Table 1.
LC-ESI-MS molecular and fragment ions detected for free and thioether adducts of curcumin, demethoxy- (DMC), and bisdemethoxy-(BDMC) curcumin and their dioxygenated products (m/z; negative ion mode).
| Compound | free | Adduct with |
||
|---|---|---|---|---|
| βME (+78 amu) | NAc (+163 amu) | GSH (+307 amu) | ||
| Curcumin | 367 | 445.2(→367.2) | 530.3(→162.4) | 674.3(→306.0) |
| Dioxygenated curcumin (spiroepoxide, BCP)1 | 3992 | 477.0(→226.8) | 562.0(→370.9) | 706.0(→272.2) |
| DMC | 337 | 415.2(→337.1) | 500.0(→163.0) | 644.0(→305.8) |
| Dioxygenated DMC (spiroepoxide, BCP)1 | 369 | 447.3(→226.8) | 532.0(→341.5) | n.d.4 |
| BDMC | 307 | 385.1(→306.5) | n.d. | n.d. |
| Dioxygenated BDMC (spiroepoxide)3 | 339 | 417.0(→277.4) | n.d. | n.d. |
1
Thiol adducts are formed by the spiroepoxide but not by the bicyclopentadione (BCP).
2
Spiroepoxide and BCP give the same molecular ion.
3
Oxidative transformation of BDMC stalls at the spiroepoxide, no BCP is formed.16
4
n.d., not detected.