Objective:To determine the dissociation constants of syringopicroside and its partition coefficients for the n-octanol-water/buffer solution systems.Method: To determine the dissociation constants of syringopicroside were determined by UV-visible spectrophotometer

at the same time

the partition coefficients in the n-octanol-water /buffer solution systems of syringopicroside were determined by shaking flask method.Result: The pka value is 9.628 4±0.14

and the n-octanol/water partition coefficient Papp is 1.206 9（logPapp=0.081 7）.When the pH is 4.5

5.5

6.5

7.5

8.5

the n-octanol/water partition coefficient Papp is 1.388 1

1.352 9

1.335 8

1.370 4

1.133 3 respectively

indicating that there is little effect on the n-octanol/water partition coefficient of syringopicroside in different pH values buffer solution.Conclusion: In the physiological environment

drugs most existed as most molecular state.The syringopicroside has good hydrophilicity

but poor liposolubility

it maybe affect the absorption

distribution of syringopicroside and the design of dosage forms.