Abstract
Ligusticum grayi (syn: Ligusticum cusickii), also commonly known as oshála or Gray’s lovage, is used among Native California tribes, such as the Atsugewi tribe, as a relief for upper respiratory congestion, analgesic, gastrointestinal and pancreas problems. The purpose of this study is to identify the chemical constituents in the essential oils of L. grayi. Identification is important because so many of the ligusticum species are used interchangeably in medicine. Since L. grayi has not yet been characterized chemically, L. porteri was used as a standard and compared in order to assure accuracy and proper technique. To determine the best extraction method, identical extraction and analytical procedures were performed on both L. grayi and L. porteri using several different extraction methods. These solvent extraction methods included using hexane, ethanol, dichloromethane, soxhlet extraction with hexane, and solvent assisted flavor extraction (SAFE). Chemical identification was achieved using gas chromatography with flame ionization detection (GC-FID) and gas chromatography with mass spectrometry (GC-MS), comparing retention indices and mass spectra to those of known compounds. The SAFE method produced the best extraction method, resulting in identification of 31 compounds for L. grayi (154 total peaks) and 46 compounds for L. porteri (160 total peaks) than soxhlet (9 identified of 53 peaks for L. grayi and 7 identified of 49 peaks for L. porteri) or hexane (4 identified of 8 total peaks for L. porteri) extraction. Chemical resemblance between L. grayi and L. porteri was 60%, consisting mainly of monoterpenes, sesquiterpenes, thymol and carvacol ether.