Extraction, Purification, Identification of A-type Procyanidine from Litchi Fruitlet and Its Antioxidant Activity

In this study, polyphenol fractions were extracted from litchi fruitlet which drop naturally, then purified by AB-8 macroporous resin and separated by Sephadex LH-20. After comparing the antioxidant activities of each sample in vitro, the polyphenol components were identified by LC-ESI-Q-TOF. The results showed that the content of total phenols and total procyanidines in litchi fruitlet were (49.96±2.66) mg GAE/g DW and (27.25±0.44) mg EPE/g DW, respectively. In vitro antioxidant activity text indicated that the fourth polyphenol component (P4) had strong ABTS⁺· and DPPH· scavenging ability, and its free radical scavenging rate could reach 92.52% and 46.98% in 100 μg/mL respectively. According to LC-ESI-Q-TOF analysis, PLFE contained 10 types of A procyanidines, which were much more than B procyanidines. P4 was composed of pure A-type procyanidine, which were procyanidine A₄, procyanidine A₂, A-type procyanidine dimer and tetramer. Therefore, A-type procyanidine isolated and purified from litchi fruitlet have remarkable antioxidant activity, which can be used as an excellent source of new A-type procyanidine.