Analytical Methods for Compound Characterization

LC analysis was performed in a Dionex Ultimate 3000 liquid chromatograph with an autosampler (WPS-3000TSL), a pump (LPG-3400SD), a column thermostat (TCC-3000SD), and a diode detector (DAD-3000) (Thermo-Fisher Scientific, Sunnyvale, CA, USA). The system was connected with Chromeleon 7 software.
Spectrophotometric measurements were conducted using a Multiskan GO Spectrophotometer (Thermo-Fisher Scientific). The %Inhibition was calculated from the formula
$$\% \mathrm{inhibition}=\left(\frac{{\mathrm{A}}_{\mathrm{Control}}-{ \mathrm{A}}_{\mathrm{Sample}}}{{\mathrm{A}}_{\mathrm{Control}}} \right)\times 100$$
MS spectra in the negative mode were recorded on an ESI-qTOF Compact mass spectrometer (Bruker, Bremen, Germany). The mass spectrometer was re-calibrated for every run [31 (link)]. ¹H-NMR, ¹³C-NMR, HSQC, HMBC, and COSY experiments were recorded on Avance 300 MHz spectrometer (Bruker) in DMSO-d6 and calibrated using the residual solvent peak. The data were processed with MestReNova 12 software (Mestrelab Research, Santiago de Compostela, A Coruña, Spain).