Preparation of extract
Fresh bulbs of onions were purchased from a local market
in Allahabad, India. Among the various local varieties of onion
in India, the red onion (Pusa cultivar) was preferably selected
because of its reported high antioxidant potential [3]. The plant
was collected, its botanical identification and authentication was
confirmed and the herbarium sheets were sent to the herbarium of
the Department of Botany, University of Allahabad. The voucher
specimen number (reference number 25840) was obtained. The
bulbs were carefully dressed and frozen (4 C). About 100 g
of onion was crushed in a grinding machine with 100 mL of
chilled, distilled water. The resultant slurry was squeezed and
filtered through a fine cloth and the filtrate was quickly frozen
(4 C) until used.
2.3. Animal model and study protocol