Integrated bioactivity assessment of Syzygium aromaticum bud extract from Sudan shows antimicrobial and antioxidant potential

The escalating threat of antimicrobial resistance, coupled with the significant role of oxidative stress in chronic diseases, underscores the urgent need to identify novel multifunctional agents from natural sources to combat these issues. Clove (Syzygium aromaticum) is a well-known medicinal plant; however, comprehensive and standardized evaluations of its extracts are limited. This study provides an integrated pharmacological evaluation of an 80% ethanolic extract of clove (Syzygium aromaticum) buds. Phytochemical characterization revealed a rich composition, including high levels of total flavonoids (65.56 ± 0.05 mg QE/g) and phenolics (15.50 ± 0.02 mg GAE/g), along with alkaloids, tannins, and triterpenes content. The extract exhibited potent broad-spectrum antimicrobial activity against five standard strains (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Candida albicans), with inhibition zones ranging from 12.0 to 16.3 mm at 100 mg/mL. The minimum inhibitory concentration (MIC) values ranged from 390 to 780 µg/mL, and the minimum bactericidal/fungicidal concentration (MBC/MFC) ratios (≤ 4) confirmed a cidal mechanism of action. Activity Index analysis further highlighted its relative efficacy, demonstrating superior activity to erythromycin against E. coli (AI = 1.03) and moderate activity against other pathogens. In the antioxidant assessment, the extract outperformed the standard propyl gallate, showing 91 ± 0.03% DPPH radical scavenging activity and a significantly lower IC₅₀ (6.09 µg/mL vs. 17.39 µg/mL). Preliminary toxicity screening using the brine shrimp lethality assay indicated a favorable safety margin, with an LD₅₀ of 882.97 µg/mL (classified as slightly toxic), which was markedly higher (less toxic) than that of the control drug etoposide (LD₅₀ = 7.46 µg/mL). These findings underscore the potential of clove extract as a multifunctional natural agent against microbial infections and oxidative stress, offering a promising alternative for combating antimicrobial resistance.