¹H NMR metabolic profiling revealed characteristic metabolites in mud crab Scylla paramamosain for different geographical origins

Figures & data

Figure 1. Typical ¹H NMR spectra of muscle extracts of S. paramamosain collected from Cixi (CX), Sanmen (SM), Xiapu (XP), and Qinzhou (QZ). The dotted regions were vertically expanded by a factor 64 relative to the δ 4.7–0.9 regions. Lac: lactate; Ala: alanine; Glu: glutamate; Gln: glutamine; Bet: betaine; Arg: arginine; TMAO: trimethylamine-N-oxide; Tau: taurine; Gly: glycine; α-Glc: α-Glucose; Fum: fumarate; HQ: hydroquinone; Tyr: tyrosine; Phe: phenylalanine; His: histidine; Ino: inosine; IMP: inosine 5’-monophosphate; AMP: adenosine 5’-monophosphate; PM: 2-pyridinemethanol; Tri: trigonelline; MeOH: methanol; U1: unidentified signal 1.

Table 1. ¹H and ¹³C NMR data and assignments of the metabolites in muscle extracts of S. paramamosain.

Metabolites	Moieties	δ^1 H (ppm) and multiplicity^a	δ^13 C (ppm)
Lactate	αCH, βCH3, COOH	4.11(q), 1.33(d)	71.5, 20.2, 185.5
Alanine	αCH, βCH3, COOH	3.79(q), 1.48(d)	53.4, 19.1, 178.2
Glutamate	αCH, βCH2, γCH2, δCO, COOH	3.77(m), 2.12(m), 2.05(m), 2.36(dt)	57.1, 29.8, 36.2, 184.2, 177.7
Glutamine	βCH2, γCH2	2.14 (m), 2.46(m)	29.2, 33.5
Arginine	COOH, αCH, βCH2, γCH2, δCH2, εC	3.78(t), 1.92(m), 1.69(m), 3.24(t)	177.1, 57.3, 31.6, 28.6, 43.4, 160.0
Betaine	CH3, CH2, COO^−	3.27(s), 3.91(s)	56.2, 69.0, 172.1
Trimethylamine-N-oxide	CH3	3.28(s)	62.3
Taurine	CH2NH2, CH2SO3	3.43(t), 3.27(t)	38.2, 50.6
Glycine	αCH2, COOH	3.56(s)	44.4, 175.6
β-Glucose	C1H, C2H, C3H	4.65(d), 3.25(dd), 3.50(m)	98.6, 77.1, 78.7
α-Glucose	C1H, C2H, C3H	5.24(d), 3.54(dd), 3.70(m)	95.0, 74.4, 75.6
Fumarate	CH, COOH	6.53(s)	138.7, 177.5
Hydroquinone	CH	6.81(s)	118.3
Tyrosine	βCH2, C1, C2,6H, C3,5H, C4	3.20(dd), 3.06(dd), 7.20(d), 6.90 (d)	38.4,128.7, 133.6, 118.8, 156.7
Histidine	C1H, C2H, C3	8.04(d), 7.15(d)	138.5, 119.8, 133.6
Phenylalanine	C2,6H, C3,5H, C4H	7.33(q), 7.43(t), 7.38(m)	132.2, 132.0, 131.5
Inosine	C1H, C2, C3, C4H, C5, C1’H	8.34(s), 8.23(s), 6.10(d)	143.3, 149.1, 91.3
Inosine monophosphate	C2H, C4, C8H, C1’H	8.24(s), 8.58(s), 6.15(d)	149.4, 151.4, 142.7, 90.0
Adenosine monophosphate	C2H, C4, C8H, C1’H	8.28(s), 8.61(s), 6.14(d)	155.5, 151.5, 142.8, 90.0
2-Pyridinemethanol	C2, C3H, C4H, C5H, C6H, C7H	8.73(dd), 7.99(td), 8.57(td), 8.05(dd), 4.38(s)	154.3, 147.9, 129.6, 148.8, 128.6, 49.3
Trigonelline	C2H, C4H, C5H, C6H, CH3	9.13(s), 8.85(m), 8.09(m), 8.84(m), 4.44(s)	148.9, 148.3, 130.6,148.4, 51.2
Residual methanol	CH3	3.36(s)	51.9
U1		3.11(s)

^aMultiplicity: s: singlet; d: doublet; t: triplet; q: quartet; dd: doublet of doublets; dt: doublet of triples; td: triple of doublets; m: multiplet; U: unidentified signal.

Figure 2. PCA scores plot of the muscle extracts of S. paramamosain collected from Cixi (black stars), Sanmen (blue diamonds), Xiapu (orange triangles), and Qinzhou (purple circles).

Figure 3. OPLS-DA scores (left) and coefficient-coded loadings plots (right) for the models discriminating extracts of Cixi crabs (CX, black stars) from the extracts of crabs from Sanmen (SM, blue diamonds, A), Xiapu (XP, orange triangles, B), and Qinzhou (QZ, purple circles, C). Gln: glutamine; Fum: fumarate; TMAO: trimethylamine-N-oxide; AMP: adenosine 5’-monophosphate; 2-PM: 2-pyridinemethanol; U1: unidentified signal 1.

Figure 4. OPLS-DA scores (left) and coefficient-coded loadings plots (right) for the models discriminating the extracts of Sanmen crabs (SM, black stars, A), Xiapu crabs (XP, orange triangles, B), and Qinzhou crabs (QZ, purple circles, C). Ala: alanine; Glu: glutamate; Gln: glutamine; Tyr: tyrosine; Phe: phenylalanine; IMP: inosine 5’-monophosphate; 2-PM: 2-pyridinemethanol; U1: unidentified signal 1.

Figure 5. Content of selected significantly changed metabolites identified from the muscle extracts of S. paramamosain collected from Cixi (CX), Sanmen (SM), Xiapu (XP), and Qinzhou (QZ). Data are given as the average concentration (mg/g crab muscle) and standard deviation obtained from eight parallel samples. Significant differences were obtained by one-way ANOVA. *p < 0.05.