The amount of femorotibial alignment correction through total knee arthroplasty may affect postoperative hindfoot alignment.

Purpose: This study was performed to investigate the relationship between the amount of femorotibial alignment correction and the amount of improvement of hindfoot alignment in total knee arthroplasty (TKA). Methods: A total of 159 knees undergoing TKA in 120 patients were assessed preoperatively and at 2 weeks, 1 month, 3 months and 6 months postoperatively. Standing hindfoot alignment was evaluated using the leg-heel angle (LHA). The amount of change in hindfoot alignment was compared between patients with severe varus knee (Group 1) and those with moderate varus, neutral or valgus knee (Group 2). Results: The mean values of pre- and postoperative hip-knee-ankle (HKA) angle were -14 ± 4° and -1 ± 3° in Group 1 and -7 ± 5° and -1 ± 3° in Group 2, respectively. The differences between pre- and postoperative LHA were significantly larger in Group 1 than in Group 2 at 2 weeks, 1 month and 3 months postoperatively (p = 0.006, 0.001 and 0.03, respectively). At 6 months postoperatively, no differences were observed between the two groups (p = 0.31). Conclusion: The amount of change in hindfoot alignment was larger in Group 1 than in Group 2 at 2 weeks, 1 month and 3 months after TKA, but there was no significant difference between the two groups at 6 months after TKA. Level of Evidence: Prognostic Level II.

Immunostick colorimetric assay for highly sensitive detection of food allergens by bio-nanocapsule-scaffolding technology.

The detection sensitivity of immunostick colorimetric assay has been increased by using a bio-nanocapsule as a scaffold for oriented immobilization of immunoglobulin Gs. This immunostick produced ∼82-folds stronger coloration in the detection of food allergens and reduced detection time by a factor of 5.

Does Augmented Reality-based Portable Navigation Improve the Accuracy of Cup Placement in THA Compared With Accelerometer-based Portable Navigation? A Randomized Controlled Trial.

BACKGROUND: Previous studies reported good outcomes of acetabular cup placement using portable navigation systems during THA. However, we are aware of no prospective studies comparing inexpensive portable navigation systems using augmented reality (AR) technology with accelerometer-based portable navigation systems in THA. QUESTIONS/PURPOSES: (1) Is the placement accuracy of the acetabular cup using the AR-based portable navigation system superior to that of an accelerometer-based portable navigation system? (2) Do the frequencies of surgical complications differ between the two groups? METHODS: We conducted a prospective, two-arm, parallel-group, randomized controlled trial involving patients scheduled for unilateral THA. Between August and December 2021, we treated 148 patients who had a diagnosis of osteoarthritis, idiopathic osteonecrosis, rheumatoid arthritis, or femoral neck fracture and were scheduled to undergo unilateral primary THA. Of these patients, 100% (148) were eligible, 90% (133) were approached for inclusion in the study, and 85% (126) were finally randomized into either the AR group (62 patients) or the accelerometer group (64 patients). An intention-to-treat analysis was performed, and there was no crossover between groups and no dropouts; all patients in both groups were included in the analysis. There were no differences in any key covariates, including age, sex, and BMI, between the two groups. All THAs were performed via the modified Watson-Jones approach with the patient in the lateral decubitus position. The primary outcome was the absolute difference between the cup placement angle displayed on the screen of the navigation system and that measured on postoperative radiographs. The secondary outcome was intraoperative or postoperative complications recorded during the study period for the two portable navigation systems. RESULTS: There were no differences between the AR and accelerometer groups in terms of the mean absolute difference in radiographic inclination angle (3° ± 2° versus 3° ± 2° [95% CI -1.2° to 0.3°]; p = 0.22). The mean absolute difference in radiographic anteversion angle displayed on the navigation screen during surgery compared with that measured on postoperative radiographs was smaller in the AR group than that in the accelerometer group (2° ± 2° versus 5° ± 4° [95% CI -4.2° to -2.0°]; p < 0.001). There were few complications in either group. In the AR group, there was one patient each with a surgical site infection, intraoperative fracture, distal deep vein thrombosis, and intraoperative pin loosening; in the accelerometer group, there was one patient each with an intraoperative fracture and intraoperative loosening of pins. CONCLUSION: Although the AR-based portable navigation system demonstrated slight improvements in radiographic anteversion of cup placement compared with the accelerometer-based portable navigation system in THA, whether those small differences will prove clinically important is unknown. Until or unless future studies demonstrate clinical advantages that patients can perceive that are associated with such small radiographic differences, because of the costs and the unquantified risks associated with novel devices, we recommend against the widespread use of these systems in clinical practice. LEVEL OF EVIDENCE: Level I, therapeutic study.

Nano-visualization of the in vitro antiviral activity of black tea based on production area using a liposome-based virus membrane model.

Black tea extracts (BTEs) from four different production areas showed a higher aggregation strength for phosphatidylcholine-based liposomes containing cholesterol used as a viral membrane model. Furthermore, the anti-influenza A virus (IAV) activity of each BTE in vitro demonstrated that although Sri Lanka, Kenya, and Assam had higher anti-IAV activities, Darjeeling had a lower anti-IAV activity, showing a correlation between each BTE and the liposome aggregation strength. Moreover, the antiviral activity strength of BTEs was consistent with the antioxidant activity strength of BTEs, suggesting that the component(s) in black tea that exhibits antioxidant activity would also be the component(s) that accounts for its antiviral activity. Thus, our results propose that BTEs exert their antiviral effects by binding not only hemagglutinin and neuraminidase but also viral membranes directly, especially "cholesterol-rich lipid rafts" and affect the membrane structure, causing the virus to aggregate, thereby inhibiting infection of the host cells.

Inhibitory effects of thiol compounds on theaflavin browning and structural analysis of the causative substances.

Theaflavin, a polyphenol responsible for the bright orange color and various bioactivities of black tea exudates, is susceptible to autoxidation at neutral and mild alkaline pH, changing its color to brown. In the presence of cysteine (Cys), glutathione (GSH), or N-acetyl cysteine (NAC), the browning of theaflavin solution was inhibited concomitantly with time-dependent decreases in the concentrations of both theaflavin and thiol group. The rank order of the decrease was Cys â‰… GSH > NAC, suggesting the relevance of the nucleophilic property of the thiol group to its reaction with theaflavin. LC-MS analysis of the reaction products indicated formation of novel derivatives that were mono- or di-molecular adducts of thiol compounds. We determined the chemical structures of theaflavin-Cys and theaflavin-GSH adducts by NMR and proposed the reaction mechanisms. It was found that the theaflavin-Cys adduct was not a simple adduct, to which a new cyclic structure was added.

Bio-nanocapsules for oriented immobilization of DNA aptamers on aptasensors.

The oriented immobilization of sensing molecules (e.g., IgGs, receptors, lectins, and DNA aptamers) on sensor chips is particularly important for maximizing the potential of the sensing molecules, thereby enhancing the sensitivity and target-binding capacity of biosensors. We previously developed ∼30 nm bio-nanocapsules (ZZ-BNCs) consisting of the hepatitis B virus envelope L protein fused with the tandem form of protein A-derived IgG Fc-binding Z domain (ZZ-L protein). ZZ-BNC acts successfully as a scaffold, enhancing both the sensitivity and binding capacity of IgG, a Fc-fused receptor, and Fc-fused lectin to antigens, cytokines, and sugar chains through an oriented immobilization on a biosensor surface. To expand the versatility of ZZ-BNC, we modified ZZ-BNC by replacing the ZZ domain with a DNA-binding single-chain lambda Cro (scCro) domain, thereby developing scCro-BNC. The scCro-BNC was synthesized in yeast cells and homogeneously purified as ∼30 nm sized nanoparticles. In a quartz crystal microbalance, an scCro-BNC-coated sensor chip immobilized with thrombin-binding DNA aptamers showed an ∼5.5-fold higher thrombin-binding capacity and ∼6000-fold higher detection sensitivity than a sensor chip directly coated with DNA aptamers. In addition, the number of bound thrombin molecules per molecule of DNA aptamer increased by ∼7.8-fold with an scCro-BNC coating, consistent with the theoretical thrombin-binding capacity. Collectively, scCro-BNC was shown to perform as an ideal scaffold for maximizing the potential of the DNA aptamer by immobilizing it in an oriented manner. Facilitating a highly sensitive detection of various target molecules, these BNC-based scaffolds are expected to improve a wide range of biosensors while minimizing the number of sensing molecules required.

Addition of corticosteroid to periarticular injections reduces postoperative pain following total hip arthroplasty under general anaesthesia: a double-blind randomized controlled trial.

AIMS: Although periarticular injection plays an important role in multimodal pain management following total hip arthroplasty (THA), there is no consensus on the optimal composition of the injection. In particular, it is not clear whether the addition of a corticosteroid improves the pain relief achieved nor whether it is associated with more complications than are observed without corticosteroid. The aim of this study was to quantify the safety and effectiveness of cortocosteroid use in periarticular injection during THA. METHODS: We conducted a prospective, two-arm, parallel-group, randomized controlled trial involving patients scheduled for unilateral THA. A total of 187 patients were randomly assigned to receive periarticular injection containing either a corticosteroid (CS group) or without corticosteroid (no-CS group). Other perioperative interventions were identical for all patients. The primary outcome was postoperative pain at rest during the initial 24 hours after surgery. Pain score was recorded every three hours until 24 hours using a 100 mm visual analogue scale (VAS). The primary outcome was assessed based on the area under the curve (AUC). RESULTS: The CS group had a significantly lower AUC postoperatively at 0 to 24 hours compared to the no-CS group (AUC of VAS score at rest 550 ± 362 vs 392 ± 320, respectively; mean difference 158 mm; 95% confidence interval (CI) 58 to 257; p = 0.0021). In point-by-point evaluation, the CS group had significantly lower VAS scores at 12, 15, 18, 21, 24, and 48 hours. There were no significant differences in complication rates, including surgical site infection, between the two groups. CONCLUSION: The addition of corticosteroid to periarticular injections reduces postoperative pain without increasing complication rate following THA. Cite this article: Bone Joint J 2020;102-B(10):1297-1302.

Enhanced sugar chain detection by oriented immobilization of Fc-fused lectins.

We report a novel scaffold for clustering and oriented immobilization of human IgG1 Fc-fused lectins on biosensors without chemical modifications. This approach uses a bio-nanocapsule (BNC) displaying a tandem form of IgG Fc-binding Z domains derived from Staphylococcus aureus protein A (ZZ-BNC). Incorporating ZZ-BNC effectively increased both the sensitivity and sugar chain-binding capacity compared with the condition without ZZ-BNC.

Two-dimensional membrane scaffold for the oriented immobilization of biosensing molecules.

The orientation and density of biosensing molecules on sensor chip should be precisely controlled to improve sensitivity and ligand-binding capacity. We previously developed a ~30-nm bio-nanocapsule (ZZ-BNC), consisting of the hepatitis B virus envelope L protein fused with the tandem form of protein A-derived IgG Fc-binding Z domain (ZZ-L protein). This is used as a robust nanoparticle scaffold to enhance the sensitivity and ligand-binding capacity of IgGs and Fc-fused sensing molecules (Fc-fused receptors). However, due to their rigid particle structure, the surface density of ZZ-L proteins could not be optimized for biosensor functions, and useless ZZ-L proteins become stuck between ZZ-BNC and the sensor chip. Here, we have developed a planar lipid membrane embedded with ZZ-L micelles (ZZ-L membrane), which could modify the surface of any biosensor chip with a controlled density of ZZ-L proteins. Compared with ZZ-BNC, the sensitivity and ligand-binding capacity of IgGs were enhanced about 10-fold with the ZZ-L membrane. Furthermore, the immobilized IgGs could capture their respective antigens almost stoichiometrically, indicating that ZZ-L membrane is the most ideal scaffold for Fc-fused sensing molecules in terms of both clustering and oriented immobilization.

Efficient Synthesis of Theaflavin 3-Gallate by a Tyrosinase-Catalyzed Reaction with (-)-Epicatechin and (-)-Epigallocatechin Gallate in a 1-Octanol/Buffer Biphasic System.

Theaflavins, the orange-red pigments contained in black tea, have attracted attention as a result of their health-promoting effects. However, their synthetic preparation, in which the enzymatic oxidation of catechol-type catechin is followed by the quinone-induced oxidative dimerization of selectively combined catechol- and pyrogallol-type catechins, provides only a low yield. In the present study, we found that a 1-octanol/buffer biphasic system improved the yield of theaflavin 3-gallate in a tyrosinase-catalyzed synthetic reaction with (-)-epicatechin and (-)-epigallocatechin gallate. When the enzymatic reaction proceeded in a buffer solution, oxidized (-)-epigallocatechin gallate was preferentially used for self-dimerization. However, self-dimerization was suppressed in the octanol phase, allowing oxidized (-)-epigallocatechin gallate to participate in coupling with (-)-epicatechin quinone, leading to effective production of theaflavin 3-gallate. Furthermore, the preferential localization of theaflavin 3-gallate in the octanol phase prevented (-)-epicatechin-quinone-induced degradation.

No Clinically Important Difference in Pain Scores After THA Between Periarticular Analgesic Injection and Placebo: A Randomized Trial.

BACKGROUND: Periarticular analgesic injection (PAI) is being used more commonly for pain relief after orthopaedic surgeries. However, there is conflicting evidence regarding the effectiveness of PAI for post-THA pain relief. QUESTIONS/PURPOSES: In a double-blind, randomized, controlled trial among patients undergoing same-day bilateral THA, with each patient serving as his or her own control, we asked: (1) Did the pain score as measured on a 100-mm VAS differ between the hips that received PAI versus placebo? (2) Were there differences in complications between the treatment and control hips in these patients? METHODS: Over a 1-year period at one center, 45 patients underwent same-day bilateral THA; three were excluded for prespecified reasons, and two declined participation in this randomized, controlled trial, leaving 40 patients (80 THAs) in the study. Patients randomly received PAI in one hip and placebo in the contralateral hip; patients, surgeons, and nurses were blinded in terms of which hip received the PAI and which hip received a placebo saline injection. The PAI solution included ropivacaine, morphine hydrochloride hydrate, methylprednisolone, ketoprofen, and epinephrine. The primary outcome was the VAS for pain at rest 24 hours after THA, measured using a 100-mm horizontal VAS. The VAS score was compared between two groups and assessed to reach the reported threshold values for the minimum clinically important difference (MCID) of 20 mm for the postoperative VAS score. No patients were lost to followup, and there were no missing data for the primary outcome. Complications that occurred during the trial were recorded prospectively with emphasis on infection, wound complications, nerve palsy and allergic reactions to the injections. RESULTS: There were no clinically important differences between hips treated with the PAI and those treated with the placebo injection at any point. The hips that received PAI had less pain than those receiving placebo 24 hours after THA (16 ± 17 mm versus 22 ± 20 mm; mean difference, 6 mm; 95% confidence interval [CI], 2-9 mm; p = 0.006), but this effect size was below the MCID of 20 mm and thus is unlikely to be clinically important. The hips that received PAI also had better VAS scores in the recovery room (38 ± 29 mm versus 52 ± 33 mm; mean difference 14 mm; 95% CI, 5-23 mm; p = 0.004) and 3 hours after THA than placebo controls (28 ± 22 mm versus 37 ± 24 mm; mean difference 9 mm; 95% CI, 2-16 mm; p = 0.010). Neither of these differences exceeded the MCID and likewise were unlikely to be clinically important. No complications, including surgical site infections, were observed in either group. CONCLUSIONS: Periarticular analgesic injection for pain control after THA did not result in a clinically important reduction in pain at any point examined. Given the expense associated with this PAI mixture and the lack of effectiveness outside this timeframe, we cannot recommend its use. Other mixtures or concentrations of drugs may be helpful in short-stay admissions for THA, but this will require further research. LEVEL OF EVIDENCE: Level I, therapeutic study.

Theaflavin-3-gallate specifically interacts with phosphatidylcholine, forming a precipitate resistant against the detergent action of bile salt.

Black tea is a highly popular beverage, and its pigments, polymerized catechins such as theaflavins (TFs), are attracting attention due to their beneficial health effects. In this study, to test the inhibitory activities of TFs on the intestinal absorption of cholesterol, we investigated their effects on phosphatidylcholine (PC) vesicles in the absence or presence of a bile salt. (-)-Epicatechin gallate, (-)-epigallocatechin gallate, and TFs formed insoluble complexes with PC vesicles. Galloylated TFs such as TF2A, TF2B, and TF3 precipitated far more than other polyphenols. The subsequent addition of taurocholate redispersed the polyphenol-PC complexes, except that a large amount of TF2A remained insoluble. After incubation with taurocholate-PC micelles, TF2A elevated the turbidity of the micelle solution, providing red sediments. The TF2A-specific effect was dependent on the PC concentration. These results suggest that TF2A interacts with PC and aggregates in a specific manner different from catechins and other TFs.

Impact of Active Ankle Movement Frequency on Velocity of Lower Limb Venous Flow following Total Hip Arthroplasty.

Background. Although active ankle movement plays a predominant role in mechanical thromboprophylaxis following total hip arthroplasty (THA), the most effective frequency of movement remains unclear. Materials and Methods. In 29 consecutive patients undergoing THA, the velocity of blood flow in the profunda femoris was measured after various frequencies of ankle movement two days after THA using a pulse wave Doppler ultrasound system. To test the interobserver reliabilities for the velocity measured with Doppler ultrasound system, the intraclass correlation coefficient was calculated based on the measurement in 10 limbs of healthy volunteers. Results. At 0, 1, and 2 minutes after ankle movement, the velocity after movement at 60 contractions per minute was significantly faster than that after movement at 40 or 80 contractions per minute (p = 0.0007, repeated-measures analysis of variance). The intraclass correlation coefficient score in two investigators was 0.849 (95% confidence interval, 0.428 to 0.962). Conclusions. Active ankle movement at 60 contractions per minute is recommended in patients receiving THA to obtain optimal venous blood flow.

The impact of theaflavins on systemic-and microcirculation alterations: The murine and randomized feasibility trials.

Theaflavins are polyphenols found in black tea; their physiological activities were not well investigated. The present study in rats evaluated the influence of theaflavins on circulation. In addition, an intervention pilot study examined the influence of a theaflavin drink on postprandial hemodynamic change. In an animal study, a single oral dose of theaflavin rich fraction (TF, 10mg/kg) caused transient increase in mean blood pressure (MBP) and heart rate (HR). TF also elevated cremastric blood flow significantly, and the magnitude of this effect was in this order: theaflavin 3'-O-gallate (TF2B) >>theaflavin-3-O-gallate (TF2A) >>theaflavin (TF1)=theaflavin-3, 3'-di-O-gallate (TF3). In addition, these hemodynamic alterations in mammals totally disappeared when pretreated with carvedilol as an adrenaline blocker. We also treated 10-mg/kg/day TF to the rats for 2 weeks. At the end of the ingestion period, MBP was reduced significantly, and aortic eNOS level was elevated by the repeated ingestion of TF compared with distilled water. In the intervention trial, blood pressure of the volunteers was increased significantly 2 and 4h after ingestion of the TF drink (45mg/drink) compared with before treatment. A significant difference was observed in FMD between the placebo and theaflavin groups 4h after ingestion. These results suggested that theaflavin has potent activity to alter hemodynamics in both murine and healthy subjects. Further studies is needed to elucidate the details; however, the results of animal study suggested that the possible involvement of sympathetic nervous system in the hemodynamic changes caused by TF.

A Single Oral Administration of Theaflavins Increases Energy Expenditure and the Expression of Metabolic Genes.

Theaflavins are polyphenols found in black tea, whose physiological activities are not well understood. This study on mice evaluated the influence of a single oral administration of theaflavins on energy metabolism by monitoring the initial metabolic changess in skeletal muscle and brown adipose tissue (BAT). Oxygen consumption (VO2) and energy expenditure (EE) were increased significantly in mice treated with theaflavin rich fraction (TF) compared with the group administered vehicle alone. There was no difference in locomotor activity. Fasting mice were euthanized under anesthesia before and 2 and 5, 20-hr after treatment with TF or vehicle. The mRNA levels of uncoupling protein-1 (UCP-1) and peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) in BAT were increased significantly 2-hr after administration ofTF. The levels of UCP-3 and PGC-1α in the gastrocnemius muscle were increased significantly 2 and 5-hr after administration of TF. The concentration of phosphorylated AMP-activated protein kinase (AMPK) 1α was also increased significantly in the gastrocnemius 2 and 5-hr after treatment with TF. These results indicate that TF significantly enhances systemic energy expenditure, as evidenced by an increase in expression of metabolic genes.

Mechanism of papain-catalyzed synthesis of oligo-tyrosine peptides.

Di-, tri-, and tetra-tyrosine peptides with angiotensin I-converting enzyme inhibitory activity were synthesized by papain-catalyzed polymerization of L-tyrosine ethyl ester in aqueous media at 30 °C. Varying the reaction pH from 6.0 to 7.5 and the initial concentration of the ester substrate from 25 to 100 mM, the highest yield of oligo-tyrosine peptides (79% on a substrate basis) was produced at pH 6.5 and 75 mM, respectively. In the reaction initiated with 100 mM of the substrate, approx. 50% yield of insoluble, highly polymerized peptides accumulated. At less than 15 mM, the reaction proceeded poorly; however, from 30 mM to 120 mM a dose-dependent increase in the consumption rate of the substrate was observed with a sigmoidal curve. Meanwhile, each of the tri- and tetra-tyrosine peptides, even at approx. 5mM, was consumed effectively by papain but was not elongated to insoluble polymers. For deacylation of the acyl-papain intermediate through which a new peptide bond is made, L-tyrosine ethyl ester, even at 5mM, showed higher nucleophilic activity than di- and tri-tyrosine. These results indicate that the mechanism through which papain polymerizes L-tyrosine ethyl ester is as follows: the first interaction between papain and the ester substrate is a rate-limiting step; oligo-tyrosine peptides produced early in the reaction period are preferentially used as acyl donors, while the initial ester substrate strongly contributes as a nucleophile to the elongation of the peptide product; and the balance between hydrolytic fragmentation and further elongation of oligo-tyrosine peptides is dependent on the surrounding concentration of the ester substrate.

Genome-wide screening of salt tolerant genes by activation-tagging using dedifferentiated calli of Arabidopsis and its application to finding gene for Myo-inositol-1-p-synthase.

Salinity represents a major abiotic stress factor that can adversely limit the production, quality and geographical distribution of crops. In this study we focused on dedifferentiated calli with fundamental cell functions, the salt tolerance of which had not been previously examined. The experimental approach was based on activation tagging without regeneration of plants for the identification of salt-tolerant mutants of Arabidopsis. Among 62,000 transformed calli that were screened, 18 potential mutants resistant to 150 mM NaCl were obtained. Thermal asymmetric interlaced (TAIL)-PCR was performed to determine the location of T-DNA integration in the genome. In one line, referred to as salt tolerant callus 1 (stc1), expression of a gene [At4g39800: myo-inositol-1-P-synthase 1 (MIPS1)] was considerably enhanced in calli. Plants regenerated from calli showed tolerance to salt in germination and subsequent growth. Retransformation of wild-type Arabidopsis with MIPS1 conferred salt tolerance, indicating that MIPS1 is the causal gene. The over-expression of MIPS1 increased the content of total inositol. The involvement of MIPS1 in salt tolerance through the fundamental cell growth has been proved in Arabidopsis.

Tea polyphenols ameliorate fat storage induced by high-fat diet in Drosophila melanogaster.

BACKGROUND: Polyphenols in tea are considered beneficial to human health. However, many such claims of their bioactivity still require in vitro and in vivo evidence. RESULTS: Using Drosophila melanogaster as a model multicellular organism, we assess the fat accumulation-suppressing effects of theaflavin (TF), a tea polyphenol; epitheaflagallin (ETG), which has an unknown function; and epigallocatechin gallate (EGCg), a prominent component of green tea. Dietary TF reduced the malondialdehyde accumulation related to a high-fat diet in adult flies. Other physiological and genetic responses induced by the high-fat diet, such as lipid accumulation in the fat body and expression of lipid metabolism-related genes, were ameliorated by the addition of TF, ETG, and EGCg, in some cases approaching respective levels without high-fat diet exposure. Continuous ingestion of the three polyphenols resulted in a shortened lifespan. CONCLUSION: We provide evidence in Drosophila that tea polyphenols have a fat accumulation-suppressing effect that has received recent attention. We also suggest that tea polyphenols can provide different desirable biological activities depending on their composition and the presence or absence of other chemical components.

Structural specificity of electric potentials in the coulometric-array analysis of catechins and theaflavins.

We have established a novel method to evaluate the redox properties of tea polyphenols by HPLC-coulometric-array analysis. We plotted the quantity of electricity (µC) on the vertical axis and the electric potential (mV), adjusted with the associated palladium reference electrode, on the horizontal axis to provide "quantity versus potential (QP) plot". The patterns of the plots correspond to the derivative of a hydrodynamic voltammogram or a current-voltage curve, with the electric potentials of the peaks in the QP plot corresponding to the half-wave potentials in the current-voltage curve. We confirmed that catechins and theaflavins are oxidized depending on the electric potentials of their partial structures, and found that all compounds showing a peak at 0 mV in the QP plots produce hydrogen peroxide (H2O2) during the autoxidation process.

The human bitter taste receptor hTAS2R39 is the primary receptor for the bitterness of theaflavins.

We purified several hundred mgs of four major theaflavins (theaflavin, theaflavin-3-O-gallate, theaflavin-3'-O-gallate, and theaflavin-3,3'-O-digallate). Among the 25 hTAS2Rs expressed in HEK293T cells, hTAS2R39 and hTAS2R14 were activated by theaflavins. Both hTAS2R39 and hTAS2R14 responded to theaflavin-3'-O-gallate. In addition, hTAS2R39 was activated by theaflavin and theaflavin-3,3'-O-gallate, but not by theaflavin-3-O-gallate. In contrast, hTAS2R14 responded to theaflavin-3-O-gallate.