Bioactive Evaluation and Antimicrobial Activities of Nigerian Mistletoe (Phragmanthera incana) Leaf Extracts

Abstract

Mistletoe is a hemiparasitic medicinal plant traditionally used for several human and animal ailments. This study evaluated the phytochemical constituents and antibacterial activity of aqueous and methanolic leaf extracts of Nigerian mistletoe parasitic on Stereospermum kunthianum. The leaves were air-dried, powdered, and extracted using 80% methanol or de-ionised distilled water. Qualitative and quantitative phytochemical analyses were performed, and antibacterial activity was assessed against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa using the agar diffusion method. Both extracts contained alkaloids, saponins, tannins, flavonoids, and steroids, whereas anthraquinones were absent. The extraction yields of the methanolic and aqueous extracts were 16.12% and 15.62%, respectively. The methanolic extract showed higher measured values for the assessed phytochemicals than the aqueous extract. Antibacterial activity varied with extract concentration and test organism. The highest inhibition zone, 27 mm, was recorded for the methanolic extract at 10,000 µg/ml against Staphylococcus aureus, whereas the smallest inhibition zone, 9 mm, was recorded for the aqueous extract at 1,000 µg/ml against Pseudomonas aeruginosa. Overall, the methanolic extract demonstrated greater antibacterial activity than the aqueous extract under the experimental conditions. The findings indicate that the aqueous and methanolic extracts differed in their measured phytochemical composition and antibacterial activity. These results provide a comparative assessment of the two extraction solvents under the study conditions.