Screening Of Bioactive Compounds In Traditional Chinese Medicines Using Mimic Biomembrane

Traditional Chinese medicines (TCMs) have attracted ever-increasing attention due to their long history in clinical practice and reliable therapeutic efficacy. The traditional method for screening bioactive components involves extraction and isolation of TCMs followed by pharmacological screening of the purified compounds. This technique consumes time and samples, it is laborious, and it is inefficient for the direct screening of bioactive compounds from TCMs.Liposomes are structurally similar to biological membranes because of their lipid bilayer structure. This similarity allows the liposomes to mimic the biological membrane and predict the penetrability of the compounds into cells. How much each compound penetrates the membrane is a key factor in evaluating the bioactivity of the compound.In chapter 1, a fluorescent liposome model was developed for the screening of natural products. This model was used to predict the permeability of natural products by fluorescence quenching of liposome.In chapter 2, the erythrocyte membrane was labeled by fluorescent dye DPH. The erythrocyte membrane fluorescence quenching caused by natural products was determined and used to estimate the permeability of natural products. It was found good correlation between fluorescence liposome and erythrocyte membrane by comparing fluorescence quenching percentage of the two models.The above fluorescent liposome model can be used for the rapid, high throughput screening of single compound in TCMs. However, there are some limitations in the model. It was ignored that the characteristics of TCMs are their systematism, multi-target and multi-channel due to their complex chemical constituents. Therefore, a new method for the screening of membrane-permeable compounds in traditional Chinese medicines (TCMs), using ultrafiltration and HPLC analysis, has been proposed in chapter 3. We hypothesized that exposure of the TCM extract to the liposome membrane, the concentration of membrane-permeable compounds in the solution should decrease. Using this approach, the permeability of compounds in Flos Lonicerae Japonicae (Jinyinhua in Chinese), was investigated. By comparing chromatograms of samples prepared before and after interaction with a liposome membrane, eight permeable compounds of Flos Lonicerae Japonicae were identified, and all of them were proven to be biologically active. Based on the significance of these results, this method could be a novel approach for identifying potentially bioactive components in other TCMs.In the last chapter, the screening model proposed above was used to investigate membrane-permeable compounds in Radix Salviae miltiorrhizae (Danshen in Chinese).12 permeable compounds were identified, and they were also proven to be bioactive compounds except vanillic acid. In addition, Radix Salviae miltiorrhizae was investigated by the above strategy with the erythrocyte membrane and myocyte membrane which replaced liposomes. It is found that permeable compounds for the liposome membrane could also combine with erythrocyte membrane. There was good correlation between the liposome model and erythrocyte membrane by comparing the binding degree of the permeable compounds. It was interesting that dihydrotanshinoneâ… , cryptotanshinone, tanshinoneâ… , tanshinoneâ…¡A were combined with myocyte membrane specifically, which might be a useful approach for revealing the cardiovascular effects of Radix Salviae miltiorrhizae.