Characterization of (-)-5-demethoxygrandisin B

The assessment of (-)-5-demethoxygrandisin B at 100 ppm in methanol: H₂O (80:20) was conducted using a Xevo^® G2-S QTof coupled with an ACQUITY Ultra Performance LC™ system (Waters Corp., Milford, MA, USA). The ionization source was configured with a desolvation gas flow (N2) at 600 L/h and a desolvation temperature of 150 °C. The cone gas flow (N2) was set at 50 L/h, and the source temperature was maintained at 120 °C. Adjustments were made to the capillary and sampling cone voltages, setting them at 1.0 kV and 40 V, respectively. The data acquisition was executed utilizing MassLynx 4.1 software (Waters, Milford, USA) [19 (link),20 (link)]. NMR 1D (¹H and ¹³C) and 2D homonuclear-correlated spectroscopy (COSY ¹Hx¹H), HMBC, and HSQC analyses were acquired with a Bruker 400 spectrometer AscendTM (Rheinstetten, Germany) model at 400.15 MHz (¹H) and 100.62 MHz (¹³C). The chemical shifts were determined relative to CDCl₃ at 0 ppm. A total of 20 mg of (-)-5-demethoxygrandisin B was solubilized in 600 μL of CDCl₃. TopSpin 3.6.0 software was used for data control and processing. Thereby, the spectra were manually evaluated. The optical rotation of the (-)-5-demethoxygrandisin was measured on a Perkin–Elmer 341 polarimeter (Perkin–Elmer Inc., Waltham, MA, USA).