Evaluation of the Phytochemical and Antibacterial Activity of Four Selected Plant Extracts against Some Pathogenic Bacteria

This study aimed to evaluate the phytochemical and antibacterial activity of Acanthus eminens, Celosia trigyna, Drymaria cordata, and Phytolacca dodecandra against the selected pathogenic bacteria; Two strains of Gram-positive (Staphylococcus aureus and Bacillus cereus) and three strains of Gram-negative (Escherichia coli, Salmonella typhi, and Pseudomonas aeruginosa) bacteria. The presences of phytochemicals were analyzed using the standard methods of phytochemical analysis, while the antibacterial activities were analyzed using the disc diffusion method. The results indicated the presence of terpenoids, cardiac glycosides, saponins, flavonoids, and alkaloids in the extracts of A. eminens and C. trigyna. Alkaloids, flavonoids, and phenols are present in the extract of D. cordata and P. dodecandra. Methanolic extracts of Acanthus eminens, Celosia trigyna, Drymaria cordata, and Phytolacca dodecandra were potentially effective with variable efficiency against the tested bacterial strains at a concentration of 4 mg/ml while Celosia trigyna extract was found to be the most effective with a concentration of against all tested bacterial strains. On the other hand, Phytolacca dodecandra extract was found to be effective with a concentration of against B. cereus, S. aureus, S. typhi, and P. Aeruginosa suppressing their growth with inhibition zones of 10.3, 16.7, 11.6, and 11.1 mm, respectively. Celosia trigyna and Phytolacca dodecandra methanolic extracts were the most effective plant extracts and showed bacteriostatic and bactericidal activities against the highly susceptible strains of pathogenic bacteria (Bacillus cereus, Staphylococcus aureus, and Pseudomonas aeruginosa) with MIC's ranging from 20 to 0.8 mg/ml and MBC of 4.0 and 0.16 mg/ml, respectively. These plant extracts have high potential antibacterial effects on bacterial strains tested, especially Bacillus cereus, Staphylococcus aureus, and Pseudomonas aeruginosa. They have been highly effective to be used as a natural alternative treatment to control pathogenic bacteria.