Non-competitive Research Articles

Inhibitory mechanism of vortioxetine on CYP450 enzymes in human and rat liver microsomes.

Vortioxetine is a novel anti-major depression disorder drug with a high safety profile compared with other similar drugs. However, little research has been done on drug-drug interactions (DDI) about vortioxetine. In this paper, the inhibitory effect of vortioxetine on cytochrome P450 (CYP450) and the type of inhibitory mechanism were investigated in human and rat liver microsomes. We set up an in vitro incubation system of 200μL to measure the metabolism of probe substrates at the present of vortioxetine at 37°C. The concentrations of the metabolites of probe substrates were all measured by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method. It was found no time-dependent inhibition (TDI) of vortioxetine through determination of half-maximal inhibitory concentration (IC50) shift values. The enzymes and metabolites involved in this experiment in human and rats were as follows: CYP3A4/CYP3A (midazolam); CYP2B6/CYP2B (bupropion); CYP2D6/CYP2D (dextromethorphan); CYP2C8/CYP2C-1 (amodiaquine); CYP2C9/CYP2C-2 (losartan); and CYP2C19/CYP2C-3 (mephenytoin). We found that vortioxetine competitively inhibited CYP2C19 and CYP2D6 in human liver microsomes (HLMs) with inhibition constant (Ki) values of 2.17μM and 9.37μM, respectively. It was noncompetitive inhibition for CYP3A4 and CYP2C8, and its Ki values were 7.26μM and 6.96μM, respectively. For CYP2B6 and CYP2C9, vortioxetine exhibited the mixed inhibition with Ki values were 8.55μM and 4.17μM, respectively. In RLMs, the type of vortioxetine inhibition was uncompetitive for CYP3A and CYP2D (Ki = 4.41 and 100.9μM). The inhibition type was competitive inhibition, including CYP2B and CYP2C-2 (Ki = 2.87 and 0.12μM). The inhibition types of CYP2C-1 and CYP2C-3 (Ki = 39.91 and 4.23μM) were mixed inhibition and noncompetitive inhibition, respectively. The study of the above mechanism will provide guidance for the safe clinical use of vortioxetine so that the occurrence of DDI can be avoided.

Evaluating the effects of pH and temperature on sulphate-reducing bacteria and modelling of their effects in stirred bioreactors

ABSTRACT Sulphate (SO4) abundance in the earth’s crust contributes largely to industrial wastewater contamination lowering the pH, which exuberates the dissolution of metals forming acidic drainages. Biological sulphate reduction as a remediation process can be affected by factors such as pH, temperature and high sulphide concentrations. In this study, sulphate-reducing bacterial community enriched from mine wastewaters was applied in semi-automated bioreactors to assess the effects of these factors on microbial sulphate reduction capacities. Low pH (3.5) and temperature (10°C) were observed to promote the toxicity of sulphur-reduced species on the consortium while mesophilic temperature (25°C) and near neutral pH (6.2) were observed to induce optimum SO4 reduction attaining a maximum of 95% SO4 reduction. Obtained SO4 reduction dynamics data was then applied in formulating a unique non-competitive inhibition equation that models biogeochemical events during SO4 reduction under varied pH and temperature conditions and predicts the efficacy of a bioremediation system.

Development and In silico ADMET Analysis of Novel Flavonoids Derivatives as Potent, Non-Competitive and Selective PTP1B Inhibitors

Diabetes mellitus is a serious disease that threatens human health. The most prevalent type of diabetes mellitus is type 2 (T2DM) which is characterized by the lack of insulin secretion and resistance to insulin in target tissues. Protein Tyrosine Phosphatase 1B (PTP1B) plays an important role in the dephosphorylation of phospho-tyrosine residues from the insulin receptor and its substrate. Studies have shown that overexpression of PTP1B protein and its increased activation have been associated with insulin resistance and thus it is a promising therapeutic target for type 2 diabetes. The discovery of selective and effective inhibitors on the active target site present a great challenge due to the site charge and the high degree of conserved active site. Therefore, the identified allosteric site of enzyme PTP1B was chosen to design and evaluate ligands based on effectiveness and selectivity, then filter the compounds based on their ADMET properties in silico to identify the potential inhibitors of the PTP1B enzyme. Among the designed molecules, 14 compounds were obtained with better affinity and selectivity for PTP1B. Some of these compounds showed acceptable pharmacokinetic properties of ADMET and were expected to be non-mutagenic. Thus, they can be considered as promising PTP1B inhibitors.

The influence of coordination compounds with malatogermanate/stannate anions and 1,10-phenanthroline cations of 3D metals on α-L-rhamnosidase activity of Penicillium tardum, Penicillium restrictum and Eupenicillium erubescens

The search for effectors capable of influencing the catalytic activity of enzymes is an important area of modern enzymology. The aim of the study was to investigate the ability of 6 coordination compounds with malatogermanate/stannate anions and 1,10-phenanthroline cations of 3d metals to modify α-L-rhamnosidase activity of Penicillium tardum, Penicillium restrictum and Eupenicillium еrubescens strains. α-L-Rhamnosidase activity was determined by the Davis method using naringin as a substrate. It was demonstrated­ that [Ni(phen)3]2[{Sn(HMal)2(Mal)}Cl]•14H2O) in 0.1% concentration had the most pronounced activating effect on α-L-rhamnosidase activity of all strains studied. Noncompetitive inhibition of α-L-rhamnosidase in E. еrubescens by [Cu(phen)3]2[{Sn(HMal)2(Mal)}Cl]•10H2O was shown. The obtained results expand the idea of glycosidases possible activators and inhibitors and indicate the perspective of their use in modern biotechnological processes. Keywords: d-metals, double coordination compounds, Eupenicillium erubescens, germanium(IV), Penicillium restrictum, Penicillium tardum, stannum(IV), α-L-rhamnosidase

Redefine the role of d-α-Tocopheryl polyethylene glycol 1000 succinate on P-glycoprotein, multidrug resistance protein 1, and breast cancer resistance protein mediated cancer multidrug resistance

Cancer drug resistance is an ever-changing problem that most patients need to face in their later stages of treatment, especially the multidrug resistant (MDR) type. The drug efflux transporters, including P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP1), and breast cancer resistance protein (BCRP), play the crucial roles in this sophisticated battle. In recent decades, researchers try to find potential inhibitors to impede the drug efflux function of above transporters. d-α-Tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS) is a prevalently used excipient in the formulation design. In the present study, the modulatory effects and mechanisms of vitamin E TPGS on the efflux transporters were investigated. And the cancer MDR reversing ability of vitamin E TPGS was evaluated as well. Stable-cloned transporter over-expressed cell lines were used for mechanisms study, while several types of MDR cancer cell lines were adopted as reversing evaluation models. The results exhibited that vitamin E TPGS significantly inhibited the efflux function of P-gp, MRP1, and BCRP under non-cytotoxic concentrations, but not influencing the protein expression levels. Through efflux assay and molecular docking, vitamin E TPGS was found to be an uncompetitive, non-competitive, and competitive inhibitor on chemotherapeutic drug doxorubicin efflux in P-gp, MRP1, and BCRP over-expressing cell lines, respectively. Furthermore, the basal ATPase activity of three transporters were significantly inhibited by vitamin E TPGS at 10 μM. And the cell membrane fluidity of P-gp over-expressing cell line was enhanced by 22.58% with 5 μM vitamin E TPGS treatment, compared to the parental Flp-In™-293 cell line (without P-gp). The resistance reversing ability of vitamin E TPGS was prominent in MCF-7/DOX MDR breast cancer cell line, which over-expressed P-gp, MRP1, and BCRP. These significant results suggested that vitamin E TPGS is a promising modulator on transporters mediated cancer MDR. Vitamin E TPGS is not an inert excipient, but possesses MDR-reversing pharmacological effects, and deserves a re-purposing application on the future combinatorial regimen design for MDR cancer treatment.

Identification of 1,3,4-oxadiazolyl-containing β-carboline derivatives as novel α-glucosidase inhibitors with antidiabetic activity

In this study, we designed and synthesized a novel class of 1,3,4-oxadiazolyl-containing β-carboline derivatives, i.e., compounds f1∼f35 as potential α-glucosidase inhibitors. All the synthesized compounds possessed outstanding α-glucosidase inhibitory activity with the IC50 values in the range of 3.07–15.49 μM, representing that they are 36∼183-fold more active than a positive control, acarbose (IC50 = 564.28 μM). Among them, compound f26 exhibited the highest α-glucosidase inhibitory activity (IC50 = 3.07 μM) and was demonstrated to function as a reversible and noncompetitive inhibitor. Mechanistic studies by means of 3D fluorescence spectra, CD spectra and molecular docking suggested that complexation of compound f26 with α-glucosidase through hydrogen bonds and hydrophobic interactions, led to changes in the conformation and secondary strictures of α-glucosidase and further the inhibition of the enzymatic activity. In vivo results showed that oral administration of compound f26 (50 mg/kg/day) could obviously reduce the levels of fasting blood glucose and improve glucose tolerance and dyslipidemia in diabetic mice. The present findings suggest that compound f26 is exploitable as a potential lead compound for the development of new α-glucosidase inhibitors with antidiabetic activity.

Uncovering the anti-obesity constituents in Ginkgo biloba extract and deciphering their synergistic effects

Obesity has been recognized as a key risk factor for multiple metabolic disorders, including diabetes, cardiovascular diseases and many types of cancer. Herbal medicines have been frequently used for preventing and treating obesity in many countries, but in most cases, the key anti-obesity constituents in herbs and their anti-obesity mechanisms are poorly understood. This study demonstrated a case study for uncovering the anti-obesity constituents in an anti-obesity herbal medicine (Ginkgo biloba extract) and deciphering their synergistic effects via targeting human pancreatic lipase (hPL). Following screening the anti-hPL effects of eighty herbal medicines, Ginkgo biloba extract (GBE50) was found with the most potent anti-hPL activity. Global chemical profiling of herbal constituents coupling with hPL inhibition assay revealed that the bioflavonoids and several flavonoids in GBE50 were key anti-hPL constituents. Among all tested thirty-eight constituents, sciadopitysin, bilobetin, quercetin, isoginkgetin, and ginkgetin showed potent anti-hPL effects (IC50 values <2.5 μM). Inhibition kinetic analyses suggested that sciadopitysin, bilobetin, quercetin, isoginkgetin, and ginkgetin acted as non-competitive inhibitors of hPL, with the Ki values were <2 μM. Docking simulations revealed that four bioflavonoids (sciadopitysin, bilobetin, isoginkgetin, and ginkgetin) could tightly bind on hPL at cavity 2, which it is different from the binding cavity of quercetin on hPL. Further investigations demonstrated that the combinations of quercetin and one bioflavonoid-type hPL inhibitor (sciadopitysin or bilobetin) showed synergistic anti-hPL effects, suggesting that the multi-components in GBE50 may generate more potent anti-hPL effect. Collectively, our findings uncovered the anti-obesity constituents in GBE50, and explored their anti-hPL mechanisms as well as synergistic effects at molecular levels, which will be very helpful for further understanding the anti-obesity mechanisms of Ginkgo biloba.

Novobiocin blocks nucleic acid binding to Polθ and inhibits stimulation of its ATPase activity.

Polymerase theta (Polθ) acts in DNA replication and repair, and its inhibition is synthetic lethal in BRCA1 and BRCA2-deficient tumor cells. Novobiocin (NVB) is a first-in-class inhibitor of thePolθ ATPase activity, and itiscurrently being tested in clinical trials as an anti-cancer drug. Here, we investigated the molecular mechanism of NVB-mediated Polθ inhibition. Using hydrogen deuterium exchange-mass spectrometry (HX-MS), biophysical, biochemical, computational and cellular assays, we found NVB is a non-competitive inhibitor of ATP hydrolysis. NVB sugar group deletion resulted indecreased potency and reduced HX-MS interactions, supporting a specific NVB binding orientation. Collective results revealed that NVB binds toan allosteric site to block DNA binding, both in vitro and in cells. Comparisons of The Cancer Genome Atlas (TCGA) tumors and matched controls implied that POLQ upregulation in tumors stems from its role in replication stress responses to increased cell proliferation: this can now be tested in fifteen tumor types by NVB blocking ssDNA-stimulation of ATPase activity, required for Polθ function at replication forks and DNA damage sites. Structural and functional insights provided in thisstudy suggest a path for developing NVB derivatives with improved potency for Polθ inhibition by targeting ssDNA binding with entropically constrained small molecules.

Antihypertensive peptide resources map of ribulose-1,5-bisphosphate carboxylase/oxygenases (RuBisCO) in angiosperms: Revealed by an integrated in silico and in vitro approach

As the most abundant protein on earth, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) has been considered a promising resource of functional foods. This study aimed to explore the full potential of plant RuBisCO proteins as precursors of antihypertensive peptides on a large scale. In total, 12,766 RuBisCO large subunit and 1,020 RuBisCO small subunit sequences of angiosperms were collected for simulated proteolysis and evaluation of antihypertensive potential, revealing a vast reservoir of antihypertensive peptides. Moreover, RuBisCO-derived novel antihypertensive peptides TTVW, TMW, and VPCL were identified with in vitro IC50 of 12.89 ± 0.82, 23.97 ± 1.02, and 339.12 ± 21.64 μM, respectively. Notably, TTVW and TMW are noncompetitive inhibitors predicted to bound adjacent to the catalytic region of ACE, while VPCL is a competitive inhibitor predicted to bound to the central active site inside ACE. Overall, this work provides a powerful theoretical guidance in developing antihypertensive functional foods utilizing plant RuBisCO.

Isolation of new bibenzyl derivatives from Bulbophyllum auricomum and evaluation of their α-glucosidase inhibitory activity

Bulbophyllum auricomum Lindl., commonly referred to as the 'Royal Thazin' in Myanmar, holds the esteemed status of being the national flower of the country. In our research, we delved into the ethyl acetate extract derived from the pseudobulbs and roots of this plant. This extract exhibited significant inhibitory activity against the α-glucosidase enzyme, prompting a detailed investigation into its active compounds. Our study resulted in the isolation and characterization of several compounds, including a novel natural product named 2-(4-hydroxyphenyl) ethyl 3-(2-hydroxyphenyl) propanoate. Additionally, we identified two previously unreported inseparable isomeric bibenzyls, namely 7-hydroxybatatasin III and 8-hydroxybatatasin III. Furthermore, we isolated six known compounds, including batatasin III, lusianthridin, tristin, phochinenin G, phoyunnanin E, and phoyunnanin C. Significantly, our study unveiled that phochinenin G acts as a reversible noncompetitive inhibitor of the α-glucosidase enzyme. This compound displayed greater inhibitory activity than the standard drug acarbose.

Design, Synthesis, and Assay of New N-acyl-4-(4-aminoalkoxy- phenyl)- thiazole-2-amine Derivatives as Acetylcholinesterase Inhibitors

Background: Thiazoles are an important class of heterocyclic compounds with many biological effects, including anticholinesterase activity. Objective: The purpose of this work was to synthesize new thiazole derivatives and evaluate as acetylcholinesterase inhibitors (AChEIs) for Alzheimer’s disease. Methods: A series of new N-acyl-4-(4-aminoalkoxy-phenyl)-thiazole-2-amine derivatives was designed and synthesized. Ellman assay protocol was used for the AchE and BuChE inhibitory activity. To correlate better the drug-like property, the theoretical prediction was calculated using Mol inspiration software 2015 online. The potential binding mode of compounds with AChE and BuChE was investigated by the molecular docking simulation. Results: All synthesized compounds exhibited a certain inhibitory activity on AChE and 5p had the most effective selective inhibitory effect on AChE. The inhibitory form of 5p on AChE was shown to be a combination of competitive and noncompetitive inhibition, according to enzyme kinetic tests. Docking simulation studies revealed that the binding energy of 5p with AChE was lower than that of it with BuChE, which also explained the selective inhibitory activity of 5p on AChE. Conclusion: These results provided valuable information for the design of potent AChEIs, and it was believed that 5p could be a promising lead structure for its further development for the treatment of AD.

Spectral characterization and binding dynamics of bioactive compounds from Chlorella minutissima against α-glucosidase: An in vitro and in silico approach

Management of type-II diabetes through regulating the activity of α-glucosidase is a promising therapeutic approach. Here, bioassay-guided isolation of algal secondary metabolites (ASM) from microalgae (Chlorella minutissima) inhibiting α-glucosidase was explored. In this study, the purified column fractions (SIV-P2) of C. minutissima acetone extract obtained from flash chromatography exhibited α-glucosidase inhibition potential with the IC50 value of 1.61 mg mL−1, and the active fractions were dominated by terpenoids and alkaloids. Further, molecular dynamics simulations revealed that Lucidine B, an alkaloid compound possesses the least binding energy (BE) of −318 KJ mol−1 when compared to the standard drug acarbose (−216.781 KJ mol−1). Lucidine B formed a hydrogen bond with Glu408 which possibly induced cleft closure and prevented the substrate entry to the active site (non-competitive inhibition). The present study unveils that ASM could be exploited as a potential inhibitor of α-glucosidase and may be used for the alleviation of type-II diabetes.

Docking Complexes of Active Phytochemicals with VK-deficient Genes

Background:: Vitamin K (VK) deficiency occurs when the body does not have enough vitamin K to produce proteins that are essential for blood clotting and bone health. Vitamin K is a cofactor that plays a major role in various comorbidities. Over the years, efforts have been made to identify the interaction between natural compounds, such as K vitamers, that could play a sig-nificant role in regulation of the blood coagulation. We intended to obtain insights into the poten-tial therapeutic implications of phytochemicals for treating VK deficiency-related diseases by in-vestigating the interactions between phytochemicals and VK-deficient genes. Methods:: On active phytochemical docking complexes with VK-deficient genes, there is no spe-cific information available as of yet. In this computationally aided docking study, we were inter-ested in finding the pathogenic blood coagulation-related genes that are linked to VK deficiency. Based on literature reviews and databases, bioactive phytochemicals and other ligands were con-sidered. To provide precise predictions of ligand-protein interactions, docking parameters and scoring algorithms were thoroughly optimized. We have performed molecular docking studies and observed the way the complexes interact. Results:: Specific binding interactions between active phytochemicals and VK pathogenic muta-tions have been identified by the docking study. Hydrogen bonds, van der Waals interactions, and hydrophobic contacts, which are indications of high binding affinities, have been observed in the ligand-protein complexes. Few phytochemicals have demonstrated the ability to interact with the targets of VK-deficient genes, indicating their capacity to modify pathways relevant to VK defi-ciency. The results of the docking study have explained the three pathogenic genes, viz. VWF, F8, and CFTR, wherein VWF and F8 play important roles in blood coagulation and people with cyst-ic fibrosis, to have a deficiency in vitamin K. Thirty-five compounds from different plant and natural sources were screened through molecular docking, out of which two compounds have been considered as controls, including curcumin and warfarin (R-warfarin and S-warfarin), which are the most common anticoagulants readily available in the market. They act by inhibiting vita-min K epoxide reductase (VKOR), which is needed for the gamma-carboxylation of vitamin K-dependent factors. Conclusion:: A focus on other compounds, like theaflavin, ellagic acid, myricetin, and catechin was also made in this study as they show more binding affinity with the three pathogenic proteins. Based on the results, the complexes have been found to possess great potential and thus may be considered for further interaction studies. The potential for active phytochemicals to generate docking complexes with VK-deficient genes is highlighted in this computational analysis. Health disorders related to VK insufficiency may be significantly impacted by these interactions. To val-idate the expected interactions and determine the therapeutic potential of the identified phyto-chemicals, more experimental research, including in vitro and in vivo experiments, is needed.

Novel spiro[pyrrolidine-2,3′-quinoline]-2′-one derivatives containing piperazine fragment as potential chitin synthase inhibitors and antifungal agents: Design, synthesis and biological evaluation

A series of spiro[pyrrolidine-2,3′-quinoline]-2′-one derivatives were designed and synthesized for the discovery of novel antifungal drugs. The bioactivities of all derivatives were screened by evaluating their inhibitory effects against chitin synthase (CHS) and antimicrobial activities in vitro. Enzyme inhibition experiments showed that all the synthesized compounds inhibited the chitin synthase. Compounds 4d, 4k, 4n and 4o showed inhibitory effects against CHS with IC50 values which were close to that of the control drug (polyoxin B). The results of enzyme kinetics experiment showed that these compounds were non-competitive inhibitors of chitin synthase (Ki of compound 4o is 0.14 mM). Antimicrobial experiments showed that these compounds exhibited moderate to excellent antifungal activity against pathogenic fungal strains while the compounds showed little potency against bacteria. Among them, compounds 4d, 4f, 4k and 4n showed stronger antifungal activities against C. albicans than those of fluconazole and polyoxin B. Compounds 4f, 4n and 4o showed better antifungal activities against A. flavus than those of fluconazole and polyoxin B. Compound 4d showed similar activity to that of fluconazole and stronger activity than those of polyoxin B against C. neoformans and A. fumigatus. It is also showed that these compounds have the potency against drug-resistant fungal variants. The results of sorbitol protection assay and evaluation of antifungal activity against micafungin-resistant strains experiment further illustrated that these compounds inhibited the synthesis of chitin of fungal cell wall. Drug combination experiments showed that these compounds had synergistic or additive effects when combined with fluconazole or polyoxin B. The synergistic effects with polyoxin B further confirmed the compounds were non-competitive inhibitors of chitin synthase. Additionally, docking studies showed that these compounds had strong affinity with chitin synthase from C. albicans (CaChs2). These results indicate that the target of these synthesized compounds is chitin synthase, and these compounds had excellent antifungal activity while possessed the potency against drug-resistant fungal variants.

Identification of Three Novel Angiotensin-I-Converting Enzyme Inhibitory Peptides from Cassia Obtusifolia Seeds and Evaluation of their Inhibition Mechanisms

Angiotensin-I-converting enzyme inhibitory peptides were isolated from Cassia obtusifolia seeds by alcalase hydrolysis. Using ultrafiltration, the peptides were divided into four fractions (&lt;1, 1–3, 3–5, &gt;5 kDa). The fraction below 1 kDa exhibited the appropriate ACE inhibition (IC50 = 65.88 μg/mL), and was further purified by gel filtration chromatography, which displayed better angiotensin-I-converting enzyme inhibitory activity (IC50 = 53.67 μg/mL). The amino acid sequences of three novel angiotensin-I-converting enzyme inhibitory peptides were identified by liquid chromatography with tandem mass spectrometry as follows: IFPGCAN (IC50 = 23.71 μM), TEDFLTQ (IC50 = 32.82 μM), and GDEGSGGIIR (IC50 = 18.21 μM). Further experiments demonstrated that IFPGCAN and TEDFLTQ were competitive inhibitors, while GDEGSGGIIR was a noncompetitive inhibitor of the angiotensin-I-converting enzyme. Three peptides could form hydrogen bonds with the active site of the angiotensin-I-converting enzyme, according to molecular docking simulations of their interaction with the angiotensin-I-converting enzyme.

Design, synthesis and evaluation the bioactivities of novel 8‑methoxy-1-azacoumarin-3-carboxamide derivatives as anti-diabetic agents

In this study, a novel series of 8‑methoxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acid and N-substituted 8‑methoxy-2-oxo-1,2-dihydroquinoline-3-carboxamide derivatives 2–10 were designed, synthesized, and screened for their in vitro α-amylase, α-glucosidase and DPP-4 enzymes resulting in effective anti-diabetic agents. The research results showed that these compounds had significant inhibitory effects on both α-amylase and α-glucosidase enzymes. Specifically, compound 4 demonstrated the most potency with IC50 of 30.50±2.67 and 19.98±3.24µM for α-glucosidase and α-amylase activities respectively, which was significantly more powerful than the drug Acarbose (IC50 = 48.97±3.42µM and 16.59±3.78µM). Also, compound 4 Exhibits strong inhibitory activity against DPP-4 with an IC50 value of 0.035±6.65nM as compared to the positive control sitagliptin (IC50 =0.014±6.91nM).Also, we had performed the kinetic study for the most potent compound 4 on α-amylase and α-glucosidase enzymes to study the type of inhibition of enzymes. The results showed that compound 4 was non-competitive inhibitor that can bind to an enzyme at a site other than the active site, known as the allosteric site. Investigating the potential of compound 4 to treat diabetes, we evaluated its cytotoxic and antioxidant properties. Our results indicated that it had a highly effective scavenging ability for DPPH with an IC50 value of 15.45±3.83µM, outperforming ascorbic acid (IC50 =7.24±8.01µM), the positive control. Exhilarated by these promising findings, we continue to explore the varied possibilities for these compounds.

Allosteric inhibition of myosin by phenamacril: a synergistic mechanism revealed by computational and experimental approaches.

Myosin plays a crucial role in cellular processes, while its dysfunction can lead to organismal malfunction. Phenamacril (PHA), a highly species-specific and non-competitive inhibitor of myosin I (FgMyoI) from Fusarium graminearum, has been identified as an effective fungicide for controlling plant diseases caused by partial Fusarium pathogens, such as wheat scab and rice bakanae. However, the molecular basis of its action is still unclear. This study used multiple computational approaches first to elucidate the allosteric inhibition mechanism of FgMyoI by PHA at the atomistic level. The results indicated the increase of adenosine triphosphate (ATP) binding affinity upon PHA binding, which might impede the release of hydrolysis products. Furthermore, simulations revealed a broadened outer cleft and a significantly more flexible interface for actin binding, accompanied by a decrease in signaling transduction from the catalytic center to the actin-binding interface. These various effects might work together to disrupt the actomyosin cycle and hinder the ability of motor to generate force. Our experimental results further confirmed that PHA reduces the enzymatic activity of myosin and its binding with actin. Therefore, our findings demonstrated that PHA might suppress the function of myosin through a synergistic mechanism, providing new insights into myosin allostery and offering new avenues for drug/fungicide discovery targeting myosin. © 2023 Society of Chemical Industry.

The Combined Effect of Donepezil and Lovastatin on the Electrical Activity of Hippocampal Pyramidal Neurons in a rat model of Alzheimer’s disease

Background: Donepezil, a noncompetitive acetylcholinesterase inhibitor, is prescribed to treat mild to moderate Alzheimer's disease but it only has moderate performance. Therefore, combination therapies are more effective. There is much evidence suggesting that statins have neuroprotective effects on neurological disorders including Alzheimer's disease. The present study aimed to investigate the combined effects of Donepezil and Lovastatin on the activity of the pyramidal neurons of the CA1 hippocampus.&#x0D; Methods: In the present experiment study, adult male rats were divided into 3 groups: Nucleus Basalis Magnocellularis (NBM) lesion (which received electrically- induced lesion (0.5 mA, 3s) in NBM) group, NBM lesion + injection Donepezil 5mg/kg-Lovastatin 10mg/kg, NBM lesion+ injection Donepezil 15mg/kg-Lovastatin 30mg/kg. Spontaneous activity of pyramidal neurons in CA1 region to injection of Donepezil-Lovastatin was investigated in a rat model of Alzheimer's disease.&#x0D; Results: The results of this study showed that electrical lesion of NBM leads to a decrease in the activity frequency of pyramidal neurons in the CA1 region. Administration of Donepezil 5mg/kg-Lovastatin 10mg/kg increased the frequency of pyramidal neurons in rat model of Alzheimer's disease.&#x0D; Conclusion: The results of this study suggest that co-administration of Donepezil-Lovastatin (low doses) increases the activity of the CA1 pyramidal neurons in a rat model of Alzheimer’s disease.

DNA protection, molecular docking, enzyme inhibition and enzyme kinetic studies of 1,5,9-epideoxyloganic acid isolated from Nepeta aristata with bio-guided fractionation

1,5,9-epideoxyloganic acid (ELA) was isolated from the aerial parts of endemic Nepeta aristata Boiss Et Kotschy Ex Boiss crude extract (methanol:chloroform) using silica gel (hexane, chloroform, ethyl acetate, and methanol) and sephadex LH-20 (65% methanol-35% chloroform) columns. Activity-guided isolation was performed on methanol sub-fractions with DNA protection and enzyme inhibitory activities, and then the ELA was purified by prep-HPLC. The ELA structure, bio-guided isolate, was determined via 1H NMR, 13C NMR, and MS spectrometry. ELA's enzyme inhibition and DNA protection activities were investigated and compared with standard drugs. The inhibition capacity of ELA against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), urease, carbonic anhydrase (CA), α-glucosidase, α-amylase, lipase, and tyrosinase enzymes was evaluated by kinetic and molecular docking results. The ELA displayed the best inhibitory activity on AChE, BChE, α-glucosidase, urease, α-amylase, and tyrosinase with IC50 values of 2.53 ± 0.27, 3.75 ± 0.11, 3.98 ± 0.07, 4.40 ± 0.01, 6.43 ± 0.54 and 7.39 ± 0.00 µg/mL, respectively. ELA acted as a competitive inhibitor against BChE and α-glucosidase and a non-competitive inhibitor against AChE. The ELA’s binding affinity values on AChE, BChE, and α-glucosidase were −7.70, −8.50, and −8.30 kcal/mol, respectively. DNA protection activity of the ELA molecule was determined as 57.53% for form I and 53.57% for form II. In conclusion, the inhibitory activity of ELA demonstrated its effectiveness in terms of its suitability in the pharmaceutical industry. Communicated by Ramaswamy H. Sarma

Partial Reversible Inhibition of Enzymes and Its Metabolic and Pharmaco-Toxicological Implications.

Partial reversible inhibition of enzymes, also called hyperbolic inhibition, is an uncommon mechanism of reversible inhibition, resulting from a productive enzyme-inhibitor complex. This type of inhibition can involve competitive, mixed, non-competitive and uncompetitive inhibitors. While full reversible inhibitors show linear plots for reciprocal enzyme initial velocity versus inhibitor concentration, partial inhibitors produce hyperbolic plots. Similarly, dose-response curves show residual fractional activity of enzymes at high doses. This article reviews the theory and methods of analysis and discusses the significance of this type of reversible enzyme inhibition in metabolic processes, and its implications in pharmacology and toxicology.