TABLE 3.
Selected examples of Phase II metabolic reactions of phytochemicals leading to bioactive metabolites
| Parent compound | Active metabolite(s) | Reaction | Food sources1 | Reference |
|---|---|---|---|---|
| Hydroxytyrosol and tyrosol | Hydroxytyrosol 3-O-sulfate; hydroxytyrosol 3-O-glucuronide; tyrosol 4-O-sulfate; tyrosol 4-O-glucuronide; homovanillyl alcohol | Sulfation, glucuronidation, and methylation | Olive oil, olives, wine, beers | (15, 122, 123) |
| Resveratrol | Resveratrol-3-O-glucuronide; resveratrol-3-O-sulfate; resveratrol-4′-O-sulfate; dihydro-resveratrol-3-O-glucuronide | Glucuronidation and sulfation | Grapes, wine | (124) |
| Quercetin | Quercetin 3-O-sulfate; quercetin 3-O-glucuronide; isorhamnetin-3-glucuronide | Sulfation and glucuronidation | Cocoa, berries, apples, onions | (125–128) |
| Epicatechin | Epicatechin sulfate; epicatechin glucuronide | Sulfation and glucuronidation | Tea, cocoa, wine, fruits, beans | (125) |
| (+)-Catechin | Catechin sulfate; catechin glucuronide | Sulfation and glucuronidation | Tea, cocoa, wine, fruits, beans | (126) |
| Daidzein | Daidzein 4′-sulfate | Sulfation | Soy and soy products | (129) |
1
Information regarding the food sources of the phenolic compounds was obtained from the database phenol-explorer.eu (49)