Discriminative Analysis of Different Grades of Gaharu (Aquilaria malaccensis Lamk.) via 1H-NMR-Based Metabolomics Using PLS-DA and Random Forests Classification Models
Abstract
:1. Introduction
2. Results and Discussion
2.1. Identification of Gaharu Metabolites
2.2. Discriminative Analysis of Gaharu Samples
2.3. Identification of Discriminating Metabolites
3. Experimental Section
3.1. Samples and Chemicals
3.2. 1H-NMR Sample Preparation
3.3. 1H-NMR Data Acquisition and Data Preprocessing
3.4. Metabolite Assignment
3.5. Development of PLS-DA and Random Forests Models
3.6. Statistical Analysis
4. Conclusions
Supplementary Materials
Acknowledgments
Author Contributions
Conflicts of Interest
References
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Sample Availability: Samples of the compounds are not available from the authors. |
Tentative Compound | Chemical Shifts |
---|---|
6-Hydroxy-2-(2-phenylethyl)chromone (1) | 8.09 (d, J = 2.5 Hz, H-5); 7.26–7.19 (m, H-2′-H-6′); 7.14 (d, J = 8.5 Hz, H-8);6.10 (s, H-3); 3.02–2.99 (m, H-7′); 2.92–2.90 (m, H-8′) |
6-Hydroxy-2-[2-(4-hydroxyphenyl)ethyl]chromone (2) | 7.98 (d, J = 2.5 Hz, H-5); 7.21 (d, J = 8.0 Hz, H-2′); 7.17 (d, J = 8.0 Hz, H-6′); 6.73 (dd, J = 8.0, 2.5 Hz, H-7); 6.11 (s, H-3); 2.95 (m, H-7'); 2.87 (m, H-8') |
Jinkohol (3) | 2.01 (dd, J = 4.9, 4.4 Hz, H-8); 1.86 (m, H-3); 1.80 (m, H-2); 1.69 (dd, J = 9.8 Hz, H-5); 1.56 (ddd, J = 10.6, 1.5 Hz, H-11); 1.38 (dd, J = 10.6, 4.4 Hz, H-11); 0.90 (s, 6-Me); 0.84 (d, J = 6.5 Hz, 2-Me) |
usunol (4) | 5.32 (ddd, J = 5.7, 2.2 Hz, H-1); 2.27 (dddd, J = 13.8, 12.4, 3.3 Hz, H-9); 1.62 (dddd, J = 12.4, 3.3 Hz, H-7); 1.41 (m, H-4) |
α-Agarofuran (5) | 5. 59 (s, H-3); 2.22 (dd, J = 12.5, 4.0 Hz, H-9); 1.72 (s, H-12); 1.23 (s, H-14); 0.91 (s, H-13) |
10-epi-γ-Eudesmol (6) | 2.12 (d, J = 15.8 Hz, H-3); 1. 68 (s, H-12); 1.19 (s, H-13); 1.09 (s, H-11) |
Isoeugenol (7) | 7.09 (dd, J = 1.9, 0.5 Hz, H-5); 3.79 (s, H-10); 1.55 (d, J = 7.3 Hz, H-9); 6.32 (d, J = 16.9 Hz, H-7); 6.29 (dq, J = 16.9, 6.9 Hz, H-8); 7.40 (dd, J = 8.6, 1.9 Hz, H-3) |
Vanillic acid (8) | 3.94 (s, H-8); 6.92 (d, J = 8.2 Hz, H-3); 7.43 (dd, J = 8.2, 1.7 Hz, H-4); 7.52 (d, J = 1.7 Hz, H-6) |
Cinnamic acid (9) | 7.60 (dd, J = 7.9, 1.1 Hz, H-6); 7.45 (m, H-5); 7.40 (d, trans, J = 16.0 Hz, H-7); 6.54 (d, trans, J = 16.0 Hz, H-8) |
o-Cresol (10) | 2.29 (s, H-8); 6.82 (m, H-4, H-6); 7.14 (m, H-5); 7.20 (m, H-3) |
Xanthosine (11) | 7.88 (s, H-7); 5.85 (d, J = 6.4 Hz, H-2); 4.69 (t, J = 5.7 Hz, H-3); 4.25 (q, J = 2.7 Hz, H-5); 3.89 (m, H-17) |
Catechol (12) | 6.87 (m, H-4, H-5); 6.94 (m, H-3, H-6) |
Fatty acid: (13) | 1.28 (m) |
Aquilarone derivatives (14) | 4.72 (d, J = 2.7 Hz, H-5); 4.55 (d, J = 7.3 Hz, H-8); 4.29 (m, H-6); 3.99 (dd, J = 6.2, 2.4 Hz, H-7); 2.70–2.80 (m, 2H) |
Random Forests Class | Producer Accuracy | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
A | B | C | D | E | F | G | H | Total | Percent Correct | Omission Error (%) | ||
Reference class | A | 4 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 6 | 67 | 33 |
B | 2 | 3 | 0 | 1 | 0 | 0 | 0 | 0 | 6 | 50 | 50 | |
C | 0 | 0 | 5 | 0 | 0 | 0 | 1 | 0 | 6 | 83 | 17 | |
D | 0 | 2 | 0 | 3 | 0 | 1 | 0 | 0 | 6 | 50 | 50 | |
E | 0 | 0 | 0 | 0 | 6 | 0 | 0 | 0 | 6 | 100 | 0 | |
F | 0 | 0 | 0 | 1 | 0 | 5 | 0 | 0 | 6 | 83 | 17 | |
G | 0 | 0 | 1 | 1 | 0 | 1 | 3 | 0 | 6 | 50 | 50 | |
H | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 6 | 6 | 100 | 0 | |
Total | 6 | 7 | 6 | 6 | 6 | 7 | 4 | 6 | 48 | |||
Users accuracy | ||||||||||||
Percent correct | 67 | 43 | 83 | 50 | 100 | 71 | 75 | 100 | 72.92 | |||
Commission error (%) | 33 | 57 | 17 | 50 | 0 | 29 | 25 | 0 | ||||
Agreement | 4 | 3 | 5 | 3 | 6 | 5 | 3 | 6 | 35 | |||
By chance | 0.75 | 0.88 | 0.75 | 0.75 | 0.75 | 0.875 | 0.5 | 0.75 | 6.00 | |||
Kappa | 0.69 |
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Ismail, S.N.; Maulidiani, M.; Akhtar, M.T.; Abas, F.; Ismail, I.S.; Khatib, A.; Ali, N.A.M.; Shaari, K. Discriminative Analysis of Different Grades of Gaharu (Aquilaria malaccensis Lamk.) via 1H-NMR-Based Metabolomics Using PLS-DA and Random Forests Classification Models. Molecules 2017, 22, 1612. https://doi.org/10.3390/molecules22101612
Ismail SN, Maulidiani M, Akhtar MT, Abas F, Ismail IS, Khatib A, Ali NAM, Shaari K. Discriminative Analysis of Different Grades of Gaharu (Aquilaria malaccensis Lamk.) via 1H-NMR-Based Metabolomics Using PLS-DA and Random Forests Classification Models. Molecules. 2017; 22(10):1612. https://doi.org/10.3390/molecules22101612
Chicago/Turabian StyleIsmail, Siti Nazirah, M. Maulidiani, Muhammad Tayyab Akhtar, Faridah Abas, Intan Safinar Ismail, Alfi Khatib, Nor Azah Mohamad Ali, and Khozirah Shaari. 2017. "Discriminative Analysis of Different Grades of Gaharu (Aquilaria malaccensis Lamk.) via 1H-NMR-Based Metabolomics Using PLS-DA and Random Forests Classification Models" Molecules 22, no. 10: 1612. https://doi.org/10.3390/molecules22101612