Microwave-assisted extraction and rapid isolation of ursolic acid from the leaves of Eucalyptus x hybrida Maiden and its quantification using HPLC-diode array technique

Ursolic acid (UA) is the most important bioactive phytoconstituent of Eucalyptus x hybrida Maiden leaves and exhibits anticancer, antimutagenic, anti-inflammatory, antioxidative, and antiprotozoal activities. In this study, microwave-assisted extraction technique was employed for rapid isolation of UA from the leaves of Eucalyptus x hybrida and simultaneously HPLC-diode array method was developed for the quantification of UA. Effects of several experimental parameters on the extraction efficiencies of UA, such as type and volume of extraction solvents, microwave power and extraction time, were evaluated. The optimal extraction conditions were found to be 20 mL of a mixture of chloroform/methanol, 60:40; liquid-to-material ratio, 4:1; preleaching time, 10 min; microwave power, 600 W; temperature, 50 degrees C; and microwave irradiation time, 5 min. Under the optimum conditions, the yield of UA was found to be 1.95 +/- 0.08% in the dry leaves of Eucalyptus x hybrida. The results showed that microwave-assisted extraction is a more rapid extraction method with higher yield and lower solvent consumptions than the conventional method. It is a faster, convenient, and appropriate method and it may be used for rapid isolation and quantification of UA and other important phytoconstituents present in the leaves of Eucalyptus x hybrida.