Development of anti-inflammatory agents from the aromatic plants, Origanum spp. and Mentha spp., and analytical methods on the quality control of bioactive phenolic compounds

The development of new anti-inflammatory drugs comes at high cost and risk, as evidenced by the fact that several novel prescription non-steroidal anti-inflammatory drugs (NSAIDs) have been withdrawn from the market due to potential health risks. Meanwhile, natural dietary supplements with anti-inflammatory activities are gaining increased interest by consumers and industry as they are perceived to be of lower cost, with fewer adverse effects and yet function as complementary and alternative medicines. We successfully identified the anti-inflammatory constituents from post-distillation material of oregano, an aromatic plant long prized as a food seasoning and spice in western and Middle Eastern cuisine and a rich source of essential oil. The anti-inflammatory compounds in oregano were identified as rosmarinic acid, oleanolic acid and ursolic acid by using bioactivity-guided isolation, LC/MS and NMR techniques. We subsequently elucidated their possible inhibitory mechanisms during the inflammatory cell signaling pathways by screening different bioassays, and a synergistic action for the combination of these three compounds was observed on the LPS-induced nitrite production assay. An LC/MS (SIM mode) method employing a tandem column system was developed for the simultaneous quantitation of these three compounds in oregano. 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. In order to investigate genetic diversity between species and within a species relative to the anti-inflammatory compounds, different oregano species, varieties and breeding lines were collected from around the world, vegetatively field transplanted into a Rutgers Agricultural Research Experiment Station farm, where the plants were field grown, harvested and quantitated for their anti-inflammatory contents based upon the LC/MS method developed in this study. We next examed mint, another aromatic plant in the Lamiaceae family, and proved that these three anti-inflammatory compounds also accumulated in this plant. An analytical survey was further performed to determine anti-inflammatory agent-rich sources from eight commercial mint species as well as many specialty varieties within the different species. To facilitate the frequent quality control requirement and material pre-evaluation, we developed and validated a near-infrared spectroscopy (NIR) method for the fast quantitation of anti-inflammatory constituents in oregano and mint. Finally, we investigated the anti-inflammatory compound distribution and related chemical properties of the oregano post-distillation materials.