Characterization of Anti-Cancer Effects of the Ethyl Acetate Fraction from <i>Orostachys</i><i> </i><i>japonicus</i> on HT-29 Human Colon Cancer Cells

The ethyl acetate fraction from Orostachys japonicus (OJE) is a mixture of flavonols (kaempferol and quercetin) and flavonol glycosides (afzelin, astragalin, quercitrin, and isoquercitrin), and there is little information about the interactive effects of these components on the anti-colon cancer activities. A comprehensive investigation of the anti-colon cancer activities obtained by combined or single treatment of OJE, kaempferol, or quercetin was performed to confirm the roles of key components contained in OJE. OJE alone or OJE supplemented with kaempferol and quercetin showed greater anti-colon cancer activities, namely, in inducing apoptosis, cell cycle arrest, anti-metastasis, and upstream signal transduction than the combination of kaempferol and quercetin without OJE, kaempferol alone or quercetin alone. The combination of kaempferol and quercetin without OJE was also superior to kaempferol or quercetin alone in exerting anti-colon cancer activities via various manners. The consistent cooperative effects were revealed among flavonols and flavonol glycosides.