eng Oriental Scientific Publishing Company Biomedical and Pharmacology Journal 0974-6242 2025-12-30 18 4 2850 2861 10.13005/bpj/3299 69380 article Anak Agung Gede Indraningrat 1 Pande Putu Christine Putri Purnami 1 Ketut Agus Yogi Indrawan 2 Ni Made Ayu Suardani Singapurwa 2 Made Dharmesti Wijaya 3 Desak Putu Oki Lestari 4 Department of Microbiology and Parasitology, Faculty of Medicine and Health Sciences, Warmadewa University, Denpasar, Indonesia Department of Food Science and Technology, Faculty of Agriculture, Science and Technology, Warmadewa University, Denpasar, Indonesia Department of Pharmacology, Faculty of Medicine and Health Sciences, Warmadewa University, Denpasar, Indonesia Department of Pathology Anatomy, Faculty of Medicine and Health Sciences, Warmadewa University, Denpasar, Indonesia Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia Muntingia calabura has long been used in traditional medicine for its antioxidant and antimicrobial benefits, yet scientific validation of its ethyl acetate leaf extract, particularly against multidrug-resistant (MDR) bacteria, remains limited. This study assessed the phytochemical profile, antioxidant potential, and antibacterial efficacy of the ethyl acetate leaf extract of M. calabura. Qualitative phytochemical screening revealed the presence of flavonoids, tannins, saponins, and steroids. Antioxidant evaluation using the DPPH assay demonstrated very strong radical-scavenging activity, with an IC₅₀ value of 37.32 ppm. Antibacterial testing showed clear inhibitory effects against standard pathogenic strains, with the strongest activity observed against Streptococcus mutans (13.04±2.03 mm), followed by Escherichia coli and Staphylococcus aureus. The extract also exhibited measurable activity against clinically relevant MDR isolates, including ESBL-producing E. coli (8.01±0.10 mm), Klebsiella pneumoniae (7.8±0.5 mm), and Acinetobacter baumannii (8.3±0.2 mm). GC/MS profiling identified 64 compounds, with δ-tocopherol, a chromenone derivative, and a benzopyran analog as the most abundant constituents known for antioxidant and antibacterial properties. Collectively, these findings provide scientific support for the ethnomedicinal use of M. calabura and highlight its potential as a natural source of bioactive compounds active against both standard and MDR bacteria. https://biomedpharmajournal.org/vol18no4/potent-antioxidant-and-antibacterial-activities-of-muntingia-calabura-leaf-extract-a-natural-defence-against-mdr-bacteria/ Antibacterial Antioxidant Bioprospecting Herbal plants Muntingia calabura