Tracing antibacterial compounds from Acalypha australis Linn. by spectrum-effect relationships and semi-preparative HPLC.

Several Acalypha australis Linn. species are used in traditional medicine in Southeast Asia. In this work, the ultra-performance liquid chromatography/mass spectrometry fingerprints and the antibacterial activities of A. australis Linn. were investigated. An in-depth discussion on the reliability of identifying and obtaining potentially active compounds by spectrum-effect relationship and semi-preparative high performance liquid chromatography was conducted. The result shows that gallic acid and a compound with molecular weight of 634.1 in the fingerprints were the main antibacterial compounds. Compared to the crude extract of A. australis Linn., both compounds increase the antibacterial efficacy 10 to 20 times. Compounds with molecular weights of 154.0, 292.0, and 485.1 in the fingerprints were the auxiliary antibacterial compounds. Through the entire isolation procedure, we obtained these antibacterial compounds with purities of 92.53, 87.98, 90.73, 89.36, and 88.14%, respectively. This work provides a general model of the combination of ultra-performance liquid chromatography/mass spectrometry fingerprinting and antibacterial test to study the spectrum-effect relationships of A. australis Linn. This model can be used to discover further the active compounds of this herb.