eng Oriental Scientific Publishing Company Biomedical and Pharmacology Journal 0974-6242 2026-09-30 19 3 2588 2596 10.13005/bpj/3517 73248 article Ni Wayan Arini 1 I Nyoman Wirata 2 Ni Komang Erny Astiti 2 Ni Made Dwi Mahayati 2 Ni Ketut Nuratni 1 Dept. of Dental Health, Poltekkes Kemenkes Denpasar, Denpasar, Indonesia Dept. of Midwifery, Poltekkes Kemenkes Denpasar, Denpasar, Indonesia The increasing prevalence of bacterial resistance to antibiotics has encouraged the exploration of natural products as potential sources of antibacterial agents. Calophyllum inophyllum L. has been traditionally used for various medicinal purposes, but evidence regarding the antibacterial activity and acute oral toxicity of its leaf extract remains limited. This study aimed to evaluate the antibacterial activity of ethanolic Calophyllum inophyllum L. leaf extract against Streptococcus mutans and Staphylococcus aureus and to assess its acute oral toxicity in mice. The leaf extract was prepared by maceration using ethanol. Antibacterial activity was evaluated using the disc diffusion method at extract concentrations of 10–50%, with 0.2% chlorhexidine and the extraction solvent serving as positive and negative controls, respectively. Each treatment was performed in quadruplicate. Acute oral toxicity was assessed in mice administered single oral doses of 250–2,000 mg/kg body weight and observed for 14 days. Data were expressed as mean ± standard deviation (SD), and inhibition zone diameters were analyzed using one-way analysis of variance (ANOVA), followed by Tukey’s honestly significant difference (HSD) post hoc test at a significance level of p < 0.05. The extraction yield was 11.248 ± 0.568%. Antibacterial activity against Streptococcus mutans was first observed at 20%, with the highest inhibition zone of 7.290 ± 0.796 mm at 30%. Against Staphylococcus aureus, antibacterial activity was detected from 10%, with the highest inhibition zone of 9.170 ± 0.893 mm. No mortality or apparent signs of acute toxicity were observed in mice at doses up to 2,000 mg/kg body weight during the 14-day observation period. These findings demonstrate antibacterial activity of the ethanolic Calophyllum inophyllum L. leaf extract against both bacterial species under the tested conditions, while no apparent acute toxic effects were observed at the tested doses. https://biomedpharmajournal.org/vol19no3/antibacterial-activity-of-calophyllum-inophyllum-l-leaf-ethanolic-extract-against-streptococcus-mutans-and-staphylococcus-aureus-and-its-acute-toxicity/ Antibacterial Activity Acute Toxicity Ethanolic Leaf Extract Calophyllum inophyllum L. Streptococcus mutans Staphylococcus aureus