Measurements of distribution coefficients and lipophilicity values for oleanolic acid and betulinic acid extracted from indigenous plants by hollow fibre supported liquid membrane

Abstract

Hollow fibre supported liquid membrane (HFSLM) has been applied in the measurements of distribution constants, K_D and lipophilicity (log P) values for the isomeric triterpenic acids, betulinic acid (BA) and oleanolic acid (OA) isolated from indigenous plants. The results have shown that BA had an optimum pH of 3.5 while the optimum sample pH for OA was ranging from 0.5 to 2.5. The log P values obtained for BA and OA were 6.61 and 6.12, respectively. The K_D value obtained for BA was 0.29 while that for OA 0.16. The method has advantages of simplicity, use of minimal organic solvents and the ability to selectively extract only one isomer (OA) in the mixture with BA by optimizing pH conditions.

KEY WORDS: Betulinic acid, Oleanolic acid, Hollow fibre supported liquid membrane, Distribution coefficient, Lipophilicity

Bull. Chem. Soc. Ethiop. 2011, 25(3), 321-332.