Antibacterial Functions and Proposed Modes of Action of Novel 1,2,3,4-Tetrahydro-β-carboline Derivatives that Possess an Attractive 1,3-Diaminopropan-2-ol Pattern against Rice Bacterial Blight, Kiwifruit Bacterial Canker, and Citrus Bacterial Canker.

In recent years, naturally occurring tetrahydro-β-carboline (THC) alkaloids and their derivatives have been of biological interest. However, few studies and developments have reported the use of such structures in managing plant bacterial diseases. Herein, an array of novel THC derivatives containing an attractive 1,3-diaminopropan-2-ol pattern were prepared to evaluate the antiphytopathogen activity and and explore innovative antibacterial frameworks. Notably, target compounds exhibited excellent activities against three rebellious phytopathogens, namely, pv. actinidiae (Psa), pv. citri, and pv. oryzae, at related optimal EC values of 2.39 (), 2.06 (), and 1.69 () μg/mL, respectively. These effects were superior to those of the parent structure 1,2,3,4-THC and positive controls. assays showed that exhibited excellent control efficiencies of 51.89 and 65.45% at 200 μg/mL against rice bacterial blight and kiwifruit bacterial canker, respectively, and substantially relieved the citrus canker on the leaves. Antibacterial mechanisms indicated that these THC compounds could induce the increment of reactive oxygen species and subsequently endow the tested bacteria with distinct apoptotic behavior. In addition, could alleviate the hypersensitive response and pathogenicity of Psa. Overall, these simple THC derivatives can be further developed as versatile antibacterial agents.