M.M. WOLDEAMANUEAL*, B.S. GOSHU**#
*Department of Chemistry, Dire Dawa University, Dire Dawa, Ethiopia
**#Department of Physics, Dire Dawa University, Dire Dawa, Ethiopia
Nigella sativa oil, widely used traditionally in Dire Dawa, Ethiopia, for treating infections, inflammation, and digestive issues, is rich in bioactive compounds like thymoquinone. Purpose: This study aims to characterize its chemical composition, evaluate antioxidant and antimicrobial activities, and validate ethnobotanical claims. Methods: Chemical analysis identified thymoquinone (45.99 %), p-cymene (29.72 %), and α-pinene (26.30 %). Antioxidant activity was assessed using 2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) assays, antimicrobial activity against Staphylococcus aureus, Escherichia coli, Candida albicans, and Aspergillus niger via agar well diffusion and minimum inhibitory concentration (MIC) assays, and traditional uses validated by comparing ethnobotanical scores (infections: 90, inflammation: 75, digestive issues: 60) with pharmacological data (antimicrobial: 66.25, anti-inflammatory: 56.41, digestive support: 49.40). Findings: The oil exhibited antioxidant IC50values of 0.45–0.50 mg/mL (DPPH/ABTS) and FRAP of 320 µmol Fe (II)/g, lower than ascorbic acid (0.36–0.38 mg/mL, 350 µmol Fe(II)/g). Antimicrobial zone of inhibition (ZOI) ranged from 10–18 mm and MICs from 125–1000 µg/mL, less potent than amoxicillin (6.25–12.5 µg/mL) and fluconazole (8–16 µg/mL). Traditional uses were partially validated, with strong support for infections and moderate support for inflammation and digestive issues. Conclusion: Nigella sativaoil shows significant therapeutic potential, particularly for infections, though it is less effective than synthetic standards. Recommendation: Further research should optimize its formulation and conduct clinical trials to enhance its efficacy and safety.
Key words: Nigella sativa, antioxidant, antimicrobial, ethnobotanical validation, thymoquinone
Corresponding author’s e-mail: belaysitotaw@gmail.com