探討小分子藥物SC5005的作用機制及其合併天然物後對抗甲氧苯青黴素金黄色葡萄球菌的協同效力

Investigate the mode of action of SC5005, and the synergistic effect of SC5005 with nature products against methicillin-resistant Staphylococcus aureus

袁家敏(Chia-Min Yuan)

指導教授 ： 邱浩傑

國立臺灣大學/醫學院/醫學檢驗暨生物技術學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201701694

摘要

金黃色葡萄球菌感染會造成許多疾病，包含輕微的皮膚感染及嚴重的菌血症。隨著抗甲氧苯青黴素金黃色葡萄球菌在世界各地廣泛傳播，傳統的抗生素已無法有效的治療、預防其擴散。因此，新興藥物的研發具有迫切性，且已成為重要的公共議題。我們在先前的研究中篩選出一個小分子化合物，名為SC5005，於體外及體內試驗皆展現了良好的抗菌能力。在這次的研究中，我們透過修飾SC5005的結構以尋找更有潛力的化合物，然而篩選的結果顯示此次的結構修改並未找到優於SC5005 的化合物。同時我們也探討了SC5005 的作用機制，實驗結果顯示SC5005 會破壞細菌細胞膜的完整性，且能直接作用在細菌細胞膜上的磷脂雙層，亦能影響細菌膜電位。另一方面，在優化SC5005 於動物實驗的劑型時，我們發現HRCA 這個天然物能有效的增加SC5005 的抗菌效果。因此，在這次的研究中，我們想進一步分析SC5005 合併使用HRCA 類似物後的抗菌能力，以及評估此組合應用於治療抗甲氧苯青黴素金黃色葡萄球菌造成的皮膚感染的發展潛力。
在篩選了一系列的HRCA 類似物後，HRCA7 和SC5005 的組合展現了最佳的抗菌效果，其能大幅的提升SC5005 的抑菌效果至8000 倍。此外，HRCA7 並不會顯著的增加SC5005 的細胞毒性。SC5005 合併使用天然物HRCA 以及其類似物於體外試驗中顯現了良好的效力，因此我們進一步評估這樣的組合於體內試驗的效力。在皮膚感染方面，初步的結果顯示SC5005 組合HRCA 配置而成的藥膏能減少皮膚感染模型中小鼠的菌量。

關鍵字

皮膚感染 ； 膜電位 ； 磷脂雙層

並列摘要

Staphylococcus aureus infection leads to many diseases, from minor skin infections to severe bacteremia. With the emergence and prevalence of methicillin-resistant Staphylococcus aureus (MRSA), conventional antibiotics are not sufficient to solve this dilemma. Therefore, development of novel therapeutic agents is urgent and
important for public health. In previous studies, we have identified a small-molecule compound, SC5005, possessing potent antibacterial ability against MRSA at in vitro and in vivo assays. In this study, we aimed to optimize the structure of SC5005 to increase its antibacterial activity, while results indicated neither compound showed a better activity than SC5005. Meanwhile, we investigated antibacterial mode of action of SC5005 against S. aureus, and results demonstrated that SC5005 was able to disrupt the integrity of S. aureus membrane. Further exploration indicated SC5005 directly interacted with phospholipid bilayer of bacterial membrane and dissipated the membrane potential. On the other hand, in the development of SC5005’s formulation for in vivo test, we unexpectedly identified a nature product, HRCA, which was able to
potentiate SC5005’s antibacterial activity. Thus, we would like to further evaluate the antibacterial activity of SC5005 combined with HRCAs and to apply this combination on MRSA skin infection. After we screened a series of HRCA analogues, HRCA7 was the best potentiator that could dramatically increase SC5005’s antibacterial activity to more than 8000×. Moreover, MTT cell viability assays also indicated no significant difference in SC5005’s cytotoxicity in the presence of HRCA7. For in vivo test, preliminary results showed that topical treatment of SC5005 combined with HRCA decreased bacterial load in MRSA USA300 skin infection mice model.

並列關鍵字

Membrane potential ； Skin infection ； Phospholipid bilayer

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