and sonicated at 40◦C for 30 minwith ultrasonic cleaner (KQ-300VDV, Jiangsu, China) under itswhole power altitude model (100 KHz, 300 W). The suspensionwas subjected to centrifugation at 2500 × g for 10 min. The super-natant was collected and the residue was re-extracted by repeatingthe procedure mentioned above. The supernatants were combinedand concentrated to a final volume of 10 mL by vacuum evapora-tion at 45◦C. The concentrated supernatant was made up to 25 mLwith methanol, and filtered through 0.45 m nylon membrane toproduce stock solution.