Introduction:

Prevalence of resistant microbial strains is increasing with time; due to the extensive and indiscriminate use of the broad spectrum antimicrobial drugs that render the current used antimicrobial agents insufficient to control some microbial infections. Objective: The present study was aimed to investigate the antimicrobial and antioxidant potential of methanolic extract of the medicinal plant Hibiscus sabdariffa L. Method: The agar well diffusion technique was used to determine the antimicrobial activity of Hibiscus sabdariffa L and the antioxidant activity was determined through the 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) method. In this study the methanolic extract of Hibiscus sabdariffa L was examined against six reference bacterial strains, one fungal reference strain, and one parasitic species including E. coli (ATCC 25922) Ps. aeruginosa (ATCC27853), K. pneumoniae (ATCC 15380), S. typhi (ATCC), B. subtilis (NCTC 8236), S. aureus (ATCC 25923), C. albicans (ATCC 7596) and G. lamblia. Result: The results of the preliminary screening reveals that the extract showed activity against all microorganisms tested and the inhibition zones were between 20 and 25 mm. The minimum inhibitory concentrations were determined for the extract against the selected microorganisms. The methanolic extract of the Hibiscus sabdariffa L screened for antigiardial activity against (G. lamblia) trophozoites in vitro showed antigiardial activity with an inhibition concentration (IC50) more than 180μg/ml. The radical scavenging potential of methanolic extract of Hibiscus sabdariffa L showed 53% . Conclusion: In conclusion, methanolic extract of Hibiscus sabdariffa L used in this study had antimicrobial and antioxidant potential that justify it is use in folkloric and traditional medicine. Further studies are required to confirm these results, identify active compounds and toxicity.