The global number of bees has recently declined. One reason is pathogenic microorganisms including Paenibacillus larvae, which causes American foulbrood disease, and Melissococcus plutonius, which causes European foulbrood disease. The aim of this study was to identify new antimicrobial agents against foulbrood disease. Broth-microdilution assays with 20 natural compounds were used to detect the in vitro antimicrobial activity against foulbrood disease, and MTT assays were performed to determine cytotoxicity against a human cell line. 4-Hydroxydericin, sophoraflavanone G, acetylshikonin, and kurarinone were found to have antimicrobial activity against P. larvae and M. plutonius, with less cytotoxicity against HaCaT cells. In addition, these compounds have a synergic effect with tetracycline or macelignan, which could potentially be effective to control foulbrood disease of honey bees.

中文翻译：

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4-羟基derricin、槐黄酮 G、乙酰紫草素和 kurarinone 对蜜蜂病原菌 Paenibacillus larvae 和 Melissococcus plutonius 的抗菌活性

全球蜜蜂数量最近有所下降。原因之一是病原微生物，包括引起美洲臭虫病的幼虫类芽孢杆菌和引起欧洲臭虫病的Melissococcus plutonius。本研究的目的是确定新的抗污虫病的抗菌剂。使用 20 种天然化合物的肉汤微量稀释试验来检测体外抗污病菌的抗菌活性，并进行 MTT 试验以确定对人类细胞系的细胞毒性。发现 4-Hydroxydericin、sophoraflavanone G、乙酰紫草素和 kurarinone 对 P. larvae 和 M. plutonius 具有抗菌活性，对 HaCaT 细胞的细胞毒性较小。此外，这些化合物与四环素或肉豆蔻木脂素有协同作用，