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Published on: August 8, 2025
Inhibition of quorum sensing in gram-negative bacteria by alkylamine-modified cyclodextrins
Tomohiro Morohoshi1, Kazuho Tokita, Satoshi Ito
1Department of Material and Environmental Chemistry, Graduate School of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya 321-8585, Japan. morohosi@cc.utsunomiya-u.ac.jp
Abstract:
N-Acylhomoserine lactones (AHLs) are used as quorum-sensing (QS) signals by gram-negative bacteria. We have reported that the cyclic oligosaccharides known as cyclodextrins (CDs) form inclusion complexes with AHLs and disrupt QS signaling. In this study, a series of CD derivatives were designed and synthesized to improve the QS inhibitory activity over that of native CDs. The production of the red pigment prodigiosin by Serratia marcescens AS-1, which is regulated by AHL-mediated QS, was drastically decreased by adding 10 mg/ml 6-alkylacylamino-β-CD with an alkyl chain ranging from C7 to C12. An improvement in the QS inhibitory activity was also observed for 6-alkylamino-α- or γ-CDs and 2-alkylamino-CDs. Furthermore, 6,6'-dioctylamino-β-CD, which contains two octylamino groups, exhibited greater inhibitory activity than 6-monooctylamino-β-CD. The synthesized CD derivatives also had strong inhibitory effects on QS by other gram-negative bacteria, including Chromobacterium violaceum and Pseudomonas aeruginosa. The synthetic alkylamine-modified CD derivatives had higher equilibrium binding constants for binding with AHL than the native CDs did, consistent with the improved QS inhibition. ¹H NMR measurements suggested that the alkyl side chains of 6-alkylacylamino-β-CDs with alkyl chains up to 6 carbon atoms long could form self-inclusion complexes with the CD unit.
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