Spectrum-effect Relationship between HPLC Fingerprints and DPPH-scavenging Activities of Tea Catechins

  Objective  Correlation between the high-performance liquid chromatography (HPLC) fingerprints and the DPPH radical scavenging activities of catechins from varieties of teas was studied.

  Method  From 5 categories of teas including green tea, white tea, northern Fujian oolong, southern Fujian oolong, and black tea, 25 specimens were collected and extracted with 70% methanol. The extracts were used to determine polyphenols content by the Folin-Ciocalteu method, the free radical scavenging activity by 1,1-diphenyl-2-picrylhydrazylradical2,2-Diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl, DPPH assay, and the fingerprints by HPLC for a principal component analysis. A correlation model between the HPLC fingerprints and DPPH radical scavenging activity was established by a partial least squares regression analysis and validated by the Pearson analysis.

  Result  The HPLC fingerprints of the 25 specimens had 8 common compounds. The established regression model showed a coefficient of determination of R²=0.900 9. The 3 compounds, epigallocatechin gallate (EGCG), epigallocatechin (EGC), and epicatechin gallate (ECG), exhibited the strongest and significant correlations with DPPH radical scavenging activity. On the other hand, gallic acid (GA) correlated inversely with the scavenging activity. The Pearson analysis showed a result consistent with what the partial least squares regression test did.

  Conclusion  It appeared that the antioxidant activity of catechins in the various teas could be satisfactorily predicted by HPLC fingerprints.