the solubility of DK-507 showed a W-form change,with poor solubili-ties in lower pH solutions,which showed a gradient improvement with the increase of the solution pH values.Conclusion The quanti-tative HPLC method for the DK-507 determination,established in this study,is accurate and reliable.The present results indicate that DK-507 is a water-insoluble drug,and according to the O/W partition coefficient,DK-507 seems likely to be prepared into oral solid preparations.
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Objective To study the physical-chemical parameters of antiviral drug GZ 914 and provide data for the preparation design .Methods The appearance , crystal structure and solubility of GZ 914 were investigated .An HPLC method was established to determine the content of GZ 914 in vitro before oil/water partition coefficient and solubility in different pH experiments were calculated .Results GZ914 was a straw yellow powder with a crystalline structure , low water-solubility and good lipotropy .The HPLC method had a good linear relationship within the range of 12-60 μg/ml (r=0.9998).The oil/water partition coefficient of GZ914 was 1.9.Conclusion This analytical method is accurate and reliable.The oil/water partition coefficient indicates that the drug could be formulated as an oral solid preparation.
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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: 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 study the physical- chemical parameters of curcumenol so as to design its optimal preparations. Methods An HPLC method was established to determine the content of curcumenol. Based on the method, the equilibrium solubility, oil/water partition coefficient and stability of curcumenol were investigated. Results The equilibrium solubility in the pure water was 1.93 mg/ml (25 °C) and 2.6 mg/ml (37°), respectively. The oil/water partition coefficient was in the range of 2.2-3.0. Curcumenol solution was unstable at high temperature under light conditions, while pH value showed little effect. Conclusion The analytical method is accurate and reliable. The solubility of curcumenol can be described as strong lipotropic and slightly soluble in water. Nanoformulation and solubilization technologies could improve its bioavailability significantly. Curcumenol should be stored and operated in a dark and cool place.
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Objective To study the physical-chemical parameters of curcumenol so as to design its optimal preparations. Methods An HPLC method was established to determine the content of curcumenol. Based on the method,the equilibrium solubility, oil/water partition coefficient and stability of curcumenol were investigated. Results The equilibrium solubility in the pure water was 1.93 mg/ml(25℃)and 2.6 mg/ml(37℃),respectively. The oil/water partition coefficient was in the range of 2.2-3.0. Curcumenol solution was unstable at high temperature under light conditions,while pH value showed little effect. Conclusion The analytical method is accurate and reliable. The solubility of curcumenol can be described as strong lipotropic and slightly soluble in water. Nano-formulation and solubilization technologies could improve its bioavailability significantly. Curcumenol should be stored and operated in a dark and cool place.
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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: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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This study was aimed to determine the solubility an d oil-water partition coefficient of main active com-ponents in Ge-Gen Qin-Lian (GGQL) Tablets (puerarin, baicalin and berberine hydrochloride) in phosphate buffer solution of different pH values and under the background of many components. Solubility of puerarin, baicalin and berberine hydrochloride in different medium pH, and oil-water partition coefficient of the octanol-water and oc-tanol-buffer system were determined by HPLC method. The results showed that the solubility and oil-water partition coefficient of puerarin, baicalin and berberine hydrochloride were varied with the change of pH, and varied under the background of components. At pH 7.4, the solubility was the biggest;puerarin was 7.56 mg·mL-1;baicalin was 17.07 mg·mL-1; berberine hydrochloride was 3.57 mg·mL-1. Oil-water partition coefficient P of these components at pH 1.0 was bigger;puerarin was 0.420 (lgP=-0.38);baicalin was 10.783 (lgP=1.03);berberine hydrochloride was 0.267 (lgP=-0.57). It was concluded that lipid solubility of puerarin, baicalin and berberine hydrochloride at pH 1.0 was better. It was speculated that better absorption in the stomach, and low lipid solubility under other pH. It was speculated that lipid solubility may be one of the reasons affecting the intestinal absorption.
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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 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.