UPLC-QTOF-MS Method for Identification of Mango Leaf Tea Metabolites

Abstract Objectives The study aim was to identify bioactive compounds in mango leaf tea using a new method - UPLC/Q-TOF-MS. Mango leaf tea is a natural product being investigated to manage type 2 diabetes due to its phytochemical properties. Methods Mango tea was extracted using 80% methanol overnight. The extract was analyzed with ultra-high-performance liquid chromatography-quadrupole time-of-flight (UPLC-Q-TOF) MS system (Waters Corp., Milford, MA) and injected into an Acquity UPLC BEH C18 column (2.1 mm × 100 mm, 1.7 µm, Waters Corp.). The column was equilibrated with distilled water containing 0.1% formic acid (FA) and eluted by a linear gradient of acetonitrile (ACN) containing 0.1% FA at a flow rate of 0.35 mL/min for 10 min and 40 °C of column temperature. Results The eluents were analyzed by A Vion IMS Q-TOF MS (Waters Corp.) with positive and negative electrospray ionization (ESI). The scan range of TOF MS data was 50–1500 m/z, the scan time was 0.2 sec, and the capillary and sampling cone voltages were 3 kV and 40 V, respectively. The desolvation flow rate and temperature were 800 L/h and 400 °C, respectively, and the source temperature was 100 °C. Leucine-enkephalin ([M + H] = 556.2771 Da; [M-H] = 554.2615 Da), used as a lack mass, was infused at a flow rate of 0.35 μL/min and a frequency of 10 s to ensure mass measurement accuracy of the metabolites analyzed by the instrument. Mass spectral data were collected from m/z 50 to 1500 with a scan time of 0.2 s. Collision energy was ramped from 10 to 40 eV for the collection of MS/MS data. The metabolites Mangiferin, quercetin/isoquercetin and iriflophenone 3-beta-glucoside were identified using ChemSpider in negative mode while only mangiferin and quercetin were defined in positive mode with different intensites: Mangiferin (421.07), quercetin/isoquercetin (303.05) and irrflophenone 3- beta- glucoside (407.097) that confirmed their molar mass. Conclusions The UPLC/Q-TOF-MS technique is a practical and novel method for identifying the fragmentation pattern of metabolites in mango leaf tea by measuring accurate mass with excellent resolution and sensitivity. Funding Sources N/A.