Three milliliters of Nash reagent (75.0 g of
ammonium acetate, 3 ml of glacial acetic acid, and 2 ml
of acetyl acetone were mixed and raised to 1 l with distilled
water) was added to all the tubes and the tubes were
allowed to stand at room temperature for 15 min for color
development. Intensity of the yellow color formed was
measured at 412 nm against reagent blank. Percentage
hydroxyl radical scavenging was calculated by the following
formula: