Two chalcone derivatives panduratin A (PA) (1) and 4-hydroxypanduratin A (4-HPA) (2) were isolated from the rhizome of Kaempferia pandurata Roxb, along with two flavanones pinostrobin (3) and pinocembrin (4). These compounds were screened for determining their growth inhibitory properties against nine bacterial pathogens: four Gram-(+) (Bacillus cereus ATCC 21772, Bacillus subtilis ATCC 663, Listeria monocytogenes ATCC 15313, and Staphylococcus aureus ATCC 29737) and five Gram-(-) (Escherichia coli 0157:H7, Klebsiella pneumoniae ATCC 13733, Proteous mirabilis ATCC 21100, Salmonella typhi ATCC 14028, and Vibrio parahaemoliticus ATCC 17802) bacteria. The results showed that only PA (1) and 4-HPA (2) exhibited significant inhibitory properties against these bacteria. Further antibacterial test indicated that these two compounds were active against all the tested bacteria, with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values in the range of 1.2-75 µg/mL and 2.3-150 µg/mL, respectively. The Gram-(-) bacteria were found to be more affected by PA (1) and 4-HPA (2), and in general the antibacterial properties of PA (1) were two-fold higher than 4-HPA (2). Hence, PA (1) and 4-HPA (2) have the potential to be developed as new bioactive natural products that may serve as leads in new antimicrobial agents.
View Full Article