*3.3. UHPLC-ESI-QqTOF-MS*/*MS and HPLC-UV-DAD Analyses*

LnHS was chemically characterized by ultrahigh-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS) techniques. A NEXERA UHPLC system (Shimadzu, Tokyo, Japan) was used with a Luna® Omega Polar C-18 columns (1.6 µm particle size, 50 × 2.1 mm, Phenomenex, Torrance, CA, USA). Separation was achieved with a linear gradient of water (A) and acetonitrile (B), both with 0.1% formic acid: 0–3 min, 2→12.5% B; 3–12.5 min, 12.5→30% B; 12.5–17.5 min, 30→45% B; 17.5–20 min, 45→75% B; held at 75% B for other 2 min; 22–23 min, 75→98% B. The mobile phase composition was maintained at 98% B for another 1 min, then returned to the starting conditions and allowed to re-equilibrate for 1 min. The total analysis time was 26 min, the flow rate was 0.5 mL/min, and the injection volume was 2.0 µL.

MS analysis was performed using a hybrid Q-TOF MS instrument, the AB SCIEX Triple TOF® 4600 (AB Sciex, Concord, ON, Canada), equipped with a DuoSprayTM ion source (consisting of both electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) probes), which was operated in the negative ESI mode. The APCI probe was used for automated mass calibration using the Calibrant Delivery System (CDS). The CDS injects a calibration solution matching the polarity of ionization and calibrates the mass axis of the TripleTOF® system in all scan functions used (MS and/or MS/MS). The Q-TOF HRMS method, which combines TOF-MS and MS/MS with Information Dependent Acquisition (IDA) for identifying non-targeted and unexpected compounds, consisted of a full scan TOF survey (dwell time 100 ms, 100–1000 Da) and a maximum number of eight IDA MS/MS scans (dwell time 50 ms, 80–850 Da). The MS parameters were as follows: curtain gas (CUR) 35 psi, nebulizer gas (GS 1) 60 psi, heated gas (GS 2) 60 psi, ion spray voltage (ISVF) 4.5 kV, interface heater temperature (TEM) 600 ◦C, declustering potential (DP) −80 V. Collision Energy (CE) applied was −45 V with a collision energy spread (CES) of 15 V. The instrument was controlled by Analyst® TF 1.7 software, while data processing was carried out using PeakView® software version 2.2. Hydrogen/deuterium exchange experiments were carried out on pure *N*-caffeoyltyramine as previously described [54]. Furthermore, in order to achieve UV-DAD information of each peak, separation was also performed by

using a 1260 Infinity II LC System (Agilent, Santa Clara, CA, USA) equipped with an Agilent G711A quaternary pump and a WR G7115A diode array detector.
