Investigation of methanolic extract variations in milk thistle seeds under drought stress conditions

The content of phytochemicals of medicinal plants including total phenols, flavonoids, fatty acid compounds, etc. are mainly affected by drought stress.  In this study, the effects of different levels of water stress (Full irrigation at field capacity, irrigation at 70% of field capacity and irrigation at 40% of field capacity) on the phytochemicals of the medicinal plant of Milk thistle were evaluated. Soil moisture was measured by weight method and drought stress was applied to plants during the flowering stage for 8 days. Then, the seeds were oiled by Soxhlet and methanol extracted. Next, the phytochemicals of the extract were analyzed using GC-MS. GC-MS peak analysis indicated that 20 compounds were present in methanolic extract of Milk thistle. Oleic acid was the most abundant compound in irrigation treatments of Field Capacity (F.C) (75.8%) and 40%F.C. (73.7%), while methyl linoleate (22.5%) was highest in 70%F.C. Except of oleic acid, which had the highest amount in F.C and 40%F.C, the other compounds had the highest amount in 70%F.C compared to the other two treatments. According to the results, mild stress increased most of the plantchr('39')s phytochemical compounds, possibly due to the osmotic regulation of the plant in dehydration. However, under extreme stress, these compounds were reduced, and these metabolites may have been used to provide energy for plant growth and survival. According to the results of this study, since the seeds of this plant have important phytochemical compounds such as fatty acids, phytosterols, methyl esters, flavonoids, etc. Therefore, the above compounds can be used in the food, pharmaceutical, health and other industries after extraction and purification.