Novel betaines were synthesized from esterquats, which in turn were obtained from the reaction of 11-bromo undecanoic acid, different alkyl amines, and methyl iodide. The synthesized betaines were characterized by fourier transform infrared, proton nuclear magnetic resonance, carbon-13 nuclear magnetic resonance, and mass spectral analysis. These betaines were synthesized in four steps; in the first step, 11-bromo undecanoic acid was converted into methyl 11-bromoundecanoate followed by the synthesis of secondary amine monoester, and tertiary amine mono and diesters by the reaction of 11-bromoundecanoate with different aliphatic amines (hexyl, dodecyl, octadecyl, dioctyl, and dicyclohexyl amine). In the third step, the prepared secondary amine monoesters, tertiary amine mono, and diesters were converted into monoesterquats and diesterquats by reacting with methyl iodide. The resultant esterquats were converted into betaines by saponification reaction using LiOH.H₂O in water and tetrahydrofuran. The synthesized compounds (5a–h) were studied for their antimicrobial activity. Some of the compounds showed good to moderate antibacterial activity with minimum inhibitory concentration values ranging between 3.9–31.2 µg mL⁻¹ and antifungal activity with minimum inhibitory concentration values ranging between 7.8–62.4 µg mL⁻¹. Further, some of the betaines also showed good anti-biofilm activity with IC₅₀ values ranging between 2.1–25.3 µg mL⁻¹ on the tested pathogenic microbial and fungal strains.

中文翻译：

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新型基于11-溴癸酸的甜菜碱的合成，表征，抗微生物和抗生物膜活性

由酯季铵盐合成了新型甜菜碱，这些酯季铵盐又是由11-溴十一烷酸，不同的烷基胺和甲基碘的反应制得的。通过傅立叶变换红外，质子核磁共振，碳13核磁共振和质谱分析对合成的甜菜碱进行表征。这些甜菜碱通过四个步骤合成。在第一步中，将11-溴十一酸转化为11-溴十一酸甲酯，然后通过11-溴十一酸与不同脂肪族胺（己基，十二烷基，十八烷基，二辛基和二环己基胺）。在第三步中，制备仲胺单酯，叔胺单酯，通过与碘甲烷反应，将二酯转化为单酯季铵盐和二酯季铵盐。通过使用LiOH.H的皂化反应将生成的酯季铵盐转变为甜菜碱₂ O溶于水和四氢呋喃。研究了合成的化合物（5a – h）的抗菌活性。一些化合物显示出良好至中度的抗菌活性，最小抑菌浓度范围为3.9-31.2 µg mL ^-1，而抗真菌活性则抑菌浓度最小范围为7.8-62.4 µg mL ^-1。此外，某些甜菜碱还显示出良好的抗生物膜活性，对所测试的病原微生物和真菌菌株的IC ₅₀值在2.1–25.3 µg mL ^-1之间。