A simple extraction procedure was performed for preparation of onion extract and was not used any solvent for this work. First, the bulbs of onion layers were separated and washed. Second, the onion bulbs
were put in particular container, and kept in freezer at -20°C for two days. This leads to the comfortably
destroy of the cells and make it easier for extraction. After 48 h the onion bulbs were removed from the
freezer and were defrosted in 30 minutes. Finally, the aqueous extracts were obtained with a filter and poured
into particular containers (Wilson et al., 1997).