Antibacterial activity of the Chinese traditional medicine, Zi Hua Di Ding

The antibacterial activity of extracts from species of plants used in the Chinese medicine, Zi Hua Di Ding (Viola yedoensis, V. prionantha, Corydalis bungeana and Gueldenstaedtia verna), was tested against Bacillus subtilis and Pseudomonas syringae using a bioautographic assay. The petroleum ether and ethyl acetate extracts of all four species of plants showed activity against both species of bacteria, whereas the methanol and aqueous methanol extracts were inactive. Three fractions from the petroleum ether extracts of V. yedoensis, V. prionantha and C. bungeana showed activity against B. subtilis at 6.25 microg/mL. Preliminary analysis of these active fractions indicates that they contain long chain carboxylic acids.