Chemical composition of two samples of Humulus lupulus flowers (vernalized and wild hops)

Background and objectives: Humulus lupulus, a plant belonging to the family Cannabaceae, is used as a medicinal plant with therapeutic applications in different nations. In this study, two samples of H. lupulus (vernalized and wild hops) were selected for further analysis about differences of their essential oils. Methods: The essential oils from the flowers of two H. lupulus (vernalized and wild hops) were achieved through hydrodistillation and analyzed via gas chromatography-mass spectrometry. Retention indices for all compounds were determined according to the kovats retention indices using n-alkanes series as standards. The components of the essential oils were identified by comparison of the retention indices and mass spectral data with those for the standards. Results: Analysis of the vernalized hops essential oil resulted in the identification of 64 components, representing 87.04 % of the total essential oil that principally contained β-caryophyllene (25.3%), β-bisabolole (16.7%) and β-elemene (5.3%). In the case ofwild hops, 49 components were identified, representing 80.9% of theessential oil, among them β-bisabolole (35.2%), β-myrcene (13.3%) and β-sesquiphellandrene (11.3%) were the main compounds. Overall, both vernalized and wild hops possessed sesquiterpene hydrocarbons inhigher contents, followed bynon-terpenoid compounds, oxygenated sesquiterpenes and finally monoterpenoids in less amounts. Conclusion: Concerning the results of this study we found some similarities and differences among vernalized and wild hops and also in comparison with other species of the genus Humulus. Generally, mentioned similarities and differences might be attributed to both intrinsic and extrinsic factors affecting both the quality and quantity of the obtained essential oils.