Evaluation of the Antibacterial Activity of Aqueous and Alcoholic Extracts of Syzygium aromaticum against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae

Herbal medicinal products have been documented as a significant source for discovering new pharmaceutical molecules that have been used to treat serious diseases. Many plant species have been reported to have pharmacological activities attributable to their phytoconstituents such are glycosides, saponins, flavonoids, steroids, tannins, alkaloids, terpenes, etc. Syzygium aromaticum (clove) is a traditional spice that has been used for food preservation and possesses various pharmacological activities. S. aromaticum is rich in many phytochemicals as follows: sesquiterpenes, monoterpenes, hydrocarbon, and phenolic compounds. Eugenyl acetate, eugenol, and β-caryophyllene are the most significant phytochemicals in clove oil. Clove essential oil has biological activity relevant to human health, including antimicrobial, antioxidant, and insecticidal activity. This study was designed to determine the phytochemical constituents and antibacterial activity of aqueous and ethanolic extract of Syzygium aromaticum (clove) seed at varying concentrations; against Staphylococcus aureus, Escherichia coli, Streptococcus pneumonia, and Pseudomonas sp. Preliminary phytochemical screening of the S. aromaticum extracts was done using standard analytical methods. The aqueous and ethanol extracts of S. aromaticum were evaluated for antimicrobial activities against the isolates using agar well diffusion and broth dilution assay. The results of the phytochemical components revealed the presence of Alkaloids, flavonoids, Tannins, saponins, Glycosides, Terpenoids, and Phenol in the extracts. Ethanol extract of S. aromaticum displayed antibacterial activity against all the tested organisms with the highest activity (24mm at 100mg/ml concentration) on Pseudomonas sp. The aqueous extract of clove was found to be less active, though, it was active against all the organisms tested, with the highest activity on E. coli (2omm at 100mg/mL concentration). Both the aqueous and ethanolic extracts showed MIC at 6.25 mg/mL on all the tested isolates except the aqueous extract against E. coli which showed MIC at 12.5 mg/ml. MBC was only observed on ethanolic extract against Salmonella sp. and S. aureus both at 6.25 mg/ml. The results provide a scientific basis for the centuries-old traditional usage of S. aromaticum.