Table 4.
13C NMR spectroscopic characteristics of melanin.
| Source and type of melanin | Chemical shift range (ppm) | Possible assignments | References |
|---|---|---|---|
| Oidiodendron tenuissimum, Trichoderma harzianum, Ulocladium atrum, Hendersonula toruloidea, Eurotium echinulatum | 220–160 | Carboxyl/carbonyl groups | Knicker et al. (1995) |
| 160–140 | Aromatic COR or CNR groups | ||
| 140–110 | Aromatic C–H carbons, guaiacyl C-2/C-6 Olefinic carbons | ||
| 110–90 | Anomeric carbon of carbohydrates, C-2/C-6 of Syringyl | ||
| 90–60 | Carbohydrate- derived structures (C-2 to C-5) in hexoses, C-2 of some amino acids & higher alcohols | ||
| 60–45 | Methoxyl groups, C-6 of carbohydrates, C-2 of most amino acids | ||
| 45–0 | Methylene groups in aliphatic rings & chains, methyl groups bound to carbon | ||
| Dopa melanin | 172 | Carbonyl carbon | Duff et al. (1988) |
| 143, 118 | Aromatic carbons | ||
| 55, 35 | Aliphatic carbons | ||
| Melanoma melanin | 173 | Carbonyl carbon | |
| 125 | Aromatic carbons | ||
| 53,33 | Aliphatic carbons | ||
| Sepia melanin | 173 | Carbonyl carbon | |
| 140–110 | Aromatic carbons | ||
| 70–30 | Aliphatic carbons | ||
| Sepia melanin | 200–160 | Carbonyl carbon | Adhyaru et al. (2003) |
| 160–135 | Aromatic & Indolic Cq (non-protonated) | ||
| 135–90 | Aromatic & Indolic CH (protonated) | ||
| 95–10 | Aliphatic carbons | ||
| Sepia melanin Free acid (MFA) | 200–160 | Carbonyl carbon | |
| 165–135 | Aromatic & Indolic Cq (non-protonated) | ||
| 135–100 | Aromatic & Indolic CH (protonated) | ||
| 95–10, 50–0 | Aliphatic carbons | ||
| Sepia melanin | 200–187, 167, 164 | Carbonyl carbon | Hervé et al. (1994) |
| 147–110 | Aromatic & ethylenic Cq (non-protonated) | ||
| 131–127, 119–95 | Aromatic & ethylenic CH (protonated) | ||
| 75–15 | Aliphatic carbons | ||
| T. albuminosus melanin | 200–170 | Carbonyl carbon | Present study |
| 160–110 | Aromatic carbons | ||
| 45–40 | =C–S | ||
| 71, 56, 52, 33, 30 | Aliphatic carbons in cysteine/DOPA |