Abstract:

The antioxidant activity of anthocyanins extracted from purple sweet potato by organic solvent, ultrasonicassisted
or microwave-assisted extraction was comparatively evaluated by radical scavenging activities against hydroxyl,
DPPH and superoxide anion radicals, total antioxidant capacity (TAC), reducing power and ferrous ion chelating activity.
The results showed that the anthocyanins extracted from purple sweet potato, irrespective of the extraction method used,
exerted antioxidant activities except for ferrous ion chelation. Moreover, the results from 5 antioxidant assays consistently
indicated that the antioxidant capacity of anthocyanins extracted by microwave-assisted, ultrasonic-assisted and organic
solvent extraction revealed a decreasing trend in turn. The extracted anthocyanins showed the strongest ability to scavenge
free radicals followed by reducing power and total antioxidant capacity, and possessed the lowest ferrous ion-chelating
activity. Both ultrasonic-assisted and microwave-assisted extraction are beneficial for maintaining antioxidant activity of
anthocyanins extracted from purple sweet potato, with the latter being superior to the former.

Key words: anthocyanins from purple sweet potato, antioxidant activity, comparison