To screen eminent litchi varieties suitable for the development of natural antioxidant products,the total phenol,total proanthocyanidin,total flavonoid contents and A-type oligomeric procyanidin fractions in the pericarps of seven diverse litchi cultivars were analyzed.The in vitro antioxidant activities including DPPH,ABTS+free radical scavenging and FRAP were determined.The results demonstrated that the total phenols,total proanthocyanidins,total flavonoids as well as total A-type oligomeric procyanidins contained in the pericarp extract of'Hemaoli'were the highest.In addition,the primary and secondary mass spectra of the contained substances were analyzed and identified by electrospray liquid-mass spectrometry with quadrupole time-of-flight mass spectrometry(HPLC-Q-TOF-MS/MS).The mass spectrometry results demonstrated that the oligomeric procyanidin fractions contained in litchi pericarps were mainly epicatechin,procyanidin A2,procyanidin A4,A-type trimer and tetramer.Moreover,the content of A-type oligomeric procyanidins in litchi pericarp varied significantly(P＜0.05)among diverse cultivars.The pericarp extract of'Hemaoli'possessed potent free radical scavenging activity(DPPH·:1144.60 μmol Trolox/g DW,ABTS+·:2905.56 μmol Trolox/g DW,FRAP:868.84 μmol Trolox/g DW).The contents of A-type procyanidin monomer,dimer and trimer were significantly correlated with antioxidant activity by Pearson's correlation analysis(P＜0.05).In summary,a comprehensive analysis indicated that the pericarp extract of'Hemaoli'contained the highest content of A-type oligomeric procyanidins as well as remarkable antioxidant activity compared to other cultivars.Therefore,'Hemaoli'could be utilized as a novel potential material for the development of natural antioxidant products.
维普
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