Preliminary phytochemical analysis, antibacterial and anti-biofilm activities of Curcuma zedoaria (Christm.) Roscoe extracts

Aims: Plant extracts are a rich source of natural compounds that have some degree of antimicrobial efficacy and have less side effects compared to antibiotics. The aim of this research was to screen the phytochemical compounds and investigate the potency of Curcuma zedoaria (Christm.) Roscoe rhizome (CZR) extracts to inhibit the growth and biofilm formation of some pathogenic bacteria. Methodology and results: Antimicrobial and antibiofilm effects of CZR extracts in different solvents were examined by agar well diffusion and the broth microdilution method after phytochemical screening. The 95% ethanolic extract of CZR exhibited broad-spectrum antibacterial properties against Gram-negative and Gram-positive bacteria with inhibition zones of 7.25 ± 0.58-12.00 ± 0.26 mm and MIC values ranging from 50-200 mg/mL. The extract also showed rapid bacteriostatic and bactericidal activities towards Enterococcus faecalis DMST 4736 and Staphylococcus aureus ATCC 25923 by time-kill assays. Moreover, the 95% ethanolic extracts of CZR also acted as a potent anti-biofilm agent against E. faecalis DMST 4736, S. aureus ATCC 25923, S. epidermidis , Escherichia coli ATCC 25922, Klebsiella pneumoniae , Pseudomonas aeruginosa ATCC 27853 and Proteus mirabilis DMST 8212 (54.62 ± 0.30-71.25 ± 0.20% inhibition of biofilm formation). The bioactive potency of compounds of the crude 95% ethanolic extract (tannins, flavonoids, cardiac glycosides, steroids, terpenoids and alkaloids) play important roles in the observed antibacterial and anti-biofilm activities. Conclusion, significance and impact of study: Curcuma zedoaria (Christm.) Roscoe extract had broad-spectrum antibacterial activity. The ethanolic CZR extract revealed bacteriostatic and bactericidal capacities, depending on time of exposure and concentration of the extracts. Thus, the present results indicate that C. zedoaria (Christm.) Roscoe rhizomes are a potential natural alternative antibacterial agent for preventing bacterial diseases.