1H and 13C NMR chemical shifts of M21 and M16
| C/H | M21 | M16 | ||
|---|---|---|---|---|
| 1H NMR | 13C NMR | 1H NMR | 13C NMR | |
| Aglycone | ||||
| 2 | 4.80 (<2.0) | 79.63 | 4.78 (<2.0) | 79.99 |
| 3 | 4.20 (<2.0, 2.5, 4.5) | 67.30 | 4.18 (<2.0, 2.5, 4.5) | 67.33 |
| 4α | 2.85 (4.5, 16.5) | 29.21 | 2.88 (4.5, 17.0) | 29.24 |
| 4β | 2.73 (2.5, 16.5) | 2.76 (2.5, 17.0) | ||
| 5 | 157.14 | 157.93 | ||
| 6 | 5.93 | 96.17 | 6.21 (2.0) | 97.73b |
| 7 | 157.56 | 158.40 | ||
| 8 | 5.91 | 96.17 | 6.19 (2.0) | 97.62b |
| 9 | 157.91 | 157.22 | ||
| 10 | 100.06 | 103.28 | ||
| 1′ | 131.71 | 131.28 | ||
| 2′ | 6.85 (2.0) | 109.33 | 6.52 | 106.90c |
| 3′ | 146.90a | 146.68 | ||
| 4′ | 136.27 | 133.62 | ||
| 5′ | 146.85a | 146.68 | ||
| 6′ | 6.77 (2.0) | 110.88 | 6.52 | 107.04c |
| Glucuronic acid | ||||
| 1" | 4.86 (7.4) | 104.78 | 4.86 (7.0) | 102.66 |
| 2" | 3.53 (7.4, 9.2) | 77.12 | 3.45 (7.0, 9.2) | 74.58 |
| 3" | 3.50 (9.2, 9.1) | 74.58 | 3.48 (9.2, 9.2) | 77.41 |
| 4" | 3.60 (9.1, 9.5) | 73.10 | 3.59 (9.2, 10.0) | 73.09 |
| 5" | 3.91 (9.5) | 76.62 | 3.91 (10.0) | 76.63 |
| 6" | 172.65 | 172.63 | ||
Chemical shifts were referenced to CD3OD at 3.30 ppm for1H and 49.0 ppm for 13C, respectively. Coupling constants in Hz are in parentheses. Thea, b, c assignments are interchangeable, respectively.