摘要：Background and Objective: Secondary metabolites are complex compounds. Many citrus fruits contain such compounds in the skin, seeds and pulp that act as phytochemicals with bacterial growth-inhibiting, anti-fungal and anti-cancer activities. This study was designed to identify phytochemical compounds in ethyl acetate extracts of orange and assess their antibacterial activities. Methodology: An ethyl acetate extract of orange silage (EAEOS) at 250, 500, 750 and 1000 ppm was fermented for 28 days. Treatments were replicated four times. The samples were placed in a jar serving as a silo under anaerobic conditions. At the end of fermentation, phytochemical screening was performed. Data were analysed using analysis of variance under a completely randomized design. Results: The EAEOS contains alkaloid, flavonoid, steroid, triterpenoid, phenolic, saponin and coumarin compounds. The antibacterial activity of EAEOS was assessed using disc and MIC (minimum inhibition concentration) methods with Escherichia coli ( E. coli ), Staphylococcus aureus ( S. aureus ), Salmonella typhi ( S. typhi ) and Bacillus subtilis ( B. subtilis ). The extract inhibited the growth of all test organisms, with zones of inhibition ranging from 9.75±0.00 to 16.75±0.14 mm ( E . coli ), 8.00±0.23 to 12.50±0.24 mm ( S. aureus ), 8.50±0.24 to 11.75±0.00 mm ( S. typhi ) and 7.75±0.11 to 11.75±0.12 mm ( B. subtilis ). The MICs were 38.72±0.23 to 59.54±0.23% ( E. coli ), 15.08±0.54 to 23.25±0.59% ( S. aureus ), 10.46±0.12 to 19.65±0.02% ( S. typhi ) and 9.64±0.45 to 11.28±0.44% ( B. subtilis ). Conclusion: The tested EAEOS compounds exhibited inhibitory activities against both gram-positive ( S. aureus , B. subtilis ) and gram-negative ( E. coli and S. typhi ) bacteria.
