Phytochemical Composition and Broad-spectrum Antimicrobial Activity of Guiera senegalensis Methanolic Leaf Extract Against Clinical Isolates

Background: The growing threat of antimicrobial resistance has intensified the search for alternative therapies using natural sources. Guiera senegalensis, a medicinal shrub widely used in African traditional medicine, has shown promising antimicrobial properties due to its rich phytochemical content.  Objectives: This study evaluated the phytochemical composition and the in vitro antibacterial and antifungal activities of the methanolic leaf extract of G. senegalensis against selected bacterial isolates. Methods: Fresh leaves of G. senegalensis were collected, shade-dried, and extracted by maceration in ۷۰% methanol for ۷۲ hours. Phytochemical testing was conducted using standard qualitative methods. Antibacterial activity was assessed using the agar disk diffusion method on Mueller-Hinton agar, while antifungal activity was evaluated using the agar well diffusion method on potato dextrose agar (PDA). Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by broth microdilution and tube dilution methods, respectively. Results: Phytochemical testing revealed the presence of flavonoids, tannins, saponins, glycosides, and steroids, while alkaloids were absent. Antimicrobial activity was concentration-dependent, with E. coli and S. aureus showing the highest bacterial susceptibility (zones of inhibition up to ۲۹ mm) and F. oxysporum exhibiting strong antifungal sensitivity (zone of inhibition= ۲۵ mm at ۵۰۰ mg/mL). MIC values ranged from ۳۱.۲۵ to ۱۲۵ mg/mL for bacteria and fungi, while MBC values ranged from ۶۲.۵ to ۲۵۰ mg/mL. Conclusion: The methanolic leaf extract of G. senegalensis demonstrated high antibacterial and antifungal activity, particularly against gram-positive bacteria and filamentous fungi, supporting its potential as a natural antimicrobial agent.

کلیدواژه ها:

Guiera senegalensis ، antimicrobial activity ، antifungal ، antibacterial ، bacterial isolates