Antitumor and Immunomodulatory Effect of Gastrodia elata on Colon Cancer in Vitro and in Vivo

Gastrodia elata Blume (GE) is a well-known kind of herb that has been used in traditional medicine for thousands of years. The extrusion of raw materials from it could improve flavor and enhance bioavailability in food and drug development. The purpose of this study is to investigate antitumor and immune boosting effects of extruded GE in human colon carcinoma cells, splenocytes, and mice-bearing CT26 colon carcinoma cell. Treatment with 100μg/mL of extruded GE decreased cell viability and induced the expression of Caspase-3 and Bax in HT29 cells (p<0.05). When we performed DAPI staining, apoptotic bodies with condensed chromatin and fragmented nuclei, known as indicative of apoptotic morphology, increased 24h after treatment with 100μg/mL of extruded GE. Treatments with extruded GE significantly promoted splenocyte proliferation and IL-2 or IFN-γ secretion, compared with that of control cells (p<0.05). The administration of extruded GE of 200 mg/kg/day decreased tumor growth and Ki-67 or β-catenin expression in mice (p<0.05). Additionally, we investigated the contents of compounds in extruded GE extracts using ultra performance liquid chromatography. The contents of p-hydroxylbenzyl alcohol and p-hydroxybenzaldehyde in extruded GE were 2.97mg/g and 0.04mg/g, respectively. It was supposed that antitumor and immunomodulatory effects of extruded GE might exert by the p-hydroxylbenzyl alcohol and p-hydroxybenzaldehyde of many compositions analyzed from extruded GE. These results suggest that extruded GE have the potential to be developed into a natural pharmaceutical and functional food as a cancer chemopreventive agent.