Allium cepa L. (red onion) is one of the most famous vegetable crops grown in Egypt due to its medical and nutritional importance. In vitro antischistosomal bioassay of ethyl acetate (EtOAc) and butanolic (BuOH) fractions derived from methanolic (MeOH) extract of A. cepa as well as the essential oil of plant bulbs was carried out using ascending doses. The chemical constituents of essential oil were further investigated using GC-MS analysis. The results revealed that the MeOH extract, EtOAc fraction, BuOH fraction and essential oil have a significant effect on adult Schistosoma mansoni worms. The essential oil of A. cepa gave high worm mortality (%) at the concentration 500 µg/mL (75%), 250 µg/mL (50%) and 125 µg/mL (30%) death rate after 24 hours. GC-MS analysis of A. cepa essential oil exhibited different chemical volatile constituents such as organosulfur compounds, alcohols, acids, esters, furans, phenols, and aldehyde. 3, 5-Diethyl -1, 2, 4-trithiolane (10.17%), 1, 3, 5-trithiolane (7.80%), and 3-(2H-furanone, 2-hexyl-5-methyl) (7.74%) represented the highest contents percent in essential oil of A. cepa bulbs.
In conclusion, the bulbs of A. cepa exhibited antischistosomal activities and contain a variety of bioactive chemical constituents and can be considered as a natural antischistosomal agent.