LC-MS Method for the Simultaneous Quantitation of the Anti-inflammatory Constituents in Oregano (Origanum Species)
DIANDIAN SHEN,†,# MIN-HSIUNG PAN,‡ QING-LI WU,† CHUNG-HEON PARK,† H. RODOLFO JULIANI,† CHI-TANG HO,§ AND JAMES E. SIMON*,†
New Use Agriculture and Natural Plant Products Program, Department of Plant Biologyand Pathology, Rutgers, The State University of New Jersey, 59 Dudley Road, New Brunswick, New Jersey 08901, ‡ Department of Seafood Science, National Kaohsiung Marine University, Kaohsiung 811, Taiwan, and § Department of Food Science, Rutgers, The State University of New Jersey, 65 Dudley Road, New Brunswick, New Jersey 08901. # Present address: National Institute for the Control ofPharmaceutical and Biological Products, 2 Tian Tan Xi Li, Beijing 100050, People’s Republic of China.
Oregano (Origanum spp.), a popular herb in western and Middle Eastern cuisine, was reported to show anti-inflammatory activities in vitro and in vivo but without any information as to the compounds responsible, whether the plants were authenticated or only contained true Origanum spp. Using a wide rangeof botanically authenticated oregano, we were able to show that oregano had anti-inflammatory activity and then using biodirected-guided fractionation, identified the anti-inflammatory agents in oregano as rosmarinic acid, oleanolic acid, and ursolic acid. In this study, we successfully developed an LC-MS (SIM mode) method to achieve coquantitation of these three organic acids with theapplication of a unique tandem column system. The detection of rosmarinic acid was optimal under negative ion mode of SIM, whereas oleanolic acid and ursolic acid were sensitive to positive ion mode. The simultaneous quantitation was attained by setting two time segments in one run to facilitate the ESI polarity switch. For the investigated analytes romarinic acid, oleanolic acid, and ursolic acid, goodlinearities (r2 > 0.999) were obtained for each calibration curve. Validation for this method showed a precision (relative standard deviation) ranging from 4.84 to 6.41%, and the recoveries varied from 92.2 to 100.8% for the three analytes. A quantitative survey of these anti-inflammatory constituents in different oregano species (O. vulgare ssp. hirtum, O. vulgare, and O. syriacum) and chemotypeswithin the species varied significantly in their accumulation of rosmarinic, oleanolic, and ursolic acids. Significant variation in chemical composition between species and within a species was found.
KEYWORDS: Oregano; LC-MS; anti-inflammation; rosmarinic acid; oleanolic acid; ursolic acid
Anti-inflammatory drugs are among the most frequently prescribed class of drugs in theworld (1). The withdrawal of several novel prescription nonsteroidal anti-inflammatory drugs (NSAIDS) from the market due to potential health risk has elevated the safety concern for all such drugs and medicines, particularly those used in the treatment of chronic conditions (2, 3). Meanwhile, natural dietary botanicals with anti-inflammatory activities are gaining increased interest both for theirpotential novel chemistry and therapeutic activities and for their ability to be made available as dietary supplements, where they are perceived to be of lower cost and less toxic while still providing the targeted health-promoting applications. Oregano (Origanum spp.), an aromatic plant in the Lamiaceae family and popular as a fresh or dried culinary herb and food seasoning, has been used sinceancient times. Oregano is also a rich source of aromatic volatile compounds, most notably carvacrol, and the essential oil is used in a variety of flavoring and industrial
*Author to whom correspondence should be addressed [telephone (732) 932-9711, ext. 355; fax (732) 932-9441; e-mail jimsimon@aesop. rutgers.edu].
applications. Greek oregano (O. vulgare ssp. hirtum) represents the most...