Inhibition of Magnolol and Honokiol on Cytochrome P450 Enzymes in Rat and Human Liver Microsomes

Abstract

ObjectiveThe purpose of this work is to evaluate the in vitro inhibitory effect of magnolol (MN) and honokiol (HN) on rat/human cytochrome P450 (CYP) enzymes (1A2/1A2, 2D/2D6, 3A/3A4, 2E1/2E1, and 2C/2C9). MethodsRat liver microsomes (RLM) and human liver microsomes (HLM) were used as the enzyme sources. After the probe substrate of each CYP isoforms was co-incubated individually with MN or HN in RLM or HLM, the metabolite production of each probe substrate in RLM and HLM incubation medium was determined and used to evaluate the activity of corresponding CYP isoforms. ResultsMN inhibited rat CYP1A2 and human CYP3A4 with the IC50 values of 10.0 and 56.2 μmol/L, respectively. HN inhibited rat CYP1A2 and CYP2E1, human CYP1A2 and CYP3A4 with the IC50 values of 12.1, 12.6, 17.8, and 43.9 μmol/L, respectively. ConclusionHN is a moderate or weak inhibitor of human CYP1A2. Both MN and HN are weak or non inhibitors of the other tested human CYP isoforms. The results suggest that no significant metabolic interaction seems likely to occur when the substrate drugs of CYP isoforms tested in the present work are co-administered with MN and HN.