Investigation on changes in some quantitative, morphological and physiological parameters of (Verbascum thapsus) in various elevation classes in Hezar Jarib

Background and purpose: The use of rangeland medicinal plants and their active ingredients have recently been considered due to their therapeutic and industrial use. The quantity and quality of active ingredients in plants are influenced by environmental factors and ecological stresses of the area. One of the most important factors in extracting the active ingredients of plants is solvent, the choice of which depends on the different parts of a plant and its constituents. Plant organs and solvent systems can affect the quantity and type of compounds extracted. The purpose of this study is to investigate these cases on Verbascum speciosum. Methods: The habitat of Verbascum speciosum in Chaharbagh rangelands was first identified, then flower and leaf samples of the species were collected from altitude classes of 2100 - 2300 - 2500 - 2700 meters in three replications. According to the distribution, dimensions and coefficient of variation of canopy cover, 30 plots were established. After purification in the open air, the samples were placed in an oven at 45 ° C for 24 hours. Finally, they were stored in paper bags and transferred to a laboratory to evaluate some phytochemical properties such as total phenol content, total flavonoids and antioxidant activity. Samples were then extracted with ethanol and methanol solvents by two extraction methods including soaking and using microwave ultrasound. Results: According to the results, the highest amount of total phenol (119.46 mg / g dry weight)was found  in flower organs taken at  height of 2100 m, ethanol solvent, and microwave-ultrasonic extraction method, the highest amount of total flavonoids (31.07 mg / g dry weight) In leaf limb of height 2100 m, methanol solvent, and microwave-ultrasonic extraction method and the highest amount of antioxidant activity (81.49%) was observed in flower limb, 2100 m height, ethanol solvent and extraction method by soaking. Also, analysis of variance of IC50 of the samples showed that the inhibitory power of DPPH free radicals alone or interaction was significantly different at P <0.01). The results of comparing the mean of three factors of height, limb, and solvent on the IC50 level of the samples showed that the studied plant species at 2500 m altitude, in the flower limb, and with methanol solvent type has the highest IC50 and consequently the lowest antioxidant activity. Conclusion: Considering the distribution of Verbascum speciosum in mountainous areas, it seems that the altitude gradient, extraction method and type of plant organs have a significant effect on the secondary metabolites, and antioxidant properties of the plant. Therefore, these factors must be considered to produce, exploit, process, and use the active ingredients of Verbascum speciosum in medicinal compounds.