Simultaneous Quantification of Four Triterpenoids in Eucalyptus globulus Leaves and Barks using an Optimized HPTLC Method

Eucalyptus globulus is one of the most important medicinal plants known for its volatile oil content. It has several uses in respiratory disorders as well as cough and cold, due to the presence of certain triterpenoids. In the present work a simple, consistent, and robust densitometric HPTLC method was devised and validated for simultaneous estimation of four triterpenoids in E. globulus leaves and bark, namely ursolic acid, betulinic acid, oleanolic acid, and lupeol. Various extraction procedures, including maceration, ultra sonication, heat reflux, and Soxhlet, were utilized to produce optimal extraction conditions of four triterpenoids from the plant sources. Pet. ether: ethyl acetate: acetone (8:2:0.5v/v/v) was used as the mobile phase for the chromatographic separation. After derivatization, the measurement of four triterpenoid was done using densitometric reflection/absorption mode at 366nm. In the linear working concentration range of 0.25-1.25µg/spot, precise quantification of UA, BA, OA, and lupeol were done with good correlation (r²=0.9917, 0.9986, 0.9950 and 0.990, respectively). Soxhlet extraction method provided best extraction yield, selectivity, and efficiency for all four triterpenoids. By this method, the estimated amounts of UA, BA, and, OA in leaves were found to be 6.85±0.273, 2.443±0.076, and 5.3±0.615mg/g dry weight [DW] , respectively, but the highest content of lupeol was detected in bark (0.377±0.035mg/g DW). The present work can serve as an exhaustive standardization tool for E. globulus since four of its bioactive phytochemicals have been estimated simultaneously, as well as throw light on the best extraction method.