Plant material and extract preparation
The rhubarb plant was obtained from Shahroud, Semnan, Iran. Subsequently, it was approved in the Department of Medicinal Plants, Faculty of Pharmaceutical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran. The voucher specimen was deposited in the herbarium of Iran University of Medical Sciences, Tehran, Iran (93–02-27–24,367). The study complies with relevant institutional, national, and international guidelines and legislation for plant ethics. For extraction, the whole plants were first washed and disinfected. Then they were completely dried by aeration and cut into small pieces. In the next step, equal amounts of the plant were used for ethanolic and aqueous extraction. The extraction process followed the soaking method. For this purpose, 100 g of dried rhubarb plant was first placed in a container, crushed and mixed with 1000 ml of distilled water and 1000 ml of absolute ethyl alcohol to produce an aqueous and alcoholic extract, respectively. Then, the contents of the container were spread on a flat paper for 4 h and placed on a bain-marie. The extract was obtained by evaporating the solvent, so that 8 g of extract were obtained from 100 g of the plant. The alcoholic extract was placed in ethanol alcohol in dark and sealed containers for 4 days. Then its content was filtered, the solid content was removed and the pure extract was prepared (1:10 w/v). To prepare the aqueous extract, the plant was immersed in water and boiled in a metal container, then brought to room temperature and placed on bain-marie after straining a filter paper. Finally, the extracts were converted into dry extracts and processed with corn starch to form granules and powder. Finally, the encapsulation step was performed.