Phytochemical Screening, Antimicrobial, and Antioxidant Activities of Olea europaea Leaf Extracts

Abstract

Olea europaea L. (family Oleaceae) is a medicinal plant traditionally used to 
manage infections, hypertension, diabetes, and inflammatory conditions. This 
study evaluated the phytochemical composition, antimicrobial, and antioxidant 
activities of O. europaea leaves. Dried leaves were sequentially extracted using 
n-hexane, methanol, and water. Phytochemical screening revealed that 
methanolic and aqueous extracts contained phenolics, flavonoids, tannins, 
saponins, alkaloids, and cardiac glycosides, whereas n-hexane lacked cardiac 
glycosides and steroids. Antimicrobial activity was assessed against Salmonella 
spp., Escherichia coli, Aspergillus niger, and Candida albicans using the agar 
well diffusion method, with Ceftriaxone (10–30 mg/mL) and fluconazole (10–30 
mg/mL) as controls. Minimum inhibitory concentration (MIC) and minimum 
fungicidal concentration (MFC) were determined by broth dilution. All extracts 
exhibited antimicrobial activity, with inhibition zones of 0–2.9 mm (bacteria) and 
0–2.8 mm (fungi). Methanolic extract demonstrated the highest antibacterial 
activity against Salmonella spp. (2.20 mm at 30 mg/mL), while the aqueous 
extract showed the strongest antifungal activity against C. albicans (2.80 mm at 
30 mg/mL). MICs ranged from 0.05 to 8.56 mg/mL and MFCs from 0.56 to 
14.32 mg/mL. Antioxidant activity, measured by DPPH free radical scavenging 
(5–640 µg/mL), was concentration-dependent, with methanolic extract achieving 
87.36% inhibition at 640 µg/mL. These findings indicate that O. europaea 
leaves are a rich source of bioactive compounds with moderate antimicrobial 
and potent antioxidant properties, highlighting their potential as natural 
therapeutic agents for managing infections and oxidative stress-related 
conditions.