Synthesis and In Vitro Antibacterial Activity of Quaternized 10-Methoxycanthin-6-one Derivatives

Background: Based on our previous work, we found that 10-methoxycanthin-6-one displayed potential Antibacterial activity and quaternization was an available method for increasing the Antibacterial activity. Here, we explored the Antibacterial activity of quaternized 10-methoxy canthin-6-one derivatives.

Methods and results: Twenty-two new 3-N-benzylated 10-methoxy canthin-6-ones were designed and synthesized through quaternization reaction. The in vitro Antibacterial activity against three bacteria was evaluated by the double dilution method. Moreover, the structure-activity relationships (SARs) were carefully summarized in order to guide the development of Antibacterial canthin-6-one agents. Two highly active compounds (6p and 6t) displayed 8-fold superiority (MIC = 3.91 µg/mL) against agricultural pathogenic bacteria R. solanacearum and P. syringae compared to agrochemical streptomycin sulfate, and showed potential activity against B. cereus. Moreover, these two compounds exhibited good "drug-like" properties, low cytotoxicity, and no inhibition on seed germination.

Conclusions: This work provides two new effective quaternized canthin-6-one derivatives as candidate bactericide, promoting the development of natural-sourced bactericides and Preservatives.