E carried out according to a protocol approved by the Institutional animal Care and Use Committee of the University of North Carolina at Chapel Hill. Eight week-old 129 SvEv mice were bred and housed in the Gnotobiotic Animal Facility at the University of North Carolina at Chapel Hill. TFDG was dissolved in dimethyl sulfoxide (DMSO) and then filtered sterilized using 0.22 mm filters (Fisher, Pittsburgh, PA). To insure sterility, aliquots of TFDG were placed on heart-brain infusion agar (Becton Dickinson, Franklin Lakes, NJ) and incubated in aerobic or anaerobic conditions for 24 h. After fasting for 12 hours, TFDG (200 mg/kg) was administered to germ-free (GF) mice by oral gavage. All feces were collected from the cage within 24 h after administration of DMSO (control group, n = 5) or TFDG (treated group, n = 5). Concurrently, age-matched 129 SvEv mice raised in specific pathogen free (SPF) (conventionalized-raised) conditions were administered TFDG (200 mg/kg; n = 5/group) by oral gavage. Feces were collected as described above. All Solvent Yellow 14 site Samples were stored at 280uC before AZ 876 analysis.and 1.2 mL of MeOH/H2O (50/50)+0.1 acetic acid was added to each sample. Samples were sonicated for 90 minutes, and then centrifuged at 17000 RPM for 10 minutes. The supernatants (650 mL) were removed from the centrifuged samples and transferred to LC/MS vials for analysis.Human Fecal Slurry Preparation and in vitro FermentationThe Institutional Review Board approved the protocol for human experimentation through the Protection of Human Subjects in Research at North Carolina Agricultural and Technical State University (Greensboro, NC). Three healthy male volunteers (30?9 years old, weighing 60?0 kg, nonsmokers) participated in the study. They had not taken antibiotics for at least 6 months prior to the study, and had avoided polyphenol-rich foods for at least 48 h before fecal collection. Fecal samples were collected and transferred immediately to anaerobic condition to be processed within 2 h. Under aseptic conditions, 50 g of fresh collected fecal sample was homogenized under anaerobic conditions with 100 mL 0.05 peptone water in a sterilized stomacher bag using a Seward stomacher (Model: 400 circulator) for 3 min at 200 rpm. The mixture was briefly centrifuged (2? min at 3000 rpm) to remove particulate materials. The supernatant (fecal slurry) was mixed with 35 pre-sterile glycerol, divided into 15 mL sterilized tubes, and stored at 280uC for later use. The in vitro fermentation experiment was performed under conditions described in Gross et al. with some modifications [13].Fecal Sample PreparationFor acquisition of the metabolic profile, eight pieces of each fecal sample (control and treated) were chosen and put into 2 mL tubes. Each set was weighted (control: 78 mg and treated: 81 mg)Microbial Metabolites of TheaflavinsFigure 7. HPLC-ECD chromatograms of microbial metabolites of TFDG after incubation with Lactobacillus plantarum 299v (A) and Bacillus subtilis (B). TFDG: theaflavin 3,39-digallate. doi:10.1371/journal.pone.0051001.gFermentation basal medium was prepared by mixing 1000 mL of distilled water with 4 mL of Tween 80 and 2 g of peptone and autoclaved at 121uC for 15 minutes then stored in refrigerator for later use. TFDG, TF3G, TF39G, and GA were dissolved in water/ ethanol (1:1) to obtain a concentration of 10 mg/mL. Then, 100 mL of the dissolved sample was added to 8.9 mL of fermentation medium and 1 mL of fecal slurry. The mixture was vigorous.E carried out according to a protocol approved by the Institutional animal Care and Use Committee of the University of North Carolina at Chapel Hill. Eight week-old 129 SvEv mice were bred and housed in the Gnotobiotic Animal Facility at the University of North Carolina at Chapel Hill. TFDG was dissolved in dimethyl sulfoxide (DMSO) and then filtered sterilized using 0.22 mm filters (Fisher, Pittsburgh, PA). To insure sterility, aliquots of TFDG were placed on heart-brain infusion agar (Becton Dickinson, Franklin Lakes, NJ) and incubated in aerobic or anaerobic conditions for 24 h. After fasting for 12 hours, TFDG (200 mg/kg) was administered to germ-free (GF) mice by oral gavage. All feces were collected from the cage within 24 h after administration of DMSO (control group, n = 5) or TFDG (treated group, n = 5). Concurrently, age-matched 129 SvEv mice raised in specific pathogen free (SPF) (conventionalized-raised) conditions were administered TFDG (200 mg/kg; n = 5/group) by oral gavage. Feces were collected as described above. All samples were stored at 280uC before analysis.and 1.2 mL of MeOH/H2O (50/50)+0.1 acetic acid was added to each sample. Samples were sonicated for 90 minutes, and then centrifuged at 17000 RPM for 10 minutes. The supernatants (650 mL) were removed from the centrifuged samples and transferred to LC/MS vials for analysis.Human Fecal Slurry Preparation and in vitro FermentationThe Institutional Review Board approved the protocol for human experimentation through the Protection of Human Subjects in Research at North Carolina Agricultural and Technical State University (Greensboro, NC). Three healthy male volunteers (30?9 years old, weighing 60?0 kg, nonsmokers) participated in the study. They had not taken antibiotics for at least 6 months prior to the study, and had avoided polyphenol-rich foods for at least 48 h before fecal collection. Fecal samples were collected and transferred immediately to anaerobic condition to be processed within 2 h. Under aseptic conditions, 50 g of fresh collected fecal sample was homogenized under anaerobic conditions with 100 mL 0.05 peptone water in a sterilized stomacher bag using a Seward stomacher (Model: 400 circulator) for 3 min at 200 rpm. The mixture was briefly centrifuged (2? min at 3000 rpm) to remove particulate materials. The supernatant (fecal slurry) was mixed with 35 pre-sterile glycerol, divided into 15 mL sterilized tubes, and stored at 280uC for later use. The in vitro fermentation experiment was performed under conditions described in Gross et al. with some modifications [13].Fecal Sample PreparationFor acquisition of the metabolic profile, eight pieces of each fecal sample (control and treated) were chosen and put into 2 mL tubes. Each set was weighted (control: 78 mg and treated: 81 mg)Microbial Metabolites of TheaflavinsFigure 7. HPLC-ECD chromatograms of microbial metabolites of TFDG after incubation with Lactobacillus plantarum 299v (A) and Bacillus subtilis (B). TFDG: theaflavin 3,39-digallate. doi:10.1371/journal.pone.0051001.gFermentation basal medium was prepared by mixing 1000 mL of distilled water with 4 mL of Tween 80 and 2 g of peptone and autoclaved at 121uC for 15 minutes then stored in refrigerator for later use. TFDG, TF3G, TF39G, and GA were dissolved in water/ ethanol (1:1) to obtain a concentration of 10 mg/mL. Then, 100 mL of the dissolved sample was added to 8.9 mL of fermentation medium and 1 mL of fecal slurry. The mixture was vigorous.