Protocatechuic aldehyde attenuates chondrocyte senescence via the regulation of PTEN-induced kinase 1/Parkin-mediated mitochondrial autophagy.

This study aimed to investigate whether the beneficial effects of PCA on chondrocyte senescence are mediated through the regulation of mitophagy. Chondrocyte senescence plays a significant role in the development and progression of knee osteoarthritis (OA). The compound protocatechuic aldehyde (PCA), which is abundant in the roots of Salvia miltiorrhiza, has been reported to have antioxidant properties and the ability to protect against cellular senescence. To achieve this goal, a destabilization of the medial meniscus (DMM)-induced mouse OA model and a lipopolysaccharide (LPS)-induced chondrocyte senescence model were used, in combination with PINK1 gene knockdown or overexpression. After treatment with PCA, cellular senescence was assessed using Senescence-Associated ß-Galactosidase (SA-ß-Gal) staining, DNA damage was evaluated using Hosphorylation of the Ser-139 (γH2AX) staining, reactive oxygen species (ROS) levels were measured using Dichlorodihydrofluorescein diacetate (DCFH-DA) staining, mitochondrial membrane potential was determined using a 5,5',6,6'-TETRACHLORO-1,1',3,3'-*. TETRAETHYBENZIMIDA (JC-1) kit, and mitochondrial autophagy was examined using Mitophagy staining. Western blot analysis was also performed to detect changes in senescence-related proteins, PINK1/Parkin pathway proteins, and mitophagy-related proteins. Our results demonstrated that PCA effectively reduced chondrocyte senescence, increased the mitochondrial membrane potential, facilitated mitochondrial autophagy, and upregulated the PINK1/Parkin pathway. Furthermore, silencing PINK1 weakened the protective effects of PCA, whereas PINK1 overexpression enhanced the effects of PCA on LPS-induced chondrocytes. PCA attenuates chondrocyte senescence by regulating PINK1/Parkin-mediated mitochondrial autophagy, ultimately reducing cartilage degeneration.

6-Gingerol modulates miRNAs and PODXL gene expression via methyltransferase enzymes in NB4 cells: an in silico and in vitro study.

This investigation delves into the influence of predicted microRNAs on DNA methyltransferases (DNMTs) and the PODXL gene within the NB4 cell line, aiming to elucidate their roles in the pathogenesis of acute myeloid leukemia (AML). A comprehensive methodological framework was adopted to explore the therapeutic implications of 6-gingerol on DNMTs. This encompassed a suite of bioinformatics tools for protein structure prediction, docking, molecular dynamics, and ADMET profiling, alongside empirical assessments of miRNA and PODXL expression levels. Such a multifaceted strategy facilitated an in-depth understanding of 6-gingerol's potential efficacy in DNMT modulation. The findings indicate a nuanced interplay where 6-gingerol administration modulated miRNA expression levels, decreasing in DNMT1 and DNMT3A expression in NB4 cells. This alteration indirectly influenced PODXL expression, contributing to the manifestation of oncogenic phenotypes. The overexpression of DNMT1 and DNMT3A in NB4 cells may contribute to AML, which appears modulable via microRNAs such as miR-193a and miR-200c. Post-treatment with 6-gingerol, DNMT1 and DNMT3A expression alterations were observed, culminating in the upregulation of miR-193a and miR-200c. This cascade effect led to the dysregulation of tumor suppressor genes in cancer cells, including downregulation of PODXL, and the emergence of cancerous traits. These insights underscore the therapeutic promise of 6-gingerol in targeting DNMTs and microRNAs within the AML context.

Biodegradation characteristics of p-Chloroaniline and the mechanism of co-metabolism with aniline by Pseudomonas sp. CA-1.

Co-metabolism is a promising method to optimize the biodegradation of p-Chloroaniline (PCA). In this study, Pseudomonas sp. CA-1 could reduce 76.57 % of PCA (pH = 8, 70 mg/L), and 20 mg/L aniline as the co-substrate improved the degradation efficiency by 12.50 %. Further, the response and co-metabolism mechanism of CA-1 to PCA were elucidated. The results revealed that PCA caused deformation and damage on the surface of CA-1, and the -OH belonging to polysaccharides and proteins offered adsorption sites for the contact between CA-1 and PCA. Subsequently, PCA entered the cell through transporters and was degraded by various oxidoreductases accompanied by deamination, hydroxylation, and ring-cleavage reactions. Thus, the key metabolite 4-chlorocatechol was identified and two PCA degradation pathways were proposed. Besides, aniline further enhanced the antioxidant capacity of CA-1, stimulated the expression of catechol 2,3-dioxygenase and promoted meta-cleavage efficiency of PCA. The findings provide new insights into the treatment of PCA-aniline co-pollution.

[Mechanism study of 6-shogaol alleviating cerebral ischemia/reperfusion injury by regulating microRNA-26a-5p/death-associated protein kinase 1].

OBJECTIVE: To investigate whether 6-shogaol (6-SH) alleviates oxygen-glucose deprivation/reoxygenation (OGD/R)-induced neuronal autophagy and calcium overload by promoting the expression of microRNA-26a-5p (miR-26a-5p) and inhibiting death-associated protein kinase 1 (DAPK1), and to explore its potential mechanisms. METHODS: Primary cultured logarithmic growth phase mouse hippocampal neurons HT22 cells were taken and cell counting kit-8 (CCK-8) was used to detect cell viability, searching for the optimal concentration of Na2S2O4. HT22 cells were divided into blank control group (NC group), OGD/R group (sugar-free culture medium + 10 mmol/L Na2S2O4 treatment for 1.5 hours followed by normal culture medium for 4 hours), 6-SH intervention group (cultured with 10 µmol/L 6-SH for 4 hours after OGD), negative control inhibitor pretreatment group (transfected with negative control inhibitor for 48 hours followed by OGD, then cultured with 6-SH for 4 hours), and miR-26a-5p inhibitor pretreatment group (transfected with miR-26a-5p inhibitor for 48 hours followed by OGD, then cultured with 6-SH for 4 hours). Cell viability of each group was detected by CCK-8 method; cell ultrastructure was observed under transmission electron microscopy; real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the gene expressions of DAPK1 and miR-26a-5p; molecular docking were used to verify the interaction between 6-SH and miR-26a-5p; dual-luciferase assay was used to verify the targeting relationship between DAPK1 and miR-26a-5p; flow cytometry was used to determine the levels of intracellular Ca2+; Western blotting was used to detect the protein expressions of phosphorylated-glutamate receptor 2B (p-NMDAR2B) Ser1303, DAPK1, autophagy related protein Beclin1, light chain 3 (LC3), and p-DAPK1 Ser308; immunofluorescence was used to detect the expression of LC3 and Beclin1. RESULTS: The results of the CCK-8 assay showed that the cell viability of the 6-SH intervention group was significantly increased compared to the OGD/R group, while the cell viability of the miR-26a-5p inhibitor pretreatment group was significantly decreased compared to the 6-SH intervention group. Transmission electron microscopy revealed that the number of autophagosomes in the 6-SH intervention group was significantly reduced compared to the OGD/R group, while the number of autophagosomes in the miR-26a-5p inhibitor pretreatment group was significantly increased compared to the 6-SH intervention group. RT-qPCR results showed that compared with the OGD/R group, the expression of miR-26a-5p was significantly upregulated and the expression of DAPK1 mRNA was significantly downregulated in the 6-SH intervention group; compared with the 6-SH intervention group, the expression of miR-26a-5p was significantly downregulated and the expression of DAPK1 mRNA was significantly upregulated in the miR-26a-5p inhibitor pretreatment group. Molecular docking verified the interaction between 6-SH and miR-26a-5p. Dual-luciferase reporter gene assay showed that compared with the negative control group, mmu-miR-26a-5p significantly downregulated the luciferase expression of m-DAPK1-3UTR-WT, indicating a binding interaction between them. Flow cytometry results showed that compared with the OGD/R group, the level of intracellular Ca2+; was significantly decreased in the 6-SH intervention group; compared with the 6-SH intervention group, the level of Ca2+ was significantly increased in the miR-26a-5p inhibitor pretreatment group. Western blotting results showed that compared with the OGD/R group, the protein expressions of p-NMDAR2B Ser1303, DAPK1, Beclin1, and LC3 were significantly decreased in the 6-SH intervention group (p-NMDAR2B Ser1303/ß-actin: 2.34±0.27 vs. 4.78±0.39, DAPK1/ß-actin: 1.40±0.13 vs. 2.37±0.21, Beclin1/ß-actin: 2.61±0.32 vs. 4.32±0.29, LC3/ß-actin: 2.52±0.45 vs. 5.09±0.18, all P < 0.05), while the protein expression of p-DAPK1 Ser308 was significantly increased (p-DAPK1 Ser308/ß-actin: 0.66±0.09 vs. 0.40±0.02, P < 0.05); compared with the 6-SH intervention group, the protein expressions of p-NMDAR2B Ser1303, DAPK1, Beclin1, and LC3 were significantly increased in the miR-26a-5p inhibitor pretreatment group (p-NMDAR2B Ser1303/ß-actin: 4.08±0.14 vs. 2.34±0.27, DAPK1/ß-actin: 1.96±0.15 vs. 1.40±0.13, Beclin1/ß-actin: 3.92±0.31 vs. 2.61±0.32, LC3/ß-actin: 4.33±0.33 vs. 2.52±0.45, all P < 0.05), while the expression of p-DAPK1 Ser308 protein was significantly decreased (p-DAPK1 Ser308/ß-actin: 0.33±0.12 vs. 0.66±0.09, P < 0.05); immunofluorescence staining showed that compared with the OGD/R group, the fluorescence intensity of LC3 and Beclin1 was significantly decreased in the 6-SH intervention group; compared with the 6-SH intervention group, the fluorescence intensity of LC3 and Beclin1 was significantly increased in the miR-26a-5p inhibitor pretreatment group. CONCLUSIONS: 6-SH can alleviate neuronal damage by regulating miR-26a-5p/DAPK1 to reduce autophagy and calcium overload in cells.

Initial report on the multiple biological and pharmacological properties of hispolon: Exploring stochastic mechanisms.

The development of natural substances derived from nature poses a significant challenge as technologies for the extraction and characterization of active principles advance. Hispolon has received a lot of attention in recent years, ascribable to its wide range of biological activities. It is a phenolic molecule that was extracted from several mushroom species such as Phellinus igniarius, Phellinus linteus, Phellinus lonicerinus, Phellinus merrillii, and Inonotus hispidus. To provide a comprehensive overview of the pharmacological activities of hispolon, this review highlights its anticancer, anti-inflammatory, antioxidant, antibacterial, and anti-diabetic activities. Several scientific research databases, including Google Scholar, Web of Science, PubMed, SciFinder, SpringerLink, Science Direct, Scopus, and, Wiley Online were used to gather the data on hispolon until May 2024. The in vitro and in vivo studies have revealed that hispolon exhibited significant anticancer properties through modifying several signaling pathways including cell apoptosis, cycle arrest, autophagy, and inhibition of angiogenesis and metastasis. Hispolon's antimicrobial activity was proven against many bacterial, fungal, and viral pathogens, highlighting its potential use as a novel antimicrobial agent. Additionally, hispolon displayed potent anti-inflammatory activity through the suppression of key inflammatory mediators, such as inducible NO synthase (iNOS), tumor necrosis factor-α (TNF-α), and cyclooxygenases-2 (COX-2), and the modulation of mitogen-activated protein kinases (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways. The antioxidant potential of hispolon was attributed to its capacity to neutralize reactive oxygen species (ROS) and to increase the activity of antioxidant enzymes, indicating a possible involvement in the prevention of oxidative stress-related illnesses. Hispolon's antidiabetic activity was associated with the inhibition of aldose reductase and α-glucosidase. Studies on hispolon emphasized its potential use as a promising scaffold for the development of novel therapeutic agents targeting various diseases, including cancer, infectious diseases, inflammatory disorders, and diabetes.

Moment analysis method for determination of rate constants of solute permeation across interface of spherical molecular aggregates by means of high-performance liquid chromatography.

A moment analysis method was developed for the study of solute permeation at the interface of spherical molecular aggregates. At first, new moment equations were developed for determining the partition equilibrium constant (Kp) and permeation rate constants (kin and kout) of solutes from the first absolute (µ1A) and second central (µ2C) moments of elution peaks measured by using high-performance liquid chromatography (HPLC). Then, the method was applied to the analysis of mass transfer phenomena of three solutes, i.e., hydroquinone, resorcinol, and catechol, at the interface of sodium dodecylsulfate (SDS) micelles. HPLC data were measured by using an ODS column and an aqueous phosphate buffer solution (pH = 7.0) as the mobile phase solvent. Pulse response experiments were conducted while changing SDS concentration (5 - 20 mmol dm-3) in the mobile phase under the conditions that the surface of ODS stationary phase was dynamically coated by SDS monomers. In order to demonstrate the effectiveness of the moment analysis method using HPLC, the values of Kp, kin, and kout were determined for the three solutes as 35 - 69, 2.4 × 10-8 - 1.4 × 10-6 m s-1, and 7.0 × 10-10 - 2.1 × 10-8 m s-1, respectively. Their values increase with an increase in the hydrophobicity of the solutes. The method has some advantages for the study of interfacial solute permeation of molecular aggregates. For example, neither immobilization nor chemical modification of both solute molecules and molecular aggregates is required when elution peaks are measured by using HPLC. Interfacial solute permeation takes place in the mobile phase without any chemical reaction or physical action on molecular aggregates. The values of Kp, kin, and kout were analytically determined from those of µ1A and µ2C by using the moment equations. The results of this study must contribute to the dissemination of an opportunity for studying the interfacial solute permeation of molecular aggregates to many researchers because of extremely high versatility of HPLC.

Red-emitting 4-methyl coumarin fused barbituric acid as an electrochemical sensor for catechol detection and probe for latent fingerprints.

Herein, we have reported a red-emitting 4-methyl coumarin fused barbituric acid azo dye (4-MCBA) synthesized by conventional method. Density functional theory (DFT) studies of tautomer compounds were done using (B3LYP) with a basis set of 6-31G(d,p). NLO analysis has shown that tautomer has mean first-order hyperpolarisabilities (ß) value of 1.8188 × 10-30 esu and 1.0470 × 10-30 esu for azo and hydrazone forms, respectively, which is approximately nine and five times greater than the magnitude of urea. 4-MCBA exhibited two absorption peaks in the range of 290-317 and 379-394 nm, and emission spectra were observed at 536 nm. CV study demonstrated that the modified 4-MCBA/MGC electrode exhibited excellent electrochemical sensitivity towards the detection of catechol and the detection limit is 9.39 µM under optimum conditions. The 4-MCBA employed as a fluorescent probe for the visualisation of LFPs on various surfaces exhibited Level-I to level-II LFPs, with low background interference.

Unraveling the mechanisms of benzo[a]pyrene degradation by Pigmentiphaga kullae strain KIT-003 using a multi-omics approach.

Polycyclic aromatic hydrocarbons (PAHs), notably benzo[a]pyrene (BaP), are environmental contaminants with multiple adverse ecological implications. Numerous studies have suggested the use of BaP biodegradation using various bacterial strains to remove BaP from the environment. This study investigates the BaP biodegradation capability of Pigmentiphaga kullae strain KIT-003, isolated from the Nak-dong River (South Korea) under specific environmental conditions. The optimum conditions of biodegradation were found to be pH 7.0, 35°C, and a salinity of 0 %. GC-MS analysis suggested alternative pathways by which KIT-003 produced catechol from BaP through several intermediate metabolites, including 4-formylchrysene-5-carboxylic acid, 5,6-dihydro-5,6-dihydroxychrysene-5-carboxylic acid (isomer: 3,4-dihydro-3,4-dihydroxychrysene-4-carboxylic acid), naphthalene-1,2-dicarboxylic acid, and 2-hydroxy-1-naphthoic acid. Proteomic profiles indicated upregulation of enzymes associated with aromatic compound degradation, such as nahAc and nahB, and of those integral to the tricarboxylic acid cycle, reflecting the strain's adaptability to and degradation of BaP. Lipidomic analysis of KIT-003 demonstrated that BaP exposure induced an accumulation of glycerolipids such as diacylglycerol and triacylglycerol, indicating their crucial role in bacterial adaptation mechanisms under BaP stress. This study provides significant scientific knowledge regarding the intricate mechanisms involved in BaP degradation by microorganisms.

Antimicrobial peptide immobilization on catechol-functionalized PCL/alginate wet-spun fibers to combat surgical site infection.

Surgical site infection (SSI) caused by pathogenic bacteria leads to delayed wound healing and extended hospitalization. Inappropriate uses of antibiotics have caused a surge in SSI and common antibiotics are proving to be ineffective against SSI. Antimicrobial peptides (AMPs) can be a potential solution to prevent SSI because of their broad spectrum of antimicrobial activities. In this study, naturally sourced AMPs were studied along with microfibers, fabricated by a novel wet-spinning method using sodium alginate and polycaprolactone. Afterward, fibers were functionalized by the catechol groups of dopamine immobilizing nucleophilic AMPs on the surface. Conjugation between PCL and alginate resulted in fibers with smooth surfaces improving their mechanical strength via hydrogen bonds. Having an average diameter of 220 µm, the mechanical properties of the fiber complied with USP standards for suture size 3-0. Engineered microfibers were able to hinder the growth of Proteus spp., a pathogenic bacterium for at least 60 hours whereas antibiotic ceftazidime failed. When subjected to a linear incisional wound model study, accelerated healing was observed when the wound was closed using the engineered fiber compared to Vicryl. The microfibers promoted faster re-epithelialization compared to Vicryl proving their higher wound healing capacity.

Long-Term Prevention of Biofilm Formation by Polycatechol-Based Supramolecular Assemblies with Low Molecular Weight Polymers on Surfaces.

Achievement of a stable surface coating with long-term resistance to biofilm formation remains a challenge. Catechol-based polymerization chemistry and surface deposition are used as tools for surface modification of diverse materials. However, the control of surface deposition of the coating, surface coverage, coating properties, and long-term protection against biofilm formation remain to be solved. We report a new approach based on supramolecular assembly to generate long-acting antibiofilm coating. Here, we utilized catechol chemistry in combination with low molecular weight amphiphilic polymers for the generation of such coatings. Screening studies with diverse low molecular weight (LMW) polymers and different catechols are utilized to identify lead compositions, which resulted in a thick coating with high surface coverage, smoothness, and antibiofilm activity. We have identified that small supramolecular assemblies (∼10 nm) formed from a combination of polydopamine and LMW poly(N-vinyl caprolactam) (PVCL) resulted in relatively thick coating (∼300 nm) with excellent surface coverage in comparison to other polymers and catechol combinations. The coating properties, such as thickness (10-300 nm) and surface hydrophilicity (with water contact angle: 20-60°), are readily controlled. The optimal coating composition showed excellent antibiofilm properties with long-term (>28 days) antibiofilm activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) strains. We further utilized the combination of optimal binary coating with silver to generate a coating with sustained release of silver ions, resulting in killing both adhered and planktonic bacteria and preventing long-term surface bacterial colonization. The new coating method utilizing LMW polymers opens a new avenue for the development of a novel class of thick, long-acting antibiofilm coatings.

Renoprotective effect of a novel combination of 6-gingerol and metformin in high-fat diet/streptozotocin-induced diabetic nephropathy in rats via targeting miRNA-146a, miRNA-223, TLR4/TRAF6/NLRP3 inflammasome pathway and HIF-1α.

BACKGROUND: MiRNA-146a and miRNA-223 are key epigenetic regulators of toll-like receptor 4 (TLR4)/tumor necrosis factor-receptor-associated factor 6 (TRAF6)/NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome pathway, which is involved in diabetic nephropathy (DN) pathogenesis. The currently available oral anti-diabetic treatments have been insufficient to halt DN development and progression. Therefore, this work aimed to assess the renoprotective effect of the natural compound 6-gingerol (GR) either alone or in combination with metformin (MET) in high-fat diet/streptozotocin-induced DN in rats. The proposed molecular mechanisms were also investigated. METHODS: Oral gavage of 6-gingerol (100 mg/kg) and metformin (300 mg/kg) were administered to rats daily for eight weeks. MiRNA-146a, miRNA-223, TLR4, TRAF6, nuclear factor-kappa B (NF-κB) (p65), NLRP3, caspase-1, and hypoxia-inducible factor-1 alpha (HIF-1α) mRNA expressions were measured using real-time PCR. ELISA was used to measure TLR4, TRAF6, NLRP3, caspase-1, tumor necrosis factor-alpha (TNF-α), and interleukin-1-beta (IL-1ß) renal tissue levels. Renal tissue histopathology and immunohistochemical examination of fibronectin and NF-κB (p65) were performed. RESULTS: 6-Gingerol treatment significantly reduced kidney tissue damage and fibrosis. 6-Gingerol up-regulated miRNA-146a and miRNA-223 and reduced TLR4, TRAF6, NF-κB (p65), NLRP3, caspase-1, TNF-α, IL-1ß, HIF-1α and fibronectin renal expressions. 6-Gingerol improved lipid profile and renal functions, attenuated renal hypertrophy, increased reduced glutathione, and decreased blood glucose and malondialdehyde levels. 6-Gingerol and metformin combination showed superior renoprotective effects than either alone. CONCLUSION: 6-Gingerol demonstrated a key protective role in DN by induction of miRNA-146a and miRNA-223 expression and inhibition of TLR4/TRAF6/NLRP3 inflammasome signaling. 6-Gingerol, a safe, affordable, and abundant natural compound, holds promise for use as an adjuvant therapy with metformin in diabetic patients to attenuate renal damage and stop the progression of DN.

6-shogaol against 3-Nitropropionic acid-induced Huntington's disease in rodents: Based on molecular docking/targeting pro-inflammatory cytokines/NF-κB-BDNF-Nrf2 pathway.

BACKGROUND: Huntington's disease (HD) is an extremely harmful autosomal inherited neurodegenerative disease. Motor dysfunction, mental disorder, and cognitive deficits are the characteristic features of this disease. The current study examined whether 6-shogaol has a protective effect against 3-Nitropropionic Acid (3-NPA)-induced HD in rats. METHODS: A total of thirty male Wistar rats received 6-shogaol (10 and 20 mg/kg, per oral) an hour before injection of 3-NPA (10 mg/kg i.p.) for 15 days. Behavioral tests were performed, including narrow beam walk, rotarod test, and grip strength test. Biochemical tests promoting oxidative stress were evaluated [superoxide dismutase (SOD), reduced glutathione (GSH), catalase (CAT) and malondialdehyde (MDA)], including changes to neurotransmitters serotonin (5-HT), dopamine (DA), norepinephrine (NE), homovanillic acid (HVA), (3,4-dihydroxyphenylacetic acid (DOPAC), γ-aminobutyric acid (GABA), and 5-hydroxy indole acetic acid (5-HIAA), nuclear factor kappa-B (NF-κB), tumor necrosis factor-α (TNF-α), interleukins-1ß (IL-1ß), IL-6, brain-derived neurotrophic factor (BDNF), and nuclear factor erythroid 2-related factor 2 (Nrf2). The 6-shogaol was docked to the active site of TNF-α (2AZ5), NF-κB (1SVC), BDNF) [1B8M], and Nrf2 [5FZN] proteins using AutoDock tools. RESULTS: The 6-shogaol group significantly improved behavioral activity over the 3-NPA-injected control rats. Moreover, 3-NPA-induced significantly altered neurotransmitters, biochemical and neuroinflammatory indices, which could efficiently be reversed by 6-shogaol. The 6-shogaol showed favorable negative binding energies at -9.271 (BDNF) kcal/mol. CONCLUSIONS: The present investigation demonstrated the neuroprotective effects of 6-shogaol in an experimental animal paradigm against 3-NPA-induced HD in rats. The suggested mechanism is supported by immunohistochemical analysis and western blots, although more research is necessary for definite confirmation.

Inhibition mechanism of different structural polyphenols against α-amylase studied by solid-state NMR and molecular docking.

Polyphenol has the considerable effects for inhibition of digestive enzymes, however, inhibition mechanism of molecular size-dependent polyphenols on enzyme activity is still lacking. Herein, inhibition effect and binding interactions of three different structural polyphenols (catechol, quercetin and hesperidin) on α-amylase were studied. Inhibition assays proved that polyphenols significantly inhibited α-amylase and their effects were increased with their molecular sizes. Hesperidin showed the highest inhibition ability of α-amylase, which was determined as IC50 = 0.43 mg/mL. Fluorescence and FT-IR spectroscopy proved that inter-molecular interactions between polyphenols and α-amylase occurred through non-covalent bonds. Besides, the secondary structure of α-amylase was obviously changed after binding with polyphenols. Inter-molecular interactions were investigated using solid-state NMR and molecular docking. Findings proved that hydrogen bonds and π-π stacking interactions were the mainly inter-molecular interactions. We hope this contribution could provide a theoretical basis for developing some digestive enzyme inhibitors from natural polyphenols.

Tailoring the Molecular Structure of 6-Gingerol for Targeting the Phase Separation in Human Lysozyme.

Human lysozyme undergoes a phase-separation process to form insoluble amyloid-architects that cause several pathologies including systemic amyloidosis. Here we have tailored 6-gingerol by extending its molecular framework with active functional groups to specifically target lysozyme phase-transition events. Aggregation assay revealed that tailored 6-gingerol with 4-aromatic moieties (MTV4) substantially suppressed the conversion of the lysozyme low-density liquid phase (LDLP) to solid-phase structured amyloids. The data obtained from biophysical, computational, and microscopic imaging tools suggest direct intervention of MTV4 with the liquid-liquid phase separation. The CD data suggest that MTV4 was able to retain the native conformation of lysozyme. Both biomolecular and computational data reveal the interference of MTV4 with the aggregation-prone hydrophobic stretches within the lysozyme, thereby retaining the native structure and reversing the misfolded intermediates to active monomers. Also, MTV4 was able to induce rapid dissolution of preformed-toxic amyloid fibrils. These results reinforce the importance of the aromatic-aromatic interaction in preventing human lysozyme phase separation.

Inactivation of polyphenol oxidase by low intensity DC field: Experiment and mechanism analysis via molecular dynamics simulation and molecular docking.

In this study, inactivation of mushroom polyphenol oxidase (PPO) by low intensity direct current (DC) electric field and its molecular mechanism were investigated. In the experiments under 3 V/cm, 5 V/cm, 7 V/cm and 9 V/cm electric fields, PPOs were all completely inactivated after different exposure times. Under 1 V/cm, a residual activity of 11.88 % remained. The inactivation kinetics confirms to Weibull model. Under 1-7 V/cm, n value closes to a constant about 1.3. The structural analysis of PPO under 3 V/cm and 5 V/cm by fluorescence emission spectroscopy and molecular dynamics (MD) simulation showed that the tertiary structure was slightly changed with increased radius of gyration, higher potential energy and rate of C-alpha fluctuation. After exposure to the electric field, most of the hydrophobic tryptophan (TRP) residues turned to the hydrophilic surface, resulting the fluorescence red-shifted and quenched. Molecular docking indicated that the receptor binding domain of catechol in PPO was changed. PPO under electric field was MD simulated the first time, revealing the changing mechanism of the electric field itself on PPO, a binuclear copper enzyme, which has a metallic center. All these suggest that the low intensity DC electric field would be a promising option for enzymatic browning inhibition or even enzyme activity inactivation.

Cigarette butts as a source of phenolic compounds for the environment.

Cigarette butts (CBs) are small residues with mixed composition. Produced in large amounts, their accumulation in the environment has become alarming. It is possible to classify more than 7000 chemical components generated either in the burning process or when distilled from the tobacco. The aim of this work was to describe the rate of release of phenolic compounds from CBs, to determine the content of these compounds in freshly smoked CBs and to monitor the release of phenols from CBs into fresh natural waters. The kinetics of release of selected phenolic compounds (hydroquinone, resorcinol, pyrocatechol, phenol, guaiacol, o-cresol, m-cresol, p-cresol) into water was monitored for 48 h. More than 90% of the content was extracted within 10 h for all analytes. The phenolic content was determined in the CBs of five different brands. The total content of phenols determined for each sample of freshly smoked CB was 215-861 µg/CB. For all CBs analysed, phenol, pyrocatechol and hydroquinone were the most abundant analytes, accounting for up to 75% of the content of all phenols determined. Phenol was the most abundant analyte (64.6-267.8 µg/CB) in all analysed samples. The content of pyrocatechol, the second most abundant analyte, was 45.6-221.2 µg/CB and the third most abundant analyte was hydroquinone (41.71-157.5 µg/CB). Monitoring the release of phenols from CBs into fresh natural waters (river, stream, pond) under steady and slight moving conditions showed that the kinetics of release is not influenced by the type of water. On the contrary, the process of decomposition of the released compounds is influenced by the type of water. The maximum concentrations of individual phenols in CBs extracts were comparable to those determined via laboratory extraction, thus indicating that within 72 h, most of the phenolic compounds are released from CBs into natural water. This research provides missing information on the phenolic content in CBs and the rate of release into water. It thus complements previously published information on CBs as a source of environmental contamination.

[Microorganism Immobilization Device Using Artificial Siderophores].

Inspired by the mechanism by which microorganisms utilize siderophores to ingest iron, four different FeIII complexes of typical artificial siderophore ligands containing catecholate and/or hydroxamate groups, K3[FeIII-LC3], K2[FeIII-LC2H1], K[FeIII-LC1H2], and [FeIII-LH3], were prepared. They were modified on an Au substrate surface (Fe-L/Au) and applied as microorganism immobilization devices for fast, sensitive, selective detection of microorganisms, where H6LC3, H5LC2H1, H4LC1H2, and H3LH3 denote the tri-catecholate, biscatecholate-monohydroxamate, monocatecholate-bishydroxamate, and tri-hydroxamate type of artificial siderophores, respectively. Their adsorption properties for the several microorganisms were investigated using scanning electron microscopy (SEM), quartz crystal microbalance (QCM), and electric impedance spectroscopy (EIS) methods. The artificial siderophore-iron complexes modified on the Au substrates Fe-LC3/Au, Fe-LC2H1/Au, Fe-LC1H2/Au, and Fe-LH3/Au showed specific microorganism immobilization behavior with selectivity based on the structure of the artificial siderophores. Their specificities corresponded well with the structural characteristics of natural siderophores that microorganisms release from the cell and/or use to take up an iron. These findings suggest that release and uptake are achieved through specific interactions between the artificial siderophore-FeIII complexes and receptors on the cell surfaces of microorganisms. This study revealed that Fe-L/Au systems have specific potential to serve as effective immobilization probes of microorganisms for rapid, selective detection and identification of a variety of microorganisms.

Ascorbate peroxidase catalyses synthesis of protocatechualdehyde from p-hydroxybenzaldehyde in Lycoris aurea.

Protocatechualdehyde is a plant natural phenolic aldehyde and an active ingredient with important bioactivities in traditional Chinese medicine. Protocatechualdehyde is also a key intermediate in the synthesis of Amaryllidaceae alkaloids for supplying the C6-C1 skeleton. However, the biosynthesis of protocatechualdehyde in plants remains obscure. In this study, we measured the protocatechualdehyde contents in the root, bulb, scape and flower of the Amaryllidaceae plant Lycoris aurea (L'Hér.) Herb., and performed the correlation analysis between the protocatechualdehyde contents and the transcriptional levels of the phenolic oxidization candidate protein encoding genes. We found that a novel ascorbate peroxidase encoded by the contig_24999 in the L. aurea transcriptome database had potential role in the biosynthesis of protocatechualdehyde. The LauAPX_24999 gene was then cloned from the cDNA of the scape of L. aurea. The transient expression of LauAPX_24999 protein in Arabidopsis protoplasts demonstrated that LauAPX_24999 protein was localized in the cytoplasm, thus belonging to Class II L-ascorbate peroxidase. Subsequently, LauAPX_24999 protein was heterogenously expressed in Escherichia coli, and identified that LauAPX_24999 biosynthesized protocatechualdehyde from p-hydroxybenzaldehyde using L-ascorbic acid as the electron donor. The protein structure modelling and molecular docking indicated that p-hydroxybenzaldehyde could access to the active pocket of LauAPX_24999 protein, and reside at the δ-edge of the heme group while L-ascorbic acid binds at the γ-heme edge. To our knowledge, LauAPX_24999 is the first enzyme discovered in plants able to biosynthesize protocatechualdehyde from p-hydroxybenzaldehyde, and offers a competent enzyme resource for the biosynthesis of Amaryllidaceae alkaloids via synthetic biology.

Catechol compounds as dual-targeting agents for fish protection against Ichthyophthirius multifiliis infections.

Aquaculture is one of the fastest growing sectors in global food production, recognized as a significant contributor to poverty alleviation, food security, and income generation. However, the frequent occurrence of diseases caused by pathogen infections result in reduced yields and economic losses, posing a substantial constraint to the sustainable development of aquaculture. Here, our study identified that four catechol compounds, quercetin, luteolin, caffeic acid, and chlorogenic acid, exhibited potent antiparasitic effects against Ichthyophthirius multifiliis in both, in vitro and in vivo. The parasite is recognized as one of the most pathogenic to fish worldwide. Using a combination of in silico methods, the dipeptidyl peptidase (DPP) was identified as a critical target for catechol compounds. The two hydroxyl radicals of the catechol group were essential for its binding to and interacting with the DPP protein. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses indicated that catechol compounds disrupt pathways associated with the metabolism and growth of I. multifiliis, thereby exerting antiparasitic effects. Furthermore, these compounds attenuated the expression of proinflammatory cytokines in vivo in fish and promoted macrophage polarization toward M2 phenotype by inhibiting the STAT1 signaling pathway. The dual activity of catechol compounds, acting as both direct antiparasitic and anti-inflammatory agents in fish, offers a promising therapeutic approach for combating I. multifiliis infections in aquaculture.

Polydopamine Adhesion: Catechol, Amine, Dihydroxyindole, and Aggregation Dynamics.

While polydopamine (PDA) possesses the surface-independent adhesion property of mussel-binding proteins, significant differences exist between them. Particularly, PDA's short and rigid backbone differs from the long and flexible protein sequence of mussel-binding proteins. Given that adhesion relies on achieving a conformal contact with large surface coverage, PDA has drawbacks as an adhesive. In our study, we investigated the roles of each building block of PDA to build a better understanding of their binding mechanisms. Initially, we anticipated that catecholamine oligomers form specific binding with substrates. However, our study showed that the universal adhesion of PDA is initiated by the solubility limit of growing oligomers by forming agglomerates, complemented by multiple binding modes of catechol. Notably, in the absence of amines, poly(catechol) either remained in solution or formed minor suspensions without any surface coating, underscoring the essential role of amines in the adhesion process by facilitating insoluble aggregate formation. To substantiate our findings, we induced poly(catechol) aggregation using quaternized poly(4-vinylpyridine) (qPVP), leading to subsequent surface adhesion upon agglomerate formation.