N-Acetylserotonin is an oxidation-responsive activator of Nrf2 ameliorating colitis in rats.

N-Acetylserotonin (NAS) is an intermediate in the melatonin biosynthetic pathway. We investigated the anti-inflammatory activity of NAS by focusing on its chemical feature oxidizable to an electrophile. NAS was readily oxidized by reaction with HOCl, an oxidant produced in the inflammatory state. HOCl-reacted NAS (Oxi-NAS), but not NAS, activated the anti-inflammatory nuclear factor erythroid 2-related factor 2 (Nrf2)-heme oxygenase (HO)-1 pathway in cells. Chromatographic and mass analyses demonstrated that Oxi-NAS was the iminoquinone form of NAS and could react with N-acetylcysteine possessing a nucleophilic thiol to form a covalent adduct. Oxi-NAS bound to Kelch-like ECH-associated protein 1, resulting in Nrf2 dissociation. Moreover, rectally administered NAS increased the levels of nuclear Nrf2 and HO-1 proteins in the inflamed colon of rats. Simultaneously, NAS was converted to Oxi-NAS in the inflamed colon. Rectal NAS mitigated colonic damage and inflammation. The anticolitic effects were significantly compromised by the coadministration of an HO-1 inhibitor.

Investigation of the factors responsible for the low oral bioavailability of alizarin using a sensitive LC-MS/MS method: In vitro, in situ, and in vivo evaluations.

Alizarin (1,2-dihydroxyanthraquinone) is an anthraquinone reddish dye widely used for painting and textile dyeing. As the biological activity of alizarin has recently attracted increasing attention from researchers, its therapeutic potential as complementary and alternative medicine is of interest. However, no systematic research has been conducted on the biopharmaceutical and pharmacokinetic aspects of alizarin. Therefore, this study aimed to comprehensively investigate the oral absorption and intestinal/hepatic metabolism of alizarin using a simple and sensitive tandem mass spectrometry method developed and validated in-house. The present method for the bioanalysis of alizarin has merits, including a simple pretreatment procedure, small sample volume, and adequate sensitivity. Alizarin exhibited pH-dependent moderate lipophilicity and low solubility with limited intestinal luminal stability. Based on the in vivo pharmacokinetic data, the hepatic extraction ratio of alizarin was estimated to be 0.165-0.264, classified as a low level of hepatic extraction. In an in situ loop study, considerable fractions (28.2%-56.4%) of the alizarin dose were significantly absorbed in gut segments from the duodenum to ileum, suggesting that alizarin may be classified as the Biopharmaceutical Classification System class II. An in vitro metabolism study using rat and human hepatic S9 fractions revealed that glucuronidation and sulfation, but not NADPH-mediated phase I reactions and methylation, are significantly involved in the hepatic metabolism of alizarin. Taken together, it can be estimated that the fractions of oral alizarin dose unabsorbed from the gut lumen and eliminated by the gut and liver before reaching the systemic circulation are 43.6%-76.7%, 0.474%-36.3%, and 3.77%-5.31% of the dose, respectively, resulting in a low oral bioavailability of 16.8%. Therefore, the oral bioavailability of alizarin depends primarily on its chemical degradation in the gut lumen and secondarily on first-pass metabolism.

Lactobacillus plantarum Metabolites Elicit Anticancer Effects by Inhibiting Autophagy-Related Responses.

Lactobacillus plantarum (L. plantarum) is a probiotic that has emerged as novel therapeutic agents for managing various diseases, such as cancer, atopic dermatitis, inflammatory bowel disease, and infections. In this study, we investigated the potential mechanisms underlying the anticancer effect of the metabolites of L. plantarum. We cultured L. plantarum cells to obtain their metabolites, created several dilutions, and used these solutions to treat human colonic Caco-2 cells. Our results showed a 10% dilution of L. plantarum metabolites decreased cell viability and reduced the expression of autophagy-related proteins. Moreover, we found co-treatment with L. plantarum metabolites and chloroquine, a known autophagy inhibitor, had a synergistic effect on cytotoxicity and downregulation of autophagy-related protein expression. In conclusion, we showed the metabolites from the probiotic, L. plantarum, work synergistically with chloroquine in killing Caco-2 cells and downregulating the expression of autophagy-related proteins, suggesting the involvement of autophagy, rather than apoptosis, in their cytotoxic effect. Hence, this study provides new insights into new therapeutic methods via inhibiting autophagy.

A Colon-Targeted Prodrug of Riluzole Improves Therapeutic Effectiveness and Safety upon Drug Repositioning of Riluzole to an Anti-Colitic Drug.

Riluzole (RLZ) is a neuroprotective drug indicated for amyotrophic lateral sclerosis. To examine the feasibility of RLZ for repositioning as an anti-inflammatory bowel disease (IBD) drug, RLZ (2, 5, and 10 mg/kg) was administered orally to rats with colitis induced by 2,4-dinitrobenzenesulfonic acid. Oral RLZ was effective against rat colitis in a dose-dependent manner, which was statistically significant at doses over 5 mg/kg. To address safety issues upon repositioning and further improve anti-colitic effectiveness, RLZ was coupled with salicylic acid (SA) via an azo-bond to yield RLZ-azo-SA (RAS) for the targeted colonic delivery of RLZ. Upon oral gavage, RAS (oral RAS) was efficiently delivered to and activated to RLZ in the large intestine, and systemic absorption of RLZ was substantially reduced. Oral RAS ameliorated colonic damage and inflammation in rat colitis and was more effective than oral RLZ and sulfasalazine, a current anti-IBD drug. Moreover, oral RAS potently inhibited glycogen synthase kinase 3ß (GSK3ß) in the inflamed distal colon, leading to the suppression of NFκB activity and an increase in the level of the anti-inflammatory cytokine interleukin-10. Taken together, RAS, which enables RLZ to be delivered to and inhibit GSK3ß in the inflamed colon, may facilitate repositioning of RLZ as an anti-IBD drug.

Intrinsic Phase Stability and Inherent Bandgap of Formamidinium Lead Triiodide Perovskite Single Crystals.

Understanding the intrinsic phase stability and inherent band gap of formamidinium lead triiodide (FAPbI3 ) perovskites is crucial to further improve the performance of perovskite solar cells (PSCs). Herein, we explored the α- to δ-phase transition and band gap of FAPbI3 single crystals grown by an inverse temperature solubility method. We found that the residual γ-butyrolactone solvents in the inner empty space of the FAPbI3 single crystal accelerate the phase transition at kinetics. By adopting 2-methoxyethanol as the solvent, over 2000 h of stable α-FAPbI3 crystals could be acquired. This proves that although FAPbI3 is regarded as unstable at thermodynamics, it could own excellent kinetic stability without any doping or additives because of the slow solid to solid phase transition instead of the fast phase transition assisted by the solvents. Furthermore, we revealed that the bulk FAPbI3 single crystal with a size above 100 µm can have an inherent band gap of 1.41 eV. Thus, our work provides key scientific guidance for high-performance FAPbI3 -based PSCs.

Preparation and Evaluation of Colon-Targeted Prodrugs of the Microbial Metabolite 3-Indolepropionic Acid as an Anticolitic Agent.

Microbial metabolites play a critical role in mucosal homeostasis by mediating physiological communication between the host and colonic microbes, whose perturbation may lead to gut inflammation. The microbial metabolite 3-indolepropionic acid (3-IPA) is one such communication mediator with potent antioxidative and anti-inflammatory activity. To apply the metabolite for the treatment of colitis, 3-IPA was coupled with acidic amino acids to yield colon-targeted 3-IPA, 3-IPA-aspartic acid (IPA-AA) and 3-IPA-glutamic acid (IPA-GA). Both conjugates were activated to 3-IPA in the cecal contents, which occurred faster for IPA-AA. Oral gavage of IPA-AA (oral IPA-AA) delivered a millimolar concentration of IPA-AA to the cecum, liberating 3-IPA. In a 2,4-dinitrobenzene sulfonic acid (DNBS)-induced rat colitis model, oral IPA-AA ameliorated rat colitis and was less effective than sulfasalazine (SSZ), a current anti-inflammatory bowel disease drug. To enhance the anticolitic activity of 3-IPA, it was azo-linked with the GPR109 agonist 5-aminonicotinic acid (5-ANA) to yield IPA-azo-ANA, expecting a mutual anticolitic action. IPA-azo-ANA (activated to 5-ANA and 2-amino-3-IPA) exhibited colon specificity in in vitro and in vivo experiments. Oral IPA-azo-ANA mitigated colonic damage and inflammation and was more effective than SSZ. These results suggest that colon-targeted 3-IPA ameliorated rat colitis and its anticolitic activity could be enhanced by codelivery of the GPR109A agonist 5-ANA.

Cerebral angiography using transauricular access in a rabbit model: a new technique.

BACKGROUND: Cerebral angiography in a rabbit model is widely used in the field of interventional radiology. Conventionally, the femoral artery is used for cerebral angiography in radiology departments. However, angiographic studies require surgical cutdown of the femoral artery, which is technically difficult. PURPOSE: To evaluate a new cerebral angiography technique involving a transauricular approach in a rabbit model. MATERIAL AND METHODS: In each of 10 rabbits, central auricular arteries were punctured in the right or left ear with a 20-gauge i.v. catheter. A microcatheter (2.0 F) with a 0.016-inch guide wire was introduced through the i.v. catheter and advanced to the aortic arch. The microcatheter and guide wire were advanced selectively into cerebral arteries and angiography was performed. RESULTS: Central auricular arteries were successfully punctured with 20-gauge i.v. catheters. After approaching the aortic arch, microcatheter tips and guide wires were advanced manually to cerebral arteries on both sides. Difficulties in selecting the carotid arteries were resolved by using a looping technique within the cardiac chamber. Microcatheter loops within the cardiac chamber disappeared or remained during artery superselection. CONCLUSION: Transauricular cerebral angiography appears to be a feasible technique for brain or carotid intervention studies in rabbits. In addition, vertebral angiography using a transauricular approach is possible using the looping technique. Selection of carotid or vertebral arteries on each side was not difficult when the microcatheter and guide wire were looped within the cardiac chamber. The ear chosen for the initial puncture does not appear to be important.

Novel Anti-Melanogenic Compounds, (Z)-5-(Substituted Benzylidene)-4-thioxothiazolidin-2-one Derivatives: In Vitro and In Silico Insights.

To confirm that the ß-phenyl-α,ß-unsaturated thiocarbonyl (PUSTC) scaffold, similar to the ß-phenyl-α,ß-unsaturated carbonyl (PUSC) scaffold, acts as a core inhibitory structure for tyrosinase, twelve (Z)-5-(substituted benzylidene)-4-thioxothiazolidin-2-one ((Z)-BTTZ) derivatives were designed and synthesized. Seven of the twelve derivatives showed stronger inhibitory activity than kojic acid against mushroom tyrosinase. Compound 2b (IC50 = 0.47 ± 0.97 µM) exerted a 141-fold higher inhibitory potency than kojic acid. Kinetic studies' results confirmed that compounds 2b and 2f are competitive tyrosinase inhibitors, which was supported by high binding affinities with the active site of tyrosinase by docking simulation. Docking results using a human tyrosinase homology model indicated that 2b and 2f might potently inhibit human tyrosinase. In vitro assays of 2b and 2f were conducted using B16F10 melanoma cells. Compounds 2b and 2f significantly and concentration-dependently inhibited intracellular melanin contents, and the anti-melanogenic effects of 2b at 10 µM and 2f at 25 µM were considerably greater than the inhibitory effect of kojic acid at 25 µM. Compounds 2b and 2f similarly inhibited cellular tyrosinase activity and melanin contents, indicating that the anti-melanogenic effects of both were due to tyrosinase inhibition. A strong binding affinity with the active site of tyrosinase and potent inhibitions of mushroom tyrosinase, cellular tyrosinase activity, and melanin generation in B16F10 cells indicates the PUSTC scaffold offers an attractive platform for the development of novel tyrosinase inhibitors.

5-Aminosalicylic Acid Azo-Coupled with a GPR109A Agonist Is a Colon-Targeted Anticolitic Codrug with a Reduced Risk of Skin Toxicity.

To develop a 5-aminosalicylic acid (5-ASA)-based anticolitic drug with enhanced therapeutic activity, a colon-targeted codrug constituting 5-ASA and a GPR109A agonist was designed. 5-ASA azo-coupled with nicotinic acid (ASA-azo-NA) was synthesized, and the colon specificity and anticolitic effects were evaluated. Approximately 89% of ASA-azo-NA was converted to 5-aminonicotinic acid (5-ANA) and 5-ASA after 24 h of incubation in the cecal contents. 5-ANA was identified as a GPR109A agonist (concentration that gives half-maximal response (EC50): 18 µM) in a cell-based assay. Upon oral gavage of ASA-azo-NA (oral ASA-azo-NA) and sulfasalazine (oral SSZ), a colon-targeted 5-ASA prodrug, cecal accumulation of 5-ASA was comparable, and 5-ANA was barely detectable in the blood, while it was detected up to 62.7 µM with oral 5-ANA. In parallel, oral ASA-azo-NA did not elicit an adverse skin response. In murine macrophage and human colon carcinoma cells, activation of GPR109A by 5-ANA elevated the level of the anti-inflammatory cytokine IL-10, suppressed NF-κB activation, and potentiated the inhibitory activity of 5-ASA on NF-κB. Oral ASA-azo-NA ameliorated rat colitis and was more effective than oral SSZ, which were substantially blunted following cotreatment with the GPR109A antagonist, mepenzolate. In conclusion, ASA-azo-NA is a colon-targeted anticolitic codrug with a reduced risk of skin toxicity induced by the GPR109A agonist, therapeutically surpassing a current 5-ASA-based anti-inflammatory bowel disease drug in a rat colitis model.

Curcumin Nanocrystal/pH-Responsive Polyelectrolyte Multilayer Core-Shell Nanoparticles for Inflammation-Targeted Alleviation of Ulcerative Colitis.

In this study, we developed oral core-shell nanoparticles composed of curcumin nanocrystals in the core and chitosan/alginate multilayers in the shell for inflammation-targeted alleviation of ulcerative colitis (UC). The release rate of curcumin from the core-shell nanoparticles was low at a pH mimicking the stomach and small intestine, whereas it was higher at a pH mimicking the colon. Further, biodistribution studies in the gastrointestinal tract of mice showed that distribution of nanoparticles was significantly higher in the colon than that in the stomach and small intestine. Quantitative analysis of drugs in colonic tissues and confocal imaging of colons revealed preferential accumulation of nanoparticles in inflamed tissues than that in healthy tissues. In vivo anti-inflammatory studies revealed that nanoparticles exhibit enhanced efficacy in alleviating inflammation-related symptoms in a mouse colitis model. The results suggest that the core-shell nanoparticles presented here can be exploited as efficient colon-targeted drug delivery systems for UC therapy.

Stabilizing Coacervate by Microfluidic Engulfment Induced by Controlled Interfacial Energy.

Low interfacial energy, an intrinsic property of complex coacervate, enables the complex coacervate to easily encapsulate desired cargo substances, making it widely used in encapsulation applications. Despite this advantage, the low interfacial energy of the complex coacervate makes it unstable against mechanical mixing, and changes in pH and salt concentration. Hence, a chemical cross-linker is usually added to enhance the stability of the complex coacervate at the expense of sacrificing all intrinsic properties of the coacervate, including phase transition of the coacervate from liquid to solid. In this study, we observed an abrupt increase in the interfacial energy of the coacervate phase in mineral oil. By controlling the interfacial energy of the coacervate phase using a microfluidic device, we successfully created double engulfed PEG-diacrylate (PEGDA) coacervate microparticles, named DEPOT, in which the coacervate is engulfed in a cross-linked PEGDA shell. The engulfed coacervate remained as a liquid phase, retained its original low interfacial energy property to encapsulate the desired cargo substances, and infiltrated into the target site by a simple solvent exchange from oil to water.

Colon-Targeted Delivery Facilitates the Therapeutic Switching of Sofalcone, a Gastroprotective Agent, to an Anticolitic Drug via Nrf2 Activation.

We investigated if the therapeutic switching of sofalcone (SFC), a gastroprotective agent, to an anticolitic agent is feasible using colon-targeted drug delivery. SFC can activate the anti-inflammatory nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-hemeoxygenase-1 (HO-1) pathway in human colon epithelial cells and murine macrophages. For the efficient treatment of colitis, SFC was coupled with acidic amino acids to yield SFC-aspartic acid (SFC-AA) and SFC-glutamic acid, and their colon targetability and therapeutic effects were assessed as an anticolitic agent in a 2,4-dinitrobenezenesulfonic acid-induced rat colitis model. The SFC derivatives were decoupled up to 72% in the cecal contents but remained stable in the small intestinal contents. Oral gavage of SFC-AA (oral SFC-AA, equivalent to 1.67 mg/kg of SFC) delivered SFC (maximal cecal concentration: 57.36 µM) to the cecum, while no SFC was detected with oral gavage of SFC (oral SFC, 1.67 mg/kg). Moreover, oral SFC-AA (equivalent to 10 mg/kg of SFC) did not afford detectable concentration of SFC in the blood but detected up to 4.64 µM with oral SFC (10 mg/kg), indicating efficient colonic delivery and limited systemic absorption of SFC upon oral SFC-AA. Oral SFC-AA ameliorated colonic damage and inflammation in rat colitis with elevating colonic levels of HO-1 and nuclear Nrf2 protein, and the anticolitic effects of SFC-AA were significantly undermined by an HO-1 inhibitor. At an equivalent dose of SFC, oral SFC-AA but not oral SFC increased colonic HO-1 and nuclear Nrf2 levels, and oral SFC-AA was more effective than oral SFC in treating rat colitis. Moreover, oral SFC-AA was as effective against colitis as oral sulfasalazine being used for the treatment of inflammatory bowel disease. In conclusion, colon-targeted delivery of SFC facilitated the therapeutic switching of the drug to an anticolitic drug via Nrf2 activation.

pH-triggered surface charge-reversal nanoparticles alleviate experimental murine colitis via selective accumulation in inflamed colon regions.

In this study, we developed pH-triggered surface charge-reversal lipid nanoparticles (LNPs), loaded with budesonide, which could precisely deliver the drug to inflamed colon segments for the treatment of ulcerative colitis. Polyethyleneimine (PEI) was used to render LNPs cationic (PEI-LNPs), and Eudragit® S100 (ES) was coated on PEI-LNPs to obtain pH-triggered charge-reversal LNPs (ES-PEI-LNPs). ES coating avoided a burst drug release under acidic conditions mimicking the stomach and early small intestine environments and showed a sustained release in the colon. The surface charge of ES-PEI-LNPs switched from negative to positive under colonic conditions owing to pH-triggered removal of the ES coating. Bioimaging of the mouse gastrointestinal tract and confocal analysis of colon tissues revealed that ES-PEI-LNPs selectively accumulated in an inflamed colon. Furthermore, ES-PEI-LNPs mitigated experimental colitis in mice. These results suggest that the pH-triggered charge-reversal LNPs could be a promising drug carrier for ulcerative colitis therapy and other colon-targeted treatments.

The In Vitro and In Vivo Anti-Inflammatory Effects of a Phthalimide PPAR-γ Agonist.

Previously, the authors found that 4-hydroxy-2-(4-hydroxyphenethyl) isoindoline-1,3-dione (PD1) (a phthalimide analogue) bound to and activated peroxisome proliferator-activated receptor-γ (PPAR-γ). Since PPAR-γ suppresses inflammatory responses, the present study was undertaken to investigate the anti-inflammatory effects of PD1. In lipopolysaccharide (LPS)-stimulated murine RAW264.7 macrophages, PD1 suppressed the inductions of pro-inflammatory factors, including inducible nitric oxide synthase (iNOS), nitric oxide (NO), cyclooxygenase 2 (COX-2), tumor necrosis factor α (TNF-α), interleukin-1ß (IL-1ß), and interleukin-6 (IL-6). Concomitantly, PD1 enhanced the expressions of anti-inflammatory factors, such as arginase-1 and interleukin-10 (IL-10), and suppressed LPS-evoked nuclear factor kappa B (NF-κB) p65 subunit phosphorylation in macrophages. In addition, PPAR-γ activated by PD1 was intensively translocated to the nucleus. These observations suggest that the anti-inflammatory mechanism of PD1 involves inhibition of the NF-κB pathway. In a subsequent in vivo animal experiment conducted using a carrageenan-induced acute inflammatory rat paw edema model, intraperitoneal injection of PD1 significantly reduced paw swelling. Histological analysis of rat paw tissue sections revealed less infiltration of immune cells in PD1-pretreated animals. These findings suggest that PD1 be viewed as a lead compound for the development of novel anti-inflammatory therapeutics.

Minoxidil Induction of VEGF Is Mediated by Inhibition of HIF-Prolyl Hydroxylase.

The topical application of minoxidil may achieve millimolar concentrations in the skin. We investigated whether millimolar minoxidil could induce vascular endothelial growth factor (VEGF), a possible effector for minoxidil-mediated hair growth, and how it occurred at the molecular level. Cell-based experiments were performed to investigate a molecular mechanism underlying the millimolar minoxidil induction of VEGF. The inhibitory effect of minoxidil on hypoxia-inducible factor (HIF) prolyl hydroxylase-2 (PHD-2) was tested by an in vitro von Hippel-Lindau protein (VHL) binding assay. To examine the angiogenic potential of millimolar minoxidil, a chorioallantoic membrane (CAM) assay was used. In human keratinocytes and dermal papilla cells, millimolar minoxidil increased the secretion of VEGF, which was not attenuated by a specific adenosine receptor antagonist that inhibits the micromolar minoxidil induction of VEGF. Millimolar minoxidil induced hypoxia-inducible factor-1α (HIF-1α), and the induction of VEGF was dependent on HIF-1. Moreover, minoxidil applied to the dorsal area of mice increased HIF-1α and VEGF in the skin. In an in vitro VHL binding assay, minoxidil directly inhibited PHD-2, thus preventing the hydroxylation of cellular HIF-1α and VHL-dependent proteasome degradation and resulting in the stabilization of HIF-1α protein. Minoxidil inhibition of PHD-2 was reversed by ascorbate, a cofactor of PHD-2, and the minoxidil induction of cellular HIF-1α was abrogated by the cofactor. Millimolar minoxidil promoted angiogenesis in the CAM assay, an in vivo angiogenic test, and this was nullified by the specific inhibition of VEGF. Our data demonstrate that PHD may be the molecular target for millimolar minoxidil-mediated VEGF induction via HIF-1.

Particle shape enhances specificity of antibody-displaying nanoparticles.

Monoclonal antibodies are used in numerous therapeutic and diagnostic applications; however, their efficacy is contingent on specificity and avidity. Here, we show that presentation of antibodies on the surface of nonspherical particles enhances antibody specificity as well as avidity toward their targets. Using spherical, rod-, and disk-shaped polystyrene nano- and microparticles and trastuzumab as the targeting antibody, we studied specific and nonspecific uptake in three breast cancer cell lines: BT-474, SK-BR-3, and MDA-MB-231. Rods exhibited higher specific uptake and lower nonspecific uptake in all cells compared with spheres. This surprising interplay between particle shape and antibodies originates from the unique role of shape in determining binding and unbinding of particles to cell surface. In addition to exhibiting higher binding and internalization, trastuzumab-coated rods also exhibited greater inhibition of BT-474 breast cancer cell growth in vitro to a level that could not be attained by soluble forms of the antibody. The effect of trastuzumab-coated rods on cells was enhanced further by replacing polystyrene particles with pure chemotherapeutic drug nanoparticles of comparable dimensions made from camptothecin. Trastuzumab-coated camptothecin nanoparticles inhibited cell growth at a dose 1,000-fold lower than that required for comparable inhibition of growth using soluble trastuzumab and 10-fold lower than that using BSA-coated camptothecin. These results open unique opportunities for particulate forms of antibodies in therapeutics and diagnostics.

(E)-2-Cyano-3-(substituted phenyl)acrylamide analogs as potent inhibitors of tyrosinase: A linear ß-phenyl-α,ß-unsaturated carbonyl scaffold.

In this study, we synthesized (E)-2-cyano-3-(substituted phenyl)acrylamide (CPA) derivatives which possess a linear ß-phenyl-α,ß-unsaturated carbonyl scaffold and examined their inhibitory activities against tyrosinase. CPA analogs exerted inhibitory activity against mushroom tyrosinase. Results from the docking simulation indicated that CPA2 could bind directly to the active site of mushroom tyrosinase and the binding affinity of CPA2 for tyrosinase might be higher than that of kojic acid, a well-known potent tyrosinase inhibitor. In B16F10 cells, CPA2 significantly suppressed tyrosinase activity and melanogenesis in a dose-dependent manner. At the concentration of 25µM, CPA2 exhibited tyrosinase inhibitory activity comparable to that of kojic acid with no cytotoxic effect. Results from the present study suggest that CPA2 bearing a linear ß-phenyl-α,ß-unsaturated carbonyl scaffold may be the potential candidate for treatment of diseases associated with hyperpigmentation and that a linear ß-phenyl-α,ß-unsaturated carbonyl scaffold might be closely related to potent tyrosinase inhibition.

Periplasmic disulfide isomerase DsbC is involved in the reduction of copper binding protein CueP from Salmonella enterica serovar Typhimurium.

Salmonella enterica serovar Typhimurium (S. Typhimurium) is a facultative intracellular pathogen with the ability to survive and replicate in macrophages. Periplasmic copper binding protein CueP is known to confer copper resistance to S. Typhimurium, and has been implicated in ROS scavenge activity by transferring the copper ion to a periplasmic superoxide dismutase or by directly reducing the copper ion. Structural and biochemical studies on CueP showed that its copper binding site is surrounded by conserved cysteine residues. Here, we present evidence that periplasmic disulfide isomerase DsbC plays a key role in maintaining CueP protein in the reduced state. We observed purified DsbC protein efficiently reduced the oxidized form of CueP, and that it acted on two (Cys104 and Cys172) of the three conserved cysteine residues. Furthermore, we found that a surface-exposed conserved phenylalanine residue in CueP was important for this process, which suggests that DsbC specifically recognizes the residue of CueP. An experiment using an Escherichia coli system confirmed the critical role played by DsbC in the ROS scavenge activity of CueP. Taken together, we propose a molecular insight into how CueP collaborates with the periplasmic disulfide reduction system in the pathogenesis of the bacteria.

Development of Clindamycin-Releasing Polyvinyl Alcohol Hydrogel with Self-Healing Property for the Effective Treatment of Biofilm-Infected Wounds.

Self-healing hydrogels have good mechanical strength, can endure greater external force, and have the ability to heal independently, resulting in a strong bond between the wound and the material. Bacterial biofilm infections are life-threatening. Clindamycin (Cly) can be produced in the form of a self-healing hydrogel preparation. It is noteworthy that the antibacterial self-healing hydrogels show great promise as a wound dressing for bacterial biofilm infection. In this study, we developed a polyvinyl alcohol/borax (PVA/B) self-healing hydrogel wound dressing that releases Cly. Four ratios of PVA, B, and Cly were used to make self-healing hydrogels: F1 (4%:0.8%:1%), F2 (4%:1.2%:1%), F3 (1.6%:1%), and F4 (4%:1.6%:0). The results showed that F4 had the best physicochemical properties, including a self-healing duration of 11.81 ± 0.34 min, swelling ratio of 85.99 ± 0.12%, pH value of 7.63 ± 0.32, and drug loading of 98.34 ± 11.47%. The B-O-C cross-linking between PVA and borax caused self-healing, according to FTIR spectra. The F4 formula had a more equal pore structure in the SEM image. The PVA/B-Cly self-healing hydrogel remained stable at 6 ± 2 °C for 28 days throughout the stability test. The Korsmeyer-Peppas model released Cly by Fickian diffusion. In biofilm-infected mouse wounds, PVA/B-Cly enhanced wound healing and re-epithelialization. Our results indicate that the PVA/B-Cly produced in this work has reliable physicochemical properties for biofilm-infected wound therapy.

The Formulation and Characterization of Wound Dressing Releasing S-Nitrosoglutathione from Polyvinyl Alcohol/Borax Reinforced Carboxymethyl Chitosan Self-Healing Hydrogel.

Self-healing hydrogels often lack mechanical properties, limiting their wound-dressing applications. This study introduced S-Nitrosoglutathione (GSNO) to self-healing hydrogel-based wound dressings. Self-healing hydrogel mechanical properties were improved via polymer blends. Applying this hydrogel to the wound site allows it to self-heal and reattach after mechanical damage. This work evaluated polyvinyl alcohol (PVA)-based self-healing hydrogels with borax as a crosslinking agent and carboxymethyl chitosan as a mechanical property enhancer. Three formulations (F1, F4, and F7) developed self-healing hydrogels. These formulations had borax concentrations of 0.8%, 1.2%, and 1.6%. An FTIR study shows that borate ester crosslinking and hydrogen bonding between polymers generate a self-healing hydrogel. F4 has a highly uniform and regular pore structure, as shown by the scanning electron microscope image. F1 exhibited faster self-healing, taking 13.95 ± 1.45 min compared to other formulations. All preparations had pH values close to neutrality, making them suitable wound dressings. Formula F7 has a high drug content (97.34 ± 1.21%). Good mechanical qualities included high tensile stress-strain intensity and Young's modulus. After 28 h of storage at -20 °C, 5 °C, and 25 °C, the self-healing hydrogel's drug content dropped significantly. The Korsmeyer-Peppas release model showed that the release profile of GSNO followed Fickian diffusion. Thus, varying the concentration of crosslinking agent and adding a polymer affects self-healing hydrogels' physicochemical properties.