Investigation of Antibacterial and Antioxidant Activity of Citrus medica L Extract on Human Pathogenic Bacteria

Natural products derived from medicinal plants are a major source of drug preparation and the main basis for the development of pharmaceutical leads. We have aimed at investigating in vitro antibacterial and antioxidant activity of various extracts of Citrus medica L. against a number of human pathogenic bacteria.

The plant samples of C. medica L were collected from Ramsar province, Iran. The gram-positive bacteria Streptococcus pyogenes, Bacillus subtilis, Bacillus cereus, Micrococcus luteus, Enterococcus faecalis, and Staphylococcus aureus, as well as the gram-negative bacteria Escherichia coli, Shigella boydii, Salmonella typhi, Pseudomonas aeruginosa, Enterobacter aerogenes and Klebsiella pneumoniae were prepared from Bu Ali Sina University, Hamadan, Iran. Agar diffusion assay was applied, and the antioxidant properties of extracts were determined by DPPH assay. Total phenolic and flavonoid contents as well as some compounds such as alkaloids, saponin, and tannin were further analyzed.

Results indicated that C. medica extracts possessed antibacterial activity, and that root, seed, and leaf exhibited the highest activities against human pathogens, especially M. luteus. Roots contained the highest total phenolics (106.1 mgGA/g), while leaves contained the highest total flavonoids (3.24 mgQ/g). Leaf methanol extract also contained alkaloids, saponins, and tannins.

The antibacterial activities of C. medica extracts could be explained by synthesizing such compounds. Moreover, seed and root extracts of C. medica showed strong radical scavenging activities