Determination of in-vitro Antimicrobial Effects of Different Solvent Extracts of Curcuma zedoaria (Kunyit putih) rhizome to inhibit the growth of certain types of Gram-negative and Gram-positive bacteria

Abstract

The importance of medicinal plants remarkably increases. Some of them possess natural products that help them resist antibiotic-resistant bacterial strains. Curcumazedoaria is among the most prominent plants of the ginger family highlighted for the presence of antibacterial agents. Methanol, ethanol and isopropanol extracts of C. zedoaria rhizome were subjected to phytochemical screening for the presence of total flavonoids content (TFC), antioxidants and phenolic compound. They were also subjected to antimicrobial susceptibility testing using agar-disc diffusion technique at concentrations of 10 mg/mL, 25mg/mL and 50mg/mL against both of Gram positive bacteria including Bacillus subtilis(ATCC 6633), Bacillus cereus(ATCC 33019), Staphylococcus aureus(ATCC 29737), Propionibacterium acne(ATCC 6919), Streptococcus mutans(ATCC 27351) and Listeria monocytogenes and gram-negative including Escherichia coli(ATCC 25922), Klebsiella pneumoniae(ATCC 13773) and Acinetobacteranitratus(A9). Their Minimum Inhibitory Concentrations (MICs) and Minimum Bactericidal Concentrations (MBCs) were also determined. All the extracts had the presence of TFC, Antioxidants and phenolic compounds and exhibited activity against S. mutans, E. coli and B. cereus at different dilutions used with the inhibition zones range of 7.33 mm to 10.67 mm. They were also active against B. subtilis and A. anitranus at 25 and 50 mg/mL concentrations. However, there was no activity of the extracts at all concentrations against the isolates of K. pneumoniae, S. aureus, L. monocytogenes and P. aeruginosa. The MIC and MBC values for all the extracts were equal against S. mutans and B. cereus. Isopropanol extract had the lowest MIC value of 1.25 mg/mL against E. coli while ethanol extract had the lowest MIC value of 0.632 mg/mL against B. subtilis. Meanwhile, both the two extracts exhibited the lowest MICs of 2.5 mg/mL against A. anitranus. Other values remain the same. The refined extracts of C. zedoaria rhizome could be alternative source of cure of diseases caused by the test organisms.