The antibacterial principle of Caesalpina sappan

Using a bioassay-directed purification scheme, the active antibacterial principle from Caesalpina sappan was isolated and identified to be brasilin. This compound showed potent activity against antibiotic-resistant bacteria, notably methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), multi-drug resistant Burkholderia cepacia as well as a number of other bacteria. The minimal inhibitory concentrations ranged from 4 to 32 microg/mL. The results from time-kill studies showed that brasilin is bactericidal against MRSA. The addition of brasilin to growing MRSA cells resulted in a rapid inhibition of incorporation of [(3)H] thymidine or [(3)H] serine into DNA and proteins, respectively. Exposure of MRSA to a sub-MIC level of brasilin for ten consecutive subcultures did not induce resistance to the compound. The Trypan blue dye exclusion test showed that brasilin lacked cytotoxicity against Vero cells. In conclusion, brasilin is an antibacterial principle from C. sappan and it has the potential to be developed into an antibiotic.