The analyses were carried out using a HP 1100 L liquid chromatograph equipped with a DAD detector, coupled to a HP 1100 MSD mass spectrometer with an API/electrospray interface (all from Agilent Technologies, Palo Alto, CA, USA). The analysis conditions were the same as those described in our previous study [28,49]. A Fusion RP18 column (150 × 2 mm i.d., 4 μm, Phenomenex, Torrance, CA, USA) was used and the mobile phases were (A) 0.1% formic acid/water and (B) CH3CN. The multi-step linear solvent gradient was: 0–15 min 15–25% B; 15–25 min, 25–35% B; 25–35 min 35–50% B; 35–40 min 50–100% B, with a final plateau of 8 min at 100% B, flow rate 0.2 mL·min−1 and oven temperature 26 °C, with an injection volume of 5 μL.

The quantitative evaluation of the main phenolic constituents was performed using three external standards: rosmarinic acid at 330 nm, genkwanin at 350 nm and carnosic acid at 284 nm. Genkwanin was used at 350 nm to quantify the flavonoids, while carnosic acid to determine the non-volatile diterpenoids. The calibration curve of rosmarinic acid (Sigma-Aldrich, Steinheim, Germany)) was in a linearity range between 0.1 and 1.8 μg, with R2 0.9998, the calibration curve of carnosic acid (Sigma-Aldrich) was in the linearity range of 0.05–3.06 μg, with R2 0.9998, and a five-point calibration curve of genkwanin (purity grade ≥ 95% by Extrasynthese) was obtained (range 0.01 to 0.85 μg), with an R2 0.9999.

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