The aqueous extract of thistle plants contains various phytochemicals, including flavonolignans like silymarin. To identify these compounds, you can use techniques such as gas chromatography-mass spectrometry (GC-MS) or high-performance liquid chromatography (HPLC).

Elaheh Soufian Thistle plants are sources of diverse phytochemicals, flavonoids in particular. You have chosen the highly polar solvent water or the phytochemical extraction, which is good for certain classes of metabolites, but not all phytochemicals are soluble in water, and low polar solvents (like ethanol or hexane) may be required to extract compounds such as essential oils, resins, or lipids.

To identify the compounds present in the crude extract you have collected, methods like HR-LCMS/MS qTOF analysis or GC-MS analysis could be opted.