Analysis of essential oils of Origanum vulgare from six production areas of China and Pakistan

Origanum vulgare L., Lamiaceae, from six different production areas of China and Pakistan were analyzed via gas chromatography equipped with a flame ionization detector (GC-FID) and examined for their volatile constituents by gas chromatography-mass spectroscopy (GC-MS). This procedure allowed the identification of 11 to 46 components among six production areas, representing 98.5% to 99.9% of the total oil extracted. The yields of the essential oil of the six production areas of O. vulgare ranged from 0.1 to 0.7%. The class of oxygenated monoterpenes was predominant in all the essential oils. However, samples S5 and S6 have high content of sesquiterpene hydrocarbons (33.7 and 43.7%); while sample S6 is high on oxygenated sesquiterpene (32.9%). The principal component analysis of O. vulgare was employed to provide a comprehensive evaluation of essential oil components. The cluster analysis of O. vulgare was classified into three subsets, characterized according to the major essential oil components. The current study investigated the composition differences of essential oil among six production areas offering foundation for quality control, resource optimization, and clinical treatments.