Phytochemical Profiling and Antibacterial Activity of Orange Peel Extract

Open Access

Abstract

Background: Orange peel (Citrus sinensis), an abundant agro-industrial by-product, is a rich source of phytochemicals with potential antibacterial properties. Increasing antimicrobial resistance has stimulated interest in plant-derived antimicrobial agents as sustainable alternatives to conventional antibiotics. Aim of the study: To characterize the phytochemical profile of aqueous and methanolic orange peel extracts and evaluate their in vitro antibacterial activity against selected pathogenic bacteria. Methods & Materials: This experimental study was conducted in the Department of Pharmacology in collaboration with the Department of Microbiology, Mymensingh Medical College, Bangladesh, from January to December 2025. Fresh orange peels were extracted separately using distilled water and methanol by maceration. Qualitative and quantitative phytochemical analyses were performed to determine the presence of major bioactive compounds and estimate total phenolic, flavonoid, and tannin contents. Antibacterial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa was assessed using the Kirby-Bauer disc diffusion method. Minimum inhibitory concentration (MIC) was determined by broth dilution method. Result: The methanolic orange peel extract (MOPE) produced a higher extraction yield than the aqueous extract (14.36% vs. 9.7%) and contained higher concentrations of total phenolics (89.6 ± 3.2 vs. 52.8 ± 2.4 mg GAE/g), flavonoids (68.4 ± 2.7 vs. 31.5 ± 1.8 mg QE/g), and tannins (33.7 ± 2.1 vs. 18.2 ± 1.3 mg TAE/g). MOPE exhibited stronger concentration-dependent antibacterial activity, producing larger inhibition zones and lower MIC value against S. aureus and E. coli than the aqueous extract. Both extracts demonstrated comparatively weaker activity against P. aeruginosa. Conclusion: Methanolic orange peel extract possesses superior phytochemical content and antibacterial activity compared with the aqueous extract, suggesting that orange peel is a promising natural source of antimicrobial compounds. This study highlights the potential of citrus peel waste for developing value-added antimicrobial products and supports further investigation into the isolation and characterization of its active compounds.