Potential Lead Structure Research Articles

Newly synthesized based Schiff of phenylferrocene: Molecular and crystal structures, Density Functional Theory calculations, Hirshfeld surface analyses, and improved molecular docking data

In three steps, ferrocene-derived Schiff bases were synthesized, beginning with an arylation reaction, followed by a reduction reaction. The last step describes a condensation reaction between 4-ferrocenylaniline 2a and various aromatic aldehydes in ethanol under reflux. Several techniques were used to determine the structures of the prepared compounds, including 1HNMR , 13CNMR , FTIR, UV/Vis and single crystal X-ray diffraction for compounds 3a, 3f, and 3j. Hirshfeld surface analysis measurements were also performed to measure the interaction energies between molecules. Moreover, the geometric structure of the selected compound (3a, 3f, and 3j) was optimized using a computational analysis involving density functional theory (DFT) calculations based on B3LYP/6–31 G (d, p). Strong binding affinities were observed via both hydrophobic and H-bond interactions with pertinent molecules when molecular docking investigations were conducted on the target crystal structure, the FabX (7e1q). The maximum binding energy is found in the 3d, at -7.99 kcal/mol. Therefore, it is feasible that this structure will work well as a potential lead structure for the synthesis and design of stronger inhibitors that can be used in conjunction with anti-corrosive drugs to treat gastric cancer.

Full Profiling of GE81112A, an Underexplored Tetrapeptide Antibiotic with Activity against Gram-Negative Pathogens.

After the first total synthesis combined with structure revision, we performed thorough in vitro and in vivo profiling of the underexplored tetrapeptide GE81112A. From the determination of the biological activity spectrum and physicochemical and early absorption-distribution-metabolism-excretion-toxicity (eADMET) properties, as well as in vivo data regarding tolerability and pharmacokinetics (PK) in mice and efficacy in an Escherichia coli-induced septicemia model, we were able to identify the critical and limiting parameters of the original hit compound. Thus, the generated data will serve as the basis for further compound optimization programs and developability assessments to identify candidates for preclinical/clinical development derived from GE81112A as the lead structure. IMPORTANCE The spread of antimicrobial resistance (AMR) is becoming a more and more important global threat to human health. With regard to current medical needs, penetration into the site of infection represents the major challenge in the treatment of infections caused by Gram-positive bacteria. Considering infections associated with Gram-negative bacteria, resistance is a major issue. Obviously, novel scaffolds for the design of new antibacterials in this arena are urgently needed to overcome this crisis. Such a novel potential lead structure is represented by the GE81112 compounds, which inhibit protein synthesis by interacting with the small 30S ribosomal subunit using a binding site distinct from that of other known ribosome-targeting antibiotics. Therefore, the tetrapeptide antibiotic GE81112A was chosen for further exploration as a potential lead for the development of antibiotics with a new mode of action against Gram-negative bacteria.

Total Synthesis of GE81112A: An Orthoester-Based Approach.

The GE81112 series, consisting of three naturally occurring tetrapeptides and synthetic derivatives, is evaluated as a potential lead structure for the development of a new antibacterial drug. Although the first total synthesis of GE81112A reported by our group provided sufficient amounts of material for an initial in depth biological profiling of the compound, improvements of the routes toward the key building blocks were needed for further upscaling and structure-activity relationship studies. The major challenges identified were poor stereoselectivity in the synthesis of the C-terminal β-hydroxy histidine intermediate and a concise access to all four isomers of the 3-hydroxy pipecolic acid. Herein, we report a second-generation synthesis of GE81112A, which is also applicable to access further representatives of this series. Based on Lajoie's ortho-ester-protected serine aldehydes as key building blocks, the described route provides both a satisfactory improvement in stereoselectivity of the β-hydroxy histidine intermediate synthesis and a stereoselective approach toward both orthogonally protected cis and trans-3-hydroxy pipecolic acid.

Inhibition Analysis and High-Resolution Crystal Structure of Mus musculus Glutathione Transferase P1-1.

Multidrug resistance is a significant barrier that makes anticancer therapies less effective. Glutathione transferases (GSTs) are involved in multidrug resistance mechanisms and play a significant part in the metabolism of alkylating anticancer drugs. The purpose of this study was to screen and select a lead compound with high inhibitory potency against the isoenzyme GSTP1-1 from Mus musculus (MmGSTP1-1). The lead compound was selected following the screening of a library of currently approved and registered pesticides that belong to different chemical classes. The results showed that the fungicide iprodione [3-(3,5-dichlorophenyl)-2,4-dioxo-N-propan-2-ylimidazolidine-1-carboxamide] exhibited the highest inhibition potency (ΙC50 = 11.3 ± 0.5 μΜ) towards MmGSTP1-1. Kinetics analysis revealed that iprodione functions as a mixed-type inhibitor towards glutathione (GSH) and non-competitive inhibitor towards 1-chloro-2,4-dinitrobenzene (CDNB). X-ray crystallography was used to determine the crystal structure of MmGSTP1-1 at 1.28 Å resolution as a complex with S-(p-nitrobenzyl)glutathione (Nb-GSH). The crystal structure was used to map the ligand-binding site of MmGSTP1-1 and to provide structural data of the interaction of the enzyme with iprodione using molecular docking. The results of this study shed light on the inhibition mechanism of MmGSTP1-1 and provide a new compound as a potential lead structure for future drug/inhibitor development.

QSAR modeling and molecular docking studies of 2-oxo-1, 2-dihydroquinoline-4- carboxylic acid derivatives as p-glycoprotein inhibitors for combating cancer multidrug resistance

Multidrug resistance (MDR) proteins related to the ATP-binding cassette family are found in a very wide range of human tumors and result in therapeutic failure. The overexpression of efflux pumps such as ABCB1 is one of the mechanisms of MDR. This paper aims to develop a reliable quantitative structure-activity relationship (QSAR) model that best describes the correlation between the activity and the molecular structures in order to predict the inhibitory biological activity towards ABCB1. In this regard, a series of quinoline derivatives of 18 compounds were analyzed using different linear and non-linear machine learning (ML) regression methods including k-nearest neighbors (KNN), decision tree (DT), back propagation neural networks (BPNN) and gradient boosting-based (GB) methods. Their aim is to explain the origin of the activity of these investigated compounds and therefore, design new quinoline derivatives with higher effect on ABCB1. A total of 16 ML predictive models were developed on different number of 2D and 3D descriptors and were evaluated using the coefficient of determination (R2) and the root mean squared error (RMSE) statistical metrics. Among all developed models, A GB-based model in particular catboost achieved the highest predictive quality, with one descriptor, expressed by R2 and RMSE of 95% and 0.283 respectively. Molecular docking studies against the target crystal structure of the outward-facing p-glycoprotein (6C0V) revealed significant binding affinities via both hydrophobic and H-bond interactions with the relevant compounds. The 17 has shown the highest binding energy of −9.22 kcal/mol. Therefore, it can suggest that 17 may prove to be a valuable potential lead structure for the design and synthesis of more potent P-glycoprotein inhibitors for combination used with anti-cancer drugs for cancer multidrug resistance management.

Anticancer potential of oroxylin A: from mechanistic insight to synergistic perspectives.

Oroxylin A (OA), a well-known constituent of the root of Scutellariae plants, has been used in ethnomedicine already for centuries in treating various neoplastic disorders. However, only recent molecular studies have revealed the different mechanisms behind its action, demonstrating antiproliferative, anti-inflammatory, and proapoptotic effects, restricting also the spread of cancer cells to distant organs. A variety of cellular targets and modulated signal transduction pathways regulated by OA have been determined in diverse cells derived from different malignant tissues. In this review article, these anticancer activities are thoroughly described, representing OA as a potential lead structure for the design of novel more potent anticancer medicines. In addition, co-effects of this natural compound with conventional anticancer agents are analyzed and the advantages provided by nanotechnological methods for more efficient application of OA are discussed. In this way, OA might represent an excellent example of using ethnopharmacological knowledge for designing modern medicines.

Design, Synthesis, Mode of Action and Herbicidal Evaluation of Quinazolin-4(3H)-one Derivatives Based on Aryloxyphenoxypropionate Motif

To discover new acetyl-CoA carboxylase (ACCase) inhibiting-based herbicides, twenty-nine novel quinazolin-4(3H)-one derivatives were designed and synthesized based on the aryloxyphenoxypropionate motif. The bioassay results showed that most of the target compounds showed better pre-emergent herbicidal activity against monocotyledonous weeds in a greenhouse. Especially, when applied at 375 g ha−1 under pre-emergence conditions, compound QPP-7 displayed excellent herbicidal activity against monocotyledonous weeds (i.e., E. crusgalli, D. sanguinalis, P. alopecuroides, S. viridis, E. indica, A. fatua, E. dahuricu, S. alterniflora) with inhibition rate >90%, and displayed excellent crop safety to O. sativa, T. aestivum, G. spp, and A. hypogaea. The study of structure-activity relationship (SAR) revealed that the herbicidal activity of target compounds is strongly influenced by the spatial position of R group and the bulk of R1 group on quinazolin-4(3H)-one, and the (R = 6-F, R1 = Me) pattern is confirmed as the optimal orientation. Furthermore, the molecular docking study and the good inhibitory activity of QPP-7 against E. crusgalli ACCase enzyme (IC50 = 54.65 nM) indicated that it may be a ACCase inhibitor. Taken together, the present work demonstrated that compound QPP-7 could serve as a potential lead structure for further developing novel ACCase inhibiting-based herbicide.

3D QSAR Analysis of Flavones as Antidiabetic agents

Diabetes is the most prevailing disease worldwide and emerged as the fourth leading cause of mortality. Inhibition of intestinal α-Glucosidase enzyme is an effective approach for controlling post prandial hyperglycemia. α-Glucosidase inhibitors are known to be very effective in decreasing post-prandial hyperglycemia but the existing drugs are weak inhibitors of α-Glucosidase and also have side effects. Hence it needs for new therapeutic candidate which can effectively inhibit the activity of α-Glucosidase. Flavones recognized as the potential lead structure for many pharmacological activities. In the present research work 3D QSAR (comparative molecular field analysis and comparative molecular similarity indices analysis) was carried out on a series of flavones to identify structural requirement for effective inhibition of α-Glucosidase enzyme. The QSAR results shows that the LOO cross-validated q2 values of CoMFA and CoMSIA models are 0.742 and 0.759, respectively. The outcome of this research work could be effectively utilized for design of better α-Glucosidase inhibitors.

Design, synthesis, in vitro antiproliferative effect and in situ molecular docking studies of a series of new benzoquinoline derivatives

Quinoline derivatives have been reported to possess multi-therapeutic potential owing to the manifestations of different pharmacological effects. The current research work describes about the design and synthesis of a series of novel benzoquinoline analogues with an objective to evaluate their antiproliferative structure–activity relationship against colon, breast and hepatocellular cancers. Upon synthesis, all derivatives’ chemical structures were elucidated through FTIR, 1HNMR and 13CNMR spectroscopic analysis. All derivatives were investigated for their in vitro anti-proliferative property against three different cancer cell lines (viz., colon carcinoma HT29, Caucasian breast adenocarcinoma MCF7, hepatocellular carcinoma HepG2) and a normal non-transformed human foreskin fibroblast Hs27 cell line. All derivatives demonstrated varied degrees of strong anticancer effect against all of the cell lines with the 2-Amino-4-(4-nitrophenyl)-5,6-dihydrobenzo[h]quinoline-3-carbonitrile (CNMP, 2) exhibited the most potent antiproliferative effect viz. LC50 21.23 μM for breast, 8.24 μM for colon, and 26.15 μM for the hepatocellular, respectively. Molecular docking studies against all the the target crystal structures of cancer proteins (1HK7, 3EQM, 3IG7 and 4FM9) revealed significant binding affinities via hydrophobic and H-bonding interactions with all the compounds in conformity with the wet lab results. CNMP showed the highest binding energy of −7.55 in the HT29, −6.9 (both in MCF7 HepG2) kcal/mol. Based on the results obtained from wet lab and dry lab experiments, it can be proposed that CNMP might prove to be a potential lead structure for the design and synthesis of more potent anticancer candidates.

Design, synthesis and biological activity of novel triketone-containing quinoxaline as HPPD inhibitor.

4-Hydroxyphenyl pyruvate dioxygenase (EC 1.13.11.27, HPPD) is one of the important target enzymes used to address the issue of weed control. HPPD-inhibiting herbicides can reduce the carotenoid content in plants and hinder photosynthesis, eventually causing albinism and death. Exploring novel HPPD-inhibiting herbicides is a significant direction in pesticide research. In the process of exploring new high-efficiency HPPD inhibitors, a series of novel quinoxaline derivatives were designed and synthesized using an active fragment splicing strategy. The title compounds were unambiguously characterized by infrared, 1 H NMR, 13 C NMR, and high-resolution mass spectroscopy. The results of the in vitro tests indicated that the majority of the title compounds showed potent inhibition of Arabidopsis thaliana HPPD (AtHPPD). Preliminary bioevaluation results revealed that a number of novel compounds displayed better or excellent herbicidal activity against broadleaf and monocotyledonous weeds. Compound III-5 showed herbicidal effects comparable to those of mesotrione at a rate of 150 g of active ingredient (ai)/ha for post-emergence application. The results of molecular dynamics verified that compound III-5 had a more stable protein-binding ability. Molecular docking results showed that compound III-5 and mesotrione shared homologous interplay with the surrounding residues. In addition, the enlarged aromatic ring system adds more force, and the hydrogen bond formed can enhance the synergy with π-π stacking. The present work indicates that compound III-5 may be a potential lead structure for the development of new HPPD inhibitors.

Introducing a potential lead structure for the synthesis of more specific inhibitors of tyrosinases and catechol oxidases

Introducing a potential lead structure for the synthesis of more specific inhibitors of tyrosinases and catechol oxidases

Design, synthesis and biological activities of novel urea derivatives with superior plant growth-inhibiting activity

In order to discover novel plant growth regulators and herbicides with new modes of action for crops production management and improvement, a series of new urea derivatives were designed and synthesized. The bioassay results demonstrated that target compounds exhibited remarkable inhibitory activities in the growth of hypocotyls and taproots and good promoting activity in the generation of lateral roots on Arabidopsis and rice, and compound Y9k showed considerable inhibition effects on germination of Bidens and growth of Abutilon in the herbicidal assay. These results suggested that compound Y9k may be a potential lead structure as a novel plant growth regulator for plant type regulation and weed control.

Design and Synthesis of Novel 4-Hydroxyl-3-(2-phenoxyacetyl)-pyran-2-one Derivatives for Use as Herbicides and Evaluation of Their Mode of Action.

In order to develop a novel herbicide containing the β-triketone motif, a series of 4-hydroxyl-3-(2-phenoxyacetyl)-pyran-2-one derivatives were designed and synthesized. The bioassay results showed that compound II15 had good pre-emergent herbicidal activity even at a dosage of 187.5 g ha-1. Moreover, compound II15 showed a broader spectrum of weed control when compared with a commercial herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), and displayed good crop safety to Triticum aestivum L. and Zea mays Linn. when applied at 375 g ha-1 under pre-emergence conditions, which indicated its great potential as a herbicide. More importantly, studying the molecular mode of action of compound II15 revealed that the novel triketone structure is a proherbicide of its corresponding phenoxyacetic acid auxin herbicide, which has a herbicidal mechanism similar to that of 2,4-D. The present work indicates that the 4-hydroxyl-3-(2-phenoxyacetyl)-pyran-2-one motif may be a potential lead structure for further development of novel auxin-type herbicides.

Radiolabeling and in vivo evaluation of [11C]AGH-44: a potential lead structure to develop a positron emission tomography radioligand for the 5-HT7 receptor

AGH-44 is described as a selective low-basicity serotonin 7 receptor (5-HT7R) agonist. In this paper, we evaluate if AGH-44 can act as a lead structure to develop a 5-HT7R selective positron emission tomography (PET) tracer. 11C-labeling of AGH-44 succeeded in a two-step, one-pot procedure in good yields. Subsequent PET studies showed that [11C]AGH-44 displays low blood–brain-barrier passage in Long–Evans rats. Moreover, [11C]AGH-44 brain accumulation showed to be independent on permeability glycoprotein (P-gp) efflux inhibition. Results from biodistribution and metabolism studies could neither explain the observed low brain uptake. As such, we believe that this scaffold is not an optimal starting point to develop a 5-HT7R selective PET tracer.

Design, synthesis, SAR and molecular docking of novel green niacin-triketone HPPD inhibitor

4-Hydroxyphenylpyruvate dioxygenase (EC 1.13.11.27, HPPD) is a very important target for the discovery of novel bleaching herbicides. In order to discover novel triketone green HPPD inhibitors with excellent herbicidal activity and crop selectivity, the natural product leptospermone was selected as the template compound, and niacin was employed as bioisostere to design and synthesize a series of novel substituted niacin-triketone derivatives. Some of the target compounds showed potent Arabidopsis thaliana HPPD (AtHPPD) inhibitory activity in vitro. Especially compound II-1 displayed the best herbicidal activity (IC50 = 0.262 μM, AtHPPD), and was safe for Zea mays at concentration of 300 g ai/ha. Molecular docking results indicated that the triketone moiety of compound II-1 could form a bidentate complex with Fe(II), and the pyridine subunit interacted with Phe430 and Phe360 via π−π packing. The present work indicated that 3-hydroxy-2-nicotinoylcyclohex-2-en-1-one could be a potential lead structure for developing novel green HPPD inhibitors.

Design, Synthesis, and Herbicidal Activity Evaluation of Novel Aryl-Naphthyl Methanone Derivatives.

4-Hydroxyphenylpyruvate dioxygenase (HPPD) is one of the most vital targets for herbicides discovery. In search for HPPD inhibitors with novel scaffolds, a series of aryl-naphthyl methanone derivatives have been designed and synthesized through alkylation and Friedel-Crafts acylation reactions. The bioassay indicated some of these compounds displayed preferable herbicidal activity at the rate of 0.75 mmol/m2 by post-emergence application, in which compound 3h displayed the best herbicidal activity. The molecular docking showed that compound 3h could bind well to the active site of the AtHPPD. This study shows that aryl-naphthyl methanone derivatives could be a potential lead structure for further development of novel herbicides.

Herbicidal Activity and Molecular Docking Study of Novel ACCase Inhibitors.

Acetyl-CoA carboxylase (ACCase) is an important target enzyme for the development of new bleaching herbicides. On the basis of structure-activity relationships and active subunit combinations, a series of novel 2-phenyl-3-cyclohexanedione enol ester derivatives was designed and synthesized by coupling and acylation reactions. The preliminary biological tests indicated good post-emergent herbicidal activity at a dosage of 150–300 g ai/ha, superior to that of clethodim against barnyard grass. Compound 3d was safe with respect to maize, even at a dosage of 300 g ai/ha. Compound 3d showed the best ACCase inhibitory activity in vitro, with a value of 0.061 nmol h-1 mg-1 protein, superior to that of clethodim. Molecular docking modeling showed that compound 3d and clethodim had the same interactions with surrounding residues, leading to an excellent combination with the active pocket of ACCase. That may have been the mechanism responsible for the death of the barnyard grass. The present work suggests compound 3d as a potential lead structure for further development of novel ACCase inhibitors.

Identification of competitive inhibitors of the human taurine transporter TauT in a human kidney cell line

The osmolyte and antioxidant taurine plays an important role in regulation of cellular volume, oxidative status and Ca2+-homeostasis. Taurine uptake in human cells is regulated by the Na+- and Cl--dependent taurine transporter TauT. In order to gain deeper structural insights about the substrate binding pocket of TauT, a HEK293 cell line producing a GFP-TauT fusion protein was generated. Transport activity was validated using cell-based [3H]-taurine transport assays. We determined the Km and IC50 values of taurine, β-alanine and γ-aminobutyrate. Additionally we were able to identify structurally similar compounds as potential new substrates or inhibitors of the TauT transporter. Substrate induced cytotoxicity was analyzed using a cell viability assay. In this study we show competitive effects of the 3-pyridinesulfonate, 2-aminoethylhydrogen sulfate, 5-aminovalerate, β-aminobutyrate, piperidine-4-sulfonate, 2-aminoethylphosphate and homotaurine. We demonstrate that taurine uptake can be inhibited by a phosphate. Furthermore our studies revealed that piperidine-4-sulfonate interacts with TauT with a higher affinity than γ-aminobutyrate and imidazole-4-acetate. We propose that piperidine-4-sulfonate may serve as a potential lead structure for the design of novel drug candidates required for specific modulation of the TauT transporter in therapy of neurodegenerative diseases.

Snake venom components in medicine: From the symbolic rod of Asclepius to tangible medical research and application.

Both mythologically and logically, snakes have always fascinated man. Snakes have attracted both awe and fear not only because of the elegant movement of their limbless bodies, but also because of the potency of their deadly venoms. Practically, in 2017, the world health organization (WHO) listed snake envenomation as a high priority neglected disease, as snakes inflict up to 2.7 million poisonous bites, around 100.000 casualties, and about three times as many invalidities on man. The venoms of poisonous snakes are a cocktail of potent compounds which specifically and avidly target numerous essential molecules with high efficacy. The individual effects of all venom toxins integrate into lethal dysfunctions of almost any organ system. It is this efficacy and specificity of each venom component, which after analysis of its structure and activity may serve as a potential lead structure for chemical imitation. Such toxin mimetics may help in influencing a specific body function pharmaceutically for the sake of man's health. In this review article, we will give some examples of snake venom components which have spurred the development of novel pharmaceutical compounds. Moreover, we will provide examples where such snake toxin-derived mimetics are in clinical use, trials, or consideration for further pharmaceutical exploitation, especially in the fields of hemostasis, thrombosis, coagulation, and metastasis. Thus, it becomes clear why a snake captured its symbolic place at the Asclepius rod with good reason still nowadays.

Determination of ligand efficiency indices in a group of 7H-purine-2,6-dione derivatives with psychotropic activity using micellar electrokinetic chromatography.

Discovering hit compounds and optimization processes in medicinal chemistry nowadays could be improved by predictive tools, based on the relationship between structure of molecules and lipophilic properties. Lipophilicity of drug candidate can affect both the pharmacokinetic and pharmacodynamics properties, in particular, the ability of a molecule to cross the cell membrane. Among the new methods for determination of the lipophilicity of compounds, micellar electrokinetic chromatography (MEKC) is considered to be an appropriate one for bioactive molecules, as it closely mimics the physiological conditions. In this paper MEKC was used for the estimation of the lipophilicity of 24 derivatives of 8-alkoxy-7H-purine-2,6-dione, designed and synthesized as potential antidepressant/anxiolytic and antipsychotic agents. The results of experimental method were compared with calculated in silico parameters (AlogPs and milogP by Virtual Computational Laboratory website, log PPallas by Pallas 3.1, Mlog P by Marvin, log PChemS by ChemSketch, log PChemDraw by ChemBioUltra) using Principal Component Analysis (PCA) method. Finally, using estimated log P values for selected compounds ligand - lipophilicity efficiency (LLE), per cent efficiency index (PEI), and binding efficiency index (BEI) parameters were calculated. Applied MEKC procedure could be used for selection of potential lead structure in a group of 7H-purine-2,6-dione derivatives.