Comparative Phytochemical Composition and Antibacterial Activity of Selected Medicinal and Aromatic Plant Extracts

Abstract

Background: Medicinal and aromatic plants are important sources of secondary metabolites with potential antibacterial properties. Aim: This study compared the phytochemical composition and antibacterial activity of ethanolic extracts from seven plant materials: Hibiscus rosa-sinensis L., Tagetes erecta L., Rosa indica L., Eucalyptus globulus L., Cymbopogon citratus DC., Citrus limon L., and Citrus sinensis L. Method: Extracts prepared from petals, leaves, and citrus fruit peels were subjected to qualitative phytochemical screening and quantitative estimation of total phenolic, tannin, flavonoid, and alkaloid contents. Antibacterial activity was evaluated against Staphylococcus aureus and Escherichia coli by agar well diffusion. Results: Qualitative tests indicated that alkaloids, carbohydrates, flavonoids, phenolic compounds, tannins, saponins, and carboxylic acid-containing compounds were present in most or all extracts. Quantitative results varied among species. Eucalyptus globulus had the highest total phenolic content (45.06 mg GAE/g) and tannin content (12.28 mg GAE/g), Tagetes erecta had the highest flavonoid content (24.9%), and Citrus limon had the highest alkaloid content (28.7%). All extracts inhibited both bacterial species. Eucalyptus globulus produced the largest inhibition zones, 36.0 ± 3.46 mm against S. aureus and 31.3 ± 3.05 mm against E. coli. Conclusion: The selected plants contained diverse phytochemicals, and Eucalyptus globulus showed the strongest antibacterial activity under the experimental conditions used.