Renewable rosin-based bisquaternary ammonium salt with pyridyl design, synthesis and antifungal activity

In order to synthesize green, low-toxicity, and novel antifungal agents. In this study, a rosin-based bisquaternary ammonium salt (Rbs) was synthesized using rosin amine and evaluated for its antifungal activity against F. oxysporum f. sp. niveum, F. graminearum, V. mali, P. capsica and A. solani. The results show that compared to benzalkonium bromide, Rbs has stronger inhibitory activity against five types of fungi, with the best activity against V. mali (EC₅₀ = 3.071 μg/mL), and has excellent sustained antifungal activity. In vivo tests have shown that Rbs has significant protective and therapeutic effects on apples. Using SEM, TEM, relative membrane permeability and density functional theory calculations, we found that Rbs causes organelle and cell membrane disruption, leading to leakage of cell contents and ultimately cell death. In addition, mouse toxicology showed that the toxicity of Rbs was low. These studies provide theoretical guidance for the development of subsequent fungicides.