Sinomenium acutum is a plant of the family Menispermaceae native to the forests of subtropical and temperate Asia and used in traditional Chinese medicine. Chromatographic separation of an extract of the stems of Sinomenium acutum resulted in the isolation of two new alkaloids, 2-O-demethyl-acutumine, and 6-O-methyl-laudanosoline-1-O-glucoside , together with three known alkaloids, sinomenine, sinomenine N-oxide, and magnoflorine. Sinomenine was found to show good inhibitory activity toward l-histidine decarboxylase from Lactobacillus 30a with an IC50 value of 969 μM but its N-oxide showed no inhibition of this enzyme. Sinomenine or Cocculine is an alkaloid found in the root of the climbing plant Sinomenium acutum which is native to Japan and China. It is traditionally used in herbal medicine in these countries, as a treatment for rheumatism and arthritis.