"Comparative Evaluation of the Antimicrobial Efficacy of Moringa oleifera and Ziziphus spina-christi (Sidr) Extracts against Gram-Positive, Gram-Negative Bacteria, and Fungi: An In Vitro Study"
Keywords:
Ziziphus spina-christi, Moringa oleifera, antimicrobial activity, medicinal plants, Gram-positive bacteria, antifungal activityAbstract
The increasing prevalence of antimicrobial resistance has intensified the search for effective natural antimicrobial agents. This study aimed to compare the antimicrobial activity of Moringa oleifera and Ziziphus spina-christi (Sidr) leaf extracts against selected Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and fungi (Candida albicans and Aspergillus niger). Antimicrobial activity was evaluated using the agar well diffusion assay, while minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) were determined using standard microdilution methods. Statistical analysis was performed using two-way ANOVA followed by Tukey's HSD test. Both plant extracts exhibited broad-spectrum antimicrobial activity against all tested microorganisms; however, Z. spina-christi consistently demonstrated significantly greater efficacy than M. oleifera. Sidr produced larger inhibition zones, ranging from 10.2 ± 1.3 to 18.5 ± 1.2 mm, compared with 8.3 ± 0.9 to 14.2 ± 0.8 mm for Moringa. The strongest activity was observed against S. aureus (18.5 ± 1.2 mm) and C. albicans (17.4 ± 1.0 mm), whereas P. aeruginosa showed the lowest susceptibility. MIC values for Sidr ranged from 12.5 to 50.0 mg/mL, whereas Moringa required 25.0–100.0 mg/mL. Similarly, Sidr exhibited lower MBC/MFC values (25.0–100.0 mg/mL) than Moringa (50.0–200.0 mg/mL). The MBC/MIC ratio was 2.0 for both extracts against all microorganisms, indicating bactericidal and fungicidal activity. Two-way ANOVA revealed highly significant effects of plant type (F = 142.200, p < 0.001) and microbial category (F = 40.800, p < 0.001), whereas their interaction was not significant (p = 0.382). Tukey's HSD test confirmed the superior antimicrobial efficacy of Sidr over Moringa, with a mean increase in inhibition zone of 4.38 mm (p < 0.001), while Gram-positive bacteria were significantly more susceptible than Gram-negative bacteria and fungi. These findings demonstrate that Z. spina-christi possesses stronger antimicrobial activity than M. oleifera and represents a promising natural source of broad-spectrum antimicrobial compounds for potential pharmaceutical and food preservation applications.
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