Investigation of antimicrobial and antibiofilm activity of Curcuma longa L. extracts against methicillin-resistant Staphylococcus aureus (MRSA) isolates

New antibacterial strategies are needed in response to increasing antibiotic resistance. Methicillin-resistant Staphylococcus aureus infections are serious problem in many countries. Morbidity and mortality due to MRSA have increased over time worldwide. Natural products continue to be a notable source for development of new antibacterial agents. Curcuma longa L. products and active constituents have been shown to exhibit remarkable bioactivity. While most studies have focused on curcumin alone, a comparative study on Curcuma longa extracts with solvents of differing polarity is needed to determine its potential against MRSA isolates and strains. In this study, antibacterial, antifungal and antibiofilm activity of hexane, dichloromethane, ethanol and water extracts of turmeric rhizomes were assessed against clinical isolates and standard strains. The hexane (MIC: 32 μg/ml, inhibition zone: 10 mm) and dichloromethane extracts (MIC: 32 μg/ml, inhibition zone: 10 mm) exhibited highest activity against clinical isolates. For standard strains of S. aureus, MIC values were determined to be 64 μg/ml and 128 μg/ml with an inhibition zone of 11 mm for hexane and dichloromethane extracts, respectively. Both extracts reduced total protein levels in clinical isolates. At MIC values, hexane extract was able to inhibit biofilm formation, whereas dichloromethane extract was not. Against standard strains of E. coli and C. albicans, highest activity was also determined with hexane and dichloromethane extracts with a MIC value of 64 μg/ml. Although dichloromethane or ethanol extracts have been the main interest to date, hexane extract from turmeric rhizomes may also be evaluated for further research against MRSA.