Lansiumamide B (LB) is a cinnamamide alkaloid isolated from Clausena lansium seeds. The compound is the main antifungal ingredient found in C. lansium . In this paper, the antifungal activity of LB against 10 plant pathogenic fungi was evaluated and found that it was the most effective to Rhizoctonia solani (EC 50 = 2.99 μg/mL). The compound also exhibits certain protective (53.06%) and curative (71.01%) activities against R. solani at 800 μg/mL. The mechanism of action of LB was further elucidated through physiological and biochemical experiments, mycelial morphology and ultrastructure observations, and transcriptomics studies with R. solani as the experimental strain. SEM and TEM observation showed that it caused abnormal mycelium growth, extravasation of contents and cell wall degradation. Physiological and biochemical tests showed that LB treatment had no significant effect on the cellular respiration of mycelium , but it could increase the membrane permeability , cause the leakage of intracellular electrolyte, reduce the content of extracellular polysaccharide and chitin in cell wall and increased the contents of intracellular reducing sugar. The results of transcriptome sequencing analysis showed that LB had significant effects on polysaccharide and oligosaccharide related metabolic pathways, such as starch and sucrose metabolic pathways, galactose metabolic pathways, and amino sugar metabolic pathways. Furthermore, LB treatment increased the specific enzyme activity of α-1, 4-glucanase, α-1,6-glucanase, cellulase and maltase of R. solani in vivo . Comprehensive analysis of the above experimental results shows that LB induces and regulates the degradation of polysaccharides and oligosaccharides of R. solani at the transcriptional level, thereby destroying the cell wall structure and ultimately leading to the death of fungi.
He Yan,Zi Xiong,Na Xie,Shanzhi Liu,Lianlian Zhang,Fang Xu,Wenhui Guo,Juntao Feng
Clausena lansium ( Lour.) Skeels is an attractive shrub or small tree, a member of the Rutaceae family. The seeds, leaves and roots of this plant have been used as herbal medicines for a long time. In this study, seven amides were isolated from the seeds of Clausena lansium . The antifungal assay indicated that lansiumamide B ( 4 ) and lansiumamide C ( 2 ) displayed the highest antifungal activity against Sclerotinia sclerotiorum with EC 50 values of 4.95 and 13.24 μg/mL, which were both lower than that of carbendazim (EC 50 = 0.64 μg/mL). The structure-activity relationships of these amides were investigated using assays to measure their in vitro antifungal activities against Sclerotinia sclerotiorum . The effect of the most potent compound lansiumamide B on morphology and physiology of S. sclerotiorum were also evaluated. Lansiumamide B caused cell rupture and mycelial abnormalities of S. sclerotiorum , and its curative efficacy (75.17%) against S. sclerotiorum infection was better than that of carbendazim (56.57%). This study demonstrated that amides isolated from C. lansium possessed the potential to be exploited as botanical fungicides for commercial application or can be used as templates for designing new fungicides with novel action modes.
危险品化学品经营许可证（带存储）