SUMMARY
Antimicrobial resistance is an important issue that should be overcome globally. Melaleuca alternifolia is a powerful antimicrobial agent that could be one of the solutions to antimicrobial resistance with its wide range of antimicrobial activity. Steam distillation is used to utilize this plant to produce tea tree oil (TTO). This process has several drawbacks and studies have stated toxicity and adverse effects associated with oral administration of TTO. The usage of other extraction methods for M. alternifolia is not extensively studied. The bioactive compound and antibacterial activity of M. alternifolia obtained from conventional extraction methods (maceration, soxhletation, and hydrodistillation) was studied to allow better utilization of this plant. Compounds present within each extract were observed using thin-layer chromatography (TLC), the antibacterial activity of the extracts was evaluated using the Kirby Bauer method against Staphylococcus aureus and Escherichia coli, whereas the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) was determined by broth dilution method. Analysis of compounds observed in TLC suggests that cardiac glycosides and terpenoids could be present in maceration and soxhlet extracts. This study suggests that maceration and soxhletation yielded different bioactive compounds from M. alternifolia. Extracts of M. alternifolia from maceration and soxhelatin method have an excellent activity to inhibit the S. aureus, and E. coli in a dose-dependent manner. Maceration extract of M. alternifolia has a stronger effect against E. coli meanwhile the soxhelation extract of M. alternifolia reveals to have stronger antimicrobial activity against S. aureus. The same MIC and MBC values for all extracts (Maceration = 0.1875%; Soxhletation = 0.1875%) were observed from E. coli. MBC of S. aureus is two to more than fourfold of the MIC, with maceration having the highest MBC (MBC = >12%). Moreover, these extract also possess similar antibacterial activity to those observed in the tea tree oil.