Anticancer and Antibacterial Activities of Eucalyptus camaldulensis

Background/Objectives: Conventional cancer treatments such as radiation therapy, chemotherapy, and surgery often severely reduce a patient’s quality of life due to their side effects. This underscores the urgent need to develop less toxic and more effective alternative therapies. Medicinal plants and their derivatives represent a valuable source for discovering such agents. In this study, we investigated the anticancer and antibacterial properties of ethanolic (EE), methanolic (ME), and aqueous (AE) leaf extracts from the Lebanese Eucalyptus camaldulensis. Methods: The cytotoxicity of the extracts and cis-diamminedichloroplatinum(II) (CDDP) was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against four human cancer cell lines: two breast cancer lines (MCF-7 and MDA-MB-231), colorectal carcinoma cells (HCT-116), and lung carcinoma epithelial cells (A-549). Morphological changes in the cells were observed via inverted phase-contrast microscopy. The antibacterial potential was determined through minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) broth microdilution assays, agar well diffusion, and time-kill tests. The antibiofilm activity of the extracts against Staphylococcus haemolyticus, Streptococcus intermedius, Escherichia coli, and Leclercia adecarboxylata was assessed using antibiofilm screening. Results: All three extracts demonstrated significant anticancer activity against the four cell lines, with particular potency against A-549 cells. The AE showed the greatest cytotoxic effect, with IC50 values ranging from 97.1 to 163.3 µg/mL after 24 h of treatment. Furthermore, all extracts induced notable morphological changes in the cancer cells. The MIC and MBC results indicated a bactericidal effect for the EE (MBC range: 1.5625–50%), ME (MBC range: 6.25–50%), and AE (MBC range: 3.125–100%). Agar well diffusion assays revealed inhibition zones of 8.1 to 20.1 mm, while time-kill tests showed bacterial inhibition within 1 to 24 h of incubation. The antibiofilm assays demonstrated that the extracts inhibited biofilm production and eradicated 50% of pre-formed biofilms. Conclusions: These findings suggest that Lebanese Eucalyptus camaldulensis leaf extracts are a promising source of bioactive compounds with both antibacterial and anticancer properties.