## 2 Materials and Methods
### Characterization of Isolated Lignin and Fractionated Biomass  
The recovered lignin fractions were analyzed by gel permeation chromatography (GPC), derivatization followed by reductive cleavage (DFRC) and 2D heteronuclear single quantum coherence nuclear magnetic resonance (2D-HSQC-NMR) spectrum according to our previous study [25]. To determine the weight average (Mw) and number average (Mn) molecular weights, each isolated fraction was first subjected to acetylation in pyridine/acetic anhydride (1:1) solution and was periodically shaken after being maintained at a temperature of 105 \({}^{\circ}\)C for 2 h. After this, almost 20 mg of this acetylated lignin was dissolved in 2 mL of tetrahydrofuran and then analyzed using a GPC, Agilent 1200, USA (equipped with an ultraviolet detector (UV) on a PL-gel 5 mm Mixed-c. column, calibrated with polystyrene standards), and THF was used as a mobile phase while it was flowed at a rate of 1 mL/min. For DFRC analysis, a previous classical approach was adapted in which the extracted lignin samples, 20 mg for each sample, were dissolved in 4 mL AcOH and 1 mL AcBr solution and kept at 50 \({}^{\circ}\)C for 1 h with rigorous periodic shaking. Afterward, the residue was obtained by evaporating the mixture on a rotary evaporator. To this residue, 2 mL of dioxane/acetic acid/water (5:4:1, v/v/v) was added, and subsequently, zinc dust (50 mg) was also added with stirring and then the whole solution was kept for 1 h at room temperature. Later on, after the intended time, a precise amount of the internal standard tetracosane was added into the solution, which was extracted by the mixture with CH\({}_{2}\)Cl\({}_{2}\) and saturated NH\({}_{4}\)Cl. After this, the pH of the aqueous phase was dropped down to 3 by adding 3% HCl, and then finally, the organic layer was separated. The water phase was extracted twice with CH\({}_{2}\)Cl\({}_{2}\), and the combined CH\({}_{2}\)Cl\({}_{2}\) fractions were dried over MgSO\({}_{4}\), and ultimately, the filtrate was evaporated under reduced pressure. The residue was then subjected to acetylation employing 0.5 mL each of acetic anhydride and pyridine for at least 1 h with periodic shaking. All the residual matter was then filtered using syringe filters and finally subjected to quantification by GC-MS (Agilent 7890B USA). For 2D-HSQC-NMR, the lignin samples were prepared using 20 mg of lignin dissolved in 0.75 mL DMSO-D6, and then the analysis data were acquired with a Bruker AVANCE 600 spectrometer (Bruker, Germany). Raw and pretreated pinewood samples were characterized in terms of their crystallinity indices as well. For this, the crystallinity index (CrI) was determined by measuring X-ray diffraction (XRD) using a powder X-ray diffractometer ([PERSON], D8 Advance with DAVINCI Germany). A sample was scanned at a rate of 2 deg/min in the 20 range of 3 deg-60 deg, and the CrI was estimated according to Equation (1).  
\[\text{CrI}\left(\%\right)=\left[\left(\text{I}_{\text{Crystalline}}-\text{I}_{ \text{Amorphous}}\right)/\text{I}_{\text{Crystalline}}\right]\times 100\% \tag{1}\]  
where \(\text{I}_{\text{crystalline}}\) = intensity at 22.26 deg and \(\text{I}_{\text{amorphous}}\) = intensity at 15.72 deg.