Figure 4
Gel-state 2D13C–1H correlation (HSQC) NMR spectra of maize cell walls lignified with coniferyl alcohol and sinapyl alcohol only (CWDHP-control), and in combination with epigallocatechin gallate (CWDHP-EGCG). (A-D) Partial HSQC spectra of CWDHP-control (A and B) and CWDHP-EGCG (C and D) before and after the alkali pretreatment at 100°C. (E-J) Expanded HSQC spectra and sliced 1D F2 (1H) spectra (at 103.3 ppm in F1, 13C) showing syringyl lignin aromatic (S2/6) and glucan anomeric (β-D-Glcp1) signals, of CWDHP-control (E-G) and CWDHP-EGCG (H-J) before and after the alkali pretreatment at 70°C, 100°C, and 130°C.