Antimicrobial Activity of Greater Galangal [Alpinia galanga (Linn.) Swartz.] Flowers

Using the agar disc diffusion method, the potential antimicrobial activity of edible galangal [Alpinia galanga (Linn.) Swartz.] flower against Salmonella, Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus, and Shigella, and the effects of different drying methods and solvent types on the flowers' antimicrobial activity were investigated. Oven-dried ethanol (OD Ethanol) extract from galangal flower was the most effective against S. aureus with inhibition zone of about 26-31 mm and the minimum inhibitory concentration (MIC) ranging from 0.352-0.547 mg/mL. No antimicrobial activity was observed on E. coli O157:H7 and Salmonella. Overall antimicrobial activity of oven-dried samples extracted with ethanol (OD Ethanol) was the highest with inhibition zone of 8.94 mm and MIC of 1.457 mg/mL. In contrast, freeze-dried samples extracted with ethanol (FD Ethanol) exhibited the lowest overall antimicrobial activity (7.05 mm and 2.470 mg/mL). This is the first report describing antimicrobial activity of galangal flowers against Gram-positive S. aureus.