Epigallocatechin-3-gallate treatment to promote neuroprotection and functional recovery after nervous system injury

Traumatic spinal cord injury （SCI） causes motor paralysis, sensory anesthesia and autonomic dysfunction below the le- sion site and additionally some SCI patients refer neuropathic pain together with these signs and symptoms. Clinical and experimental studies have revealed the main pathological changes of injured spinal cord implicated in all these signs and symptoms, including neuropathic pain. After few hours of traumatic SCI, it is usual to observe broken blood brain barrier with plasma and blood cells extravasation, cell necrosis, disruption of ascending and descending spinal cord pathways and increased potassium and glutamate. Glutamate contributes to excitotoxicity of neurons whereas potassium facilitates ectopic depolarization of survival neurons and activation of resident microglia.

Mechanism of action of (-)-epigallocatechin-3-gallate:auto-oxidation-dependent activation of extracellular signal-regulated kinase 1/2 in Jurkat cells

AIM:(-)-Epigallocatechin-3-gallate(EGCG), a major compound of tea polyphenols, exhibited antitumor activity in previous studies. In these studies, EGCG usually inhibits EGFR, and impairs the ERK1/2 phosphorylation in tumor cells. The aim was to clarify the mechanism of ERK1/2 activation induced by EGCG. METHODS: Jurkat and 293 T cells were treated with EGCG in different culture conditions. Western Blotting(WB) was employed to analyze ERK1/2 and MEK phosphorylation. Cetuximab and FR180204 were used to inhibit cell signaling. The stability of EGCG was assessed by HPLC. The concentration of hydrogen peroxide generated by the auto-oxidation of EGCG was determined by photocolorimetric analysis. RESULTS: Activation of ERK1/2 was observed to be both time- and dose-dependent. Stimulation of cell signaling was dependent on MEK activity, but independent of EGFR activity. Unexpectedly, EGCG was depleted within one hour of incubation under traditional culture conditions. Auto-oxidation of EGCG generated a high level of hydrogen peroxide in the medium. Addition of catalase and SOD to the acidic medium inhibited the oxidation of EGCG. However, this particular condition also prevented the phosphorylation of ERK1/2. The generation of ROS by hydrogen peroxide may also induce ERK1/2 activation in Jurkat cells. CONCLUSION: ERK1/2 phosphorylation was caused by auto-oxidation of EGCG. Traditional culture conditions were determined to be inappropriate for EGCG research.

Synergic Inhibition of Lung Carcinoma 95-D Cell Proliferation and Invasion by Combination with(—)-Epigallocatechin-3-Gallate and Ascorbic Acid

In this study, the anti-invasion effects of（-）-epigallocatechin-3-gallate（EGCG） mixed with ascorbic acid（Vc） on human lung carcinoma 95-D cells in vitro were examined and the synergism of the combination of EGCG and Vc was evaluated. Soft agar colony formation assay, cell migration assay, invasion assay, western blot analysis of NF-κB, in situ detection of cellular oxidative stress, and statistical analysis were assessed. The results showed that combining EGCG with Vc could inhibit clone forming rate of 95-D cell by 73.2%, reduce the migration ability of 95-D cell by 65.9%, and decrease the intracellular reactive oxygen species（ROS） level by 76.8%. The results of western blot proved that Vc enhanced the activity of EGCG in inhibiting NF-κB localization. It is speculated that the combination of EGCG and Vc can strongly suppress the proliferation and metastasis of lung carcinoma cells in a synergic manner, possibly with a mechanism associated with the scavenging of reactive oxygen species.

Separation of epigallocatechin-3-gallate from crude tea polyphenols by using Cellulose diacetate graft β-cyclodextrin copolymer asymmetric membrane

This study demonstrates a new Cellulose diacetate graft b-cyclodextrin(CDA-b-CD)copolymer asymmetric membrane prepared by a phase inversion technique for the separation of(–)-epigallocatechin-3-gallate(EGCG)from other polyphenols in crude tea.The graft copolymer,CDA-b-CD,was synthesized by pre-polymerization of cellulose diacetate(CDA)and 1,6-hexamethylene-diisocyanate(HDI),which was then grafted with b-cyclodextrin(b-CD).Surface and cross-section morphologies of the CDA-b-CD membranes were analyzed by using scanning electron microscopy(SEM).Fourier transform infrared spectroscopy(FT-IR)indicated that the b-CD was grafted onto the CDA by chemical bonding.The influences of the HDI/CDA mass ratio and the catalyst mass fraction on the b-CD graft yield were investigated.The optimum conditions of a HDI/CDA mass ratio of 0.35 g$g–1 and a catalyst mass fraction of 0.18 wt-%produced ab-CD graft yield of 26.51 wt-%.The effects of the b-CD graft yield and the concentration of the polymer cast solution on the separation of EGCG were also investigated.Under optimum conditions of a b-CD graft yield of 24.21 wt-%and a polymer concentration of 13 wt-%,the purity of EGCG increased from 26.51 to 86.91 wt-%.

Potential effect of EGCG on the anti-tumor efficacy of metformin in melanoma cells

Metformin,a first-line drug for type 2 diabetes mellitus,has been recognized as a potential anti-tumor agent in recent years.Epigallocatechin-3-gallate(EGCG),as the dominant catechin in green tea,is another promising adjuvant agent for tumor prevention.In the present work,the potential effect of EGCG on the anti-tumor efficacy of metformin in a mouse melanoma cell line(B16F10)was investigated.Results indicated that EGCG and metformin exhibited a synergistic effect on cell viability,migration,and proliferation,as well as signal transducer and activator of transcription 3/nuclear factor-κB(STAT3/NF-κB)pathway signaling and the production of inflammation cytokines.Meanwhile,the combination showed an antagonistic effect on cell apoptosis and oxidative stress levels.The combination of EGCG and metformin also differentially affected the nucleus(synergism)and cytoplasm(antagonism)of B16F10 cells.Our findings provide new insight into the potential effects of EGCG on the anti-tumor efficacy of metformin in melanoma cells.

Synergistic effects of tea polyphenols and ascorbic acid on human lung adenocarcinoma SPC-A-1 cells

Tea polyphenols have been shown to have anticancer activity in many studies.In the present study,we investigated effects of theaflavin-3-3'-digallate(TF3),one of the major theaflavin monomers in black tea,in combination with ascorbic acid(AA),a reducing agent,and(-)-epigallocatechin-3-gallate(EGCG),the main polyphenol presented in green tea,in combination with AA on cellular viability and cell cycles of the human lung adenocarcinoma SPC-A-1 cells.The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT) assay showed that the 50% inhibition concentrations(IC50) of TF3,EGCG,and AA on SPC-A-1 cells were 4.78,4.90,and 30.62 μmol/L,respectively.The inhibitory rates of TF3 combined with AA(TF3+AA) and EGCG combined with AA(EGCG+AA) at a molar ratio of 1:6 on SPC-A-1 cells were 54.4% and 45.5%,respectively.Flow cytometry analysis showed that TF3+AA and EGCG+AA obviously increased the cell population in the G0/G1 phase of the SPC-A-1 cell cycle from 53.9% to 62.8% and 60.0%,respectively.TF3-treated cells exhibited 65.3% of the G0/G1 phase at the concentration of its IC50.Therefore,TF3+AA and EGCG+AA had synergistic inhibition effects on the proliferation of SPC-A-1 cells,and significantly held SPC-A-1 cells in G0/G1 phase.The results suggest that the combination of TF3 with AA or EGCG with AA enhances their anticancer activity.