Search Results (68)

Sortase A (SrtA) enzymes covalently anchor surface proteins to Gram-positive bacterial cell walls, promoting colonization and virulence. In Streptococcus pneumoniae, previous studies identified both a domain-swapped dimer and an active refolded monomer, but the active enzyme has not been characterized at the structural and residue-specific level. Here, we performed quantitative proteomic comparisons of wild-type and SrtA knockout strains that confirmed the loss of multiple LPxTG-containing virulence factors, including ZmpB, NanA, and IgA1 protease, consistent with an essential role for SrtA in surface protein anchoring. To enable mechanistic studies, we established a biochemical framework to produce monomeric Streptococcus pneumoniae SrtA by refolding and developed a gel-based assay using recombinant substrates to monitor catalytic activity. The refolded monomer, but not the swapped dimer, catalyzed cleavage and transpeptidation of a canonical LPxTG substrate in a metal-independent manner under the conditions examined. We further report high-resolution NMR backbone assignments for the active monomer and identify substrate-induced chemical shift perturbations that localize to the active site. Together, these findings provide an integrated proteomic, biochemical, and NMR characterization of monomeric, catalytically active Streptococcus pneumoniae SrtA and reveal residue-specific interactions with a canonical LPNTG recognition peptide. Full article

Conventional strategies to enhance the hydrophobicity of polyurethane (PU) coatings typically rely on fragile micro/nanostructures or irradiation-induced crosslinking, both of which suffer from poor controllability and often compromise mechanical robustness. Herein, we report a UV-triggered crosslinking strategy based on coumarin chemistry that enables precise, controllable network formation, thereby simultaneously enhancing the hydrophobicity, adhesion strength, and thermal stability of polydimethylsiloxane (PDMS)-based PU coatings. A series of coumarin-functionalized PDMS-PU coatings (HNP-PDMS-PUx) was prepared by blending coumarin-grafted PDMS (HNP) with PDMS-PU elastomers. Upon 365 nm UV irradiation, the coumarin moieties dimerize, forming a dense, chemically crosslinked “brush-like” structure on the coating surface. The optimal coating (HNP-PDMS-PU_3/1) exhibited a significant increase in water contact angle from 108° to 129° on average, reaching a maximum of 134°. The UV-treated coating also showed enhanced adhesion strength (a 45% increase) and improved thermal stability, while maintaining good flexibility (F7 rating) and abrasion resistance (contact angle remained at 126° after 30 cycles). Moreover, the coating demonstrated excellent easy-cleaning performance against both liquid and solid contaminants. This work provides a photochemical strategy that replaces uncontrollable or irreversible crosslinking methods with a controllable UV-triggered approach, enabling synergistic enhancement of multiple properties. Full article

Oxidative stress induced by excessive hydrogen peroxide (H₂O₂) is a critical pathological factor in skin aging, inflammatory disorders, and photodamage. While tocopherol (TCP) is a gold-standard antioxidant in cosmetics, its potential in H₂O₂-responsive systems remains underexplored. In this study, we report the design and characterization of ditocopheryl peroxalate (TOT), a novel tocopherol dimer linked via a H₂O₂-cleavable peroxalate linkage. TOT remains chemically stable under physiological conditions but undergoes selective chemiluminescence-like degradation upon exposure to H₂O₂, simultaneously scavenging H₂O₂ and liberating two TCP molecules. Notably, TOT demonstrated superior H₂O₂-scavenging efficiency and enhanced antioxidant and anti-inflammatory effects in H₂O₂-stimulated cells compared to monomeric TCP, while maintaining excellent biocompatibility. Structural analysis revealed that the rigid, linear configuration of TOT facilitates seamless integration into dipalmitoylphosphatidylcholine (DPPC) bilayers, yielding highly stable H₂O₂-responsive liposomes. These findings highlight TOT as a sophisticated multifunctional antioxidant platform for advanced cosmeceutical applications targeting photo-induced oxidative damage. Full article

Background/Objectives: Boron-dipyrromethene (BODIPY) derivatives are a superior class of fluorophores prized for their exceptional photostability and tunable photophysical properties. While ideal for imaging, their translation to photodynamic therapy (PDT) has been hampered by excitation in the visible range, leading to poor tissue penetration. To overcome this, intense research has focused on developing near-infrared (NIR)-absorbing BODIPY photosensitizers (PS). This review aims to systematically summarize the hierarchical design strategies, from molecular engineering to advanced nanoplatform construction, that underpin the recent progress of NIR-BODIPY PS in therapeutic applications. Methods: We conducted a comprehensive literature review using PubMed, Scopus, and Web of Science databases. The search focused on keywords such as “BODIPY”, “aza-BODIPY”, “near-infrared”, “photodynamic therapy”, “photothermal therapy”, “nanocarriers”, “hypoxia”, “immuno-phototherapy”, and “antibacterial.” This review analyzes key studies describing molecular design, chemical modification strategies (e.g., heavy-atom effect, π-extension), nanoplatform formulation, and therapeutic applications in vitro and in vivo. Results: Our analysis reveals a clear progression in design complexity. At the molecular level, we summarize strategies to enhance selectivity, including active targeting, designing “smart” PS responsive to the tumor microenvironment (TME) (e.g., hypoxia or low pH), and precise subcellular localization (e.g., mitochondria, lysosomes). We then detail the core chemical strategies for achieving NIR absorption and high singlet oxygen yield, including π-extension, the internal heavy-atom effect, and heavy-atom-free mechanisms (e.g., dimerization). The main body of the review categorizes the evolution of advanced theranostic nanoplatforms, including targeted systems, stimuli-responsive ‘smart’ systems, photo-immunotherapy (PIT) platforms inducing immunogenic cell death (ICD), hypoxia-overcoming systems, and synergistic chemo-phototherapy carriers. Finally, we highlight emerging applications beyond oncology, focusing on the use of NIR-BODIPY PS for antibacterial therapy and biofilm eradication. Conclusions: NIR-BODIPY photosensitizers are a highly versatile and powerful class of theranostic agents. The field is rapidly moving from simple molecules to sophisticated, multifunctional nanoplatforms designed to overcome key clinical hurdles like hypoxia, poor selectivity, and drug resistance. While challenges in scalability and clinical translation remain, the rational design strategies and expanding applications, including in infectious diseases, confirm that NIR-BODIPY derivatives will be foundational to the next generation of precision photomedicine. Full article

Background/Objectives: This study focused on synthesizing novel alkenyl derivatives of azinylferrocenes and evaluating their potential as Alzheimer’s disease (AD) therapeutics. Methods: 1-Azinyl-1′-acetylferrocenes were obtained by regioselective acetylation of azinylferrocenes, followed by the Wittig reaction or reduction of 1-azinyl-1′-acetylferrocenes and subsequent dehydration of the resulting alcohols. The synthesized compounds underwent the following biological activity testing relevant to AD: inhibition of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and off-target carboxylesterase (CES); antioxidant capacity (ABTS and FRAP assays); inhibition of Aβ₄₂ self-aggregation (thioflavin method); blocking AChE-induced β-amyloid aggregation (propidium displacement); and cytotoxicity in SH-SY5Y and MSC-Neu cells (MTT assay). Results: Quinoline and bipyridine derivatives demonstrated effective cholinesterase inhibition, especially quinoline 7b (AChE IC₅₀ 3.32 μM; BChE IC₅₀ 3.68 μM), while acridine derivatives were poor inhibitors. Quantum chemical (QC) calculations predicted that acridine derivatives were especially prone to form stable dimers. Molecular docking into protein targets generated by an AlphaFold3 reproduction code showed that these dimers were too bulky to access enzyme active sites, yet they could bind to protein surfaces to inhibit Aβ₄₂ self-aggregation and displace propidium from the AChE peripheral anionic site. All compounds showed high antioxidant activity in ABTS and FRAP assays, with quinoline derivatives being 2–4 times more potent than Trolox. QC calculations supported these findings. Quinoline and bipyridine derivatives also exhibited low cytotoxicity and scant CES inhibition. Conclusions: Overall, the synthesized ferrocenes, particularly the quinoline and bipyridine derivatives, appear promising for further research as multifunctional therapeutic agents targeting AD due to their anticholinesterase, antiaggregating, and antioxidant activities combined with low toxicity. Full article

As a driver of neurodegenerative disorders, ischemic injuries, and acute organ dysfunction, ferroptosis represents a therapeutic target, and its inhibition may provide novel therapies. In our ongoing efforts to discover ferroptosis inhibitors from fungal strains, chemical investigation of the strain Diaporthe searlei CS-HF-1 led to the isolation of four polyketide-derived alkaloids (1–3 and 17) and fourteen polyketides (4–16 and 18), including three new isoindolone derivatives (1–3), a new phthalide (4), a new butyrolactone derivative (10), and three new nonenolides (11–13). The structures were determined by comprehensive spectroscopic analysis. The structures of 1, 2, and 10 were confirmed by comparison of experimental and calculated ¹³C NMR chemical shifts. The absolute configurations of compounds 10, 11, and 14 were assigned by ECD calculations, while those of 12 and 13 were assigned based on their biogenetic relationship with 14. Notably, compound 1 represents the first isoindolone featuring a primary amide group attached to the lactam nitrogen, while compound 2 is the first naturally occurring isoindolone dimer. These compounds were assessed for the anti-ferroptotic activity. As a result, asperlactone A (15) exhibited inhibition on RSL3-induced ferroptosis in HT22 cells with an EC₅₀ of 11.3 ± 0.4 μM. Preliminary mechanistic study revealed that 15 attenuated lipid peroxidation, as evidenced by reduced MDA levels, elevated GSH content, and suppression of lipid radical generation. This study offers a new chemotype for the development of novel ferroptosis inhibitors. Full article

Background/Objectives: Human Herpes Simplex Virus 1 (HSV-1) is a common pathogen that establishes lifelong latent infections. The emergence of drug resistance necessitates novel therapeutic strategies. This study introduces a novel antiviral approach: a bivalent degrader designed to induce the degradation of an essential protein. Methods: A structural model of ICP0, generated via the Chai-1 AI platform, was analyzed with fpocket, P2Rank, and KVFinder to identify a superior allosteric target site. An iterative de novo design workflow with CReM-dock then yielded a lead scaffold based on its predicted affinity and drug-like properties. This selected “warhead” was used to rationally design the final bivalent degrader, ICP0-deg-01, for the ICP0 dimer model. Results: The generative process yielded a lead chemical scaffold that was selected based on its predicted binding affinity and favorable drug-like properties. This scaffold was used to rationally design a single candidate bivalent degrader, ICP0-deg-01. Our structural model predicts that ICP0-deg-01 can successfully bridge two ICP0 protomers, forming an energetically favorable ternary complex. Conclusions: This work provides a computational proof-of-concept for a novel class of anti-herpetic agents and identifies a lead candidate for future molecular dynamics simulations and experimental validation. Full article

Bacterial chemoreceptors sense extracellular stimuli and drive bacteria toward a beneficial environment or away from harm. Their ligand-binding domains (LBDs) are highly diverse in terms of sequence and structure, and their ligands cover various chemical molecules that could serve as nitrogen, carbon, and energy sources. The mechanism of how this diverse range of LBDs senses different ligands is essential to signal transduction. Previously, we reported that the chemoreceptor MCP2201 from Comamonas testosteroni CNB-1 sensed citrate and L-malate, altered the ligand-free monomer–dimer equilibrium of LBD to citrate-bound monomer (with limited monomer) and L-malate-bound dimer, and triggered positive and negative chemotactic responses. Here, we present our findings, showing that D-malate binds to MCP2201, induces LBD dimerization, and triggers the chemorepellent response exactly as L-malate did. A single site mutation, T105A, can alter the D-malate-bound LBD dimer into a monomer–dimer equilibrium and switch the negative chemotactic response to D-malate to a positive one. Differences in attractant-bound LBD oligomerization, such as citrate-bound wildtype LBD monomer and D-malate-bound T105A dimer, indicated that LBD oligomerization is a consequence of signal transduction instead of a trigger. Our study expands our knowledge of chemoreceptor-sensing ligands and provides insight into the evolution of bacterial chemoreceptors. Full article

Using the framework of an investigation of the stimuli-responsive behavior of peptide assembly on a solid surface, this study on the behavior of a chemisorbed peptide on a gold surface was performed. The studied peptide is a dimeric form of the antimicrobial peptide Trichogin GAIV, which was also modified by substituting the glycine with lysine residues, while the N-terminus octanoyl group was replaced by a lipoic one that was able to bind to the gold surface. In this way, a chemically linked peptide assembly that is pH-responsive was obtained because of the protonation/deprotonation of the sidechains of the Lys residues. Information about the effect of protonation/deprotonation equilibria switching the pH from acid (pH = 3) to basic (pH = 11) conditions was obtained macroscopically by performing Quartz crystal microbalance with dissipation monitoring (QCM-D), Surface Plasmon Resonance (SPR), Nanoplasmonic Sensing (NPS), and FTIR techniques. Using molecular dynamics (MD) simulations, it is possible to explain, at the molecular level, our main experimental results: (1) pH changes induce a squeezing behavior in the system, consisting in thickness and mass variations in the peptide layer, which are mainly due to the pH-driven hydrophilic/hydrophobic character of the lysine residues, and (2) the observed hysteresis is due to small conformational rearrangements from helix to beta sheets occurring mainly on the first half of the peptide, closer to the surface, while the second half remains almost unaffected. The latter result, together with the evidence that the layer thickness is not simply double the assembly of the monomeric analog, indicates that the dimeric peptide does not behave as a double monomer, but assumes very peculiar features. Full article

The herb Curculigo capitulata (Lour.) Ktze is widely distributed in southern and southwestern China. The Curculigo genus and its primary chemical constituents exhibit remarkable antidepressant activities. To investigate the chemical constituents and potential health benefits of C. capitulata, a phytochemical study was conducted. In this study, seven new compounds (capitugenin A–G), including three new norlignans (1–3), a new chalcone dimer (4), a new hemiacetal (5), two novel pyrrolidine-based compounds (6 and 7), including one identified as a natural product (7), and nineteen known compounds (8–26), were isolated from C. capitulata. The chemical structures and absolute configurations of Compounds 1–7 were elucidated via comprehensive spectroscopic data analyses. The neuroprotective effects of Compounds 1–26 against glutamate-induced cell death were tested in the human neuroblastoma cell line SH-SY5Y. Compounds 1, 3, 6, 8, 11, and 17 showed significant neuroprotective effects, with protection rates ranging from 29.4 to 52.8% at concentrations ranging from 5 to 40 μM. Western blot analysis indicated that Compound 3 exerted a protective effect by regulating the expression of Nrf2/HO-1. Full article

Plants belonging to the genus Maytenus are members of the Celastraceae family. They have been widely used by different peoples as treatment for curing many diseases. The aim of this study was to explore the anti-inflammatory and antioxidant properties of Maytenus elaeodendroides stem bark extracts, an endemic Cuban plant. The antioxidant activity of four extracts (EtOH, EtOAc, n-BuOH, and diethyl ether/petroleum ether 1:1) was determined using DPPH and FRAP methods. Meanwhile, anti-inflammatory effects by the edema method were induced by croton oil in the mouse ear. The investigated extracts showed radical reduction capacity and prevented ear inflammation at doses of 4 mg/ear. In addition, FIA/ESI/IT/MSⁿ was used to determine the qualitative chemical composition of the EtOAc extract and allowed the identification of five flavan-3-ol monomers, four dimers, and other proanthocyanidin oligomers. From this extract three flavan-3-ol compounds (elaeocyanidin and 4′-O-methylgallocatechin), one of them new (2′-hydroxy-4′-methoxy-epigallocatechin), and a proanthocyanidin dimer (afzelechin-($4\mathsf{\beta }\text{→}8$)-4′-O-methylepigallocatechin) were isolated and identified by the chromatographic method and spectroscopic techniques, mainly ESI-MS and NMR spectroscopic methods. Full article

The primary aim of this research was to identify the structural characteristics of three newly derived procyanidins from cold plasma-treated (–)-epicatechin, known for their anti-inflammatory properties. The newly generated compounds were isolated through column chromatography, and their chemical structures were elucidated through spectroscopic data analyses, including both one-dimensional and two-dimensional nuclear magnetic resonance (NMR) and mass spectrometry (MS) techniques. Furthermore, their absolute configurations were determined via circular dichroism (CD) spectroscopy. The inhibitory activity of the isolated compounds on nitric oxide (NO) production and expression levels of inducible NO synthase (iNOS) in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages was evaluated. Three new procyanidins—methylenetrisepicatechin (2), isomethylenetrisepicatechin (3), and methylenebisepicatechin (4)—along with two reported dimeric flavan-3-ols (5 and 6), were identified from plasma-treated (–)-epicatechin (1). The unique oligomerized products 2 and 3 linked by methylene bridges significantly suppressed both NO production and iNOS expression, demonstrating higher anti-inflammatory activities in LPS-stimulated RAW 264.7 cells compared with the parent compound. The newly oligomerized procyanidins have potential applications in the treatment of inflammatory diseases owing to their significant anti-inflammatory properties. Full article

Hemozoin (Hz) is a heme crystal produced during malaria infection that stimulates immune cells, leading to the production of cytokines and chemokines. The immunostimulatory action of Hz has previously been applied in the development of alternative adjuvants. Crystallization of hemin is a chemical approach for producing Hz. Here, we focused on an enzymatic production method for Hz using the heme detoxification protein (HDP), which catalyzes heme dimer formation from hemin in Plasmodium. We examined the immunostimulatory effects of an enzymatically synthesized analog of Hz (esHz) produced by recombinant Plasmodium falciparum HDP. Enzymatically synthesized Hz stimulates a macrophage cell line and human peripheral mononuclear cells, leading to the production of interleukin (IL)-6 and IL-12p40. In mice, subcutaneous administration of esHz together with an antigen, ovalbumin (OVA), increased the OVA-specific immunoglobulin (Ig) G2c isotype level in the serum, whereas OVA-specific IgG1 was not induced. Our findings suggest that esHz is a useful Th-1 cell adjuvant. Full article

Over the past few decades, dengue fever has emerged as a significant global health threat, affecting tropical and moderate climate regions. Current vaccines have practical limitations, there is a strong need for safer, more effective options. This study introduces novel vaccine candidates covering all four dengue virus (DENV) serotypes using virus-like particles (VLPs), a proven vaccine platform. The dengue virus envelope protein domain III (EDIII), the primary target of DENV-neutralizing antibodies, was either genetically fused or chemically coupled to bacteriophage-derived AP205-VLPs. To facilitate the incorporation of the large EDIII domain, AP205 monomers were dimerized, resulting in sterically optimized VLPs with 90 N- and C-termini. These vaccines induced high-affinity/avidity antibody titers in mice, and confirmed their protective potential by neutralizing different DENV serotypes in vitro. Administration of a tetravalent vaccine induced high neutralizing titers against all four serotypes without producing enhancing antibodies, at least not against DENV2. In conclusion, the vaccine candidates, especially when administered in a combined fashion, exhibit intriguing properties for potential use in the field, and exploring the possibility of conducting a preclinical challenge model to verify protection would be a logical next step. Full article

Overwhelming evidence points to an aberrant Wnt/β-catenin signaling as a critical factor in hepatocellular carcinoma (HCC) and cervical cancer (CC) pathogenesis. Dicerandrol C (DD-9), a dimeric tetrahydroxanthenone isolated from the endophytic fungus Phomopsis asparagi DHS-48 obtained from mangrove plant Rhizophora mangle via chemical epigenetic manipulation of the culture, has demonstrated effective anti-tumor properties, with an obscure action mechanism. The objective of the current study was to explore the efficacy of DD-9 on HepG2 and HeLa cancer cells and its functional mechanism amid the Wnt/β catenin signaling cascade. Isolation of DD-9 was carried out using various column chromatographic methods, and its structure was elucidated with 1D NMR. The cytotoxicity of DD-9 on HepG2 and HeLa cells was observed with respect to the proliferation, clonality, migration, invasion, apoptosis, cell cycle, and Wnt/β-catenin signaling cascade. We found that DD-9 treatment significantly reduced tumor cell proliferation in dose- and time-dependent manners in HepG2 and HeLa cells. The subsequent experiments in vitro implied that DD-63 could significantly suppress the tumor clonality, metastases, and induced apoptosis, and that it arrested the cell cycle at the G₀/G₁ phase of HepG2 and HeLa cells. Dual luciferase assay, Western blot, and immunofluorescence assay showed that DD-9 could dose-dependently attenuate the Wnt/β-catenin signaling by inhibiting β-catenin transcriptional activity and abrogating β-catenin translocated to the nucleus; down-regulating the transcription level of β-catenin-stimulated Wnt target gene and the expression of related proteins including p-GSK3-β, β-catenin, LEF1, Axin1, c-Myc, and CyclinD1; and up-regulating GSK3-β expression, which indicates that DD-9 stabilized the β-catenin degradation complex, thereby inducing β-catenin degradation and inactivation of the Wnt/β-catenin pathway. The possible interaction between DD-9 and β-catenin and GSK3-β protein was further confirmed by molecular docking studies. Collectively, DD-9 may suppress proliferation and induce apoptosis of liver and cervical cancer cells, possibly at least in part via GSK3-β-mediated crosstalk with the Wnt/β-catenin signaling axis, providing insights into the mechanism for the potency of DD-9 on hepatocellular and cervical cancer. Full article