Establishment of a method to screen for medical herbs that act via Toll-like receptor 4 signaling pathway

• Main Authors: Ya-hui Hsu, 徐雅慧
• Other Authors: Shu-ling Fu
• Format: Others
• Language: en_US
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/68559947332464130069

碩士 === 國立陽明大學 === 傳統醫藥學研究所 === 91 === Many traditional medical herbs are believed to modulate immune system. Toll-like receptor 4 (TLR4) is a critical protein linking innate and adaptive immunity, and appears to be a potential molecular target for these drugs. The present study aims to establish a method to screen for herbs or pure compounds that act via TLR4 signaling pathways. We had established an efficient system to screen herbs or pure compounds that activate NF-kappaB and the procedure to detect TNF-a expression in bone marrow cells isolated from wild type or TLR4-defective mice for selecting TLR4-dependent drugs. For identification of drugs that can activate NF-kappaB, murine macrophage RAW 264.7 cells were transfected with pELAM1-Luc, contains NF-kappaB-responsive region followed by the luciferase gene. We observed activation of NF-kappaB by monitoring luciferase activity. We applied this method to screen 34 pure compounds, 23 partially purified fractions, 26 herbal ethanol extracts and 31 herbal water extracts. In our study, we found some of these herbal extracts were LPS-contaminated. LPS is known as a TLR4 ligand, so the LPS contamination of drugs might lead to mislead conclusion. In order to remove the effects from contaminated LPS, we added polymyxin B to neutralize LPS effects. Among all drugs we tested, LPS-depleted Patatin, Dioscorin-a and Cordyceps sinensis exhibit ability to activate NF-kappaB. LPS-depleted Patatin, Dioscorin-a and C. sinensis will be tested to determine whether they exhibit different expression of TNF-a in wild type and TLR4-defective mice.