Investigation of effective compounds and antioxidant properties of five cultivar of hops (Humulus Lupulus L.) in different regions of Golestan province

To investigate the effect of the environment on phenolic and flavonoid contents and antioxidant and phytochemical properties of essential oils in five cultivars of hop, in four regions of Golestan province (Gorgan, Aliabad, Galikesh, and Azadshahr), an experiment was conducted as randomized complete block design with three replications during 2021-2022. Fruit extracts were prepared by soaking method using acetone solvent and the phenolic and flavonoid contents and the antioxidant properties were determined via Folin-Ciocalteu, aluminum chloride colorimetric, and DPPH method, respectively. Extraction of essential oils from fruit and identification of the compounds in the essential oil were carried out by water distillation method (Clevenger machine) and a gas chromatograph connected to a mass spectrometer (GC/MS), respectively. Overall, 32 compounds were identified, including Beta-acid, Alpha-acid, Co-humulone, total oil, Caryophyllene, Humulene, and Myrcene compounds, as the main components of the essential oil. Cascade cultivar in Gorgan region had the highest rate of phenolic and flavonoid contents as well as antioxidant activity, which can be related to the climatic conditions of the region and the higher potential of this cultivar. Also, all cultivars in Gorgan region had the highest content of secondary metabolites than others. Among the cultivated cultivars, Cascade and then Centennial had the highest content of secondary metabolites in all cultivation areas. Therefore, in order to achieve higher secondary metabolites, cultivation of Cascade in Gorgan region is recommend. On the other hand, Nugget in Galicash had the lowest content of secondary metabolites, which can be related to its lower potential in production of secondary metabolites and the climatic conditions of Galicash region which is located at a higher altitude and has a negative effect on the production of secondary metabolites. Therefore, considering the effect of different environmental conditions on the medicinal compounds of the species, it is recommended to evaluate the effect of the other factors, including the soil of the habitats.