1.Characterization of the mouse cold-menthol receptor TRPM8 and vanilloid receptor type-1 VR1 using a fluorometric imaging plate reader (FLIPR) assay.
Behrendt HJ1, Germann T, Gillen C, Hatt H, Jostock R. Br J Pharmacol. 2004 Feb;141(4):737-45. Epub 2004 Feb 2.
1. TRPM8 (CMR1) is a Ca(2+)-permeable channel, which can be activated by low temperatures, menthol, eucalyptol and icilin. It belongs to the transient receptor potential (TRP) family, and therefore is related to vanilloid receptor type-1 (VR1, TRPV1). We tested whether substances which are structurally related to menthol, or which produce a cooling sensation, could activate TRPM8, and compared the responses of TRPM8 and VR1 to these ligands. 2. The effects of 70 odorants and menthol-related substances on recombinant mouse TRPM8 (mTRPM8), expressed in HEK293 cells, were examined using a FLIPR assay. In all, 10 substances (linalool, geraniol, hydroxycitronellal, WS-3, WS-23, FrescolatMGA, FrescolatML, PMD38, CoolactP and Cooling Agent 10) were found to be agonists. 3. The EC(50) values of the agonists defined their relative potencies: icilin (0.2+/-0.1 microM)>FrescolatML (3.3+/-1.5 microM) > WS-3 (3.7+/-1.7 microM) >(-)menthol (4.
2.The monoterpenoids citral and geraniol are moderate inhibitors of CYP2B6 hydroxylase activity.
Seo KA1, Kim H, Ku HY, Ahn HJ, Park SJ, Bae SK, Shin JG, Liu KH. Chem Biol Interact. 2008 Aug 11;174(3):141-6. doi: 10.1016/j.cbi.2008.06.003. Epub 2008 Jun 20.
Monoterpenes are found in the volatile essence of flowers, plants oils, and herbal medicines. Some are commonly used as food additives and fragrance components, and many are found in cosmetics, soaps, cleaning products, disinfectants, preservatives, and medicines. We have recently discovered a moderate inhibitory effect of borneol and isoborneol toward CYP2B6-catalyzed bupropion hydroxylase activity. Based on that result, we expanded our study to evaluate the inhibitory effects of 22 monoterpenoids on CYP2B6 activity in vitro. Among the monoterpenoids screened, borneol, camphor, cineole, isoborneol, menthol, and perillaldehyde showed slight inhibition of CYP2B6-catalyzed bupropion hydroxylation, displaying greater than 50% inhibition at 50muM. Citral and geraniol strongly inhibited CYP2B6 hydroxylase activity in a competitive manner, with K(i) values of 6.8 and 10.3muM, respectively, which are higher than the K(i) (1.8muM) of the well-known CYP2B6-selective inhibitor thio-TEPA.