The aims of this research was to study active ingredients from natural products that
could inhibit bovine mastitis bacteria. There were 4 plants in this study; Acacia catechu (L.f.)
Willd., Acanthus ebracteatus Vahl., Garcinia mangostana Linn. and Punica granatum Linn.
Preliminary bacterial inhibitory testings were performed by agar disc diffusion assay and
microdilution broth assay. Synergism of the active plant extracts was also examined by
checkerboard analysis. The crude extracts were separated by TLC and then bioautographed
to indicate the active antibacterial compound. The active compound was the analyzed by
liquid chromatography. It was found that Garcinia mangostana Linn. extract had promising
compound with antibacterial effects against Gram positive and Gram negative bacteria
including drug-resistant bacteria (MRSA). However, with the synergism examination between
Garcinia mangostana Linn. and Punica granatum Linn. extracts, no synergistic and antagonistic
effect was shown. Therefore, these two extracts could together use for bovine mastitis
treatment. The active antibacterial compound from Garcinia mangostana Linn. was specified
as ?-mangostin.