Abstract:

Mechanical shaking extraction with ethanol was applied to extract anthocyanins from the fruits of Rubus coreanus
Maq., and the optimal extraction conditions were determined by orthogonal array design. An extraction temperature of 50 ℃
and 1 h extraction repeated twice using a 30-fold volume of 85% ethanol aqueous solution containing hydrochloric acid
(pH 3) as the extraction solvent provided optimum extraction of anthocyanins. An anthocyanin yield of 211.05 mg/100 g
was achieved. In addition, the anthocyanins from fresh fruits of Rubus coreanus Maq. were evaluated for their antioxidant
activity. It was found that the anthocyanins displayed dose-dependent reducing power and strong abilities to scavenge
hydroxyl, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) free
radicals in decreasing order with linear concentration dependence in the concentration range investigated here. The IC50
values for hydroxyl, DPPH and ABTS free radicals were 1.71, 2.27 and 3.44 μg/mL, respectively, indicating much higher free
radical scavenging activity than VC and BHT as positive controls. These results demonstrate that anthocyanins from Rubus
coreanus Maq. possess potent antioxidant activity and thus deserve to be used as natural antioxidants and functional foods.

Key words: Rubus coreanus Maq., anthocyanins, mechanical shaking extraction, antioxidant activity