TABLE 3.
1H and 13C NMR chemical shifts (in ppm) and proton coupling constants (Hz, in parentheses) of the novel MAA as N-(4,5-dihydroxy-5-(hydroxymethyl)-2-methoxy-3-oxocyclohex-1-en-1-yl)-N-methyl-O-((2S,3R,4R,5S,6S)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)-L-serine (klebsormidin A) isolated from the terrestrial green alga Klebsormidiumcrenulatum.
| N | 13C | 1H | COSY | HMBC |
| 1 | 190.5 | – | ||
| 2 | 135.5 | – | ||
| 3 | 174.4 | – | ||
| 4 | 40.2 | a) 257, d (17.8), | 4b | 2,3,5,6 |
| b) 2.97, d (17.8) | 4a | 2,3,5,6 | ||
| 5 | 78.2 | – | ||
| 6 | 75.1 | 4.46, s | 1 | |
| 7 | 67.7 | a) 3.55, d (11.6), | 7b | 4,5,6 |
| b) 3.69, d (11.6) | 7a | 4,5,6 | ||
| 8 | 62.98 | 3.61, s | 2 | |
| 9 | 173.5 | – | ||
| 10 | 65.52 | 3.85, m | 11b | 9 |
| 11 | 67.96 | a) 4.18, dd (10.8, 3.0) | 10, 11b | 9,1 |
| b)3.94, m | 10, 11a | 9,1´ | ||
| 12 | 34.7 | 2.77, s | ||
| 1´ | 102.3 | 4.98, d (3.7) | 2´ | 3´, 5´ |
| 2´ | 71.12 | 3.82, dd (10.4, 3.7) | 3´, 1´ | |
| 3´ | 74.58 | 3.93, m | 4´, 2´ | 4´ |
| 4´ | 64.06 | 3.74 d (7.6) | 3´ | |
| 5´ | 68.14 | 3.93 m | 6´ | 4´ |
| 6´ | 72.15 | a) 3.97, m | 5´ | 5´ |
| b) 3.83, m | 5´ |