Preliminary Phytochemical and Antimicrobial Activity of Citrus x limon (L) Burm. f. (lemon) Leaf Extract against Some Pathogenic Microorganisms

To authenticate the claims by local users of Citrus x limon (lemon) in the control of some human infections, preliminary phytochemical screening and antimicrobial evaluation of lemon leaf extract was investigated Extraction of plant leaves was performed using successive reflux, with n-hexane, ethyl acetate, ethanol and water as extracting solvents. Ethanol gave the highest percentage yield of 10.93% followed closely by ethyl acetate with 9.42% while water extract gave the lowest yield of 3.67%. 11 phytochemicals classes were present in the leaf extract and they include alkaloids, flavonoids, saponins, anthraquinon, cardiac glycosides, tannins, steroids, terpenes, resins, phenols and volatile oils. Saponins was absent in the n-hexane extract and ethyl acetate extracts. Agar diffusion and tube dilution methods were used to evaluate the antimicrobial activities. The test organisms were susceptible to the ethyl acetate and ethanol extracts but resistant to the oil and aqueous extracts. Salmonella paratyphi C was more susceptible to the extract; ethanol extract precisely having the highest mean zones of inhibition (MZI) of 13.00±1.00 mm followed closely by Salmonella paratyphi B with 12.33±2.89 mm while Salmonella paratyphi A was least susceptible to the plant extract having MZI of 6.33±5.51 mm. The activity of the plant extract generally as shown by the MZI is within the intermediate and resistant zones when compared with the control. Results of the acute oral toxicity shows no adverse toxic effect on the animals and the LD50 is above 5000 mg/kgbw. Based on the result of these research, Citrus limon leaf extract may be considered safe for consumption and may be use to control infections by the test organisms in high dosage.