以兜唇石斛多糖（DAP）为研究对象，借助人小肠上皮细胞Caco-2（the human colon carcinoma cell line）单层细胞模型，体外模拟DAP在小肠中的转运情况。在前期得到的DAP为基础，探究DAP的粘度对其转运情况的影响，同时建立Caco-2细胞的模型，采用MTT法测定DAP对Caco-2细胞存活率的影响，并考察了DAP在小肠的吸收转运的特征。实验表明：DAP的粘度与其在Caco-2细胞中的转运能力呈负相关趋势，粘度越大，转运速率越慢；在测定TEER值及荧光素钠渗透情况，观察Caco-2细胞的形态，建立了良好的细胞模型；DAP的存在下，Caco-2细胞的存活率为91.8%以上，因此DAP对Caco-2细胞存活无影响；DAP在Caco-2不同单边层的转移率分别为0.35%±0.02%和0.32%±0.02%，表观渗透率分别为(0.42±0.02)×10-6 cm/s和(0.19±0.18)×10-6 cm/s，表明DAP在小肠中不易被吸收。本研究所得结果为进一步研究DAP在肠道中的吸收机制奠定基础。

Dendrobium aphyllum polysaccharides (DAP) was used as the study object, and the monolayer cell model of the human intestinal epithelial (Caco-2) cells (the human colon carcinoma cell line) was used to simulate in vitro the transport/translocation of DAP in the small intestine. Based on the DAP obtained at the early stage, the influence of the viscosity of DAP on its transport was investigated, and the Caco-2 cell model was established at the same time. The effect of DAP on the survival rate of Caco-2 cells was determined by the MTT method, and the absorption and transport of DAP in the small intestine were investigated. The results showed that the viscosity of DAP was negatively correlated with its transport capacity in the Caco-2 cells. The higher the viscosity, the lower the transport rate was. The TEER value and the permeation of sodium luciferin were measured, while the morphology of the Caco-2 cells was observed. The obtained results indicated that a suitable cell model was established. In the presence of DAP, the survival rate of the Caco-2 cells was greater than 91.8%, thus, DAP had no effect on the survival of the Caco-2 cells. The transfer rates of DAP in different Caco-2 monolayers were 0.35%±0.02% and 0.32%±0.02% respectively, with the apparent permeability being (0.42±0.02)×10-6 cm/s and (0.19±0.18)×10-6 cm/s, indicating that DAP was not easily absorbed in the small intestine. The findings obtained in this study lay a foundation for further study on the absorption mechanism of DAP in the intestinal tract.

广东省科技计划项目（2016A040402045）；广州市科技计划项目（201704030084）