Covalent polyphenols-proteins interactions in food processing: formation mechanisms, quantification methods, bioactive effects, and applications.

Proteins and polyphenols are abundant in the daily diet of humans and their interactions influence, among other things, the texture, flavor, and bioaccessibility of food. There are two types of interactions between them: non-covalent interactions and covalent interactions, the latter being irreversible and more powerful. In this review, we systematically summarized advances in the investigation of possible mechanism underlying covalent polyphenols-proteins interaction in food processing, effect of different processing methods on covalent interaction, methods for characterizing covalent complexes, and impacts of covalent interactions on protein structure, function and nutritional value, as well as potential bioavailability of polyphenols. In terms of health promotion of the prepared covalent complexes, health effects such as antioxidant, hypoglycemic, regulation of intestinal microbiota and regulation of allergic reactions have been summarized. Also, the possible applications in food industry, especially as foaming agents, emulsifiers and nanomaterials have also been discussed. In order to offer directions for novel research on their interactions in food systems, nutritional value, and health properties in vivo, we considered the present challenges and future perspectives of the topic.

Preparation, characterization and application of antioxidant packaging films based on chitosan-epicatechin gallate conjugates with different substitution degrees.

In this study, chitosan (CS) was conjugated with epicatechin gallate (ECG) to prepare CS-ECG conjugates with different substitution degrees (5.18 %, 6.36 % and 7.74 %). Then, antioxidant packaging films were fabricated by blending CS and CS-ECG conjugates. The impact of CS-ECG conjugates' substitution degree on the functionality of CS/CS-ECG films was determined. CS-ECG conjugates showed UV absorption at 275 nm, proton signal at 6.85 ppm and infrared absorption at 1533 cm-1, assigning to the conjugated ECG. As compared with CS, CS-ECG conjugates exhibited less crystalline state but higher antioxidant activity. The structural characterization of CS/CS-ECG films showed CS and CS-ECG conjugates formed hydrogen bonds. CS/CS-ECG films displayed 26.35 %-29.23 % water solubility, 85.61°-86.96° water contact angle, 3.11-3.41 × 10-11 g m-1 s-1 Pa-1 water vapor permeability, 0.29-0.34 cm3 mm m-2 day-1 atm-1 oxygen permeability, 31.54-36.20 MPa tensile strength, 50.12 %-56.40 % elongation at break, as well as potent antioxidant activity and oil oxidation inhibitory ability. Notably, the film containing CS-ECG conjugate with 7.74 % substitution degree had the strongest barrier ability, mechanical property, antioxidant activity and oil oxidation inhibitory ability. Results suggested the substitution degree of CS-ECG conjugates was positively correlated with the barrier, mechanical and antioxidant properties of CS/CS-ECG films.

Clinical Application and Evaluation of Metagenomic Next-Generation Sequencing for Lower Respiratory Tract Infections and Human Tumor Screening.

Background: To evaluate the clinical value of metagenomic next-generation sequencing (mNGS) in screening of lower respiratory tract infections (LRTIs) and human tumors. Methods: Human samples included bronchoalveolar lavage fluid (BALF), sputum, lung biopsy tissue, and peripheral blood from 188 patients who were admitted to our hospital between January 2020 and September 2022 were analyzed using mNGS for simultaneous pathogen and chromosome copy number variation (CNV) detection. Traditional microbial culture and comprehensive microbial test (CMT) were also conducted. The diagnostic efficiencies of the three methods (mNGS, traditional culture, and CMT groups) were compared. Results: Among the 188 patients, 149 (79.3%) were in the LRTIs group and 39 (20.7%) were in the non-LRTIs group. The diagnostic sensitivity and accuracy of the mNGS group were higher than those of the traditional culture and CMT groups (P < 0.001; P < 0.001; P < 0.001; P < 0.001), and the specificity was higher than that of the CMT group (P = 0.039) but lower than that of the traditional culture group (P = 0.006). The positive predictive values of the mNGS and traditional culture groups were higher than that of the CMT group (P = 0.004; P = 0.011). The negative predictive value of the mNGS group was higher than that of the CMT group (P = 0.003). In addition, all samples were subjected to simultaneous chromosome CNV detection, and 8% (15/188) were positive for CNV. Of the 15 patients, 10 were initially misdiagnosed as non-neoplastic diseases, with a misdiagnosis rate of 66.7% (10/15). The BALF CNV test was performed on 13 patients diagnosed with primary or metastatic lung cancer, with a positivity rate of 38.5%. Conclusion: The sensitivity and accuracy of pathogen diagnosis using mNGS were better than those of traditional culture and CMT. CNV detection is an important auxiliary diagnostic tool for cancer, particularly for screening occult tumors.

Mechanisms underlying large-leaf yellow tea mediated inhibition of cognitive impairment in the 5xFAD model of Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is the most common cause of dementia and is characterized by amyloid-ß (Aß) peptides and hyperphosphorylated Tau proteins. Evidence indicates that AD and type 2 diabetes mellitus (T2DM) share pathophysiological characteristics, including impaired insulin sensitivity. Large-leaf yellow tea (LYT) has been widely recognized for its health benefits, and we previously found that LYT can improve peripheral insulin resistance. PURPOSE: This study aimed to investigate the protective effects and underlying mechanisms of LYT in the 5xFAD mouse model of AD. METHODS: HPLC and spectrophotometric methods determined the chemical composition of the LYT extract. 5xFAD mice were treated with LYT supplementation (2 and 4 mg/ml) in drinking water for six months. Barnes and Y mazes were used to evaluate cognitive function, and the open field test assessed anxiety-like behavior. Immunofluorescence, silver, and Nissl staining were used to evaluate the pathological effects of LYT extract. A FRET-based assay assessed ß-site APP cleavage enzyme 1 (BACE1) activity, ELISA measured Aß levels in the brain, and Western blot analyses explored protein expression levels. RESULTS: Our results revealed that LYT significantly attenuated memory impairment and anxiety levels and alleviated cerebral neural damage. A reduction of senile plaques was also observed in both the cortex and hippocampus. LYT significantly inhibited the activity of BACE1, which resulted in a lower Aß protein level. In addition, LYT enhanced insulin receptor substrate 1 (IRS-1)-mediated phosphorylation of phosphoinositide 3-kinase (PI3K) and protein kinase B (AKT), further suppressed glycogen synthase kinase-3ß (GSK3ß), and ultimately inhibited hyperphosphorylation of the protein Tau. The inhibitory effect of the LYT extract on the phosphorylation of Tau and BACE1 activity was dose-dependent. CONCLUSION: LYT improves cognitive ability and reduces Aß production by inhibiting BACE1 activity. Decreases of Tau protein hyperphosphorylation upon LYT treatment appear to be associated with the regulation of the IRS-1/PI3K/AKT/GSK3ß axis. Thus, the findings of this study also provide new evidence that LYT regulates insulin signaling pathways within the central nervous system.

A mechanistic and kinetic investigation on the oxidative thermal decomposition of decabromodiphenyl ether.

The thermal processes of materials containing decabromodiphenyl ether (BDE-209) normally result in the exposure of BDE-209 to high-temperature environments, generating a series of hazardous compounds. However, the evolution mechanisms of BDE-209 during oxidative thermal processes remain unclear. Thus, this paper presents a detailed investigation on the oxidative thermal decomposition mechanism of BDE-209 by utilizing density functional theory methods at the M06/cc-pVDZ theoretical level. The results show that the barrierless fission of the ether linkage dominates the initial degradation of BDE-209 at all temperatures, with branching ratio over 80%. The decomposition of BDE-209 in oxidative thermal processes is mainly along BDE-209 → pentabromophenyl and pentabromophenoxy radicals → pentabromocyclopentadienyl radicals → brominated aliphatic products. Additionally, the study results on the formation mechanisms of several hazardous pollutants indicate that the ortho-phenyl-type radicals created by ortho-C-Br bond fission (branching ratio reached 15.1% at 1600 K) can easily be converted into octabrominated dibenzo-p-dioxin and furan, which require overcoming the energy barriers of 99.0 and 48.2 kJ/mol, respectively. The O/ortho-C coupling of two pentabromophenoxy radicals also acts as a non-negligible pathway for the formation of octabrominated dibenzo-p-dioxin. The synthesis of octabromonaphthalene involves the self-condensation of pentabromocyclopentadienyl radicals, followed by an intricately intramolecular evolution. Results presented in this study can enhance our understanding of the transformation mechanism of BDE-209 in thermal processes, and offer an insight into controlling the emissions of hazardous pollutants.

Investigation on the formation mechanism of main products from TBBPA pyrolysis using DFT method.

The formation mechanisms of the main pyrolysis products of tetrabromobisphenol A (TBBPA) such as hydrogen bromide (HBr), bisphenol A compounds, and phenolic compounds were studied through using density functional theory (DFT) method at the theoretical level of B3P86/6-311 + G (d,p), and the effects of H and Br radicals on the formation mechanism of each product were analyzed. For the formation of each pyrolysis product, this paper presented various possible reaction pathways and acquired their thermodynamic parameters. Calculation results show that HBr can be produce. d continuously during the pyrolysis of TBBPA, and combination and abstraction reactions are the main ways for the generation of HBr. Br radical can abstract H atom from the phenolic hydroxyl groups of TBBPA to produce HBr, and this reaction is barrierless. When H radicals are involved in the initial reaction, the significance of the keto-enol tautomerism is negligible at all debrominations. The Br atom abstraction by H radical is the optimal pattern for debromination. TBBPA can be transformed into low-brominated bisphenol A through consecutive hydrodebromination reactions with trivial activation energies of 8.7-9.5 kJ/mol. The demethylation reaction is an initiation reaction for monomolecular pyrolysis of TBBPA and low-brominated bisphenol A, which is beneficial to the formation of phenolic compounds. During the pyrolysis of TBBPA, para-position Br atom of polybrominated phenol is easier to be removed and the energy barriers of rate-determining steps of the optimal reaction paths for the formation of 2,4,6-tribromophenol, 2,6-dibromophenol, 2,4-dibromophenol, 2-bromophenol, 4-bromophenol and phenol are 108.8, 7.6, 8.7, 8.1, 9.5, and 8.7 kJ/mol, respectively.

Disseminated cryptococcal infection with pulmonary involvement presenting as diffuse cavitary nodules in an immunocompromised patient: a case report.

BACKGROUND: Disseminated cryptococcal infection is especially prone to occur in immunosuppressed hosts. We herein report the case of an immunosuppressed girl with disseminated cryptococcal infection in whom pulmonary cryptococcosis (PC) presented as diffuse cavitary pulmonary nodules, a finding which has rarely been reported. CASE PRESENTATION: A 16-year-old immunocompromised girl presented with fever and a non-productive cough. A chest computed tomography (CT) scan revealed diffuse pulmonary nodules with cavities. Subsequent results were consistent with disseminated cryptococcosis with Cryptococcus identified in her blood, bone marrow and cerebrospinal fluid cultures. Thus, the patient was diagnosed with disseminated cryptococcal infection with PC, cryptococcus meningitis, cryptococcus osteomyelitis and cryptococcus sepsis. After antifungal treatment, the patient demonstrated both clinical and chest radiological improvement. CONCLUSION: The atypical clinical manifestations of a disseminated cryptococcal infection and the rare manner of chest CT findings of PC reported in our case are easy to misdiagnose. It is necessary to carry out a thorough search for a definitive diagnosis using various methods.

Theoretical study on pyrolysis mechanism of decabromodiphenyl ether (BDE-209) using DFT method.

Decabromodiphenyl ether (BDE-209), as a brominated flame retardant (BFR), is widely applied to various consumer products due to its superior performance and affordable pricing to improve the flame resistance of materials. To better comprehend the pyrolysis behavior of BDE-209 and the evolution process of main pyrolysis products, the thermal degradation mechanism of BDE-209 was studied using density functional theory (DFT) method at the theoretical level of M06/cc-pVDZ, and thermodynamic parameters were calculated in this paper. Unimolecular degradation was dominated by cleavage of the ether linkage, which results in a high yield of hexabromobenzene, and fission of the ortho-position C-Br bond is the main competitive reaction channel. In the system of BDE-209 + H, the pyrolysis reaction is majorly characterized by debromination, leading to the formation of considerable HBr and low-brominated diphenyl ethers. Additionally, the hydrogen-derived splitting of the ether bond acts as a mainly competitive channel, which is the source of polybromophenols and polybromobenzenes. The formation of polybrominated dibenzofuran (PBDF) derives from the cyclization reaction of ortho-phenyl-type radicals, which are readily generated through the ortho-position Br atom abstraction by H radical. The formation of polybrominated dibenzo-p-dioxin (PBDD) involves the ortho-C-O coupling reaction of polybromophenoxy radicals, debromination reaction, and cyclization reaction. And the total yield of PBDD/Fs was significantly increased when H was involved. Results presented in this work will provide the helpful information for the treatment and reuse of BDE-209-containing waste plastics through using pyrolysis technology.

Clitoria ternatea blue petal extract protects against obesity, oxidative stress, and inflammation induced by a high-fat, high-fructose diet in C57BL/6 mice.

This study examined the chemical compounds and bioactivity of the aqueous extract of Clitoria ternatea blue petals and investigated its beneficial effects in vivo on a mouse model of obesity and metabolic syndrome. The extract mainly contained flavonoids, and nine compounds were tentatively identified. Male C57BL/6J mice were either fed a standard diet (SD) or a high-fat, high-fructose diet (HFFD) for 16 weeks, and HFFD-fed animals were treated with 0.25%, 0.5%, and 2% (w/w) of the aqueous extract in drinking water. The aqueous extract ameliorated oxidative stress and inflammation mediators. Furthermore, the aqueous extract reduced plasma leptin, free fatty acid, low-density lipoprotein cholesterol levels and hepatic malondialdehyde content. The aqueous extract significantly reduced total cholesterol and ameliorated insulin resistance. The results demonstrated that the aqueous extract of C. ternatea blue petals contains bioactive anthocyanins that exert substantial hypolipidemic and anti-inflammatory effects by promoting reverse cholesterol transport in HFFD-fed mice.

Pulmonary Co-infection with Cryptococcus Species and Pneumocystis jirovecii in an Old Patient Without a Previous Predisposing Illness.

BACKGROUND: Cryptococcosis and pneumocystosis are opportunistic infections which are more common in immunosuppressed individuals. Herein, we report a rare case of coinfection of pulmonary cryptococcosis (PC) and Pneumocystis jirovecii pneumonia (PJP) in a patient without a previous predisposing illness. Case presentation A 76-year-old man was admitted to our hospital with complaints of cough, expectoration, shortness of breath, and fever. A chest computed tomography (CT) showed multiple nodules with diffuse ground-glass opacities (GGOs) in both lungs. The patient was diagnosed as extrinsic allergic alveolitis (Pigeon breeder's lung). After treatment with corticosteroids, the patient improved with significant absorption of GGOs on chest CT. However, pulmonary nodules gradually enlarged and such lesions could not be explained by EAA. Based on the positivity of serum cryptococcal antigen and pathological examination of lung nodule which confirmed the presence of Cryptococcus spores, PC was diagnosed later and fluconazole was administered. However, repeated chest CT performed about 2 months after antifungal treatment showed significantly increased GGOs in both lungs. The pathological examination of new lung lesions revealed the presence of P. jirovecii. The patient was finally diagnosed having coinfection of PC and PJP and sulfamethoxazole was further prescribed. Thereafter, the patient improved again with significant absorption of GGOs as noted on chest CT. CONCLUSIONS: Concomitant PC and PJP is very rare, especially in a patient without a previous predisposing illness. Additionally, when pulmonary lesions cannot be completely explained by one kind of infectious disease, the possibility of mixed infection should be considered.

Convalescent plasma therapy for patients with severe COVID-19: A case series study.

Coronavirus disease 2019 (COVID-19) is a novel acute respiratory infectious disease that can lead to multiple-organ dysfunction in patients with severe disease. However, there is a lack of effective antiviral drugs for COVID-19. Herein, we investigated the efficacy and safety of convalescent plasma (CP) therapy for treating severe COVID-19 in an attempt to explore new therapeutic methods. The clinical data of 3 imported patients with severe COVID-19 who underwent treatment with CP and who were quarantined and treated in a designated COVID-19 hospital from March 2020 to April 2020 were collected and analyzed. The 3 patients, including a 57-year-old male, 65-year-old female, and 59-year-old female, were clinically classified as having severe COVID-19. The main underlying diseases included hypertension, diabetes, sequelae of cerebral infarction, and postoperative thyroid adenoma. The common symptoms included cough, fever, and shortness of breath. All patients received antiviral drugs and other supportive treatments. Additionally, CP treatment was administered. At 48 to 72 hours after the CP transfusion, all 3 of the patients exhibited an improvement and alleviation of symptoms, an elevated arterial oxygen saturation, and decreased C-reactive protein and interleukin-6 levels. The counts of the total lymphocytes and T lymphocytes (CD3+) and their subsets (CD4 + and CD8+) were also obviously increased. Repeated chest computed tomography also revealed obvious absorption of the lesions in the bilateral lungs. Only 1 patient had a mild allergic reaction during the CP infusion, but no severe adverse reactions were observed. The early treatment with CP in patients with severe COVID-19 can rapidly improve the condition of the patients, and CP therapy is generally effective and safe.

Effects of Keemun and Dianhong Black Tea in Alleviating Excess Lipid Accumulation in the Liver of Obese Mice: A Comparative Study.

The chemical compositions of black teas differ greatly and may have different health benefits; however, systematic investigations into such benefits are lacking. Here, the chemical profiles of Keemun black tea (KBT) and Dianhong black tea (DBT), two common categories of tea in China, were analyzed, and their lipid-lowering effects in male C57BL/6 mice fed a high-fat diet (60% energy from fat) or the diet supplemented with 2% black tea powder for 15 weeks were investigated. The compounds most crucial in differentiating KBT and DBT were determined to be phenolic compounds, theanine, and D-psicose. DBT was more effective than KBT in preventing excess hepatic fat accumulation. Both black teas effectively and comparably altered the mRNA levels of hepatic lipid-metabolizing genes. DBT had more favorable effects in stimulating fecal fat excretion than did KBT. The differentiating compounds with the higher values of variable importance in the projection (VIP) might predominantly contribute to the different health benefits; however, the most essential compound or combination of compounds requires clarification.

Insights into the thermal degradation mechanisms of polyethylene terephthalate dimer using DFT method.

The thermal degradation mechanisms of polyethylene terephthalate (PET) dimer were studied by the B3P86 density functional theory (DFT) approach at 6-31++G (d, p) base set in this paper. Seven possible reaction paths were designed and analyzed, and the thermodynamic parameters for all reactions were computed. The calculated results indicate that the bond dissociation energy values (BDEs) of C-C bonds on the main-chain are the smallest, followed by those of C-O bonds. The kinetics analysis indicates that the concerted reactions are obviously liable to occur rather than radical reactions in the initial thermal decomposition process. In the processes of initial reactions, all concerted reactions occurred by six-membered cyclic transition states (TSs) are more prone to carry out than those happened by four-membered cyclic transition states. The research results show that the primary products of PET dimer pyrolysis are terephthalic acid, vinyl terephthalate, CH3CHO and divinyl terephthalate. CH3CHO is mainly formed by a concerted reaction in the initial degradation process, and CO2 is mainly produced by the decarboxylation via a concerted reaction and CO is mainly produced by the decarbonylation of a radical in secondary degradation.

Prolonged SARS-Cov-2 shedding with rapid IgG antibody decay in a COVID-19 patient: A case report.

BACKGROUND: The coronavirus disease 2019 (COVID-19) epidemic is still spreading rapidly around the world. Recent cases with prolonged severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA detection have been successively reported, and the phenomenon of false-negative real-time polymerase chain reaction (RT-PCR) results of SARS-CoV-2 RNA or "repositive" was also described in COVID-19 patients. METHODS: We report a 69-year-old female patient with hypertension, suspected lung tumor, and previous history of total hysterectomy for hysteromyoma who presented with moderate COVID-19 symptoms and was positive for SARS-CoV-2 RNA by RT-PCR when she traveled from the USA to China. RESULTS: The patient required second and third re-hospitalizations due to "repositive" SARS-CoV-2 throat swab test results during post-charge solitary isolation and observation, and serum SARS-CoV-2-IgG decayed rapidly before disappearing on illness Day 139 when the throat swab was still positive. The virus shedding lasted for at least 146 days (the last positive throat swab test result was on illness Day 146, and the first true-negative test result was on illness Day 151) since her initial positive test. CONCLUSION: Prolonged SARS-CoV-2 RNA viral shedding is prone to occur in an immunocompromised host, wherein changes in the host immune status can lead to repeated positive SARS-CoV-2 detection. Moreover, the SARS-CoV-2-IgG may decrease rapidly and disappear before virus removal, indicating there may be certain limitations on the protective effect of the SARS-CoV-2 antibody, which deserves clinical attention.

Green Tea Suppresses Amyloid ß Levels and Alleviates Cognitive Impairment by Inhibiting APP Cleavage and Preventing Neurotoxicity in 5XFAD Mice.

SCOPE: The consumption of green tea is considered to be associated with a lower incidence of neurodegenerative diseases. In the present study, it is investigated the role of amyloid precursor protein cleavage, glial cell activation, neuroinflammation, and synaptic alterations in the protective effects of green tea against the amyloid ß (Aß) accumulation and cognitive impairment. METHODS AND RESULTS: 5XFAD mice are treated with green tea extract (GTE) for 8 or 16 weeks. Barnes maze and Y maze testing demonstrated that spatial learning and memory ability are markedly improved by GTE treatment. Immunofluorescence staining, ELISA, and western blot showed GTE significantly alleviate the formation of Aß and reduce the levels of sAPPß and C99, as well as sAPPα and C83. Meanwhile, GTE suppressed GFAP and Iba1 levels in the glial cells, increased PSD95 and synaptophysin levels in synaptic cells. Further, the IL-1ß level is decreased, RNA sequencing reveals the genes annotated in response to stimulus and immune response are regulated. CONCLUSION: Our findings indicate GTE suppresses Aß levels and alleviate cognitive impairment in 5XFAD mice. These beneficial effects are accompanied by inhibition of APP cleavage pathways, suppression of glial cell activation and pro-inflammatory responses, and a reduction of synapse loss.

DFT studies on pyrolysis mechanisms of tetrabromobisphenol A (TBBPA).

Tetrabromobisphenol A (TBBPA) is the most widely used brominated flame retardant. In order to better understand the decomposition process of TBBPA and clarify the evolution process of the main pyrolysis products, the density functional theory (DFT) method PBE0/6-311G(d) has been used to investigate the pyrolysis mechanisms of TBBPA in this study. Seven possible pyrolysis reaction paths were proposed, and the kinetic parameters in all pyrolysis paths were calculated. The calculation results indicate that in initial degradation of TBBPA without the involvement of hydrogen radical, the demethylation reaction is the main pyrolysis reaction channel, and the keto-enol tautomerization reaction is the main competitive pyrolysis reaction channel. The brominated cyclohexadienone formed through the keto-enol tautomerization is prone to further debromination to generate Br radical. The involvement of hydrogen radical significantly lowers the energy barrier of TBBPA decomposition. When a hydrogen radical is involved in the pyrolysis process, the debromination reaction becomes the major pyrolysis reaction channel, and the homolytic cleavage of Caromatic-C bond becomes the major competitive pyrolysis reaction channel.

Comparison of the clinical characteristics of patients with novel coronavirus pneumonia between China and overseas.

BACKGROUND: To explore the clinical manifestation, imaging examination, and serology of patients with novel coronavirus pneumonia (COVID-19) between China and overseas. METHODS: Ninety patients with COVID-19 who admitted to Fuzhou Pulmonary Hospital from January 23, 2020, to May 1, 2020, were included in this retrospective study. They were divided into domestic group and overseas group according to the origin regions. The clinical manifestations, imaging examination, serology, treatment, and prognosis between the two groups were compared and analyzed. RESULTS: The clinical manifestations of patients in the two groups mainly included fever (83.1% and 47.4%), cough (62% and 31.6%), expectoration (47.9% and 31.6%), anorexia (28.2% and 47.4%), fatigue (21.1% and 10.5%), and dyspnea (22.5% and 0%). The main laboratory characteristics in the two groups were decreased lymphocyte count, increased lactate dehydrogenase, decreased oxygenation index, decreased white blood cell count, increased erythrocyte sedimentation rate (ESR), and increased C-reactive protein. The computed tomography (CT) examinations of chest showed bilateral and peripheral involvement, with multiple patch shadows and ground glass shadows. However, pleural effusions were rare. CONCLUSION: Fever, cough, and dyspnea are more common in domestic cases than overseas cases. However, patients with COVID-19 from overseas may have the symptoms of loss of taste and smell that domestic cases do not have.

Effects of different dietary polyphenols on conformational changes and functional properties of protein-polyphenol covalent complexes.

In this study, conjugates of whey protein isolate (WPI) and four polyphenols (epigallocatechin gallate [EGCG], quercetin [QC], apigenin [AG], and naringenin [NG]) were prepared through free-radical grafting. The results for polyphenol binding equivalents and content of free amino and sulfhydryl groups as well as those from sodium dodecyl sulfate-polyacrylamide gel electrophoresis confirmed the covalent interaction between WPI and the polyphenols. Fourier transform infrared spectroscopy and fluorescence spectrum analysis identified the potential binding sites of the complexes and determined changes in the protein structure. The particle size distribution and scanning electron microscopy data demonstrated increases in conjugate particle sizes and surface changes in the complexes. The conjugation process significantly increased the polyphenols' antioxidant properties and thermal stabilities, whereas surface hydrophobicity was substantially reduced. WPI-EGCG had the best functional properties, followed by WPI-QC, WPI-AG, and WPI-NG.

SARS-CoV-2 suppresses mRNA expression of selenoproteins associated with ferroptosis, endoplasmic reticulum stress and DNA synthesis.

Higher selenium status has been shown to improve the clinical outcome of infections caused by a range of evolutionally diverse viruses, including SARS-CoV-2. However, the impact of SARS-CoV-2 on host-cell selenoproteins remains elusive. The present study investigated the influence of SARS-CoV-2 on expression of selenoprotein mRNAs in Vero cells. SARS-CoV-2 triggered an inflammatory response as evidenced by increased IL-6 expression. Of the 25 selenoproteins, SARS-CoV-2 significantly suppressed mRNA expression of ferroptosis-associated GPX4, DNA synthesis-related TXNRD3 and endoplasmic reticulum-resident SELENOF, SELENOK, SELENOM and SELENOS. Computational analysis has predicted an antisense interaction between SARS-CoV-2 and TXNRD3 mRNA, which is translated with high efficiency in the lung. Here, we confirmed the predicted SARS-CoV-2/TXNRD3 antisense interaction in vitro using DNA oligonucleotides, providing a plausible mechanism for the observed mRNA knockdown. Inhibition of TXNRD decreases DNA synthesis which is thereby likely to increase the ribonucleotide pool for RNA synthesis and, accordingly, RNA virus production. The present findings provide evidence for a direct inhibitory effect of SARS-CoV-2 replication on the expression of a specific set of selenoprotein mRNAs, which merits further investigation in the light of established evidence for correlations between dietary selenium status and the outcome of SARS-CoV-2 infection.

Highly efficient synthesis and characterization of starch aldehyde-catechin conjugate with potent antioxidant activity.

In this study, cassava starch aldehyde was functionalized with catechin through acid catalyzed condensation reaction. The structural characterization, stability and antioxidant activity of starch aldehyde-catechin conjugates were investigated. Thin layer chromatography revealed the conjugates did not contain free catechin. UV-vis spectra of the conjugates exhibited an absorption band at 280 nm, attributing to the B-ring of catechin moiety. Fourier-transform infrared and proton nuclear magnetic resonance spectroscopy demonstrated the conjugation occurred between the H-6/H-8 of catechin A-ring and the aldehyde groups of starch aldehyde. X-ray diffraction pattern indicated that the conjugates had an amorphous structure. Scanning electron microscopy showed the conjugates were fragmentary slices with rough surfaces. Notably, the conjugates were more stable than catechin in phosphate buffered saline (pH 7.4). In addition, the conjugates could not be digested in simulated saliva, gastric and small intestinal juices. The reducing power and free radical scavenging activity of starch aldehyde were remarkably elevated by conjugating with catechin. Meanwhile, the conjugates were non-cytotoxic to RAW264.7 mouse macrophage cells and possessed higher resistant starch contents than starch. Our results suggest starch aldehyde-catechin conjugates can be used as antioxidants in food industry.