Asian Food Science Journal

Plants have long served as important sources of food and therapeutic agents because of their diverse phytochemical constituents and associated biological activities. This study investigated the phytochemical composition, analytical characterisation, and combined antioxidant and antimicrobial potential of Citrus sinensis peel extract and Boswellia serrata resin extract. Phytochemical screening showed that the methanolic extract of C. sinensis contained steroids, alkaloids, flavonoids, tannins, carbohydrates, saponins, and proteins, whereas the ethanolic extract of B. serrata was rich in terpenoids, flavonoids, tannins, phenolics, glycosides, and saponins. High-performance liquid chromatography (HPLC) confirmed hesperidin in C. sinensis peel extract (7.01%) at a retention time of 2.140 min, while boswellic acid showed retention times of 14.34±0.21 and 16.16±0.25 min. Infrared spectroscopy further supported the structural features of hesperidin. Antimicrobial activity was evaluated against Staphylococcus aureus and Escherichia coli using the agar well diffusion method. C. sinensis peel extract showed larger zones of inhibition (32.02±0.39 to 79.01±0.47 mm) than B. serrata (18.02±0.19 to 56.05±0.51 mm), with dose-dependent activity (p≤0.05). Antioxidant activity assessed using the DPPH assay showed that the methanolic extract of C. sinensis had an IC₅₀ value of 0.215 mg/ml, whereas the boswellic acid extract showed comparatively stronger activity. A 1:1 combination of both extracts showed enhanced radical-scavenging activity, indicating a possible synergistic effect, although the activity remained lower than that of ascorbic acid (IC₅₀ = 0.05 mg/ml). Overall, the findings indicate the phytochemical richness and combined bioactivity of the extracts, suggesting their preliminary potential as natural antioxidant and antimicrobial agents for pharmaceutical and nutraceutical applications.