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Table 3 Quantification of aromatic moieties (lignin, hydroxycinnamates, inter-unit bondages) by combination analysis of 13 C and HSQC NMR spectra of wheat straw isolated CEL

From: Effects of lignin modification on wheat straw cell wall deconstruction by Phanerochaete chrysosporium

Aromatic moieties

σ C/σ H(ppm) and assignments

Control CEL

Two weeks CEL

Four weeks CEL

Six weeks CEL

Eight weeks CEL

Lignin aromatic units

      

Syringyl (S)

103.9/6.7 (S2/6),

27.3

20.5

19.4

21.3

24.5

106.4/7.4 (S'2/6 with α oxidization)

Guaiacyl (G)

110.8/6.97 (G2)

39.3

40.8

37.2

40.9

39.8

115.0/6.94 (G5),118.9/6.81 (G6)

p-hydroxyphenyl (H)

127.7/7.21 (H2/6)

1.4

2.2

2.4

2.3

1.8

S/G ratio

 

0.69

0.50

0.52

0.52

0.61

Hydroxycinnamates

      

p-benzonate (PB)

132.4/7.63 (PB2/6)

1.2

ND

ND

ND

0.2

p-coumarate (pCA)

130.0/7.47 (pCA2/6),115.5/6.79 (pCA3/5)

5.5

2.5

2.7

3.3

3.1

Ferulate (FA)

110.9/7.32 (FA2), 122.5/7.15 (FA6)

6.4

3.9

4.6

5.4

4.5

p-coumarate/ferulate

 

0.86

0.65

0.58

0.60

0.68

Cinnamates/lignin and tricin

 

0.18

0.09

0.10

0.12

0.11

Lignan

      

Tricin (T)

104.04/7.30 (T 2′/6'), 104.65/7.03 (T3)

5.6

10

12

9.0

6.6

94.1/6.56 (T8), 98.8/6.22 (T6)

Inter-unit bondages

      

α-OH/β-O-4

71.1/4.74 (Aα-G), 71.8/4.8 (Aα-S)

33.8

33.9

28.1

33.9

36.5

α-keto/β-O-4

82.7/5.1 (Aα-keto)

2.4

0.8

0.6

0.8

1.1

Total β-O-4

 

36.5

34.7

28.7

34.7

37.6

Phenylcoumaran (β-5)

85.9/5.5 (Bα), 53.0/3.4 (Bβ)

5.7

4.2

3.3

5.2

4.2

Pino/resinol (β-β')

84.8/4.7 (Cα), 53.5/3.1 (Cβ),

0.9

1.2

1.6

1.5

1.2

Dibenzodioxocin (D)

83.4/4.9 (Dα), 85.5/3.8 (Dβ)

2.0

3.8

2.7

4.0

2.5

Spirodienone (SD)

81.4/5.0 (SDα), 59.5/2.8 (SDβ)

ND

ND

ND

ND

ND

α,β-diaryl ether (F)

79.6/5.5 (Fα)

2.1

ND

ND

ND

1.3

γ-ending groups

      

γ-OH in X1 structure

62-58/3.8-3.0

1.5

0.9

0.8

1.0

0.9

Acylation on γ position

60.8-58.8/3.8-3.35

15.6

11.1

13.1

11.8

10.1