Antibacterial Activity of Eucalyptus (<i>Melaleuca leucadendron</i>) Leaf Extracts Against Acne-Causing Bacteria

Melaleuca leucadendron (Ecalyptus) plant has been widely utilized in both traditional and modern medicine due to its diverse pharmacological properties. The plant contains various bioactive compounds contributing to its medicinal properties, such as anti-inflammatory, analgesic, antidiabetic, and anticancer effects. This study aimed to evaluate the antibacterial activity of M. leucadendron leaf extracts against acne-related bacteria. Dried M. leucadendron leaf powder was sequentially macerated with n-hexane, dichloromethane (DCM), and methanol to yield MLEH, MLED, and MLEM extracts, respectively. The antibacterial activity of M. leucadendron leaf extracts (MLEH, MLED, and MLEM) was assessed via disc diffusion against Staphylococcus epidermidis and Propionibacterium acnes at various concentrations (1%–20%). Additionally, gas chromatography–mass spectrometry (GC-MS) analysis was conducted to identify the phytochemical constituents. Among the extracts, MLEM yielded the highest extraction efficiency (11.41%) and tested positive for flavonoids, phenolics, saponins, and terpenoids. The MLEH exhibited antibacterial activity against S. epidermidis and P. acnes at a 20% concentration, with inhibition zones of 11.56 mm and 10.36 mm, respectively. MLED showed stronger antibacterial activity, with an inhibition zone of 17.41 mm against S. epidermidis at 20% concentration, and 12.29 mm against P. acnes at 10% concentration. Meanwhile, MLEM displayed antibacterial activity only against P. acnes at 20% concentration (10.47 mm), with no observed inhibition against S. epidermidis. These findings suggest that M. leucadendron leaf extracts, particularly the MLEH and MLED, possess notable antibacterial activity against acne-associated bacteria and hold potential for development in topical antimicrobial applications.