Standard Solutions Preparation for Quantification Analysis

Sakuranetin and 7-methoxyaromadendrin were dissolved in 1 mL of MeOH/H2O 8:2 (*v*/*v*) solution (1 mg/mL) and filtered through a 0.22 μm nylon filter membrane. An aliquot was diluted with MeOH/H2O 8:2 (*v*/*v*) up to a volume of 1 mL (100 ppm, solution A). The solution A was diluted to obtain the solutions patterns between 1 and 50 μg/mL (three replicas for each concentration).

#### *4.7. UPLC-ESI-MS Analysis of the Extracts*

Analysis was performed on a Waters ® Acquity UPLC system coupled with a XevoTqD ® mass spectrometer (Waters Corp., Milford, MA, USA). The analytical column used was an ACQUITYTM UPLC X bridge C18 (2.1 × 50 mm, 2.5 μm). Analysis was carried out with water containing 0.1% formic acid (A) and methanol (B) at a flow rate of 400 μL/min during 10 min. A gradient program was used for quantification as follows: 0–8 min, 47% B isocratic; 8–10 min, 47–100% B linear and for PCA: 0–3.2 min, 40% B isocratic; 3.2–4 min, 40–60% B linear; 4–8.2 min, 60% B isocratic; 8.2–10 min, 60–100% B linear. The injection volume was 5 μL in quantification analysis and 10 μL in PCA analysis. Mass spectrometric detection was in negative mode. The MS conditions were as follows: capillary temperature 200 ◦C; capillary voltage 3.5 kV; Cone voltage 39 kV; desolvation temperature 200 ◦C; Source gas flow: desolvation 400 L/h. Selected reaction monitoring mode was used for quantification. The monitored transitions included the following: sakuranetin (285 > 165) and 7-methoxyaromadendrin (301 > 165). All data were acquired and processed using the MasslynxTM V4.1 software (Waters Corporation, Milford, MA, USA).
