Comparative analysis of essential oil components of three Phlomis species in Qinling Mountains of China

Abstract

The essential oils of three wild-growing Phlomis species (Phlomis umbrosa Turcz., Phlomis megalantha Diels and Phlomis szechuanensis C.Y. Wu), collected from Qinling Mountains of China during the bloom stage, were obtained by hydrodistillation and analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS). Under the optimum extraction and analysis conditions, 22, 26 and 19 constituents (mainly aliphatic compounds) were identified in P. umbrosa, P. megalantha and P. szechuanensis which represented 92.5%, 96.3% and 93.1% of the oils, respectively. The main constituents were hexadecanoic acid (7.1-52.1%), trans-phytol (5.7-50.8%) and 9,12,15-octadecatrien-1-ol (2.2-24.8%). Fatty acids and aliphatic esters were the major groups of P. umbrosa and P. megalantha, but P. szechuanensis showed higher content of alcohols. P. megalantha has relatively higher amounts of oxygenated monoterpenes and oxygenated sesquiterpenes than the others. The comparison of essential oil components of Phlomis species between the present and previous work indicated that the composition of oils vary greatly with respect to the geographical environment, mainly for the proportion of aliphatic compounds and terpenoids. This study is the first report on the chemical composition of essential oils of the three wild-growing herbs mentioned above.