Low-Basicity 5-HT6 Receptor Ligands from the Group of Cyclic Arylguanidine Derivatives and Their Antiproliferative Activity Evaluation.

The serotonin 5-HT6 receptor (5-HT6R), expressed almost exclusively in the brain, affects the Cdk5 signaling as well as the mTOR pathway. Due to the association of 5-HT6R signaling with pathways involved in cancer progression, we decided to check the usefulness of 5-HT6R ligands in the treatment of CNS tumors. For this purpose, a new group of low-base 5-HT6R ligands was developed, belonging to arylsulfonamide derivatives of cyclic arylguanidines. The selected group of molecules was also tested for their antiproliferative activity on astrocytoma (1321N1) and glioblastoma (U87MG, LN-229, U-251) cell lines. Some of the molecules were subjected to ADMET tests in vitro, including lipophilicity, drug binding to plasma proteins, affinity for phospholipids, drug-drug interaction (DDI), the penetration of the membrane (PAMPA), metabolic stability, and hepatotoxicity as well as in vivo cardiotoxicity in the Danio rerio model. Two antagonists with an affinity constant Ki < 50 nM (PR 68Ki = 37 nM) were selected. These compounds were characterized by very high selectivity. An analysis of pharmacokinetic parameters for the lead compound PR 68 confirmed favorable properties for administration, including passive diffusion and acceptable metabolic stability (metabolized in 49%, MLMs). The compound did not exhibit the potential for drug-drug interactions.

Discovery of cyanoguanidine derivatives as biased µ-opioid receptor agonists.

Opioid agonists, including morphine and its derivatives, have historically been utilized in conventional pain relief therapies. However, the morphine-like side effects associated with these compounds have constrained their broader application in clinical environments. Fortunately, novel compounds that selectively activate µ-opioid receptors (MOR) without activating the ß-arrestin2 pathway, such as PZM21 and TRV130, demonstrate the potential to mitigate side effects while maintaining analgesic efficacy. In this study, we structurally modified PZM21 to get a series of compounds with a 2-cyanoguanidine scaffold, the majority of which display significant analgesic effects. Notably, Compound I-11 exhibited an analgesic effect comparable to that of morphine and selectively activates µ-opioid receptors while avoiding the activation of the ß-arrestin2 pathway. Our work not only introduces a novel biased µ-opioid receptor agonist but also serves as a valuable reference for the further optimization of PZM21.

Ionic Liquids-Induced Recovery of the G-Quadruplex DNA Destabilized by Dodine Fungicide.

Dodine is an important surfactant-based chemical fungicide used widely to kill fungi associated with black spot and foliar diseases on several fruit plants, such as apples, pears, peaches, and strawberries. However, the extensive use of dodine depicts the genotoxic effect, which may cause gene-associated diseases. Dodine can destabilize G-quadruplex (G4) DNA, which is one of the key targets for cancer therapy. Hence, finding an eco-friendly medium that can reduce or reverse the destabilization effect of dodine on G4 is important. This study investigates the efficacy of ionic liquids (ILs) containing a 1,1,3,3-tetramethyl guanidinium (TMG) cation with various anions (chloride, acetate, trifluoroacetate, octanoate, and perfluorooctanoate) in restoring the structure and stability of G4 induced by dodine. Our findings demonstrate that all ILs effectively reverse dodine-induced destabilization of G4, with the required concentration varying based on the lipophilicity of IL's anions. Specifically, higher concentrations of TMG-chloride and TMG-acetate are needed compared to TMG-perfluorooctanoate for the same effect. The IL anions remove dodine from G4 binding sites, while the TMG cation's interaction with G4 mitigates the destabilizing effect of dodine. This study indicates that ILs can be an eco-friendly medium for the storage of dodine to reverse the effect of dodine on G4.

Dicyandiamide Applications Mitigate the Destructive Effects of Graphene Oxide on Microbial Activity, Diversity, and Composition and Nitrous Oxide Emission in Agricultural Soil.

The widespread production and utilization of graphene oxide (GO) raise concerns about its environmental release and potential ecological impacts, particularly in agricultural soil. Effective nitrogen (N) management, especially through nitrification inhibitors like dicyandiamide (DCD), might mitigate the negative effects of GO exposure on soil microbes via N biostimulation. This study quantified changes in soil physicochemical properties, nitrous oxide (N2O) emissions, microbial activity, biomass, and community after treatments with GO and DCD. The GO exposure significantly reduced bacterial 16S rRNA gene abundance and the biomass of major bacterial phyla. It also stimulated pathways linked to human diseases. However, DCD application alleviated the negative effects of GO exposure on soil bacterial biomass. While DCD application significantly reduced soil N2O emission, the GO application tended to hinder the inhibiting performance of DCD. Our findings highlight the hazards of GO exposure to soil microbes and the potential mitigation strategy with soil N management.

Modification of the Trizol Method for the Extraction of RNA from Prorocentrum triestinum ACIZ_LEM2.

In samples of harmful algal blooms (HABs), seawater can contain a high abundance of microorganisms and elemental ions. Along with the hardness of the walls of key HAB dinoflagellates such as Prorocentrum triestinum, this makes RNA extraction very difficult. These components interfere with RNA isolation, causing its degradation, in addition to the complex seawater properties of HABs that could hinder RNA isolation for effective RNA sequencing and transcriptome profiling. In this study, an RNA isolation technique was established through the modification of the Trizol method by applying the Micropestle System on cell pellets of P. triestinum frozen at -20 °C, obtained from 400 mL of culture with a total of 107 cells/mL. The results of the modified Trizol protocol generated quality RNA samples for transcriptomics sequencing, as determined by their measurement in Analyzer Agilent 4150.

Design and Mechanistic Insights into α-Helical p-Terphenyl Guanidines as Potent Small-Molecule Antifreeze Agents.

Ice formation is a critical challenge across multiple fields, from industrial applications to biological preservation. Inspired by natural antifreeze proteins, we designed and synthesized a new class of small-molecule antifreezes based on α-helical p-terphenyl scaffolds with guanidine side chains. These p-terphenyl guanidines 1, among the smallest molecules that mimic α-helical structures, exhibit potent ice recrystallization inhibition (IRI) activity, similar to that of existing large α-helical antifreeze compounds. The most effective compound, 1a, with four C1-carbon guanidine moieties, demonstrated a superior IRI activity of 0.46 (1 mg/mL). Using molecular dynamics simulations with density-functional theory and separate pKa calculations, we elucidated the mechanisms underlying their antifreeze properties.

Photolysis of dinotefuran and nitenpyram in water and ice phase: Influence mechanism of temperature over photolysis.

Neonicotinoids are widely used pesticides around the world, but the photolysis of neonicotinoids in cold agricultural region are still in blank. This paper aimed to study the influence of cold temperature over photolysis of neonicotinoids. To this end, the photolysis rates and photoproducts of dinotefuran and nitenpyram in water, ice and freeze-thawing condition were determined. Coupled with quantum chemistry calculation, the influence mechanisms of temperature and medium were investigated. The results showed the photolysis rates of neonicotinoids in water condition slightly declined with the lowered temperature due to the photolysis reactions were endothermic reactions. However, the photolysis rates increased by 89.8 %, 59.2 %, 49.4 % and 9.5 % for dinotefuran and nitenpyram in ice and thawing condition, respectively. This phenomenon was posed by the concentration-enhancing effect and change of photo-chemical properties of neonicotinoids in ice condition, which included lowered bond cleavage energy, lowered first excited singlet state energy and expanded light absorption range. The photolysis pathways of the two neonicotinoids did not change in different medium, but the concentration of carboxyl products was relatively higher than that of water condition due to the more amounts of reactive oxygen species in ice medium, which might increase the secondary pollution risk after ice-off in spring due to the higher ecotoxicity to nontarget organism of these photoproducts. The influence of cold temperature and medium change should be considered for the environmental fate and risk assessment of neonicotinoids in cold agricultural region.

Polyhexamethylene guanidine aerosol causes irreversible changes in blood proteins that associated with the severity of lung injury.

Polyhexamethylene guanidine (PHMG) is a positively charged polymer used as a disinfectant that kills microbes but can cause pulmonary fibrosis if inhaled. After the long-term risks were confirmed in South Korea, it became crucial to measure toxicity through diverse surrogate biomarkers, not only proteins, especially after these hazardous chemicals had cleared from the body. These biomarkers, identified by their biological functions rather than simple numerical calculations, effectively explained the imbalance of pulmonary surfactant caused by fibrosis from PHMG exposure. These long-term studies on children exposed to PHMG has shown that blood protein indicators, primarily related to apolipoproteins and extracellular matrix, can distinguish the degree of exposure to humidifier disinfectants (HDs). We defined the extreme gradient boosting models and computed reflection scores based on just ten selected proteins, which were also verified in adult women exposed to HD. The reflection scores successfully discriminated between the HD-exposed and unexposed groups in both children and adult females (AUROC: 0.957 and 0.974, respectively) and had a strong negative correlation with lung function indicators. Even after an average of more than 10 years, blood is still considered a meaningful specimen for assessing the impact of environmental exposure to toxic substances, with proteins providing in identifying the pathological severity of such conditions.

Structural basis for the binding of famotidine, cimetidine, guanidine, and pimagedine with serine protease.

Serine proteases are among the important groups of enzymes having significant roles in cell biology. Trypsin is a representative member of the serine superfamily of enzymes, produced by acinar cells of pancreas. It is a validated drug target for various ailments including pancreatitis and colorectal cancer. Premature activation of trypsin is involved in the lysis of pancreatic tissues, which causes pancreatitis. It is also reported to be involved in colorectal carcinoma by activating other proteases, such as matrix metalloproteinase (MMPs). The development of novel trypsin inhibitors with good pharmacokinetic properties could play important roles in pharmaceutical sciences. This study reports the crystal structures of bovine pancreatic trypsin with four molecules; cimetidine, famotidine, pimagedine, and guanidine. These compounds possess binding affinity towards the active site (S1) of trypsin. The structures of all four complexes provided insight of the binding of four different ligands, as well as the dynamics of the active site towards the bind with different size ligands. This study might be helpful in designing of new potent inhibitors of trypsin and trypsin like serine proteases.

Destabilization of the D2 domain of Thermotoga maritima arginine binding protein induced by guanidinium thiocyanate and its counteraction by stabilizing agents.

D2 is a structural and cooperative domain of Thermotoga maritima Arginine Binding Protein, that possesses a remarkable conformational stability, with a denaturation temperature of 102.6°C, at pH 7.4. The addition of potassium thiocyanate causes a significant decrease in the D2 denaturation temperature. The interactions of thiocyanate ions with D2 have been studied by means of isothermal titration calorimetry measurements and molecular dynamics simulations. It emerged that: (a) 20-30 thiocyanate ions interact with the D2 surface and are present in its first solvation shell; (b) each of them makes several contacts with protein groups, both polar and nonpolar ones. The addition of guanidinium thiocyanate causes a marked destabilization of the D2 native state, because both the ions are denaturing agents. However, on adding to the solution containing D2 and guanidinium thiocyanate a stabilizing agent, such as TMAO, sucrose or sodium sulfate, a significant increase in denaturation temperature occurs. The present results confirm that counteraction is a general phenomenon for globular proteins.

An improved Trizol method for extracting total RNA from Eleutherococcus senticosus (Rupr. & Maxim.) Maxim leaves.

INTRODUCTION: High-quality nucleic acids are the basis for molecular biology experiments. Traditional RNA extraction methods are not suitable for Eleutherococcus senticosus Maxim. OBJECTIVE: To find a suitable method to improve the quality of RNA extracted, we modified the RNA extraction methods of Trizol. METHODOLOGY: Based on the conventional Trizol method, the modified Trizol method 1 and modified Trizol method 2 were used as the control for extraction of RNA from E. senticosus Maxim leaves. The modified Trizol method 1 added ß-mercaptoethanol on the conventional Trizol method. After RNA was dissolved, a mixed solution of phenol, chloroform, and isoamyl alcohol was added to denature protein and inhibit the degradation of RNA. The modified Trizol method 2 adds PVPP to grind on the basis of modified Trizol method 1, so as to better remove phenols from leaves, and eliminates the step of incubation at -20°C to reduce extraction time and RNA degradation. Chloroform, CTAB, and CH3COONa were used instead of a phenol, chloroform, and isoamyl alcohol mixed solution to ensure complete separation of nucleic acid from plant tissues and to obtain high-purity RNA. RESULTS: The research results showed that the quality of RNA extracted by conventional Trizol method, modified Trizol method 1, was incomplete, accompanied with different degrees of contamination of polysaccharides, polyphenols, and DNA. The modified Trizol method 2 could better extract RNA from E. senticosus Maxim leaves. The ratio of A260/A280 was in the range of 1.8-2.0, and the yield of RNA was the highest, which was 1.68 and 1.15 times compared with that by conventional Trizol method and modified Trizol method 1 extraction, respectively. The reverse transcription cDNA was further tested through PCR with the specific primers. The amplified fragments are displayed in clear and bright bands in accordance with the expected size. CONCLUSION: The modified Trizol method 2 could better extract RNA from E. senticosus Maxim leaves. High-quality RNA has more advantages in molecular biology study of E. senticosus Maxim.

Preclinical studies of RA475, a guanidine-substituted spirocyclic candidate RPN13/ADRM1 inhibitor for treatment of ovarian cancer.

There is an urgent unmet need for more targeted and effective treatments for advanced epithelial ovarian cancer (EOC). The emergence of drug resistance is a particular challenge, but small molecule covalent inhibitors have promise for difficult targets and appear less prone to resistance. Michael acceptors are covalent inhibitors that form bonds with cysteines or other nucleophilic residues in the target protein. However, many are categorized as pan-assay interference compounds (PAINS) and considered unsuitable as drugs due to their tendency to react non-specifically. Targeting RPN13/ADRM1-mediated substrate recognition and deubiquitination by the proteasome 19S Regulatory Particle (RP) is a promising treatment strategy. Early candidate RPN13 inhibitors (iRPN13) produced a toxic accumulation of very high molecular weight polyubiquitinated substrates, resulting in therapeutic activity in mice bearing liquid or solid tumor models, including ovarian cancer; however, they were not drug-like (PAINS) because of their central piperidone core. Up284 instead has a central spiro-carbon ring. We hypothesized that adding a guanidine moiety to the central ring nitrogen of Up284 would produce a compound, RA475, with improved drug-like properties and therapeutic activity in murine models of ovarian cancer. RA475 produced a rapid accumulation of high molecular polyubiquitinated proteins in cancer cell lines associated with apoptosis, similar to Up284 although it was 3-fold less cytotoxic. RA475 competed binding of biotinylated Up284 to RPN13. RA475 shows improved solubility and distinct pharmacodynamic properties compared to Up284. Specifically, tetraubiquitin firefly luciferase expressed in leg muscle was stabilized in mice more effectively upon IP treatment with RA475 than with Up284. However, pharmacologic analysis showed that RA475 was more rapidly cleared from the circulation, and less orally available than Up284. RA475 shows reduced ability to cross the blood-brain barrier and in vitro inhibition of HERG. Treatment of mice with RA475 profoundly inhibited the intraperitoneal growth of the ID8-luciferase ovarian tumor model. Likewise, RA475 treatment of immunocompetent mice inhibited the growth of spontaneous genetically-engineered peritoneal tumor, as did weekly cisplatin dosing. The combination of RA475 and cisplatin significantly extended survival compared to individual treatments, consistent with synergistic cytotoxicity in vitro. In sum, RA475 is a promising candidate covalent RPN13i with potential utility for treatment of patients with advanced EOC in combination with cisplatin.

Synthesis and Carbonic Anhydrase I, II, IX, and XII Inhibition Studies with a Series of Cyclic Sulfonyl Guanidines.

A series of thirteen cyclic sulfonyl guanidines were prepared and evaluated against tumor-associated human (h) carbonic anhydrase (CA, EC 4.2.1.1) isoforms hCA IX and hCA XII, as well as against off-target cytosolic isoforms hCA I and hCA II. The compounds reported here were generally inactive against both off-target isoforms (KI>100 µM), while all of them moderately inhibited both target isoforms hCA IX and XII in the submicromolar to micromolar ranges in which KI values spanned from 0.57 to 8.4 µM against hCA IX and from 0.34 to 9.7 against hCA XII. Due to the notable selectivity of the title compounds toward isoforms hCA IX and XII, they can be considered as useful scaffolds for further chemical optimization to develop new highly selective antitumor agents.

Developing In2S3 upon modified MgTiO3 anchored on nitrogen-doped CNT for sustainable sensing and removal of toxic insecticide clothianidin.

Herein, the study introduces a novel bifunctional In2S3/MgTiO3/TiO2@N-CNT (IMTNC) nanocomposite, which is poised to revolutionize the detection and removal of clothianidin (CLD) from aquatic environments by synergistic adsorption and photodegradation. Confirmation of the material's synthesis was done using structural, optical, morphological, and chemical characterizations. An outstanding sensitivity of 2.168 µA/nM.cm2 with a linear range of 4-100 nM and a LOD of 0.04 nM, along with an exceptional elimination efficiency of 98.06 ± 0.84% for about 10 ppm CLD within 18 min was demonstrated by the IMTNC nanocomposite. Extensive studies were carried out to appraise the material's effectiveness in the presence of various interfering species, such as cations, anions, organic compounds, and different water matrices, and a comprehensive assessment of its stability throughout several cycles was made. Response Surface Methodology (RSM) study was used to determine the ideal removal conditions for improved performance. In addition, the catalytic performance in removing various other pollutants was also analyzed. Adding In2S3 and developing N-doped Carbon Nanotubes (N-CNT) increased conductivity and higher electrochemical sensing skills, improving charge transfer and increasing photocatalytic activity. This research underscores the potential of the IMTNC nanocomposite as a promising candidate for advanced environmental sensing and remediation applications.

Analytic and In Silico Methods to Understand the Interactions between Dinotefuran and Haemoglobin.

This work lies in the growing concern over the potential impacts of pesticides on human health and the environment. Pesticides are extensively used to protect crops and control pests, but their interaction with essential biomolecules like haemoglobin (Hb) remains poorly understood. Spectrofluorometric, electrochemical, and in silico investigations have been chosen as potential methods to delve into this issue, as they offer valuable insights into the molecular-level interactions between pesticides and haemoglobin. The research aims to address the gaps in knowledge and contribute to developing safer and more sustainable pesticide practices. The interaction was studied by spectroscopic techniques (UV-Visible & Fluorescence), in silico studies (molecular docking & molecular dynamics simulations) and electrochemical techniques (cyclic voltammetry and tafel). The studies showed effective binding of dinotefuran with the Hb which will cause toxicity to human. The formation of a stable molecular complex between ofloxacin and Haemoglobin was shown via molecular docking and the binding energy was found to be -5.37 kcal/mol. Further, molecular dynamics simulations provide an insight for the stability of the complex (Hb-dinotefuran) for a span of 250 ns with a binding free energy of -53.627 kJ/mol. Further, cyclic voltammetry and tafel studies show the interaction of dinotefuran with Hb effectively.

Baicalein loaded liposome with hyaluronic acid and Polyhexamethylene guanidine modification for anti methicillin-resistant Staphylococcus aureus infection.

Targeting delivery to the infection site and good affinity of vehicle to the bacterial are two main concerns in therapy of bacterial infection, and on-demand release of drug is another important issue. In this work, a liposome drug delivery system (HA/P/BAI-lip) incorporated with baicalein and modified by PHMG and HA was prepared. Several characterizations were conducted to examine the physical properties of liposome. Then it was applied to treatments of MRSA induced dorsal subcutaneous abscess model and the thigh muscle infected model. The presence of guanidine group in HA/P/BAI-lip rendered the liposome satisfactory bacterial target ability and good pH sensitive properties. The lipase secreted by bacterial could promote the hydrolysis of soybean phosphatidylcholine (SPC) in liposome. The modification of HA in HA/P/BAI-lip could lead the drug system to the exact infected site where CD44 was abundant because of inflammation. The low pH microenvironment characteristic of bacterial infection could induce the swelling of liposome following by degradation. Taken together, baicalein could be released selectively at the infected site to exert antibacterial capacity. HA/P/BAI-lip showed impressive antibacterial ability and dramatically decrease the bacterial burden of infection site and alleviate the infiltration of inflammatory cells, facilitating the recovery of infection.

Malleable, Ultrastrong Antibacterial Thermosets Enabled by Guanidine Urea Structure.

Dynamic covalent polymers (DCPs) that strike a balance between high performance and rapid reconfiguration have been a challenging task. For this purpose, a solution is proposed in the form of a new dynamic covalent supramolecular motif-guanidine urea structure (GUAs). GUAs contain complex and diverse chemical structures as well as unique bonding characteristics, allowing guanidine urea supramolecular polymers to demonstrate advanced physical properties. Noncovalent interaction aggregates (NIAs) have been confirmed to form in GUA-DCPs through multistage H-bonding and π-π stacking, resulting in an extremely high Young's modulus of 14 GPa, suggesting remarkable mechanical strength. Additionally, guanamine urea linkages in GUAs, a new type of dynamic covalent bond, provide resins with excellent malleability and reprocessability. Guanamine urea metathesis is validated using small molecule model compounds, and the temperature dependent infrared and rheological behavior of GUA-DCPs following the dissociative exchange mechanism. Moreover, the inherent photodynamic antibacterial properties are extensively verified by antibacterial experiments. Even after undergoing three reprocessing cycles, the antibacterial rate of GUA-DCPs remains above 99% after 24 h, highlighting their long-lasting antibacterial effectiveness. GUA-DCPs with dynamic nature, tuneable composition, and unique combination of properties make them promising candidates for various technological advancements.

Collection and transportation of SARS-CoV-2 and influenza A virus diagnostic samples: Optimizing the usage of guanidine-based chaotropic salts for enhanced biosafety and viral genome preservation.

Many virus lysis/transport buffers used in molecular diagnostics, including the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA, contain guanidine-based chaotropic salts, primarily guanidine hydrochloride (GuHCl) or guanidine isothiocyanate (GITC). Although the virucidal effects of GuHCl and GITC alone against some enveloped viruses have been established, standardized data on their optimum virucidal concentrations against SARS-CoV-2 and effects on viral RNA stability are scarce. Thus, we aimed to determine the optimum virucidal concentrations of GuHCl and GITC against SARS-CoV-2 compared to influenza A virus (IAV), another enveloped respiratory virus. We also evaluated the effectiveness of viral RNA stabilization at the determined optimum virucidal concentrations under high-temperature conditions (35°C) using virus-specific real-time reverse transcription polymerase chain reaction. Both viruses were potently inactivated by 1.0 M GITC and 2.5 M GuHCl, but the GuHCl concentration for efficient SARS-CoV-2 inactivation was slightly higher than that for IAV inactivation. GITC showed better viral RNA stability than GuHCl at the optimum virucidal concentrations. An increased concentration of GuHCl or GITC increased viral RNA degradation at 35°C. Our findings highlight the need to standardize GuHCl and GITC concentrations in virus lysis/transport buffers and the potential application of these guanidine-based salts alone as virus inactivation solutions in SARS-CoV-2 and IAV molecular diagnostics.

An Investigation on Linker Modifications of Cyanoguanidine-Based P2X7 Receptor Antagonists.

Despite their acknowledged significance in the inflammatory signalling cascade across a range of disease states, P2X7R antagonists have not yet proven to be effective in clinical trials. In this study, we present findings on P2X7 receptor antagonists that are based on a core adamantyl-cyanoguanidine-quinoline lead. To investigate the specific features of the cyanoguanidine moiety that influence compound potency we carried out a structure-activity relationship (SAR) study. Compound potency was assessed using an in vitro dye-uptake assay measuring P2X7R pore formation. While none of the compounds displayed superior potency to the lead, we established key structural requirements for potent P2X7R antagonism. An additional SAR using different aryl groups was performed based on the promising activity displayed by the squaramide derivative.