113 Vol. 11, No. 4, 2020 ISSN 2233-4203/ e-ISSN 2093-8950 ARTICLE www.msletters.org | Mass Spectrometry Letters Inhibitory Potential of Bilobetin Against CYP2J2 Activities in Human Liver Microsomes Zhexue Wu 1# , Su-Nyeong Jang 2# , So-Young Park 2# , Nguyen Minh Phuc 2,3 , and Kwang-Hyeon Liu 2 * 1 Mass spectrometry convergence research institute, Kyungpook National University, Daegu 41566, Korea 2 BK21 FOUR Community-Based Intelligent Novel Drug Discovery Education Unit, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu 41566, South Korea 3 Vietnam Hightech of Medicinal and Pharmaceutical JSC, Group 11 Quang Minh town, Hanoi 100000, Vietnam Received December 13, 2020; Revised December 29, 2020; Accepted December 29, 2020 First published on the web December 31, 2020; DOI: 10.5478/MSL.2020.11.4.113 Abstract : Cytochrome P450 2J2 (CYP2J2) is a member of the cytochrome P450 superfamily, and is known to be arachidonic acid epoxygenase that mediates the formation of four bioactive regioisomers of epoxyeicosatrienoic acids (EETs). CYP2J2 is also involved in the metabolism of drugs such as albendazole, astemizole, danazol, ebastine, and terfenadine. CYP2J2 is highly expressed in the heart and cancer tissues. In this study, the inhibitory potential of ten natural products against CYP2J2 activity was evaluated using human liver microsomes and tandem mass spectrometry. Among them, bilobetin, which is a kind of biflavo- noid, exhibits a strong inhibitory effect against the CYP2J2-mediated astemizole O-demethylation (IC = 0.73 μM) and terfena- dine hydroxylation (IC = 0.89 μM). This result suggests that bilobetin can be used as strong CYP2J2 inhibitor in drug metabolism study. Keywords : bilobetin, CYP2J2, human liver microsomes, liquid chromatography-tandem mass spectrometry, natural products Introduction Cytochrome P450 2J2 (CYP2J2) is an arachidonic acid- metabolizing enzyme highly expressed in the heart, kidneys, lungs, small intestine and gastrointestinal tract. 1-4 CYP2J2 plays an important role in the metabolism of human endogenous substances, such as arachidonic acid, 1 linoleic acid, 5 docosahexaenoic acid, 6,7 eicosapentaenoic acid 7 and vitamin D3. 8 CYP2J2 also involved in the metabolism of xenobiotics such as albendazole, 9 apixaban, 10 danazol, 11 ebastine, 12 eperisone, 13 thioridazine, 11 and vorapaxar. 14 Meanwhile, it has been reported that CYP2J2 is overexpressed in human tumor tissues and tumor cells. 15-17 In various tumor types, overexpression of CYP2J2 and elevated epoxyeicosatrienoic acids (EETs) promote cancer cell proliferation, migration and adhesion. 18,19 In addition, accumulating evidence on the relationship between CYP2J2 and anti-cancer activity in hepatocellular carcinoma suggest that inhibition of CYP2J2 enzyme activity by chemicals might introduce novel therapeutics for the treatment of cancer via down-regulation of EETs biosynthesis. 15 Several CYP2J2 inhibitors such as decusrin, 20 tanshinone IIA, 17 acetylshikonin, 16 and broussochalcone A 15 showed anti-cancer effects in vitro and in vivo by reducing EET biosynthesis. However, little data are available on the CYP2J2 inhibitors to date. To identify a new CYP2J2 inhibitor, 10 natural products obtained from medicinal plants were screened for their CYP2J2 inhibitory potential in human liver microsomes (HLMs) using astemizole as CYP2J2 substrate. The ten classes of natural products include 6,8-diprenylorobol (flavonoid), bilobetin (biflavonoid), geniposide (iridoid glycoside), gomisin A (lignan), physcion (anthraquinone), patchoulialcohol (sesquiterpenoid), pellitorine (amide alkaloid), resveratrol (stilbenoid), syringin (phenylpropanoid), and tomentosin (sesquiterpene lactone) (Figure 1). Experimental Materials Astemizole, O-desmethyl astemizole, terfenadine, and terfenadine alcohol were purchased from Toronto Research chemicals (North York, Canada). Glucose-6-phosphate These authors are equally contributed. *Reprint requests to Kwang-Hyeon Liu E-mail: dstlkh@knu.ac.kr All MS Letters content is Open Access, meaning it is accessible online to everyone, without fee and authors’ permission. All MS Letters content is published and distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org /licenses/by/3.0/). Under this license, authors reserve the copyright for their content; however, they permit anyone to unrestrictedly use, distribute, and reproduce the content in any medium as far as the original authors and source are cited. For any reuse, redistribution, or reproduction of a work, users must clarify the license terms under which the work was produced.