Hexanic extract of Achyrocline satureioides: antimicrobial activity and in vitro inhibitory effect on mechanisms related to the pathogenicity of Paenibacillus larvae.

Introduction: Paenibacillus larvae is a spore-forming bacillus, the most important bacterial pathogen of honeybee larvae and the causative agent of American foulbrood (AFB). Control measures are limited and represent a challenge for both beekeepers and researchers. For this reason, many studies focus on the search for alternative treatments based on natural products.

Fractionation of hexane extracts from Achyrocline satureioides and their biological activities against Paenibacillus larvae.

Previous studies carried out in our laboratory described the antimicrobial activity of the whole hexanic extract (HE) of Achyrocline satureioides (Lam.) DC against Paenibacillus larvae, the causal agent of American Foulbrood (AFB) a disease of the honey bee larvae. In this study, the HE was partitioned into five main fractions by chromatographic techniques leading to the isolation of four known compounds: two prenylated phloroglucinol α-pyrones (1 and 3), 5,7-dihydroxy-3,8-dimethoxyflavone (gnaphaliin A) (2), and 23-methyl-6-O-demethylauricepyrone (4).