Anti-listerial compounds from Asari Radix.

Asari Radix, the roots of Asarum heterotropoides F. Maekawa var. manshuricum F. Maekawa or A. sieboldii F. Maekawa, has traditionally been used for the treatment of various infectious diseases. Since its MeOH extract inhibited the growth of Listeria monocytogenes in a preliminary test, the aim of this study was to isolate and identify the anti-listerial compounds from the plant. Activity-guided fractionation led to the isolation of seven compounds 1-7 from the MeOH extract, and their chemical structures were identified by comparison of the spectroscopic data with those in the literature. Compounds 1-7 exhibited inhibitory activity against all five tested strains of L. monocytogenes with diameter of inhibition zones ranging from 7 to 11 mm in the agar disc diffusion method. Compounds 1-3 and 7 demonstrated potent antimicrobial effects on the L. monocytogenes strains, with MICs between 62.5 and 125 μg/mL. This is the first report that AR possesses inhibitory activity against L. monocytogenes.