ACS Bio & Med Chem Au最新文献

Challenges in pancreatic cancer treatment primarily arise from chemotherapy resistance, cancer cell metastasis, and frequent late-stage diagnoses. These issues significantly compromise the effectiveness of standard treatments and highlight the urgent need for targeted approaches. In this context, we explored the anticancer potential of bis-quaternary ammonium-based compounds (BQACs), which remains largely uncharted. This study examines the structure–activity relationship of amphiphilic bicationic compounds as anticancer agents, focusing on their selectivity against pancreatic cancer cells. Our analysis revealed a potent antiproliferative effect associated with mitochondrial accumulation and subsequent mitochondrial membrane depolarization. Furthermore, combination therapies involving BQACs and chemotherapeutic drugs were explored to enhance treatment efficacy. Consequently, we propose a novel combination of BQACs with metformin, resulting in enhanced cellular uptake of the latter. The synergistic effect of the combination enables a significantly lower effective dose of metformin when used alongside BQACs to achieve therapeutic outcomes.

Owing to its exceptional physicochemical and biological properties, graphene oxide (GO), the oxidized form of graphene, has attracted considerable interest in bone regenerative engineering. The oxygen-functional groups on the backbone of GO enable biomolecule adherence, protein adsorption, cell adhesion, proliferation, differentiation, calcium ion adsorption and bone matrix mineralization. These oxygen functional groups enhance GO's interaction with biological fluids, facilitating its hydrolytic biodegradation. Recent preclinical studies have indicated that GO effectively improves mechanical strength, immunomodulation, and osteoinduction when utilized within diverse matrix structures including natural and synthetic polymers and ceramics to induce osteogenesis. Advanced bone regenerative applications of GO, such as implant coating and delivery of bioactive compounds, have demonstrated enhanced osseointegration, antibacterial efficacy, and pro-healing microenvironments. However, there are still challenges regarding the high-quality large-scale synthesis and long-term biocompatibility of GO. Additionally, the variability in the characteristics of GO resulting from different synthesis methods demonstrates further challenges for therapeutic translation. This study provides a comprehensive review of the recent preclinical research on the translational potential of GO, discussing the convergence of its exceptional properties for use in bone regenerative engineering along with its current challenges and future perspectives.

The group of bacteria known as ESKAPE: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. are well recognized for their high virulence and pathogenicity, employing diverse modalities and mechanisms to resist multiple classes of clinically relevant antibiotics. Their capacity to evade treatment presents a major public health challenge, highlighting the urgent need for novel antibiotics to address the growing resistance crisis. The plant kingdom presents a promising avenue to this fight. Plants are naturally endowed with the genomic and proteomic machinery to synthesize a wide arsenal of secondary metabolites, including terpenes and terpenoids, which have demonstrated potent antimicrobial properties both as standalone agents and as synergists or enhancers of existing antibiotics. These plant-derived compounds often operate through mechanisms distinct from those of conventional antibiotics, offering a potentially effective solution against antibiotic-resistant bacteria. Brazil, home to some of the richest biodiversity on the planet, boasts 46,000 recorded plant species, with 250 new species identified annually. This review delves into the methods of preparing and isolating terpenes and terpenoids from plants, explores the techniques used to assess their antibacterial activity, and highlights ongoing research using Brazilian plants to target ESKAPE pathogens. This compilation of knowledge aims to establish a pipeline for evaluating the antibacterial potential of terpenes and terpenoids, contributing to efforts addressing the growing threat of antimicrobial resistance.

The growing threat of fungal infections, driven by increasing drug resistance, has become a major global health concern. Candidiasis, a common human infection, is associated with high mortality, particularly in invasive cases. Among non-albicans Candida (NAC) species, Candida krusei (renamed Pichia kudriavzevii) is of clinical importance because of its intrinsic resistance to fluconazole, complicating treatment options. This study evaluated the antifungal efficacy and safety of the bioinspired peptide CaDef2.1_G27-K44 (CDF-GK) against NAC species, with a specific focus on C. krusei, through a series of in vitro and in vivo tests. CDF-GK effectively inhibited the growth of several yeast species, including C. glabrata, C. guilliermondii, C. bracarensis, and C. nivariensis, with MIC values ranging from 3.12 to 200 μM. The peptide demonstrated particularly strong activity against C. krusei, with an MIC₁₀₀ of 25 μM, an MFC₁₀₀ of 50 μM, and an IC₅₀ of 5 μM, surpassing the effectiveness of fluconazole. Additionally, CDF-GK inhibited biofilm formation, caused 100% cell death within 1 h, permeabilized the cell membrane, interacted with ergosterol, induced oxidative stress, mitochondrial dysfunction, and vacuolar fragmentation, and entered the intracellular space of C. krusei. In vivo assays using Galleria mellonella larvae confirmed the low toxicity of CDF-GK, even at high concentrations, and significantly improved the survival of infected larvae with minimal activation of cellular and humoral immune responses. These findings indicate that CDF-GK holds great promise as a therapeutic agent for C. krusei infections, as it combines potent antifungal action with safety in both in vitro and in vivo models.

Substance use disorder (SUD) is a mental condition that affects a person's brain and behavior, leading to a lack of control with alcohol, drug, and medication use. The lack of efficacious and novel treatments for SUD is a growing concern. As such, we have synthesized a series of iboga alkaloid derivatives and evaluated their receptor binding profiles against a panel of CNS-based proteins, which were performed at the National Institute of Mental Health Psychoactive Drug Screening Program. These studies revealed two compounds that exhibit high affinity for the sigma-2 receptor and introduce the iboga alkaloid framework as a new scaffold for the development of sigma-2 ligands.

Engineering carbohydrates in living cells is one of the overarching goals of biology. In this Perspective, we discuss recent work in response to this challenge. Compared with eukaryotic cells, bacteria are fast-growing and genetically tractable. At the species level, glycans in prokaryotes are highly variable, contrasting with the homogeneity of surface glycans, such as capsular polysaccharides (CPSs), at the strain level. We exploited the conditional essentiality of the CPS synthesis pathway in Streptococcus pneumoniae to overcome the challenges of biochemically monitoring the engineered glycan products. While this strategy seems feasible, this glycoengineering platform is limited by the specificity of the capsule transporters and the glycosyltransferase inventories that can be introduced into the pneumococcus. Mutants that relax transporter specificity have been isolated, enabling us to inactivate otherwise essential glycosyltransferases. Ongoing work aims to harness this technology to synthesize medically relevant glycans, including Lewis antigens and tumor markers.

Lysine malonylation is a post-translational modification in which a malonyl group, characterized by a negatively charged carboxylate, is covalently attached to the ε-amino side chain of lysine, influencing protein structure and function. Our laboratory identified Mak upregulation in cartilage under aging and obesity, contributing to osteoarthritis (OA). Current antibody-based detection methods face limitations in identifying Mak targets. Here, we introduce an alkyne-functionalized probe, MA-diyne, which metabolically incorporates into proteins, enabling copper(I) ion-catalyzed click reactions to conjugate labeled proteins with azide-based fluorescent dyes or affinity purification tags. In-gel fluorescence confirms MA-diyne incorporation into proteins across various cell types and species, including mouse chondrocytes, adipocytes, HEK293T cells, and Caenorhabditis elegans. Pull-down experiments identified known Mak proteins, such as GAPDH and Aldolase. The extent of MA-diyne modification was higher in Sirtuin 5-deficient cells, suggesting these modified proteins are Sirtuin 5 substrates. Pulse-chase experiments confirmed the dynamic nature of the protein malonylation. Quantitative proteomics identified 1136 proteins corresponding to 8903 peptides, with 429 proteins showing a 1-fold increase in the labeled group. Sirtuin 5 regulated 374 of these proteins. Pull down of newly identified proteins, such as β-actin and Stat3, was also done. This study highlights MA-diyne as a powerful chemical tool to investigate the molecular targets and functions of lysine malonylation under OA conditions.

Galectin-1 (Gal-1) is a galactose-binding protein involved in various cellular functions. Gal-1's activity has been suggested to be connected to two molecular concepts, which are, however, lacking experimental proof: a) enhanced binding affinity of Gal-1 toward membranes containing monosialotetrahexosylganglioside (GM₁) over disialoganglioside GD₁a and b) cross-linking of GM₁'s by homodimers of Gal-1. We provide evidence about the specificity and the nature of the interaction of Gal-1 with model membranes containing GM₁ or GD₁a, employing a broad panel of fluorescence-based and label-free experimental techniques, complemented by atomistic biomolecular simulations. Our study demonstrates that Gal-1 indeed binds specifically to GM₁ and not to GD₁a when embedded in membranes over a wide range of concentrations (i.e., 30 nM to 20 μM). The apparent binding constant is about tens of micromoles. On the other hand, no evidence of Gal-1/GM₁ cross-linking was observed. Our findings suggest that cross-linking does not result from sole interactions between GM₁ and Gal-1, indicating that in a physiological context, additional triggers are needed, which shift the GM₁/Gal-1 equilibria toward the membrane-bound homodimeric Gal-1.

Fluorine is an important atom in many drugs because it can improve the efficacy and metabolic stability of many molecules. Strategies to incorporate monofluoromethyl groups in drugs have been limited and have received less attention than strategies for difluoromethylation or trifluoromethylation. Previously, we and others reported the enzymatic monofluoromethylation of several biologically relevant metabolites based on the transfer of a fluoromethyl group from analogs of S-adenosylmethionine (SAM) to various nucleophiles (carbon, oxygen, nitrogen, sulfur, and carbon) through a polar S_N2 mechanism. However, this strategy is limited to molecules containing nucleophilic target atoms. Inspired by a subset of enzymes within the radical SAM superfamily that can methylate inert carbon atoms, we developed an enzymatic strategy to transfer fluoromethyl groups to unactivated carbon atoms. This strategy leverages the ability of halide methyltransferase to generate a transient fluoromethyl-containing SAM analog. Our studies show that S-adenosyl-L-(fluoromethyl)-methionine can undergo reductive cleavage to a 5'-deoxyadenosyl 5'-radical, which initiates radical-dependent fluoromethylation through substrate hydrogen-atom abstraction. Adding fluoromethyl groups to unactivated C-H bonds using radical SAM enzymes is a powerful approach that can be used to derivatize molecules of interest where S_N2-based fluoromethylation is precluded.

Forced-copy-choice recombination occurs at the end of a template, differing from copy-choice recombination, which happens at internal positions. This mechanism may produce full-length genomes from fragments created by host antiviral responses. Previous studies from our laboratory demonstrated that poliovirus (PV) RNA-dependent RNA polymerase (RdRp) switches to an "acceptor" template in vitro when initiated on a heteropolymeric RNA-primed "donor" template. Surprisingly, recombinants showed template switching from the 3'-end of the donor template. We have developed a primed-template system to study PV RdRp-catalyzed forced-copy-choice RNA recombination. PV RdRp adds a single, nontemplated nucleotide to the 3'-end of a blunt-ended, double-stranded RNA product, forming a "plus-one" intermediate essential for template switching. Nontemplated addition of CMP was favored over AMP and GMP (80:20:1); UMP addition was negligible. A single basepair between the plus-one intermediate and the 3'-end of the acceptor template was necessary and sufficient for template switching, which could occur without RdRp dissociation. Formation of the plus-one intermediate was rate limiting for template switching. PV RdRp also utilized synthetic, preformed intermediates, including those with UMP 3'-overhangs. Reactions showed up to five consecutive template-switching events, consistent with a repair function for this form of recombination. PV RdRp may exclude UMP during forced-copy-choice RNA recombination to preclude creation of nonsense mutations during RNA fragment assembly. Several other picornaviral RdRps were evaluated, and all were capable of RNA fragment assembly to some extent. Lastly, we propose a structure-based hypothesis for the PV RdRp-plus-one intermediate complex based on an elongating PV RdRp structure.