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標題: | 評估以宿主為標的之抗胞內鼠傷寒沙門氏菌感染藥物 Evaluation of Host-Directed Anti-Bacterial Agents Against Intracellular Salmonella Typhimurium |
作者: | Chia-I Chiu 邱嘉儀 |
指導教授: | 邱浩傑(Hao-Chieh Chiu) |
關鍵字: | 沙門氏菌,胞內抑菌,合併藥物, Salmonella,anti-intracellular bacteria,drug combination, |
出版年 : | 2018 |
學位: | 碩士 |
摘要: | 有些具有胞內寄生特性的病原菌,例如:Salmonella spp.會導致慢性的感染,這些病原菌會藉由入侵宿主細胞,來逃避外在抗生素的作用,並持續在細胞內存活而難以抗生素完全治癒以及容易造成抗藥性的產生。以宿主為標的的治療方法在許多研究中被提出來做為胞內細菌感染的治療。AR-12 (a.k.a. OSU-03012)原先是作為抗癌藥物,在我們過去的研究中發現AR-12合併胺基糖苷類抗生素可以顯著清除胞內細菌,使得AR-12有潛力成為一種治療胞內細菌感染的藥物,但是有鑑於AR-12對細胞的半數致死量(IC50)接近於一半抑菌濃度,所以決定進行AR-12結構優化。另外先前實驗室發現一個具有抑菌效力的抗精神疾病藥物-Loxapine,於合併胺基糖苷類抗生素可以顯著清除胞內細菌,且同時具高半數細胞致死量(IC50),然而在活體實驗並沒有延長小鼠存活率,因此我們期望藉由Loxapine結構修改所合成的衍生物找出具有潛力的藥物。在本研究中,我們取得了167個以AR-12為基礎合成的化合物以及5個Loxapine衍生物,針對胞內鼠傷寒沙門氏菌感染進行抑菌能力測試,同時對細胞進行毒性測試,找尋對抗胞內鼠傷寒沙門氏菌更有效且低毒性的藥物以及以Loxapine為代表探討其抑菌機制。
首先,我們進行了一系列結構類似的AR-12衍生物篩選,我們發現7個化合物具有低毒性且和AR-12相等的抑菌能力;另外7個化合物則展現優於AR-12的抑菌能力但是毒性與AR-12相等。我們進一步評估這14個化合物合併胺基糖苷類抗生素對治療胞內鼠傷寒沙門氏菌的效果。由細胞感染實驗結果發現,14個化合物中有4個沒有顯著的抑菌能力。接著在10個化合物中挑選出3個選擇性最高的化合物進行多重抗藥菌株的抑菌能力測試也展現出相同的效果。而在Loxapine細胞感染實驗與毒性測試結果發現,3個化合物展現優於Loxapine的抑菌能力,但是其細胞毒性亦伴隨著增加,因此並無高的選擇性。目前,AR-12衍生物與Loxapine衍生物還在繼續合成並測試中。 上述的實驗證明,以優化AR-12結構所合成的化合物可以展現優於AR-12的抑菌能力以及降低的毒性,候選化合物有潛力成為臨床上多重抗藥性之鼠傷寒沙門氏菌感染的新藥,並作為胺基糖苷類抗生素的佐劑共同使用。 Some bacteria pathogens that can reside in host cells, for example: Salmonella spp. and will lead to chronic infection. These pathogens will invade host cells to evade external antibiotics’ attack and continue to survive in the cell, thus they are difficult to completely eradicated with antibiotics and often lead to drug resistance. Host-directed therapies have been proposed in many studies for the treatment of intracellular bacterial infections. AR-12 (a.k.a. OSU-03012), was originally used as an anti-cancer drug and have been showed in our previous studies that AR-12 combined with aminoglycoside antibiotics can significantly clear intracellular bacteria, making AR-12 as a potential drug for the treatment of intracellular bacterial infections. As the half-lethal dose (IC50) of AR-12 is close to half-effective concentration, we decided to conduct AR-12 structure optimization. In addition, we previously found that an antipsychotic drug - loxapine in combined with aminoglycoside antibiotics showed antimicrobial efficacy and significantly cleared intracellular bacteria with a high half-lethal dose (IC50), however, loxapine cannot prolong the survival of mice. Therefore, we hope to obtain potential drugs by synthesis of loxapine derivatives. In this study, we obtained 167 AR-12 derivatives and 5 loxapine derivatives. We tested the anti-bacterial activity against intracellular Salmonella Typhimurium of all compounds and simultaneously tested toxicity towards host cells to identify more effective and low toxicity drugs. At the same time, we used loxapine as the representative to explore its antibacterial mechanism. First, we performed AR-12 derivative screening. We found that seven compounds have lower toxicity and equal antibacterial activity to AR-12. Another seven compounds showed better antibacterial activity but equal toxicity to AR-12. We further evaluated the efficacy of these 14 compounds in combination with aminoglycoside antibiotics for the treatment of intracellular S. Typhimurium. The results of the cell infection experiments showed that 4 of 14 compounds had no significant antibacterial activity. Subsequent test of the three compounds with highest selectivity for antibacterial activity against multidrug-resistant strains also demonstrated the same effect. In the cell infection test and toxicity test of loxapine, three compounds showed better antibacterial ability than loxapine, but with high toxicity, thus there was no high selectivity. At present, the synthesis and test of AR-12 derivatives and loxapine derivatives are ongoing. The above findings demonstrated that the antibacterial activity of AR-12 can be dissociated from its antiproliferative activity via structure optimization and that hit compounds are potential to be served as antibiotic adjuvants for MDR Salmonella Typhimurium infection. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/71985 |
DOI: | 10.6342/NTU201804056 |
全文授權: | 有償授權 |
顯示於系所單位: | 醫學檢驗暨生物技術學系 |
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