论文部分内容阅读
Stepwise elution modes have been frequently applied in the CCC separation to isolate compounds with a large range of polarities.During the preparation of Dysosma versipellis (Hance) by HSCCC,all the compounds can be separated in a short time in hexane-ethyl acetate-methanol-water (4646) system,but compounds 1 ( 4′-demethylpodophyllotoxin )and 2 (β-peltatin-5-O-β-D-glucopyranoside ) cannot be separated soundly.In hexane-ethyl acetate-methanol-water (4637) system,compounds 1 and 2 can be separated much better,while it takes a much longer time.When a stepwise elution mode is applied,sound separation and short time are obtained.In this work we applied two stepwise elution modes--Linear solvent gradient CCC separation and Step-gradient CCC separation.And Step-gradient CCC separation proved more effective in this work.In linear solvent gradient CCC separation,the changes of the system are more mitigatory and the reduction of the stationary phase exists during the whole changing process.While in the step-gradient CCC separation,new hydrodynamic equilibrium can be established more quickly.And we found that the reduction of the stationary phase was the same in the two modes.The two modes are both effective methods for quick separations.According to different separation,one more effective mode should be selected.Figure2.The elution curves of the preparative CCC.1.4′-demethylpodophyllotoxin 2.β-peltatin-5-O-β-D-glucopyranoside 3.β-peltatin 4.podophyllotoxin.CCC separation conditions: A: Stationary phase,the upper phase of HEMWat (4646).Mobile phase,the lower phase of HEMWat (4646),Retention of the stationary phase,59.26%.B: A Stationary phase,the upper phase of HEMWat (4637).Mobile phase,the lower phase of HEMWat (4637),Retention of the stationary phase,61.11%.C: Stationary phase,the upper phase of HEMWat (4637).Mobile phase,0-120 min,the lower phase of HEMWat (4637),120-255 min,the lower phase of HEMWat (4637) from 100% to 0 and the lower phase of HEMWat (4646) from 0 to 100%,after 255 min,the lower phase of HEMWat (4646).D: Stationary phase,the upper phase of HEMWat (4637).Mobile phase,0-120 min,the lower phase of he HEMWat (4637),after 120 min,the lower phase of HEMWat (4646).Flow rate,2 mL/min.Rotation speed,900 rpm.Detection,254 nm.Sample size,77 mg of the fraction two was prepared by dissolving the crude in a solution composed of the upper and lower phases (1:1,v/v,4 mL of the total volume).