A biologically active composition to treat colorectal cancer includes an extract of the plant Schisandra chinensis and a suitable pharmaceutical formulation. The extract can be at least one of gomisin A, angeloylgomisin H, deoxyschisandrin and gomisin N, showing activities against human tumor cell line HT-29 in the range of about 716 μM to about 43 μM. A suitable pharmaceutical formulation can be any one of a pill, a tablet, a capsule, a liquid solution, a liquid suspension, a powder, an intravenous solution, a gel and a suppository form. The extract is prepared by grinding the dried berries, extracting with hexane, extracting the marc with dichloromethane, extracting the dichloromethane soluble fraction with ethyl acetate, removing fatty materials in the dichloromethane-ethyl acetate soluble fraction with hexane, and fractionating the total hexane insoluble material extract using analytical high performance liquid chromatography equipped with automated repeat injection/collection cycles.
