Determination of Ursolic Acid and Ursolic Acid Lactone in the Leaves of Eucalyptus tereticornis by HPLC

A simple isocratic HPLC method has been developed for the simultaneous quantification of two bioactive triterpenes, ursolic acid and ursolic acid lactone in E. tereticornis leaves. Samples were analyzed on RP-18 (4.6 x 250 mm, 5 mu m) column with methanol and water acidified to pH 3.5 with TFA (88:12) at 210 nm. The method was validated and applied for the simultaneous quantification of the individual triterpenes in E. tereticornis extract. The calibration curves were linear over a concentration range of 0.05-0.3 mg mL(-1) (r = 0.999 and 0.998, respectively). The limits of detection and quantification were 0.190 and 0.644 mu g for ursolic acid, and 0.176 and 0.587 mu g for ursolic acid lactone, while the percentage recoveries were 97.32 and 96.23% for ursolic acid and ursolic acid lactone, respectively. This is the first report on the HPLC method of ursolic acid lactone with high precision and accuracy.