Theaflavine-3,3'-digallate

Theaflavin-3,3'-digallate, a component of black tea: an inducer of oxidative stress and apoptosis.[Pubmed:18248951]

Toxicol In Vitro. 2008 Apr;22(3):598-609.

Treatment of human oral squamous carcinoma HSC-2 cells and normal GN46 fibroblasts with theaflavin-3,3'-digallate (TF-3), a polyphenol in black tea, showed a concentration and time dependent inhibition of growth, with the tumor cells more sensitive than the fibroblasts. In buffer and in cell culture medium, TF-3 generated reactive oxygen species, with lower levels detected in buffer amended with catalase and superoxide dismutase, indicating the generation of hydrogen peroxide and superoxide, respectively, and suggesting that TF-3 may be an inducer of oxidative stress. The toxicity of TF-3 was decreased in the presence of catalase, pyruvate, and divalent cobalt, all scavengers of reactive oxygen species, but was potentiated in the presence of diethyldithiocarbamate, an inhibitor of superoxide dismutase. The intracellular level of glutathione in HSC-2 cells was lessened after a 4-h exposure to 250 and 500 microM TF-3. However, for GN46 fibroblasts, a 4-h exposure to 250 microM TF-3 stimulated, but to 500 microM TF-3 lessened, intracellular glutathione. Treatment of the cells with the glutathione depleters, 1,3-bis(2-chloroethyl)-N-nitrosourea, 1-chloro-2,4-dinitrobenzene, and d,l-buthionine-[S,R]-sulfoximine potentiated the toxicity of TF-3. Induction of apoptotic cell death in HSC-2 cells treated with TF-3 was noted by apoptotic cell morphologies, by TUNEL staining, by PARP cleavage, and by elevated activity of caspase-3. Apoptosis was not noted in GN46 fibroblasts treated with TF-3.

Suppression of lipopolysaccharide-induced nuclear factor-kappaB activity by theaflavin-3,3'-digallate from black tea and other polyphenols through down-regulation of IkappaB kinase activity in macrophages.[Pubmed:10644043]

Biochem Pharmacol. 2000 Feb 15;59(4):357-67.

We investigated the inhibition of IkappaB kinase (IKK) activity in lipopolysaccharide (LPS)-activated murine macrophages (RAW 264.7 cell line) by various polyphenols including (-)-epigallocatechin-3-gallate, theaflavin, a mixture of theaflavin-3 gallate and theaflavin-3'-gallate, theaflavin-3,3'-digallate (TF-3), pyrocyanidin B-3, casuarinin, geraniin, and penta-O-galloyl-beta-D-glucose (5GG). TF-3 inhibited IKK activity in activated macrophages more strongly than did the other polyphenols. TF-3 strongly inhibited both IKK1 and IKK2 activity and prevented the degradation of IkappaBalpha and IkappaBbeta in activated macrophage cells. The results suggested that the inhibition of IKK activity by TF-3 could occur by a direct effect on IKKs or on upstream events in the signal transduction pathway. Furthermore, geraniin, 5GG, and TF-3 all blocked phosphorylation of IKB from the cytosolic fraction, inhibited nuclear factor-kappaB (NFkappaB) activity, and inhibited increases in inducible nitric oxide synthase levels in activated macrophages. These results suggest that TF-3 may exert its anti-inflammatory and cancer chemopreventive actions by suppressing the activation of NFkappaB through inhibition of IKK activity.

Theaflavin-3,3'-digallate and penta-O-galloyl-beta-D-glucose inhibit rat liver microsomal 5alpha-reductase activity and the expression of androgen receptor in LNCaP prostate cancer cells.[Pubmed:14963012]

Carcinogenesis. 2004 Jul;25(7):1109-18.

Androgens play a critical role in regulating the growth, differentiation and survival of epithelial cells in many androgen-responsive organs, such as prostate and skin. The enzyme steroid 5alpha-reductase (EC 1.3.99.5) catalyzes the conversion of testosterone (T) to a more active androgen, dihydrotestosterone (DHT). DHT then binds to androgen receptors (AR) and functions in the nucleus to regulate specific gene expression. Androgens via their cognate receptor may be involved in the development and progression of benign prostate hyperplasia, prostate cancer, hirsutism, male pattern alopecia and acne. The aim of this study was to determine whether theaflavin-3,3'-digallate (TF3) and penta-O-galloyl-beta-D-glucose (5GG) have inhibitory effects on androgen production and action. We found that TF3 and 5GG inhibit rat liver microsomal 5alpha-reductase activity. Furthermore, TF3 and 5GG significantly reduced androgen-responsive LNCaP prostate cancer cell growth, suppressed expression of the AR and lowered androgen-induced prostate-specific antigen secretion and fatty acid synthase protein level. In conclusion, our result suggests that TF3 and 5GG might be useful chemoprevention agents for prostate cancer through suppressing the function of androgen and its receptor.

Theaflavin-3,3'-digallate represses osteoclastogenesis and prevents wear debris-induced osteolysis via suppression of ERK pathway.[Pubmed:27838465]

Acta Biomater. 2017 Jan 15;48:479-488.

Peri-implant osteolysis (PIO) and the following aseptic loosening is the leading cause of implant failure. Emerging evidence suggests that receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclast formation and osteoclastic bone resorption are responsible for particle-stimulated PIO. Here, we explored the effect of theaflavin-3,3'-digallate (TF3) on titanium particle-induced osteolysis in vivo and in vitro. Twenty-eight male C57BL/6 mice were randomly separated into four groups: sham control (sham), titanium particles only (titanium), titanium particles with low TF3 concentration (low-TF3, 1mg/kg TF3), and titanium particles with high TF3 concentration (high-TF3, 10mg/kg TF3). Two weeks later, micro-computed tomography and histological analysis were performed. Bone-marrow-derived macrophages and RAW264.7 murine macrophages were applied to examine osteoclast formation and differentiation. TF3 significantly inhibited titanium particle-induced osteolysis and prevented bone destruction compared with titanium group. Interestingly, the number of mature osteoclasts reduced after treatment with TF3 in vivo, suggesting osteoclast formation might be inhibited by TF3. In vitro, TF3 suppressed osteoclast formation, polarization and osteoclastic bone resorption by specifically targeting the RANKL-induced ERK signal pathway. Collectively, these results suggest that TF3, a natural active compound derived from black tea, is a promising candidate for the treatment of osteoclast-related osteolytic diseases, such as wear debris-induced PIO. STATEMENT OF SIGNIFICANCE: Total joint arthroplasty is widely accepted for the treatment of end-stage joint diseases. However, it is reported that aseptic loosening, initiated by peri-implant osteolysis, is the major reason for prosthesis failure. Although the pathophysiology of PIO remains unclear, increasing evidence indicates that osteoclasts are excessively activated at the implant site by wear debris from materials. Here, we demonstrated that theaflavin-3,3'-digallate, a natural active compound derived from black tea, inhibited osteoclast formation and osteoclastic bone resorption mainly via suppressing the ERK pathway. Moreover, the findings of this study have confirmed for the first time that theaflavin-3,3'-digallate has a protective effect on particle-induced osteolysis in a mouse calvarial model, thus preventing bone loss. These results indicate that theaflavin-3,3'-digallate may be a suitable therapeutic agent to treat wear debris-induced peri-implant osteolysis.