Table I.
Inhibition of GSTs by flavonoids (C50 values in μm)
| AN9 | GSTI | GSTIII | eGST | |
|---|---|---|---|---|
| Quercetin | 10–25 | >300 | 10–25 | NIa |
| Isoquercitrin | 25 | 200–250 | 10–25 | NI |
| Cyanidin | 5 | NI | 50–100 | NI |
| C3G | 50 | NI | 50–100 | NI |
| Luteolin | 5 | 50–100 | 50–100 | NI |
| Luteolin-4′-Glc | 5 | 50 | 5–10 | NI |
| Luteolin-7-Glc | >200 | >200 | 25–50 | NI |
| Naringenin | 200–250 | NI | 25 | NI |
| Ethacrynic acid | 5 | 25 | 5 | 50 |
Inhibition of the CDNB conjugating activity of AN9, GSTI, GSTIII, and horse liver GST (eGST) by flavonoid substrates. The C50 values (in μm were graphically determined by plotting activity in function of inhibitor concentration. Both AN9 and GSTIII are strongly inhibited by most flavonoids, whereas GSTI is inhibited to a lesser degree. Equine GST is not inhibited by flavonoids. Ethacrynic acid was included as a non-flavonoid inhibitor of CDNB activity.
a
NI, No inhibition.