The antioxidant capacities of the acetone, methanol and water extracts of hot-air dried lychee (Litchi chinenesis Sonn.) flowers were estimated with 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radical-scavenging assay, reducing power, Trolox equivalent antioxidant capacity (TEAC) assay, Inhibition of β-carotene bleaching assay and inhibition of Cu2＋-induced human low density lipoprotein (LDL) oxidation assay. Results showed that the acetone extracts had the best effects in all assays, followed by methanol extracts and hot water extracts.
The acetone extracts had the highest contents of phenols, flavonoids and condensed tannins, and the methanol extracts next. The water extracts also showed the lowest amounts for the three components. Flavonoids and phenolic acids in these extracts were determined by HPLC further. Epicatechin and rutin were the major flavonoids, and genitisic acid and ferulic acid were the major phenolic acids. The contents of antioxidant components in these extracts were correlated with antioxidant activities.
