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

TONELLO, NATALIA; PIMENTEL BETANCURT, DIANA; HUALLPA, CARLOS LEONEL; MARIOLI, JUAN MIGUEL; MORESSI, MARCELA BEATRIZ; OLIVA, MARÍA DE LAS MERCEDES; D?ERAMO, FABIANA

BRAZILIAN JOURNAL OF MICROBIOLOGY

SOC BRASILEIRA MICROBIOLOGIA

Año: 2022

1517-8382

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 fve 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 dimethoxyfavone (gnaphaliin A) (2), and 23-methyl-6-O-demethylauricepyrone (4). Isolated compounds were further analyzed towards structural elucidation using 1H RMN and 13C RMN spectroscopic techniques. For the frst time, the antimicrobial activity of the isolated compounds was evaluated against P. larvae strains by broth microdilution method and compared with that of the whole HE. Compounds 1?4 displayed minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranging between 0.07 and 62.5 μg/mL and 0.26 and 12.5 μg/mL, respectively. The lowest MIC and MBC values were obtained with compounds 3 and 4, respectively. The antimicrobial activity of each single compound and the combination of them showed that the presence of all compounds is needed for the antimicrobial efcacy of whole HE.