Impact of Extraction Techniques on the Phytochemical Profile and Antibacterial Activity of Syzygium aromaticum ; Bio-Guided Fractionation Reveals a Potent n-Butanol Fraction and Essential Oil Efficacy

Objective: Syzygium aromaticum (clove) is widely used as a culinary spice and is traditionally valued for its medicinal properties in treating various ailments. This study aimed to compare the efficiency of Soxhlet and maceration extraction methods in extracting bioactive phytochemicals from clove buds, evaluate their antibacterial activities, and identify the most potent solvent fractions. Methods: Clove buds were extracted using methanol through Soxhlet and maceration techniques, followed by fractionation with solvents of increasing polarity. Phytochemical screening was conducted on the crude extracts and fractions. Antibacterial activity was evaluated using the agar well diffusion method against Enterococcus faecalis , Staphylococcus aureus , Klebsiella pneumoniae , and Escherichia coli . Essential oil was also extracted via hydro-distillation and assessed for its antibacterial efficacy. Results: Both extraction methods yielded multiple phytochemicals, with maceration better preserving glycosides and Soxhlet more effectively concentrating antibacterial phenolics. All extracts demonstrated concentration-dependent inhibition against both Gram-positive and Gram-negative bacteria (P < .0001), with Soxhlet extracts producing significantly larger zones of inhibition than maceration (P < .0001). The enhanced activity of Soxhlet extracts result from increased phenolic content and thermally induced glycoside conversion. Notably, the n-butanol fraction of the Soxhlet extract exhibited the highest and most consistent antibacterial activity across all tested strains, likely due to its enrichment of polyphenolic compounds such as tannins, flavonoids, saponins, and anthraquinones. Statistical analyses confirmed significant differences among solvent fractions (P < .05), independent of bacterial species. The pronounced efficacy of the n-butanol fraction suggests the presence of previously unreported antibacterial agents with therapeutic potential. Conclusion: Soxhlet extraction outperformed maceration in isolating bioactive antibacterial phytochemicals from S. aromaticum. The potent activity of the n-butanol fraction highlights its promise as a source of novel antimicrobial compounds. This study is the new to associate saponins, anthraquinones, and phlobatannins in clove bud extracts with significant antibacterial effects, warranting further investigation for drug development.