Phytochemical Profiling and Antibacterial Activity of Methanolic Citrus sinensis Peel Extract on Staphylococcus aureus and Escherichia coli

Background: Citrus sinensis is an important commercial fruit crop widely cultivated worldwide, including Nigeria, and belongs to the family Rutaceae, with nutritional, medicinal, and economic value. Citrus sinensis is commonly called the orange and is a major source of vitamins, including vitamin C, folacin, potassium, calcium, niacin, thiamine, and magnesium. It is the second most important and widely grown fruit crop after the banana, with a total global production of over 180 million tons. Aims: This study evaluated the phytochemical composition and antibacterial activity of the methanolic peel extract of Citrus sinensis on Staphylococcus aureus and Escherichia coli. Methods: The test organisms used in the study were obtained from the Specialist Hospital, Gombe; the plant part was extracted by maceration using methanol as the solvent. The phytochemical screening was carried out using standard protocol, while the inoculation of the test organisms was performed using standard microbiological procedures, and the antibacterial evaluation of the crude extract was conducted using the agar well diffusion method. Results: Phytochemical screening revealed the presence of bioactive compounds, including tannins, steroids, flavonoids, alkaloids, saponins, and phenolic compounds. The ethanolic extract of orange peel showed a remarkable zone of inhibition at 100mg/mL concentration against E. coli (22mm) followed by 17mm at 50mg/mL concentration, whereas the same extract showed a maximum zone of inhibition at 100mg/mL concentration for S. aureus (16mm) followed by 14mm at 50gm/mL concentration. Ciprofloxacin and clindamycin served as positive controls, producing inhibition zones of 30 mm and 23 mm, respectively. MIC and MBC values were 25 mg/mL and 50 mg/mL for Escherichia coli, and 50 mg/mL and 100 mg/mL for Staphylococcus aureus. Conclusion: These findings indicate that Citrus sinensis peel possesses significant antibacterial potential and may serve as a natural alternative for combating bacterial infections. However, the study used only ethanol as a solvent and was unable to explore other solvents such as methanol, aqueous etc which may exhaustively extract all the bioactive compounds due to variation in their polarity.