Screening of Selected Stingless Bee Honey Varieties for ACE2-Spike Protein-Binding Inhibition Activity: A Potential Preventive Medicine Against SARS-Cov-2 Infection

The broader objective of this study is to identify natural materials that might inhibit the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We have focused on stingless bee honey, which has a unique taste that is both sweet and sour and sometimes bitter. We screened 12 samples of honey from 11 species of stingless bees using an angiotensin-converting enzyme 2 (ACE2)-spike protein-binding assay and phytochemical analysis. Ten of the samples showed inhibition above 50% in this assay system. Most of the honey contained tannins, alkaloids, flavonoids, triterpenoids, carotenoids and carbohydrates. Our findings in this in vitro study showed that honey from stingless bees may have a potent effect against SARS-CoV-2 infection by inhibiting the ACE2-spike protein-binding.

Early vascular responses to abluminal biodegradable polymer-coated versus circumferential durable polymer-coated newer-generation drug-eluting stents in humans: a pathologic study

Background

Recent clinical trials are testing strategies for short (1–3 months) dual antiplatelet therapy (DAPT) following newer-generation drug-eluting stent (DES) placement. However, the safety of short DAPT regimens is not supported by biological evidence in humans.

Purpose

We sought to evaluate early pathologic responses to newer-generation DES by comparing abluminal biodegradable polymer-coated DES (BP-DES) with circumferential durable polymer-coated DES (DP-DES) in human autopsy cases.

Methods

The study included a total of 37 coronary lesions with thin strut newer-generation DES (DP-DES=23 [XIENCE=18, Resolute Integrity=5] and BP-DES=14 [SYNERGY=9, Ultimaster=5]) with duration of implantation <90 days in 25 autopsy cases. The process of stent healing was precisely evaluated for every single strut in association with underlying tissue characteristics. The degree of strut coverage was defined as follows: grade 0 (bare struts), grade 1 (struts covered with thrombus, fibrin, or other tissues or cells without endothelium), grade 2 (struts covered with single-layered endothelium without underlying smooth muscle cell layers), and grade 3 (struts covered with endothelium and underlying smooth muscle cell layers) (Figure 1).

Results

Duration of implantation was similar in lesions with DP-DES and those with BP-DES (median=20 vs. 17 days). A total of 1986 struts (DP-DES=1261, BP-DES=725) were pathologically analyzed. Focal grade 2 coverage was observed as early as 5 days after the implantation in both stents. Multilevel mixed-effects ordered logistic regression model demonstrated that BP-DES exhibited greater strut coverage compared with DP-DES (odds ratio; 3.50, 95% CI; 1.31–9.41, P=0.013), which remained significant after adjustment for duration of implantation and underlying tissue characteristics (odds ratio; 2.64, 95% CI; 1.04–6.68, P=0.040). The time course of vessel healing assessed as predictive probability of strut coverage (grade 0–3) stratified by duration of implantation is shown in Figure 2. Predictive probability of grade 2 and 3 coverage was comparably limited at 30 days (DP-DES=17.7% vs. BP-DES=29.0%) and increased at 90 days (DP-DES=76.1% vs. BP-DES=85.9%). Both stents showed few inflammation and similar degree of fibrin deposition.

Conclusions

The current first pathologic study on early biological responses to newer-generation DES in humans demonstrated that single-layered endothelial coverage begins in days following the stent placement, and abluminal BP-DES potentially exhibit faster strut coverage with smooth muscle cell infiltration than circumferential DP-DES. Nevertheless, vessel healing remains suboptimal at 30 days in both DP- and BP-DES, which progresses with time to become substantial at 90 days. Our results suggest that very short duration of DAPT for 1 month should be applied with caution, taking into account the trade-off between bleeding and thrombotic risks.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Grant-in-Aid for Scientific Research (C) from the Japan Society for the Promotion of Science

The Mediation Role of Thyrotropin Receptor Antibody in the Relationship Between Age and Severity of Hyperthyroidism in Graves' Disease

Background: The severity of hyperthyroidism in Graves' disease (GD) has been reported to be worse in younger patients and to gradually improve with advancing age, accompanied by declining thyrotropin (TSH) receptor antibody (TRAb) values. This study was conducted to explore the extent to which the declining TRAb production may contribute to a decrease in severe hyperthyroidism with advancing age in patients with GD. Methods: This study was a cross-sectional analysis of retrospectively reviewed data. The medical records of patients newly diagnosed with GD at Ito Hospital, between January 2005 and June 2019, were examined. Patients were divided into age-stratified groups for evaluation. Multivariable logistic regression was performed to estimate the odds ratio (OR) of severe hyperthyroidism by increasing age. Mediation analyses were also conducted to quantify the association between age and declining severity of hyperthyroidism mediated through decreased TRAb productivity. Results: A total of 21,018 patients with newly diagnosed GD (3848 male and 17,170 female) were included. A correlation was observed between TRAb value and thyroid hormone values in each age-stratified group, which became weaker with an increase in age. Patients aged <40 years had a higher risk of severe hyperthyroidism (free thyroxine [fT4] level >7.0 ng/dL [n = 5616], OR [confidence interval, CI] = 1.80 [1.68-1.92]; free triiodothyronine [fT3] level >25 pg/mL [n = 4501], OR [CI] = 2.06 [1.92-2.23]) than those aged ≧40 years. In examining the relationship between age and severe hyperthyroidism, the proportion mediated through TRAb productivity was 8.5% and 8.4% using fT4 and fT3 as an outcome index, respectively. Conclusions: Declining TRAb value mediated only 8.5% of the negative association between age and severity of hyperthyroidism. The presence of other underlying mechanisms, such as the decline in the reactivity of thyrocytes to TSH stimulation, requires further investigation.

Prediction model of Graves' disease in general clinical practice based on complete blood count and biochemistry profile

Although untreated Graves' disease (GD) is associated with a higher risk of cardiac complications and mortality, there is no well-established way to predict the onset of thyrotoxicosis in clinical practice. The aim of this study was to identify important variables that will make it possible to predict GD and thyrotoxicosis (GD + painless thyroiditis (PT)) by using a machine-learning-based model based on complete blood count and standard biochemistry profile data. We identified 19,335 newly diagnosed GD patients, 3,267 PT patients, and 4,159 subjects without any thyroid disease. We built a GD prediction model based on information obtained from subjects regarding sex, age, a complete blood count, and a standard biochemistry profile. We built the model in the training set and evaluated the performance of the model in the test set by using the artificial intelligence software Prediction One. Our machine learning-based model showed high discriminative ability to predict GD in the test set (area under the curve [AUC] 0.99). The main contributing factors to predict GD included age and serum creatinine, total cholesterol, alkaline phosphatase, and total protein levels. We still found high discriminative ability even when we restricted the variables to these five most contributory factors in our prediction model (AUC 0.97) built by using artificial intelligence software showed high GD prediction ability based on information regarding only five factors.

Increased levels of a pro-inflammatory IgG receptor in the midbrain of people with schizophrenia

BACKGROUND

There is growing evidence that neuroinflammation may contribute to schizophrenia neuropathology. Elevated pro-inflammatory cytokines are evident in the midbrain from schizophrenia subjects, findings that are driven by a subgroup of patients, characterised as a "high inflammation" biotype. Cytokines trigger the release of antibodies, of which immunoglobulin G (IgG) is the most common. The level and function of IgG is regulated by its transporter (FcGRT) and by pro-inflammatory IgG receptors (including FcGR3A) in balance with the anti-inflammatory IgG receptor FcGR2B. Testing whether abnormalities in IgG activity contribute to the neuroinflammatory abnormalities schizophrenia patients, particularly those with elevated cytokines, may help identify novel treatment targets.

METHODS

Post-mortem midbrain tissue from healthy controls and schizophrenia cases (n = 58 total) was used to determine the localisation and abundance of IgG and IgG transporters and receptors in the midbrain of healthy controls and schizophrenia patients. Protein levels of IgG and FcGRT were quantified using western blot, and gene transcript levels of FcGRT, FcGR3A and FcGR2B were assessed using qPCR. The distribution of IgG in the midbrain was assessed using immunohistochemistry and immunofluorescence. Results were compared between diagnostic (schizophrenia vs control) and inflammatory (high vs low inflammation) groups.

RESULTS

We found that IgG and FcGRT protein abundance (relative to β-actin) was unchanged in people with schizophrenia compared with controls irrespective of inflammatory subtype. In contrast, FcGRT and FcGR3A mRNA levels were elevated in the midbrain from "high inflammation" schizophrenia cases (FcGRT; p = 0.02, FcGR3A; p < 0.0001) in comparison to low-inflammation patients and healthy controls, while FcGR2B mRNA levels were unchanged. IgG immunoreactivity was evident in the midbrain, and approximately 24% of all individuals (control subjects and schizophrenia cases) showed diffusion of IgG from blood vessels into the brain. However, the intensity and distribution of IgG was comparable across schizophrenia cases and control subjects.

CONCLUSION

These findings suggest that an increase in the pro-inflammatory Fcγ receptor FcGR3A, rather than an overall increase in IgG levels, contribute to midbrain neuroinflammation in schizophrenia patients. However, more precise information about IgG-Fcγ receptor interactions is needed to determine their potential role in schizophrenia neuropathology.

The Relationship Between Primary Thyroid Lymphoma and Various Types of Thyroid Autoimmunity: A Retrospective Cohort Study of 498 Cases, Including 9 Cases with Graves' Disease

Background: Primary thyroid lymphoma (PTL) is known to develop mostly in patients with Hashimoto's thyroiditis (HT), and it is rare for it to develop in patients with Graves' disease (GD). The objective of this study was to investigate the clinical features, pathological findings, and long-term outcomes of PTL patients, grouped according to the presence of GD, HT, or no autoimmune thyroid disease (AITDs). The GD group was of major interest due to limited knowledge of the relationship with PTL. Methods: In this single-center retrospective cohort study, we reviewed the medical records of all patients diagnosed with PTL between August 1979 and October 2021, and we characterized the patients according to the presence of HT, GD, or no AITDs. Pathological specimens were classified according to the World Health Organization classification. Staging was performed in accordance with the Ann Arbor classification. Results: During the 42-year period, 498 participants were diagnosed with PTL. The median age was 68 (interquartile range 61-76) years, and 221 patients were stage IE, whereas the remaining 277 patients were stage IIE. Of the PTL patients, 431 (86.6%) were diagnosed with HT, 9 (1.8%) were diagnosed with GD, and 58 (11.6%) did not have AITDs. All nine patients with GD were positive for anti-thyroglobulin antibody and/or anti-thyroid peroxidase antibody. All patients with GD were treated with anti-thyroid medication. There were no significant differences in the proportions of each subtype of PTL between the PTL patients with GD and all subjects with PTL (p = 0.51), PTL patients with HT (p = 0.51), or PTL patients without AITDs (p = 0.48). The median follow-up time was 6.2 (interquartile range 3.0-10.7) years after the diagnosis of PTL. The Kaplan-Meier curve analyses showed no significant differences in overall survival and event-free survival between PTL patients with GD and those with HT (p = 0.37), or between PTL patients with GD and those without AITDs (p = 0.43). Conclusions: The PTL was observed with HT in a majority of cases, and rarely with GD (1.8%). The proportions of each pathological subtype of PTL and the prognosis of PTL were not different between the patients with GD and those with HT or those without AITDs.

Antioxidant and Protective Effect of Acetone Extract of Entada phaseoloides Leaves on UVB-Irradiated Human Epidermal Keratinocytes (HaCaT cells) by Inhibiting COX-2, iNOS, and Caspase-3 Activation

Chronic ultraviolet (UV) exposure produces oxidative stress, molecular damage, and aging-related signal transduction, all of which contribute to skin photoaging. In this study, the antioxidant and anti-inflammatory activities of Entada phaseoloides are reported. High-performance liquid chromatography (HPLC) detected 7 phenolic compounds: gallic acid, protocatechuic acid, 4-hydroxybenzoic acid, quercetin, luteolin, kaempferol, and apigenin. We investigated the antioxidant and protective effect of the acetone extract of E. phaseoloides leaves (AEP) on UVB-irradiated human epidermal keratinocytes (HaCaT cells). AEP showed antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. AEP at a concentration of 40 μg/mL increased cell survival rate of the UVB-damaged cells. Moreover, AEP blocked gene expression of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in UVB-induced HaCaT cells and decreased UVB-induced apoptosis in HaCaT cells by regulating the gene expression of caspase-3. These results suggest that AEP has the potential to protect against UVB irradiation and antioxidant.

Placental pathology predicts infantile neurodevelopment

The aim of present study was to investigate the association of placental pathological findings with infantile neurodevelopment during the early 40 months of life. 258 singleton infants were enrolled in the Hamamatsu Birth Cohort for Mothers and Children (HBC Study) whose placentas were saved in our pathological division. To assess the infantile neurodevelopment, we used Mullen Scales of Early Learning (gross motor, visual reception, fine motor, receptive language, expressive language) at 10, 14, 18, 24, 32, and 40 months. For obtaining placental blocks, we carried out random sampling and assessed eleven pathological findings using mixed modeling identified ‘Accelerated villous maturation’, ‘Maternal vascular malperfusion’, and ‘Delayed villous maturation’ as significant predictors of the relatively lower MSEL composite scores in the neurodevelopmental milestones by Mullen Scales of Early Learning. On the other hand, ‘Avascular villi’, ‘Thrombosis or Intramural fibrin deposition’, ‘Fetal vascular malperfusion’, and ‘Fetal inflammatory response’ were significant predictors of the relatively higher MSEL composite scores in the neurodevelopmental milestones by Mullen Scales of Early Learning. In conclusion, the present study is the first to report that some placental pathological findings are bidirectionally associated with the progression of infantile neurodevelopment during 10–40 months of age.

Comparative Analysis of Gene Expression Profiles in the Adipose Tissue of Obese Adult Mice With Rapid Infantile Growth After Undernourishment In Utero

Rapid infantile growth (RG) markedly increases the risk of obesity and metabolic disorders in adulthood, particularly among neonates born small. To elucidate the molecular mechanisms by which RG following undernourishment in utero (UN) contributes to the deterioration of adult fat deposition, we developed a UN mouse model using maternal energy restriction, followed by RG achieved by adjustments to 4 pups per litter soon after birth. A high-fat diet (HFD) was fed to weaned pups treated or not (Veh) with tauroursodeoxycholic acid (TU). UN-RG pups showed the deterioration of diet-induced obesity and fat deposition, which was ameliorated by TU. We performed a microarray analysis of epididymal adipose tissue and two gene enrichment analyses (NN-Veh vs UN-RD-Veh and UN-RG-Veh vs UN-RG-TU). The results obtained identified 4 common gene ontologies (GO) terms of inflammatory pathways. In addition to the inflammatory characteristics of 4 GO terms, the results of heatmap and principal component analyses of the representative genes from 4 GO terms, genes of interest (GOI; Saa3, Ubd, S100a8, Hpx, Casp1, Agt, Ptgs2) selected from the 4 GO terms, and immunohistochemistry of macrophages collectively suggested the critical involvement of inflammation in the regulation of fat deposition in the responses to UN and TU. Therefore, the present results support the 'Developmental Origins of Metaflammation', the last word of which was recently proposed by the concept of metabolic disorders induced by low-grade systemic inflammation.

Delayed Follow-up Visits and Thyrotropin Among Patients With Levothyroxine During the COVID-19 Pandemic

Context

The indirect effects of the COVID-19 pandemic on clinical practice have received great attention, but evidence regarding thyroid disease management is lacking.

Objective

We aimed to investigate the association between delayed follow-up visits during the pandemic and their serum thyrotropin (TSH) levels among patients being treated with levothyroxine.

Methods

This study included 25 361 patients who made a follow-up visit as scheduled (n = 9063) or a delayed follow-up visit (< 30 d, n = 10 909; ≥ 30 d, n = 5389) during the pandemic (after April 2020) in Japan. We employed modified Poisson models to estimate the adjusted risk ratio (aRR) of TSH greater than 4.5 mIU/L and greater than 10 mIU/L during the pandemic according to the 3 types of follow-up visit group (ie, as scheduled, delayed < 30 d, and delayed ≥ 30 d). The models included age, sex, city of residence, TSH levels, underlying thyroid disease, dose of levothyroxine, and duration of levothyroxine prescriptions.

Results

The mean age was 52.8 years and women were 88%. Patients who were older and had a higher dose or longer duration of levothyroxine prescriptions were more likely to make a delayed follow-up visit during the pandemic. Changes in TSH were larger among the delayed-visit groups than the scheduled-visit group. We found increased risks of elevated TSH levels during the pandemic among the delayed visit groups, particularly those with delayed visit of 30 or more days (TSH > 4.5 mIU/L, aRR [95% CI] = 1.72 [1.60-1.85]; and TSH > 10 mIU/L, aRR [95% CI] = 2.38 [2.16-2.62]).

Conclusion

A delayed follow-up visit during the COVID-19 pandemic was associated with less well-controlled TSH among patients with levothyroxine.

Cytotoxicity effect of honey, bee pollen, and propolis from seven stingless bees in some cancer cell lines

Our effort to find new material for anti cancer from natural resources leads us to focus on stingless bee products such as honey, bee pollen, and propolis. The products were from seven stingless bees named Homotrigona fimbriata, Heterotrigona itama, Heterotrigona bakeri, Tetragonula sarawakensis, Tetragonula testaceitarsis, Tetragonula fuscobalteata, Tetragonula laeviceps. The stingless bee products were evaluated for their cytotoxicity effect on MCF-7, HeLa and Caco-2 cancer cell lines. This is the first time to be reported that the honey, ethanol extracts of bee pollen and propolis of H. fimbriata displayed more potent cytotoxicity than other stingless bee products. By chromatography and biological activity-guided fractionation, ethanol extract of propolis from H. fimbriata was fractionated and isolated its active compound named mangiferonic acid. Mangiferonic acid showed a cytotoxicity effect with IC₅₀ values 96.76 µM in MCF-7, >110.04 µM in HeLa, and > 110.04 µM in Caco-2, respectively. These results exhibited the potential of ethanol extracts from propolis of H. fimbriata to be further developed for drug and experiments to verify the function are essential.

Cardiac Troponin Is Elevated in Patients with Thyrotoxicosis and Decreases as Thyroid Function Improves and Brain Natriuretic Peptide Levels Decrease

INTRODUCTION

High-sensitive cardiac troponin reflects micro-myocardial injury in the absence of overt myocardial infarction.

OBJECTIVE

This study aimed to clarify how thyrotoxicosis affects cardiac troponin.

METHODS

This was a prospective observational study in Japan. Untreated patients with thyrotoxicosis who visited Ito Hospital were enrolled, and medical treatment was initiated for hyperthyroidism. Thyroid function, high-sensitive troponin I (hsTnI), and brain natriuretic peptide (BNP) were measured at baseline and then every 3 months for 1 year.

RESULTS

Data from a total of 143 patients (median age, 42 years; 32 men and 111 women) were investigated. At baseline, median hsTnI was 1.9 pg/mL and ranged from 0 to 69.6 pg/mL. Five patients (3.5%) had a high hsTnI value that exceeded 26.2 pg/mL, which is used as the cutoff for diagnosis of myocardial infarction, and 22 patients (15.4%) had an intermediate value between 5.0 and 26.2 pg/mL. Multivariable regression analysis showed that significant predictors of the hsTnI value were age (β = 0.20, p = 0.01) and BNP (β = 0.43, p < 0.0001) (R² = 0.27, F = 26.0, p < 0.0001), and significant predictors of the BNP value were age (β = 0.23, p = 0.001), hemoglobin (β = -0.43, p < 0.0001), free T₄ (FT₄) (β = 0.23, p = 0.001), and hsTnI (β = 0.27, p < 0.0001) (R² = 0.49, F = 33.8, p < 0.0001). Correlations were found between a decrease in hsTnI and BNP in the first 3 months (ρ = 0.49, p < 0.0001). A decrease in FT₄ in the first 3 months was weakly correlated with decreases in hsTnI (ρ = 0.32, p = 0.0004) and BNP (ρ = 0.32; p = 0.0003). Of the 27 patients with elevated hsTnI (≥5.0 pg/mL), the hsTnI level was normalized in 20 patients within a year.

CONCLUSIONS

In thyrotoxicosis, the myocardial biomarker hsTnI is elevated in about 20% of patients; hsTnI levels decrease as thyroid function improves and BNP decreases.

A case of macro-TSH consisting of IgA-bound TSH

An asymptomatic, 68-year-old Japanese man visited our hospital for further examination of subclinical hypothyroidism. At the first visit, the serum TSH level was markedly elevated (36.6 μIU/mL), but the serum level of free T4 was within the reference interval. Thyroid dysfunction due to dietary iodine excess was initially suspected. However, even after iodine restriction, his thyroid function tests were the same as at the first visit, which suggested false elevation of the TSH level. The TSH levels were compared among three different measurement systems, which showed a similar tendency of TSH elevation above the reference interval, but the different TSH elevation levels among the measurement methods suggested the existence of some interfering substance. Neither serial dilution of the patient's serum nor polyethylene glycol and protein G precipitation tests showed any significant changes in the recovery rate. IgG-bound macro-TSH was ruled out. The TSH peak on gel filtration chromatography was located at a molecular size greater than IgA, which suggested the presence of IgA-bound TSH. After precipitation with Jacalin, which binds specifically to IgA, the TSH level decreased from 30.7 μIU/mL to 2.01 μIU/mL, within the reference interval. Thus, IgA-bound macro-TSH was identified. Macro-TSH is a rare condition in which an immunoglobulin-bound, high-molecular-weight form of TSH results in a false elevation of the serum TSH level. When there is a discrepancy between the results of thyroid function tests and clinical symptoms, and macro-TSH is suspected, it is necessary to know that not only IgG-bound TSH but also IgA-bound TSH could be the cause.

Does Age or Sex Relate to Severity or Treatment Prognosis in Graves' Disease?

Background: The prognosis of Graves' disease (GD) is reportedly related to sex, age, and genetic factors, although there is no consensus. The objective of this study was to investigate the relationship between severity and prognosis of GD and sex or age. Methods: Subjects were patients newly diagnosed with GD between January 2005 and June 2019, and medical records were retrospectively reviewed. Patients diagnosed between January 2009 and December 2010 and followed up for at least 12 months were enrolled. Patients were divided into nine age-stratified groups. Remission was defined as maintenance of a euthyroid state for more than one year after withdrawal of antithyroid drugs (ATDs). Results: Participants comprised 21,633 patients (3954 males, 17,679 females). Initial free triiodothyronine (fT3) and free thyroxine (fT4) levels significantly decreased with increasing age, including after sex stratification. fT4 was significantly higher in males than females aged 20-39 years. In 2191 patients treated with ATDs alone, median durations until remission were 37.7 and 30.6 months in males and females, respectively. Remission and recurrence were observed in 1391 patients (204 males, 1187 females) and 262 patients (37 males, 225 females), respectively. By Kaplan-Meier analyses, males required a significantly longer time to achieve remission than females (p < 0.0001), although there were no significant age-related differences (p = 0.08). Cox proportional hazard modeling showed a 41% higher hazard ratio (HR) for remission in females than males (adjusted HRs [aHR] confidence interval [CI] = 1.41 [1.21-1.64]), and each additional 10 years of age had a 14% lower rate of recurrence (age [per 10-year increase], aHR [CI] = 0.86 [0.78-0.94]); no significant relationship between recurrence rate and sex was identified. Conclusions: Severity of hyperthyroidism in GD was significantly higher in males in their 20s and 30s, declining with advancing age in both sexes. Females were more likely to achieve remission than males, and younger patients had a higher risk of recurrence, although recurrence was unrelated to sex.

Analysis of Antioxidant and Antiallergic Active Components Extracted From the Edible Insect Oxya yezoensis

In recent years, entomophagy has attracted increased attention, as it was recommended as a potential source of food by the Food and Agriculture Organization of the United Nations. In Japan, Oxya yezoensisis one of the most widely eaten insect species, but studies of its functionality as a food are limited. In this study, we reported the optimal characterization of the total phenolic compounds in methanolic extract (OME) and different fractions of OME. Additionally, the antioxidant and antiallergic activities of the OME fractions were evaluated. The results showed that the ethyl acetate-soluble fraction of OME has potential antioxidant activity, whereas the n-hexane-soluble fraction showed the strongest inhibition of β-hexosaminidase, which is one of the key factors in allergic reactions. It was concluded that phenolic compounds might contribute to the antioxidant activity while unsaturated fatty acids contribute to the antiallergy activity.

Polythiophene-Doped Resorcinol-Formaldehyde Resin Photocatalysts for Solar-to-Hydrogen Peroxide Energy Conversion

The generation of hydrogen peroxide (H₂O₂) from water and dioxygen by sunlight-driven heterogeneous photocatalysis is a promising method for the artificial photosynthesis of a liquid solar fuel. We previously found that resorcinol-formaldehyde (RF) resin powders prepared by high-temperature hydrothermal synthesis act as highly active semiconductor photocatalysts for H₂O₂ generation. Herein, we report that RF resin powders doped with poly(3-hexylthiophene-2,5-diyl) (RF/P3HT) exhibit enhanced photocatalytic activities. The highly dispersed P3HT within the resin particles created charge transfer complexes with the conduction band of the resin via electron donation, facilitating efficient transfer of the photogenerated conduction band electrons through P3HT. This enhanced charge separation promoted efficient water oxidation and O₂ reduction. The solar-to-chemical conversion efficiency for H₂O₂ generation on the RF/P3HT resin in water under simulated sunlight irradiation with atmospheric pressure of O₂ was ∼1.0%, which is the highest efficiency reported for powder catalysts in artificial photosynthesis.