*5.2. Sample Preparation*

The dried samples (100 mg of powder each) were made to the same concentration by resuspending in 5 mL of 70% aqueous methanol in an ultrasonic bath for 30 min and cooled at room temperature. The tubes were centrifuged twice at 12,000 rpm at room temperature for 5 min each time. The extraction was repeated three times using fresh aliquots of the solvent. The extracts were transferred to a 5 mL volumetric flask, which was then filled up to the final volume with extraction solvent. The sample solutions were filtered through a 0.22-μm pore size nylon membrane filter before injection into the UPLC. All samples were stored in a refrigerator at a temperature of 4 ◦C until analysis.
