Compound 1 together with the standards were dissolved in MeOH (2 mg/mL) in a glass vial and dried under nitrogen. Followed by adding 6 N HCl and capping, the vial was heated at 100 °C for 16 h. After cooling to room temperature, the sample was dried under nitrogen. The residue was dissolved in 1 M NaHCO3 and treated with 1% FDAA Marfey reagent (200 µL in acetone solution) and allowed to react at 45 °C for 90 min. After cooling, the samples were quenched with 2 N HCl (20 µL), the reaction mixture was dried under nitrogen, and then dilute with 130 µL MeOH, centrifuged and transferred to 100 µL HPLC vial then analyzed by LC-MS. The absolute configuration of the non-proteogenic amino acid N-methyl-2-chloro-3-hydroxy-4-methoxyphenylalanine was determined by measuring the optical rotation following the acid hydrolysis where the DOPA derivative was subjected to 6 N HCl and heated at 100 °C for 16 h. Purification from the hydrolyzed mixture was performed by using a linear gradient from 8% to 15% MeCN in Milli-Q water over 20 min by an Agilent Infinity 1290 HPLC-DAD (Agilent Technologies) system. Finally, the specific optical rotation of the isolated compound was recorded. HPLC and Mass Spectrometry An ultra-high-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) was performed on an Agilent Infinity 1290 UHPLC system equipped with a diode array detector. UV-visible spectra were recorded from 190 to 640 nm. LC/HRMS of 1 μL crude extract and the above-mentioned fraction and subfractions was performed on a 250 × 2.1 mm i.d., 2.7 μm, Poroshell 120 phenyl-hexyl column (Agilent Technologies) at 60°C using of MeCN and H2O, both buffered with 20 mM FA, as mobile phases. Initially, a linear gradient of 10% MeCN/H2O to 100% MeCN over 15 min was employed, followed by isocratic elution of 100% MeCN for 2 min, the gradient was returned to 10% MeCN/H2O in 0.1 min, and finally isocratic condition of 10% MeCN /H2O for 2.9 min, all at a flow rate of 0.35 mL/min. MS detection was performed in positive mode on an Agilent 6545 Q-TOF LC/MS equipped with an Agilent Dual Jet Stream electrospray ion source with a drying gas temperature of 250°C, drying gas flow of 8 L/min, sheath gas temperature of 300°C, and sheath gas flow of 12 L/min. Capillary voltage was set to 4000 V and nozzle voltage to 500 V. MS spectra were recorded as centroid data, at an m/z of 100-1700, and MS data processing and analysis were performed using Agilent MassHunter Qualitative Analysis software (Agilent Technologies).