Selective effects of tea extract and its phenolic compounds on human peripheral blood mononuclear cell cytokine secretions

Abstract

Background The effects of black tea extract (BTE) and some of its pure phenolics on human peripheral blood mononuclear cell (PBMC) cytokine secretion were examined in vitro.

Materials and methods The main steps of the study included chromatographic analysis of BTE and commercial green tea extract, Polyphenon 60, determination of the total antioxidant capacity of both the extracts and their phenolics, and finally evaluation of their effects on PBMCs.

Findings Four major peaks in the chromatogram of BTE belonged to caffeine, gallic acid, epigallocatechin and epigallocatechin gallate, and the latter showed the highest antioxidant capacity. While pure phenolics at the concentration of 20 mM did not significantly affect PBMC cytokine secretion, BTE and Polyphenon 60 suppressed interleukin-1β, tumor necrosis factor-α and interleukin-6. Interestingly, the secretion of interferon-γ after 24 h was slightly, but significantly, boosted by the extracts.

Conclusion BTE has selective pro-inflammatory cytokine-suppressing effects on human PBMCs.

• Tea extract
• polyphenols
• antioxidant capacity