Golden thistle (Scolymus hispanicus) is an edible medicinal plant growing in Turkey. It has been in use since decades for the treatment of various disorders by local folks. In the past the extracts from the root barks of S. hispanicus were in use in the form of a medicine for the removal of kidney stones. Its root barks are the only eaten part and the root internal and aerial parts are considered as residues. The effect of harvesting time and plant maturity on phytochemicals composition of this plant have not been studied before. Besides that, in previous studies only the edible part was analyzed for bioactive constituents and the residues (aerial parts and root internal parts) have not been analyzed before. In this study, various phytochemicals and total antioxidant activities in the ethanol extracts of aerial parts, root barks and root internal tissues of S. hispanicus harvested from November 2016 to July 2017 were measured. The dominant phytochemicals were different in the roots and the aerial parts, whereas phytochemicals were influenced differently by the harvesting time. Total phenol contents and total antioxidant activities were higher in the aerial parts than the root parts, while total triterpenoid contents were higher in root barks and root internal tissues. Thin Layer Chromatography (TLC) analysis showed that there were not any free triterpenoids in the extracts, however there were glycosides, which may have contained triterpenoids. The crude extracts of S. hispanicus showed cytotoxic effects on Caco-2 cells growth. The results suggested that these extracts might have potential preventative effects on colon cancer.