4.4.2. NMR

For the acquisition of a 1H NMR spectrum, the remaining methanol extract was mixed with deuterated methanol MeOD-d4 (up to a final volume of 600 μL), which was used as an internal lock and chemical shift reference at δH = 3.3 ppm. The 1H NMR experiments were performed at 300 K on a Bruker (Rheinstetten, Germany) spectrometer Avance III HD 600 (nominal proton frequency 600.13 MHz) equipped with a 5 mm QCI cryo-probe (1H, 13C, 15N and 19F). The 1H and 13C chemical shifts are expressed in ppm, referenced to the proton signal of the MeOD-d4 (3.3 ppm for 1H and 47.6 for 13C). Compounds were characterized by one-dimensional 1H, as well as two-dimensional 1H/ 1H COSY, 1H/ 1H TOCSY, 1H/ 13C HSQC, 1H/ 13C HMBC and 1H/ 15N HMBC experiments.
