These functions are essential in cell division and are being widely studied as a target for treatment of cancer. As a chaperone protein, it stabilizes and maintains many client proteins and assists with normal protein folding and trafficking. EGCG is carried by serum albumin and has been identified as a novel inhibitor of heat shock protein 90 (HSP90), a cytoplasmic chaperone protein, which has recently received much attention as a drug target for treatment of cancer. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Ĭompeting interests: The authors have declared that no competing interests exist.ĮGCG ( Figure 1A), a major catechin in green tea, exhibits antioxidant, antimutagenic, anticancer, antiallergic, and antiatherosclerotic properties. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.įunding: This work was supported by the Margaret and Herman Sokol Fellows Program to VS, and by the Sokol Endowment fund to DPR. Received: JAccepted: OctoPublished: November 22, 2013Ĭopyright: © 2013 Snitsarev et al. PLoS ONE 8(11):Įditor: Heidar-Ali Tajmir-Riahi, University of Quebec at Trois-Rivieres, Canada We conclude that significant solvent-dependent changes in both fluorescence intensity and fluorescence emission shifts can be effectively used to distinguish EGCG in aqueous solutions from EGCG in environments of different polarity, and, thus, can be used to study specific EGCG binding to protein binding sites where the environment is often different from aqueous in terms of polarity.Ĭitation: Snitsarev V, Young MN, Miller RMS, Rotella DP (2013) The Spectral Properties of (-)-Epigallocatechin 3-O-Gallate (EGCG) Fluorescence in Different Solvents: Dependence on Solvent Polarity. In addition, while the emission maxima of EGCG fluorescence in AB, DMSO, and EtOH follow the Lippert-Mataga equation, its fluorescence in AN points to non-specific solvent effects on EGCG fluorescence. The Stokes shifts of EGCG fluorescence were determined by solvent polarity.
We found that the fluorescence intensity (FI) of EGCG in AB at pH=7.0 is significantly quenched, and that it is about 85 times higher in an aprotic solvent DMSO. Another smaller excitation peak was found when EGCG is excited at approximately 235 nm with maximum emission between 340 and 400 nm.
We demonstrate that EGCG is a highly fluorescent molecule when excited at approximately 275 nm with emission maxima between 350 and 400 nm depending on solvent. The goal of this study is to examine the spectral properties of EGCG fluorescence in an aqueous buffer (AB) at pH=7.0, acetonitrile (AN) (a polar aprotic solvent), dimethylsulfoxide (DMSO) (a polar aprotic solvent), and ethanol (EtOH) (a polar protic solvent). Determination of the spectral properties of EGCG fluorescence in environments similar to those of binding sites found in proteins provides an important tool to directly study protein-EGCG interactions. (-)-Epigallocatechin 3- O-gallate (EGCG) a molecule found in green tea and known for a plethora of bioactive properties is an inhibitor of heat shock protein 90 (HSP90), a protein of interest as a target for cancer and neuroprotection.