Formulasi dan evaluasi gel ekstrak etanol buah belimbing wuluh (Averrhoa bilimbi L.): Karakterisasi fisik dan aktivitas antibakteri

Background: Skin infections, including diabetic wound infections, are increasingly complicated by antimicrobial resistance, supporting the search for plant-derived topical antibacterial agents. This study aimed to formulate ethanolic extract gels of Averrhoa bilimbi L. fruit and evaluate their physical properties and antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa.Methods: This laboratory experimental study was conducted from December 2025 to March 2026 at the Biosystematics and Veterinary laboratories of Universitas Syiah Kuala, and Laboratory of Poltekkes Kemenkes Aceh. Five HPMC-based formulations were prepared: an extract-free base (F0) and gels containing 1.5%, 3.0%, 4.5%, or 6.0% extract (F1–F4). Physical tests were performed in triplicate; irritation testing involved 6 panelists and hedonic testing 20 panelists. Antibacterial activity against S. aureus ATCC 25923 and P. aeruginosa ATCC 27853 was tested in triplicate using Kirby–Bauer disk diffusion. Data were analyzed using one-way ANOVA and Duncan’s test.Results: The extract contained alkaloids, flavonoids, saponins, and terpenoids. All gels were homogeneous. Extract-containing gels had pH 4.03–4.79, spreadability 5.00–6.10 cm, and viscosity 2,305–2,913 cP. No erythema or edema was observed. Hedonic scores did not differ significantly (p > 0.05). Antibacterial activity increased with extract concentration; F4 produced the largest inhibition zones against S. aureus (9.58 mm) and P. aeruginosa (8.39 mm) (p < 0.001).Discussion: A. bilimbi fruit extract can be formulated into an HPMC gel with measurable antibacterial activity, but MIC, stability, and safety studies are required before topical development.