Studies on the Antibacterial Susceptibility of Uropathogens to Senna alata Extracts in Calabar, Cross River State, Nigeria

Background: Senna alata is an underutilized shrub found in many countries and is known for its traditional use in the treatment of dermatophytes and other related diseases. Therefore, this study aimed at evaluating the phytochemical and antibacterial effects of S. alata leaves extracts against bacterial isolates obtained from urinary tract infection patients in Calabar.

Methodology: Matured fresh leaves of Senna alata were collected within Calabar, Cross River state, Nigeria, in May 2022 and identified by a botanist in the Department of Botany, University of Calabar. The leaves of S. alata were extracted with water, methanol and ethyl acetate using maceration and soxhlet methods. Phytochemical analysis was conducted to detect the presence of bioactive compounds using standard methods. The crude extracts of S. alata were investigated for antibacterial properties using agar well diffusion method and mechanisms of antibiosis determined using MBC/MIC ratio.

Results: In both methods of extraction, methanol yielded more extracts compared to other solvents. Soxhlet methanol extract (SaMeSh) had the highest (12.21%) percentage yield while maceration ethyl acetate extract (SaEaMa) had the least (4.77%) percentage yield. The phytochemicals assayed revealed the presence of saponins, tannins, flavonoids, anthraquinones, terpenoids and steroids. However, terpenoids was not detected in methanol and ethyl acetate extracts. Senna alata extracts demonstrated broad spectrum of activity against the tested isolates at various concentrations with organic solvents exhibiting the highest antibacterial activity. However, the observed activity varied with respect to concentration of extract and types of organisms. The MIC values ranged from 31.25 to 250 mg/mL and MBC values from 62.5 to 500 mg/mL. The MIC index of the crude extracts against the test uropathogens was ≤8.

Conclusion: This study indicates that S. alata could be a source of novel antimicrobial agent. Further research is required to isolate, characterize and identify bioactive constituents responsible for the observed activity.