Abstract:
Medicinal plants have been used for centuries to treat diseases. This study was carried out to screen the phytochemical composition and evaluate the antibacterial activities of crude leaf extracts of Tanacetum parthenium (feverfew) against dental pathogenic bacteria. T. parthenium is a medicinal plant which belongs to the family Asteraceae. Mature leaves of this plant were collected from Haramaya University and were shade dried and ground to powder. The crude extracts were prepared by cold maceration at room temperature using hexane, chloroform, methanol and water. Qualitative analysis were investigated using standard biochemical tests. Quantitative analyses of total phenolic contents (TPC) and total tannin contents (TTC) of each crude extracts were done colorimetrically using gallic acid as a standard. The antibacterial activities of these extracts against Streptococcus pyogenes, Streptococcus anginosus, Pseudomonas aeruginosa and Fusobacterium necrogenes were evaluated using the disc diffusion method at three different concentrations (100, 150 and 200 mg/mL) in the presence of positive and negative controls. Their inhibitory zones were recorded in millimeter. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of these crude extracts against S. pyogenes, S. anginosus, P. aeruginosa and F. necrogenes were assessed using the broth dilution method. In this study, qualitative analysis of the composition of crude extracts revealed the presence of phenols, tannins, terpenoids, flavonoids, cardiac glycosides, saponins, steroids and sterols. Among the four different solvent, methanol and water performed better than hexane and chloroform in the extraction of bioactive compounds. TPC and TTC values ranged from 1.07 to 6.17 mg/g and 0.04 to 0.99 mg/g of these crude extracts, respectively. Lower TPC and TTC values were obtained in water extract while higher values were observed in the methanol extract. From the antibacterial assay, S. anginosus and S. pyogenes were the most susceptible bacterial species to 200 mg/mL concentration (15.66 ± 0.33,15.00 ± 0.00 mm, respectively), of the methanol extract without significant different. While the least susceptible was P. aeruginosa at 100 mg/mL concentration (7.66 ± 0.33 mm) of the hexane extract. Methanolic extract were more inhibitory to the growth of the test pathogens at 200 mg/mL. The MIC values ranked from 16.66 to 66.66 mg /mL against the test bacteria. The average MIC of methanol and water extracts ranged from 16.66 to 41.66 mg/mL and 20.83 to 41.66 mg/mL, respectively, while those of hexane and chloroform extracts ranged from 25.00 to 66.66 mg/mL. The Minimum Bactericidal Concentration (MBC) values also ranged from 25.00 to 100 mg/mL against S. anginosus, S. pyogenes, F. necrogenes and P. aeruginosa. Generally, the methanol and water extracts exhibited good antibacterial activities against the test bacteria. The results indicated that crude extracts of the leaves of T. parthenium has a moderate antibacterial activity and suggest that it can be useful in the treatment of dental pathogenic bacterial infections. In addition to this, the leaf of this plant posses various secondary metabolites having the potential for the treatment of bacterial infections. However, further research is needed to authenticate which bioactive component is responsible for these antibacterial activities