Search Results (5,994)

The Jurubatiba Sandbank National Park (PARNA Jurubatiba) is an ecological reserve characterized by harsh environmental conditions, including low rainfall, high sun exposure, and sandy soil. Among its native vegetation, Eremanthus crotonoides stands out for its richness in flavonoids, phenolic compounds, and sesquiterpene lactones. The objective of this study was to isolate and quantify sesquiterpene lactones from this species using ¹H NMR and to investigate their anti-SARS-CoV-2 potential and cytotoxicity against cancer cells. UPLC-(ESI)-MS/MS analyses enabled metabolite annotation, and semi-preparative HPLC-DAD allowed the isolation of centratherin and goyazensolide, which were identified by 1D and 2D NMR. In vitro assays showed that centratherin at 10 µM concentration reduced the viability of PC-3 and HCT-116 cancer cells by 100%, while goyazensolide had no noteworthy effects. Furthermore, enzymatic inhibition assays on SARS-CoV2 targets revealed that centratherin exhibited a lower apparent IC₅₀ of 12 µM against PL^pro, while goyazensolide was more active against 3CL^pro, with an IC₅₀ of 71 µM. Notably, the dichloromethane fraction demonstrated promising activity against both enzymes, with IC₅₀ values of 30 µM for PL^pro and 11 µM for 3CL^pro. This study reports, for the first time, the isolation of goyazensolide from E. crotonoides and highlights the potential of both sesquiterpene lactones as SARS-CoV-2 enzyme inhibitors. In contrast to centratherin, goyazensolide fortunately had almost no cytotoxic effects at inhibition concentration on the cells tested. This shows that anticancer and anti-SARS effects can be separated and should have different SARs, an important prerequisite for further development. Full article

Background: Conventional HF treatment in transthyretin cardiac amyloidosis (ATTR-CA) resulting in restrictive cardiomyopathy is debated due to absent trial evidence in this specific sub-population of heart failure (HF) patients. Current European Society of Cardiology guidelines recommend the use of diuretics and mineralocorticoid receptor antagonists (MRAs). However, beta-blockers (BBs) and angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers (ACEi/ARBs) are often discontinued due to hypotension or bradycardia. This study assesses real-world HF treatment patterns and their impact on survival in a multinational ATTR-CA cohort. Methods: A retrospective analysis of 794 ATTR-CA patients examined baseline BB, ACEi/ARB, and MRA prescriptions. The cohort was divided based on guideline publication dates. Results: Patients were predominantly male (73.2%) with a median age of 78 years. Prescription of diuretics (52.8%) and disease-modifying therapy (44.9%), mostly tafamidis, was common. BBs (43.7%) and ACEi/ARBs (41.2%) were prescribed more often in patients with higher NYHA class, elevated NT-proBNP, and more comorbidities. Blood pressure and heart rate were similar regardless of BB or ACEi/ARB use. BB prescription and combination therapy with BB and ACEi/ARB increased over time. Neither BB nor ACEi/ARB use significantly impacted mortality when analyzed in a multivariate Cox proportional hazard regression. Conclusions: Use of BBs and ACEi/ARBs has increased over time, particularly in advanced-stage ATTR-CA patients, and although these therapies appear to be reasonably tolerated, survival was not significantly altered. Full article

Tunicamycins trigger endoplasmic reticulum (ER) stress by inhibiting DPAGT1 (dolichyl-phosphate N-acetylglucosamine-phosphotransferase 1): the rate-limiting enzyme that initiates N-glycan biosynthesis. Aberrant N-glycan branching is a hallmark of many solid tumors, and distinct cancer-associated N-glycan structures have been identified. Evidence shows that tunicamycins suppress key oncogenic processes, including proliferation, apoptosis resistance, metastasis, and angiogenesis. Yet their high systemic toxicity and lack of selectivity have precluded therapeutic application, and the structural complexity of tunicamycins has hindered chemical modification to mitigate these liabilities. No clinically translatable antitumor efficacy has been demonstrated in animal models. This review underscores the emergence of DPAGT1 as a novel and tractable anticancer target, outlining milestones in the discovery of selective inhibitors and their potential to transform cancer therapy. We discuss how advances in DPAGT1 inhibitor design may overcome limitations of tunicamycins and pave the way toward glycosylation-targeted oncology therapeutics. Full article

Leaf senescence is a developmental process that allows nutrients to be remobilized and transported to sink organs. Previously, papain-like cysteine proteases (PLCPs) have been found to be highly expressed during leaf senescence in different plant species. In this study, we analyzed active PLCPs in barley (Hordeum vulgare L.) leaves during the terminal stage of natural senescence. Anion exchange chromatography of protein extracts from barley leaves, harvested six weeks after anthesis, followed by activity assays using the substrates Z-FR-AMC and Z-RR-AMC, revealed a single prominent peak corresponding to active PLCPs. This hydrolytic activity was completely inhibited by E-64, a potent and irreversible inhibitor of cysteine proteases. Fractions enriched for PLCP activity were affinity-labeled with DCG-04 and subjected to SDS-PAGE fractionation, separating two major bands at 43 and 38 kDa. These bands were analyzed using tandem mass spectrometry, allowing the identification of eleven PLCPs. Identified enzymes belong to eight PLCP subfamilies, including CTB/cathepsin B-like (HvPap-19 and -20), RD19/cathepsin F-like (HvPap-1), ALP/cathepsin H-like (HvPap-12 or aleurain), SAG12/cathepsin L-like A (HvPap-17), CEP/cathepsin L-like B (HvPap-14), RD21/cathepsin L-like D (HvPap-6 and -7), cathepsin L-like E (HvPap-13 and -16), and XBCP3 (HvPap-8). Among the identified PLCPs, HvPap-6 was the most abundant. Peptides corresponding to HvPap-6 were identified in both the 43 kDa and 38 kDa bands in approximately the same quantity based on total spectral count. Thus, our results indicate that two active HvPap-6 isoforms can be isolated from barley leaves at late senescence. Full article

Background: Parkinson’s disease (PD) is a progressive neurodegenerative disorder with substantial socioeconomic impact, characterized by the gradual loss of dopaminergic neurons, dopamine deficiency, and pathological processes such as neuroinflammation, oxidative stress, and α-synuclein aggregation. Monoamine oxidases (MAOs) are enzymes responsible for the degradation of neuroactive amines, including dopamine, a neurotransmitter essential for motor, cognitive, and behavioral functions. Among these, MAO-B plays a central role in dopamine metabolism, producing reactive metabolites and oxidative species that contribute to the oxidative stress associated with PD pathophysiology. In this context, MAO-B inhibition has emerged as a promising therapeutic strategy. However, specific limitations, such as motor complications linked to prolonged levodopa use and the adverse effects of currently available MAO inhibitors, remain significant clinical challenges. Methods: A comprehensive literature search was conducted using PubMed and SciFinder databases. Keywords such as “MAO inhibitors”, “Parkinson’s pathology,” and “Parkinson’s disease” were combined with Boolean operators (AND, OR, NOT). The search covered publications from 2010 to 2025. Results: While previous reviews, particularly those by the groups of Guglielmi and Alborghetti, mainly emphasized the clinical use of MAO-B inhibitors and advances in patents, the present review identified approximately 300 compounds synthesized and evaluated as MAO inhibitors, encompassing diverse chemical classes. Among them, selective MAO-B inhibitors exhibited the greatest pharmacological potential, reinforcing the relevance of this isoform as a strategic target in PD therapy. Conclusion: These findings highlight the advances of Medicinal Chemistry in the development of novel MAO-B inhibitors, both as monotherapies for early-stage PD and as adjuvants to levodopa in advanced disease. Collectively, they emphasize the promise of MAO-B inhibitors as candidates for more effective therapeutic interventions in Parkinson’s disease. Full article

Triple-negative breast cancer (TNBC) accounts for about 10–15% of all breast cancers and is an aggressive disease with a poor prognosis. There is currently no standard treatment regimen for TNBC patients; thus, chemotherapy remains the main treatment. Anthracycline- and taxane-based regimens are the most widely used in a clinical setting, either alone or in combination with other chemotherapeutic agents, including poly (ADP-ribose) polymerase (PARP) inhibitors and platinum drugs. Platinum drugs have been used particularly in patients with BRCA1-mutated TNBC. Preclinical and clinical trials revealed that the response to PARP inhibition was directly correlated to the sensitivity to platinum chemotherapies. Inhibition of PARP enzymes has been shown to specifically target BRCA1 dysfunctional cells. Therefore, targeting breast cancer cells that possess genetic alterations that are absent in normal cells could be attained by the exploitation of synthetic lethality for the discovery of other candidate metals, i.e., ruthenium-derived compounds, as next-generation drugs for the treatment of TNBC. This prospective approach provides new insight into alternative treatments for breast cancers with BRCA1-associated TNBC. Full article

Protein homeostasis is a dynamic process essential for cellular function and survival, tightly controlled by the ubiquitin–proteasome system. Within this system, ubiquitin-specific protease 7 (USP7) plays a key role as a deubiquitinating enzyme, thus modulating the stability, localization, and activity of a wide variety of substrates. USP7 is involved in critical cellular processes such as DNA repair, apoptosis, immune response, and epigenetic regulation. The dysregulation of USP7 expressions or activity has been linked to several pathological conditions, including cancer, neurodegenerative and inflammatory diseases, and viral infections. This enzyme exerts its biological functions through the stabilization of both oncogenic and tumor suppressor proteins, highlighting its sensitive role in tumorigenesis. Despite the identification of selective USP7 inhibitors with promising preclinical activity, the development of clinically effective compounds remains a major challenge. This review summarizes the current understanding of USP7 structure, function, and biological relevance, with a particular emphasis on its potential as a therapeutic target in oncology. Full article

Background/Objectives: Melanoma cells enhance glycolysis and expand lysosomes to support energy metabolism, proliferation, and metastasis. However, lysosomal membrane permeabilization (LMP) causes cathepsin leakage into cytosol triggering cytotoxicity. This study investigated the antimelanoma effect of 2-deoxy-D-glucose (2DG), an inhibitor of glycolytic enzyme hexokinase-2, in combination with cathepsin C-dependent LMP inducer L-leucyl-L-leucine methyl ester (LLOMe) and cathepsin C-independent LMP-inducers mefloquine and siramesine. Methods: The viability of A375 and B16 melanoma cells and primary fibroblasts was measured by crystal violet. Apoptosis, necrosis, and LMP were assessed by flow cytometry; caspase activation, mitochondrial depolarization, superoxide production, and energy metabolism were analyzed by fluorimetry, and expression of cathepsins and hexokinase-2 was evaluated by immunoblot. Appropriate inhibitors, antioxidant, and energy boosters were used to confirm cell death type and mechanism. Results: LLOMe triggered LMP, mitochondrial depolarization, and mitochondrial superoxide production, while suppressing oxidative phosphorylation. 2DG suppressed glycolysis and, together with LLOMe, synergized in ATP depletion, caspase activation, and mixed apoptosis and necrosis in A375 cells. Inhibitors of lysosomal acidification, cysteine cathepsins, and caspases, as well as antioxidant and energy boosters, reduced 2DG+LLOMe-induced toxicity. Cathepsins B, C, and D were lower, while hexokinase-2 was higher in A375 cells than fibroblasts. Accordingly, 2DG exhibited lower while LLOMe exhibited higher toxicity against fibroblasts than A375 and B16 cells. However, mefloquine and siramesine induced stronger LMP in A375 cells than in fibroblasts and showed melanoma-selective toxicity when combined with 2DG. Conclusions: 2DG-mediated glycolysis inhibition in combination with lysosomal destabilization induced by mefloquine and siramesine, but not with non-selectively toxic LLOMe, may be promising antimelanoma strategy. Full article

Aromatic ring systems appear ubiquitously in active pharmaceutical substances, such as FDA-approved histone deacetylase inhibitors. However, these rings reduce the water solubility of the molecules, which is a disadvantage during application. To address this problem, azaborine rings may be substituted for conventional aromatic ring systems. These are obtained by replacing two adjacent carbon atoms with boron and nitrogen. Incorporating B–N analogs in place of aromatic rings not only enhances structural diversity but also provides a strategy to navigate around patent-protected scaffolds. We synthesized azaborines, which are isosteric to naphthalene and indole, and utilized them as capping units for HDAC inhibitors. These molecules were attached to various aliphatic and aromatic linkers with different zinc-binding units, used in established active compounds. Nearly half of the twenty-four molecules tested exhibited inhibitory activity against at least one of the enzymes HDAC1, HDAC4, or HDAC8, with three compounds displaying IC₅₀ values in the nanomolar range. We have therefore demonstrated that azaborine building blocks can be successfully incorporated into HDACis, resulting in a highly active profile. Consequently, it should be feasible to develop active substances containing azaborine rings against other targets. Full article

The investigation of the structure–function relationship in hypoxanthine-guanine phosphoribosyltransferases (HGPRT) is a direction that is relevant for the development of drugs and approaches of enzymatic synthesis of modified nucleosides and nucleotides. This research paper is dedicated to the investigation of binding of sulphonate molecules, such as HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) in the active sites of HGPRT and similar proteins. We report the crystal structure of HGPRT from Escherichia coli (EcoHGPRT) in a complex with HEPES. In the obtained X-ray structure, a HEPES molecule binds to the active site in a position that mimics one of the HGPRT substrates, namely phosphoribosylpyrophosphate (PRPP). Enzymological study has shown that HEPES is an inhibitor of EcoHGPRT, along with two structurally similar molecules, namely MES and PIPES. Comparison of the observed EcoHGPRT/HEPES complex to other reported structures in the context of inhibition study results provides an opportunity to explore the variety of binding modes of HEPES and similar molecules and to discuss the structure–function relationship in this enzyme and similar proteins. Full article

Uveal melanoma is a melanocyte-derived malignancy of the eye with a high propensity for liver metastasis. Metastatic uveal melanoma is associated with high mortality and is poorly responsive to currently available therapies. Most uveal melanoma cases are driven by activating mutations in GNAQ and GNA11 genes, which convey oncogenic signaling through the mitogen-activated protein kinase (MAPK) pathway. Despite promising early results, safe doses of pharmacological inhibitors of the MAPK cascade failed to effectively control uveal melanoma in human trials. Considering the role of the RAC/PAK signaling axis as a co-regulator of the MAPK cascade, we set forth to investigate whether the efficacy of MAPK cascade inhibitors in pre-clinical models may be enhanced by direct inhibition of RAC and PAK proteins, or by indirect control of RAC via inhibition of guanylate biosynthesis. We observed that pharmacological inhibition of RAC, PAK and the key guanylate biosynthesis enzyme IMPDH significantly synergized with various inhibitors of the MAPK cascade in suppressing oncogenic signaling and the growth of uveal melanoma cells. In a mouse model, the addition of an IMPDH inhibitor to the treatment regimen significantly enhanced the ability of a MAPK cascade inhibitor to improve the survival of tumor-bearing animals. Targeting of the RAC/PAK axis provides a new strategy to increase the efficacy of targeted therapies in uveal melanoma. While RAC and PAK inhibitors are still undergoing pre-clinical development, clinically available inhibitors of IMPDH offer an opportunity to test the efficacy of this novel synergistic combination in the context of human disease. Full article

Background/Objectives: Gliomas are the most common tumours of the central nervous system (CNS), classified into grades I to IV based on their malignancy. Genetic and epigenetic alterations play a crucial role in glioma progression. DNA methyltransferases (DNMTs) are vital enzymes responsible for DNA methylation, with DNMT1 and DNMT3 catalysing the addition of a methyl group to the 5-carbon of cytosine in CpG dinucleotides. Targeting DNMTs with DNA methyltransferase inhibitors (DNMTi) has become a promising therapeutic approach in tumour treatment. In this study, in silico screening tools were employed to evaluate potential inhibitors of DNMT1, DNMT3A, and DNMT3B for the treatment of glioblastoma multiforme (GBM). Methods: The Gene2Drug platform was used to screen compounds and rank them based on their capacity to dysregulate DNMT genes. PRISM viability assays were performed on 68 cell lines, and DepMap data were analyzed to assess the antitumor activities of these compounds and their target genes. Candidate drug similarity was evaluated using DSEA, and compounds with p < 1 × 10⁻³ were considered statistically significant. Gene-compound interactions for DNMT1, DNMT3A, and DNMT3B were confirmed using Expression Public 24Q2, while Prism Repositioning Public data were analyzed via DepMap. Results: Glioblastoma cell lines showed sensitivity to compounds including droperidol, demeclocycline, benzthiazide, ozagrel, pizotifen, tracazolate, norcyclobenzaprine, monocrotaline, dydrogesterone, 6-benzylaminopurine, and nifedipine. SwissTargetPrediction was utilised to identify alternative molecular targets for selected compounds, revealing high-probability matches for droperidol, pizotifen, tracazolate, monocrotaline, dydrogesterone, and nifedipine. Conclusions: Integrating computational approaches with biological insights and conducting tissue-specific and experimental validations may significantly enhance the development of DNMT-targeted therapies for gliomas. Full article

Additives such as surfactants (Tween-20) and cryoprotectants (glycerol and trehalose) are often used in enzymatic assays to improve the quality and long-term stabilization of proteins. However, these additives can affect the enzymatic activity and the enzyme’s affinity for active compounds, such as inhibitors, and must be considered during assay design since a slight shift in enzyme behavior may compromise the reliability of the results. In this study, the effects of Tween-20, glycerol, and trehalose on hyaluronidase (Hyal) were systematically evaluated by assessing their influence both directly—through microscale thermophoresis (MST) signals of the labeled enzyme (Hyal*)—and indirectly, by monitoring the formation of the final product of the degradation of hyaluronic acid, tetrasaccharide (Tet), using capillary electrophoresis (CE/UV). Hyal was labeled for the first time with ATTO-647 NHS ester, a commercial dye compatible with MST. Efficient labeling was achieved in a phosphate-based buffer without loss of catalytic activity. Tween-20 showed no impact on MST signals nor on enzymatic performance when used between 0.005 and 0.05% (v/v). Glycerol also did not interfere with MST measurements; however, it significantly reduced catalytic activity at concentrations above 2% (v/v). Trehalose affected Hyal* fluorescence in a concentration-dependent manner and enhanced catalytic activity even at 0.02% (v/v). Full article

Given the limitations of clinical and potent natural α-glucosidase inhibitors, novel selective inhibitors are urgently needed. To accelerate discovery, we employed machine learning-integrated virtual screening to rapidly evaluate a library of 100 K⁺ compounds, identifying a series of selective α-glucosidase inhibitors. Activity validation demonstrated that these inhibitors exhibit significantly enhanced selectivity and potency compared to the positive control acarbose. Mechanistic studies through inhibition kinetics and fluorescence quenching revealed their improved inhibitory profile. Molecular docking indicates that key interactions—hydrogen bonding or salt bridges with the catalytic residue ASP526—strengthen binding within the active site. These interactions competitively obstruct enzyme-substrate binding, thereby amplifying inhibition. In vitro and in vivo starch digestion assays further corroborated these findings. Full article

Dihydroorotase (DHOase) catalyzes the reversible cyclization of N-carbamoyl-L-aspartate to dihydroorotate, a key step in de novo pyrimidine biosynthesis. A flexible active site loop in DHOase undergoes conformational switching between loop-in and loop-out states, influencing substrate binding, catalysis, and inhibitor recognition. In this study, we identified 5-fluoroorotate (5-FOA) and myricetin as inhibitors of Saccharomyces cerevisiae DHOase and systematically analyzed 97 crystal structures and AlphaFold 3.0 models of DHOases from 16 species representing types I, II, and III. Our results demonstrate that loop conformation is not universally ligand-dependent and varies markedly across DHOase types, with type II enzymes showing the greatest flexibility. Notably, S. cerevisiae DHOase consistently adopted the loop-in state, even with non-substrate ligands, restricting accessibility for docking-based inhibitor screening. Docking experiments with 5-FOA and myricetin confirmed that the loop-in conformation prevented productive active-site docking. These findings highlight the importance of selecting appropriate loop conformations for structure-based drug design and underscore the need to account for loop dynamics in inhibitor screening. Full article