Effects of a water-soluble extract of rosemary and its purified component rosmarinic acid on xenobiotic-metabolizing enzymes in rat liver

The effects of a water-soluble extract (WSE) of rosemary and its purified a ntioxidant rosmarinic acid (RA) on xenobiotic metabolizing enzymes (XME) we re studied in rat liver after dietary administration. The modulation of pha se I enzymes such as cytochrome P450 (CYP) 1A, 2B, 2E1, 3A, and phase II en zymes such as glutathione S-transferase (GST), quinone reductase (QR) and U DP-glucuronosyltransferase (UGT) was evaluated by measuring enzyme activiti es with specific substrates. Protein levels of CYPs and rGST A1/A2, A3/A5, M1, M2 and P1 were measured using antibodies in Western blots. Caffeic acid was also studied because it results from RA biotransformation in rat after oral administration. Male SPF Wistar rats received the different compounds at 0.5% (w/w) incorporated into their diet for 2 weeks. WSE, containing RA , flavones and monoterpenes enhanced CYP 1A1, 2B1/2, 2E1 and GST (especiall y rGST A3/A5, M1 and M2), QR and UGT. On the contrary, no modification of X ME was observed in response to RA or CA (except for a slight increase of UG T activity after CA treatment). The induction of XME by WSE could be attrib uted to flavones, monoterpenes or an additive effect of all components. (C) 2001 Elsevier Science Ltd. All rights reserved.