Natural variation on free, esterified, glycosylated and insoluble-bound phenolics of Rubus chingii Hu: Correlation between phenolic constituents and antioxidant activities

This study sought to determine how the variation of soluble free phenolics (SFPs), soluble-bound (including esterified-bound phenolics (EBPs), glycosylated-bound phenolics (GBPs)) and insoluble-bound phenolics (ISBPs) affected the antioxidant properties (radical scavenging activities and oxidative damage caused by H2O2 in RAW264.7 cell) of Rubus chingii Hu during different maturity stages. Our result demonstrated that the young fruit stage could be considered as a proper harvesting period for Rubus chingii Hu to obtain high antioxidant activities. Distinct tendencies about abundance were found in four phenolic forms and followed the order: SFPs ≈ EBPs > GBPs ≈ IBPs, and antioxidant activities correlation: EBPs > GBPs > SFPs. Furthermore, total phenolic content, total flavonoid content and phenolics such as kaempferol-3-O-rutinoside, tiliroside and ellagic acid have a substantial correlation with antioxidant capacity. This study may supply a theoretical foundation for the utilization and exploitation of Rubus chingii Hu in different maturity periods.