Evaluation of antimicrobial and cytotoxic activities of polar solvent extracts from leaves of Ammi majus used by the Omanis

Ammi majus (A. majus) is an important medicinal plant traditionally used in Oman for the treatment of mouth ulcers. The objective of this study was to determine the antimicrobial and cytotoxic activities of different leaf extracts of A. majus using an established protocol. Different extracts were prepared using increasingly polar solvents. The antimicrobial activity of the extracts was determined using the disc diffusion method, and the cytotoxic activity of the extracts was assessed by the brine shrimp lethality bioassay. Exposure of the Gram-positive Staphylococcus aureus and the Gram-negative Escherichia coli, Haemophilus influenzae and Proteus spp. bacterial strains to the different extracts revealed potential antimicrobial activity measured by zones of inhibition in the range of 0–20 mm. The cytotoxicity results showed an incremental rise in shrimp larvae mortality depending on the extract concentration, reaching 100% mortality at a concentration of 1000 μg/ml for all extracts. The methanol extract had the lowest of all LC₅₀ values at 45.75 μg/ml. The LC₅₀ values in ascending order for the chloroform, hexane, ethyl acetate, water and butanol extracts are 179.41, 288.31, 305.19, 417.94 and 570.02 μg/ml, respectively. In conclusion, in vitro and in vivo studies of the isolated leaf extracts are needed to determine the therapeutic potential of this plant.