Effects of phenolic-rich litchi (Litchi chinensis Sonn.) pulp extracts on glucose consumption in human HepG2 cells

Phenolic composition of litchi (Litchi chinensis Sonn.) pulp from three cultivars was tentatively characterized and quantified by HPLC-MS. Pulp from hemaoli, a wild litchi cultivar, showed the highest content of total phenolics, flavonoids and procyanidins, the latter accounting for the majority of phenolic compounds identified. In hemaoli, (−)-epicatechin was the predominant compound, whereas flavone glycosides accounted for the majority of the phenolic compounds identified in Feizixiao and Lanzhu cultivars, with quercetin rhammosyl-rutinoside being predominant. Hemaoli pulp caused the highest enhancement of glucose consumption rate in HepG2 cells, followed by Feizixiao pulp. This bioactivity was significantly correlated with antioxidant capacity, and total content of phenolics, flavonoids, and procyanidins of different cultivars. (−)-Epicatechin, but not quercetin rhammosyl-rutinoside, also resulted in a significant rise in glucose consumption activity. These results showed that litchi cultivars with high (−)-epicatechin content or high procyanidin content may have great potential as hypoglycaemic foods.