Abstract:

The extraction of proanthocyanidins from longan pericarp was optimized using response surface methodology.
The effects of extraction time, solvent-to-solid ratio, ethanol concentration and extraction temperature on the yield of
proanthocyanidins were investigated. The results showed that the optimal extraction conditions were as follows: an
extraction time of 25 min, a ratio of liquid to material of 17:1 (mL/g), an ethanol concentration of 51% and a temperature
of 50 ℃. Under these conditions, the yield of proanthocyanidins was 1.21%. The extract was then purified by Sephadex
LH-20 column. The purified proanthocyanidins had high antioxidant activity as indicated by scavenging activities against,
1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS)
radicals and reducing power.

Key words: longan pericarp, proanthocyanidins, response surface methodology, antioxidant activity