Detoxification and biotransformation reactions found in human colonocytes
| Action | Enzyme | Substrate/cofactor |
| Phase I | ||
| Oxidation | Cytochrome P-450 | O2 |
| Hydroxylation | ||
| Sulphoxidation | ||
| Dealkylation | ||
| Azoreduction | Cytochrome P-450 reductase | H+ |
| Nitroreduction | ||
| Co-oxidation | Peroxidases | H2O2 |
| Catalases | ||
| Hydrolysis | Esterases | H2O |
| Epoxide hydrolases | ||
| Hydration | Carbonic anhydrase | CO2 + H2O |
| Phase II | ||
| Sulphation | Sulphotransferases | PAPS + ATP |
| Glucuronidation | Glucuronyl transferase | UDP-GA + ATP |
| Acetylation | Acetyl transferase | Acetyl-CoA + ATP |
| Methylation | Methyl transferase | SAM + ATP |
| Glutathione conjugation | Glutathione transferase | Glutathione + ATP |