Antibacterial Activity of Stembark and Leaves of Soursop (Annona muricata) Against some Bacterial Isolates

Abstract

Annona muricata (Soursop) is a tropical fruit that belongs to the Annonaceae family. The plant is been used as a natural remedy for a variety of illnesses. This study aimed at determining the antibacterial activities of aqueous and ethanol extracts of leaves and soursop stembark of soursop against clinical isolates of Staphylococcus aureus and Escherichia coli. The aqueous and ethanol extracts of the stembark and leaves were screened for phytochemical constituents. The stembark and leaves extracts were subjected to antibacterial analysis using agar well diffusion and broth dilution methods against the two clinical isolates. The phytochemical analysis revealed the presence of saponins, tannins, phenols, terpenoids, and steroids in both the plant parts, with quinones detected only in the stembark. The inhibitory zone of the ethanol extracts of the leaves and stembark against S. aureus ranged between 11.23±2.06 mm to 21.6±2.07 mm while that of E. coli ranged between 10.60±1.06 mm to 19.66±0.90 mm at 25 to 200 (mg/mL). The inhibitory zone of the aqueous extracts of the leaves and stembark against the clinical isolate of S. aureus ranged between 2.25±1.50 mm to 25.25±1.01 mm at 25 to 200 (mg/mL), while that of E. coli ranged between 1.66±0.08 mm to 25.25±1.05 mm at 25 to 200 (mg/mL). The Minimum Inhibitory Concentration and the Minimum Bactericidal Concentration, on the average were 50 mg/mL and 100 mg/mL respectively. This investigation highlights soursop’s antibacterial potential, specifically its effectiveness against S. aureus and E. coli. Further investigation into clinical trials and mechanisms of action of the extracts is recommended.