Phytochemical Profiling, Cytotoxicity, and Antimicrobial Activities of Gum Extracts from the Stem Bark of <I>Eucalyptus globulus</I>

Background: Eucalyptus globulus is well known for its medicinal applications. However, there are limited reports on the medicinal potential of the gum obtained from the stem bark of the plant. This study aims to evaluate the cytotoxicity, antimicrobial potential, and chemical constituents of the gum derived from the stem bark of Eucalyptus globulus. Method: The gum was collected and extracted into methanol (EG-CE) and further fractionated into dichloromethane (EG-DF) and aqueous (EG-AR) fractions. These extracts were assessed for cytotoxic and antimicrobial activities. Phytochemical profiling was conducted using GC-MS to identify bioactive compounds. Results: Bioassays revealed strong cytotoxicity of EG-CE (IC₅₀ = 0.06 μg/mL) in the brine shrimp lethality test, surpassing EG-DF and EG-AR. EG-DF exhibited superior growth inhibitory effects on Allium cepa root (IC₅₀ = 1.09 μg/mL) and Sorghum bicolor radicle (IC₅₀ = 1.43 μg/mL), suggesting its potential as a natural herbicide. The antimicrobial assays demonstrated concentration-dependent activity, with EG-CE showing the highest efficacy against both clinical and standard strains of S. aureus (ATCC 25913) and C. albicans (ATCC 3147). EG-DF was most effective against E. coli (00726), highlighting the role of non-polar constituents in antimicrobial potency. GC-MS analysisidentified bioactive compounds such as octadecenoic acid methyl ester, hexadecanoic acid, and cinnamic acid derivatives, known for antimicrobial and anti-inflammatory properties. Conclusion: This study provides new insights into the bioactivity of Eucalyptus globulus gum, suggesting its potential contributions to natural product-based innovations.