季銨鹽化合物因結構穩定且具有抗細菌與真菌之作用，常使用於個人護理產品中。文獻中指出季銨鹽類化合物之抗菌效果與其氮原子上電子雲密度呈正相關，因此雙陽離子化合物其抗菌效果較單陽離子季銨鹽佳，而目前雙陽離子抗菌劑以對稱型化合物為主。本研究利用?啶或1-甲基?咯烷與1,3-二溴丙烷進行烷化反應，再將產物與不同碳鏈長度之二甲基烷基胺進行反應，製備成十二種不對稱雙陽離子熔鹽。產物經由核磁共振光譜儀(NMR)與質譜儀(LTQ Orbitrap LC/MS/MS)進行結構鑑定。抗菌活性則經由紙錠擴散試驗法、最低抑菌濃度與最低殺菌濃度評估，並使用人類臍靜脈細胞進行細胞毒性試驗，以評估抗菌劑之安全性。抗菌活性實驗顯示本研究之不對稱雙陽離子熔鹽具抗菌效果。於紙錠擴散實驗顯示，不對稱雙陽離子熔鹽在烷基碳鏈長度C10至C16有較佳抗菌活性，對枯草桿菌以化合物5c抑制效果最佳，在0.4 mg/disc的濃度下，抑制圈範圍可達38.03±0.46 mm；對於綠膿桿菌以化合物5e抑制效果最佳，在1 mg/disc的濃度下，可達到17.57±1.29 mm的抑制圈範圍，皆較市售三甲基十四烷基溴化銨抗菌劑為佳。在最低抑菌濃度與最低殺菌濃度試驗顯示，化合物烷基碳鏈長度在C16且具芳香環結構時，有最好的抗菌效果。在五種測試菌株中，化合物5e抗菌活性依序為枯草桿菌>大腸桿菌>金黃色葡萄球菌>綠膿桿菌>白色念珠菌。在細胞毒性試驗中，與市售苯扎氯銨抗菌劑(BAC)相比，對細胞毒性大小依序為BAC >化合物5d >化合物8d。 Quaternary ammonium compounds (QACs) are often used in personal care products because the structure of compounds possess the stable and antimicrobial activity. According to the study of antibacterial activity, QACs are positive correlation with electron density in the nitrogen atom. This study utilizes the pyridine or 1-methylpyrrolidine to react with the 1,3-dibromopropane, and the product reacts with the different carbon chain length of N,N-dimethylalkylamine, then we acquire twelve of unsymmetrical dicationic molten salts. We employ nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (LTQ Orbitrap LC / MS / MS) to identify the structure.Antimicrobial activity is evaluated with disc diffusion assay, minimum inhibitory concentration and minimum microbicidal concentration. We estimate the safety of antibacterial agents by the MTT viability assay. This study shows that compounds of the alkyl chain length in C10-C16 have better antibacterial activity. Furthermore, the 1-(3-(hexadecyldimethylammonio)propyl)-1-methylpyrrolidinium dibromide(5e) has the best antibacterial activity. It is able to inhibit the growth of Bacillus subtilis at 0.9 ?g/mL.In the MTT viability assay, both of compound 5d and compound 8d are more safe than benzalkonium chloride (BAC).
