Identification and Characterization of Potent CYP2B6 Inhibitors in Woohwangcheongsimwon Suspension, an Herbal Preparation Used in the Treatment and Prevention of Apoplexy in Korea and China

Abstract

ABSTRACT:Woohwangcheongsimwon is a traditional medicine for treating hypertension, arteriosclerosis, coma, and stroke in China and Korea. To assess potential interactions of herb and drug metabolism, commercially available Woohwangcheongsimwon suspensions were examined for their potential to inhibit the activity of nine human cytochrome P450 enzymes. The Woohwangcheongsimwon suspensions showed strong inhibition of CYP2B6 activity. To identify individual constituents with inhibitory activity, the suspension was partitioned using hexane, ethyl acetate, and dichloromethane, and each fraction was tested for its inhibitory effect on CYP2B6-catalyzed bupropion hydroxylation. The hexane fraction possessed inhibitory activity, and gas chromatography/mass spectrometry analysis identified borneol and isoborneol as major constituents of the hexane fraction. These two terpenoids moderately inhibited CYP2B6-catalyzed bupropion hydroxylase activity in a competitive manner, with K i values of 9.5 and 5.9 M, respectively, as well as efavirenz 8-hydroxylase activity, with K i values of 22 and 26 M, respectively. Additionally, reconstituted mixtures of borneol and isoborneol, at the same concentrations as in the Woohwangcheongsimwon suspension, had comparable potency in inhibiting bupropion hydroxylation. These in vitro data indicate that Woohwangcheongsimwon preparations contain constituents that can potently inhibit the activity of CYP2B6 and suggest that these preparations should be examined for potential pharmacokinetic drug interactions in vivo.Herbal medicines have received much attention as alternatives to conventional clinical therapy, and consumption of herbal medicines in Asian, North American, and European countries has increased dramatically in recent years (Eisenberg et al., 1998;De Smet and Debeer, 2002). A recent report indicates that as many as 16% of prescription drug users consume herbal dietary supplements (Kaufman et al., 2002). With the widespread use of herbal medicines, the risk of herb-drug interactions is a growing medical issue, and physicians and pharmacists are concerned about adverse effects such as hepatotoxicity and drug interactions (Kaplowitz, 1997;Suchard et al., 2004). Several medicinal herbs, including St. John's wort (Henderson et al., 2002;Mills et al., 2004), ginkgo biloba (Yin et al., 2004), and kava (Anke and Ramzan, 2004), have been reported to cause herb-drug interactions. Interactions among therapeutic drugs as well as interactions of drugs with food and herbal medicines have attracted attention.The modulation of drug-metabolizing enzymes is one of the main mechanisms of drug interactions (Guengerich, 1997). Cytochrome P450 (P450) monooxygenases are probably the most important enzymes in the detoxification and bioactivation of a number of therapeutic drugs. The P450 family comprises a group of enzymes with broad substrate specificity, which leads to herb-induced drug interactions with some P450 substrates (Ueng et al., 2002). In recent years, in vitro systems using human liver microsome...

Effects of woohwangcheongsimwon suspension on the pharmacokinetics of bupropion and its active metabolite, 4‐hydroxybupropion, in healthy subjects

“…Our previous studies have reported that woohwangcheongsimwon suspension inhibited CYP2B6 activity in vitro . Two terpenoids, borneol and isoborneol, are major constituents of woohwangcheongsimwon suspension, and show competitive inhibition of CYP2B6, with K i values of 9.5 and 5.9 µ m , respectively [2]. Furthermore, we found that other monoterpenes, such as citral and geraniol, have inhibitory potency on CYP2B6‐catalyzed bupropion 4‐hydroxylation as well as isoborneol and borneol [3].…”

“…It has been officially listed in the Korean Pharmaceutical Codex for a long time and an aqueous suspension has recently been developed for convenient administration [1]. It has been widely used for treatment and prevention of stroke, hypertension, palpitations, convulsions and unconsciousness [2]. In Korea, woohwangcheongsimwon suspension can easily be obtained over the counter in local pharmacies; nowadays, it is often preferred as a preventive medicine rather than a treatment.…”

Inhibitory Effects of Cedrol, β-Cedrene, and Thujopsene on Cytochrome P450 Enzyme Activities in Human Liver Microsomes

“…This was not an unusual finding because sesquiterpenes, such as artemisinin, zederone, and germacrone, also significantly blocked CYP2B6 activity in human liver microsomes with IC 50 values of 9.1, 3.9, and 5.6 μM, respectively (Ericsson et al, 2012;Pimkaew et al, 2013;Xing et al, 2012). Monoterpenes, such as borneol and isoborneol, strongly and competitively prevent CYP2B6-mediated bupropion hydroxylation, with K i values of 9.5 and 5.9 μM, respectively, in human liver microsomes (Kim et al, 2008). Cedrol, β-cedrene, and thujopsene were found to be potent competitive inhibitors of CYP2B6 with K i values of 0.9, 1.6, and 0.8 μM, respectively, comparable with that of thioTEPA (K i , 2.9 μM) in human liver microsomes (Table 2 and Figure 7).…”

Establishment and characterization of Mardin-Darby canine kidney cells stably expressing human organic anion transporters

“…Simply because of its widespread use, Woohwangcheongsimwon is likely to be used in combination with various drugs, suggesting that Woohwangcheongsimwon has a high potential for herb-drug interactions, arising from drug metabolizing enzymes or drug transporters. Borneol and isoborneol, major components of Woohwangcheongsimwon, have been shown to inhibit microsomal CYP2B6 activity (Kim et al, 2008). In this study, we screened the interactions of Woohwangcheongsimwon with OATs transporters.…”

“…In case of OAT3, Woohwangcheongsimwon apparently enhanced ES uptake. Among them, borneol is major components of woohwangcheongsimwon (Kim et al, 2008). Borneol was reported to can accelerate the absorption of puerarin and timolol maleate in vitro (Wu et al, 2006) and also to activate TRPV3 ion channel (Vogt-Eisele et al, 2007).…”