Abstract:

The extraction of total flavonoids from leaves of Vitis viniferal L. was optimized by orthogonal array design with
the objective of developing a sample preparation method for the spectrophotometric determination of total flavonoids with rutin
as a standard reference material. Four extraction parameters were ranked in decreasing order of importance as follows: time,
ethanol concentration, temperature and solid-to-solvent ratio, and their optimal conditions were 100 min, 50%, 70 ℃ and 1:50,
respectively. The total flavonoids obtained under the optimized conditions possessed free radical scavanging activity against
DPPH, hydroxyl and superoxide anion radicals in decreasing order as well as reducing power.

Key words: Vitis viniferal L., total flavonoids, reduction power, antioxidant activity