Potential Macromolecular Targets Research Articles

Synthesis, characterization and antioxidant screening of a 1,10-phenanthroline-based tetraza-macrocyclic ligand and its nickel complex with therapeutic potential and catalytic significance

Abstract In this study, we present a synthetic route for the preparation of a novel 1,10- phenanthroline-based tetraza-macrocyclic ligand, 5,12,25,28-tetraazaheptacyclo [14.8.4.2⁴,⁷.210,13.0⁶,11.019,27.022,26]dotriaconta-1 (25),4,6,8,10,12,16(28),17,19(27),20,22(26),23,29, 31-tetradecaene, 3 and its corresponding nickel complex, (28Z)-1,3,6,31-tetraaza-2-nickelaoctacyclo [17.9.3.2⁷,28.0³,16.0⁴,13.0⁵, 10.022,30.025,29]tritriaconta-4(13),5(10),6,8,11,14,16,19(31),20,22(30), 23,25(29),26,28(32)-tetradecaene, 8. The ligand was synthesized via a condensation reaction involving 2,9-dimethyl-1,10-phenanthroline and 2,9-dicarbaldehyde-1,10 phenanthroline, followed by nickel metal complexation. Fourier-transformed infrared (FT-IR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, and thermal analyses were employed to characterize the ligand and its Ni complex. Their ADMET parameters and potential macromolecular targets calculations showed they have therapeutic potentials. The antioxidant assay shows that Ni-complex is approximately 9 times more potent than the ligand with IC50 values of 0.045 mg/ml and 0.404 mg/ml, respectively. Their microspecies distribution which was predicted using ChemAxon Predictor revealed their catalytic potentials The reaction mechanisms involved are discussed. The 1,10-phenanthroline-based macrocyclic ligand and its nickel complex significantly expand the structural diversity within the tetraza-macrocyclic ligand system and serve as base ligands for the development of possible derivatives, with concomitant applicability in drug development and catalysis.

Identification of the Anti-ischemia-reperfusion Injury Effect of Baicalein from Scutellaria Baicalensis Georgi in Liver Transplantation.

The complex etiology of Ischemia-Reperfusion Injury (IRI) induced by liver transplantation (LT) and the "one-target-focused" method limit the development of effective therapeutic interventions. We aimed to reveal the specific active ingredients and mechanisms involved in the Chinese herb Scutellaria baicalensis Georgi (SBG) in alleviating IRI in LT. The active ingredients and potential macromolecular targets of SBG were screened through related databases. The differentially expressed genes of LT were obtained from GSE151648. The protein-protein interaction network was constructed by the STRING database, and Cytoscape 3.7.1 was used to construct a compound-target-disease network. GO and KEGG enrichment analyses were performed on the DAVID database. Finally, the main active components of SBG and the corresponding mechanisms were verified in a donation after circulatory death (DCD) rat LT model. Thirty-two active ingredients of SBG and their targets were identified, and a total of 38 intersection targets were obtained. GO function and KEGG pathway enrichment analyses demonstrated that the plasma membrane and its components play an important role. Molecular docking showed baicalein, the core component of SBG, had a strong binding ability to all hub targets. Next, in DCD rats, baicalein was proven to improve liver function, alleviate pathological injury and apoptosis, and increase the survival rate. Baicalein also significantly affected the expression of 7 hub genes. Furthermore, baicalein could inhibit ferroptosis by inhibiting phospholipid peroxidation. Baicalein, the main component of SBG, could alleviate IRI, affect the expression of hub genes, and inhibit ferroptosis in LT.

Spectral, Anti-Inflammatory, Anti-Pyretic, Leishmanicidal, and Molecular Docking Studies, Against Selected Protein Targets, of a New Bisbenzylisoquinoline Alkaloid.

A new bisbenzylisoquinoline named as chondrofolinol (1) and four reported compounds (2–5) were isolated and characterized from the roots of Berberis glaucocarpa Stapf. Anti-inflammatory, anti-pyretic, and leishmanicidal studies were performed against carrageenan-induced paw edema, yeast-induced pyrexia, and the promastigotes of Leishmania tropica, respectively. The new compound significantly reduced the paw volume in carrageenan-induced paw edema and rectal temperature in yeast-induced pyrexia at 10 and 20 mg/ kg of body weight. Chondrofolinol caused almost 100% inhibition of the promastigotes of Leishmania tropica. All the compounds displayed minimal cytotoxicity against THP-1 monocytic cells. In order to ascertain the potential macromolecular targets of chondrofolinol responsible for the observed anti-inflammatory and anti-leishmanial activities, a molecular docking study was carried out on relevant protein targets of inflammation and Leishmania. Protein targets of human endoplasmic reticulum aminopeptidase 2 (ERAP2) and human matrix metalloproteinase-1 (MMP-1) for inflammation and protein targets of N-myristoyltransferase (NMT), tyrosyl-tRNA synthetase (TyrRS), and uridine diphosphate-glucose pyrophosphorylase (UGPase) for Leishmania major were selected after thorough literature search about protein targets responsible for inflammation and Leishmania major. Chondrofolinol showed excellent docking to ERAP2 and to MMP-1. The Leishmania major protein targets with the most favorable docking scores to chondrofolinol were NMT, TyrRS, and UGPase. The study indicated that bisbenzylisoquinoline and isoquinoline alkaloids possess anti-pyretic, anti-inflammatory, and anti-leishmanial properties with minimal cytotoxicity and therefore, need to be further explored for their therapeutic potential.

Schiff bases of 4-Phenyl-2-Aminothiazoles as hits to new antischistosomals: Synthesis, in vitro, in vivo and in silico studies

The treatment of schistosomiasis is based on a single drug, the praziquantel (PZQ), an oral bioavailable and efficient agent which causes minimal side effects. The main concern about this approach, however, is that relying on only one drug to treat a helminthic disease is a dangerous strategy since history shows that pathogens easily evolve to resistant forms. Actually, reports about experimental strains exhibiting low sensibility to PZQ can be found in literature. The search for new antischistosomals, consequently, is urgent. Here we report the synthesis of seventeen Schiff bases of 4-(4-Substituted phenyl)-N-(4-substituted benzylidene)thiazole-2-amines which were tested in vitro and in vivo against Schistosoma mansoni adult worms. Moreover, in silico studies to propose potential macromolecular targets and to predict the oral bioavailability were also performed. The analog GPQF-108 exhibited the best in vitro performance (IC50: 29.4 µM, SI:6.1) associated with promising in vivo activity, with a significant decrease in the adult life forms and oviposition. Oral bioavailability could be impaired by the predicted low water solubility of GPQF-108, although it also exhibited good membrane permeability. The water solubility, however, could be improved by decreasing the particles size. Serine/Threonine- and Tyrosine Kinases, Carbonic Anhydrase, Tyrosine Phosphatase and Arginase were predicted as potential macromolecular targets through which the GPQF-108 could be acting against the helminth. This class of compounds exhibited an interesting initial therapeutic profile with the advantage of being chemically diverse from the PZQ and be easily synthesized from commercial reagents which could lead to low-cost drugs. These aspects make this class of compounds interesting hits to be explored against schistosomiasis.

Synthesis, Evaluation and Proposed Binding Pose of Substituted Spiro-Oxindole Dihydroquinazolinones as IRAP Inhibitors.

Insulin‐regulated aminopeptidase (IRAP) is a new potential macromolecular target for drugs aimed for treatment of cognitive disorders. Inhibition of IRAP by angiotensin IV (Ang IV) improves the memory and learning in rats. The majority of the known IRAP inhibitors are peptidic in character and suffer from poor pharmacokinetic properties. Herein, we present a series of small non‐peptide IRAP inhibitors derived from a spiro‐oxindole dihydroquinazolinone screening hit (pIC50 5.8). The compounds were synthesized either by a simple microwave (MW)‐promoted three‐component reaction, or by a two‐step one‐pot procedure. For decoration of the oxindole ring system, rapid MW‐assisted Suzuki‐Miyaura cross‐couplings (1 min) were performed. A small improvement of potency (pIC50 6.6 for the most potent compound) and an increased solubility could be achieved. As deduced from computational modelling and MD simulations it is proposed that the S‐configuration of the spiro‐oxindole dihydroquinazolinones accounts for the inhibition of IRAP.

Interaction of gentamicin sulfate with alginate and consequences on the physico-chemical properties of alginate-containing biofilms

BackgroundAlginate is one of the main extracellular polymeric substances (EPS) in biofilms of Cystic Fibrosis (CF) patients suffering from pulmonary infections. Gentamicin sulfate (GS) can strongly bind to alginate resulting in loss of pharmacological activity; however neither the mechanism nor its repercussion is fully understood. In this study, we investigated how GS modifies the alginate macromolecular network and its microenvironment. Material and methodsAlginate gels of two different compositions (either enriched in guluronate units (G) or enriched in mannuronate units (M)) were crosslinked with Ca2+ and exposed to GS at varying times and concentrations. The complexes formed were characterized via turbidimetry, mechanical tests, swelling assay, calorimetry techniques, nuclear magnetic resonance, Ca2+ displacement, macromolecular probe diffusion and pH alteration. ResultsIn presence of GS, the alginate network and its environment undergo a tremendous reorganization in terms of gel density, stiffness, diffusion property, presence and state of the water molecules. We noted that the intensity of those alterations is directly dependent on the polysaccharide motif composition (ratio M/G). ConclusionOur results underline the importance of alginate as biofilm component, its pernicious role during antibiotherapy and could represent a potential macromolecular target to improve anti-infectious therapies.

4-Phenyl-1,3-thiazole-2-amines as scaffolds for new antileishmanial agents

BackgroundThere is still a need for new alternatives in pharmacological therapy for neglected diseases, as the drugs available show high toxicity and parenteral administration. That is the case for the treatment of leishmaniasis, particularly to the cutaneous clinical form of the disease. In this study, we present the synthesis and biological screening of eight 4-phenyl-1,3-thiazol-2-amines assayed against Leishmania amazonensis. Herein we propose that these compounds are good starting points for the search of new antileishmanial drugs by demonstrating some of the structural aspects which could interfere with the observed activity, as well as suggesting potential macromolecular targets.MethodsThe compounds were easily synthesized by the methodology of Hantzsch and Weber, had their purities determined by Gas Chromatography-Mass spectrometry and assayed against the promastigote forms of Leishmania amazonensis as well as against two white cell lines (L929 and THP-1) and the monkey’s kidney Vero cells. PrestoBlue® and MTT viability assays were the methodologies applied to measure the antileishmanial and cytotoxic activities, respectively. A molecular modeling target fishing study was performed aiming to propose potential macromolecular targets which could explain the observed biological behavior.ResultsFour out of the eight compounds tested exhibited important anti-promastigote activity associated with good selectivity indexes when considering Vero cells. For the most promising compound, compound 6, IC50 against promastigotes was 20.78 while SI was 5.69. Compounds 3 (IC50: 46.63 μM; SI: 26.11) and 4 (IC50: 53.12 μM; SI: 4.80) also presented important biological behavior. A target fishing study suggested that S-methyl-5-thioadenosine phosphorylase is a potential target to these compounds, which could be explored to enhance activity and decrease the potential toxic side effects.ConclusionsThis study shows that 4-phenyl-1,3-thiazol-2-amines could be good scaffolds to the development of new antileishmanial agents. The S-methyl-5-thioadenosine phosphorylase could be one of the macromolecular targets involved in the action.

Usnic Acid Benzylidene Analogues as Potent Mechanistic Target of Rapamycin Inhibitors for the Control of Breast Malignancies

(+)-Usnic acid (1) is a common bioactive lichen-derived secondary metabolite with a characteristic dibenzofuran scaffold. It displayed low micromolar antiproliferative activity levels and, notably, induced autophagy in a panel of diverse breast cancer cell lines, suggesting the mechanistic (formerly "mammalian") target of rapamycin (mTOR) as a potential macromolecular target. The cellular autophagic markers were significantly upregulated due to the inhibition of mTOR downstream effectors. Additionally, 1 showed an optimal binding pose at the mTOR kinase pocket aided by multiple interactions to critical amino acids. Rationally designed benzylidene analogues of 1 displayed excellent fitting into a targeted deep hydrophobic pocket at the core of the kinase cleft, through stacking with the phenolic side chain of the Tyr2225 residue. Several potent analogues were generated, including 52, that exhibited potent (nM concentrations) antiproliferative, antimigratory, and anti-invasive activities against cells from multiple breast cancer clonal lines, without affecting the nontumorigenic MCF-10A mammary epithelial cells. Analogue 52 also exhibited potent mTOR inhibition and autophagy induction. Furthermore, 52 showed potent in vivo antitumor activity in two athymic nude mice breast cancer xenograft models. Collectively, usnic acid and analogues are potential lead mTOR inhibitors appropriate for future use to control breast malignancies.

(1S,2E,4S,7E,11E)-2,7,11-Cembratriene-4,6-diol semisynthetic analogs as novel c-Met inhibitors for the control of c-Met-dependent breast malignancies

(1S,2E,4S,6R,7E,11E)-2,7,11-Cembratriene-4,6-diol (1) and its 4-epi-analog (2) are the cembranoid precursors to several key flavor ingredients in most Nicotiana (tobacco) species. Nearly 40–60% of 1 and 2 are purposely degraded during the commercial tobacco fermentation. However, 1 and 2 display promising bioactivities, including anticancer. Breast cancer is the most diagnosed cancer in women and ranked second female disease killer. The receptor tyrosine kinase c-Met correlates with aggressiveness of certain breast cancer phenotypes and thus considered a valid therapeutic target. This study reports the discovery and optimization of the tobacco-based cembranoid 1 as a novel c-Met inhibitory scaffold using combined structure- and ligand-based approaches. 1 displayed antiproliferative, anti-migratory and anti-invasive effects against the c-Met overexpressing MDA-MB-231 breast cancer cells at moderate μM concentrations. The Z′-LYTE kinase platform and Western blot analysis identified c-Met as a potential macromolecular target. Rationally designed carbamate analogs were proposed to probe additional targeted c-Met interactions and improve the cellular potency. The 6-phenyl carbamate 3 showed enhanced c-Met inhibitory activity. Structure–activity relationships of different substituents on the 3’s phenyl moiety were studied. The most active analog 20 showed potent in vitro anticancer activity against the MDA-MB-231 breast cancer cells at low μM concentrations, with minimal toxicity on the non-tumorigenic MCF-10A mammary epithelial cells. Cembranoid 20 potently inhibited the c-Met catalytic activity in Z′-LYTE kinase assay and various cellular c-Met-driven signaling pathways. Furthermore, 20 displayed a robust antitumor activity in a breast cancer xenograft athymic mouse model and thus promoted to the lead rank. Cembranoids are novel c-Met inhibitors appropriate for future use to control c-Met dependent malignancies.

Norstictic Acid Inhibits Breast Cancer Cell Proliferation, Migration, Invasion, and In Vivo Invasive Growth Through Targeting C-Met.

Breast cancer is a major health problem affecting the female population worldwide. The triple-negative breast cancers (TNBCs) are characterized by malignant phenotypes, worse patient outcomes, poorest prognosis, and highest mortality rates. The proto-oncogenic receptor tyrosine kinase c-Met is usually dysregulated in TNBCs, contributing to their oncogenesis, tumor progression, and aggressive cellular invasiveness that is strongly linked to tumor metastasis. Therefore, c-Met is proposed as a promising candidate target for the control of TNBCs. Lichens-derived metabolites are characterized by their structural diversity, complexity, and novelty. The chemical space of lichen-derived metabolites has been extensively investigated, albeit their biological space is still not fully explored. The anticancer-guided fractionation of Usnea strigosa (Ach.) lichen extract led to the identification of the depsidone-derived norstictic acid as a novel bioactive hit against breast cancer cell lines. Norstictic acid significantly suppressed the TNBC MDA-MB-231 cell proliferation, migration, and invasion, with minimal toxicity to non-tumorigenic MCF-10A mammary epithelial cells. Molecular modeling, Z'-LYTE biochemical kinase assay and Western blot analysis identified c-Met as a potential macromolecular target. Norstictic acid treatment significantly suppressed MDA-MB-231/GFP tumor growth of a breast cancer xenograft model in athymic nude mice. Lichen-derived natural products are promising resources to discover novel c-Met inhibitors useful to control TNBCs.

Molecular basis of plant secondary metabolites - proteins interaction

The secondary metabolites found in plants represent an extremely rich source of novel chemical diversity for drug discovery and chemical biology programs.1–3 One of the main problems in drug discovery from plant small molecules is the identification of their molecular targets: many compounds have been found to be more promiscuous than originally anticipated, which can potentially lead to side effects, but which may also open up additional medical uses. The drug poly-pharmacological activity can be understood only if its interactions with cellular components are comprehensively characterized. Thus the identification of target proteins and investigation of ligand-receptor interactions represents an essential step in the process of plant drug discovery and development.4,5 However, nature is far more complex, and it is only with multidisciplinary collaborative research encompassing many disciplines that such targets can be successfully studied. Owing to our interest in the field of bioactive plant molecules, we have developed approaches to target identification based on chemical proteomics procedures, supported by spectroscopic and spectrometric data, Surface Plasmon Resonances (SPR) analyses and biochemical tests.5,6 Chemical proteomics is a powerful mass spectrometry-based affinity chromatography approach aimed to identify a set of proteins captured by a small molecules.6,7 The investigated molecule has to be anchored to a solid support through a flexible space arm, and then incubated with a lysate, from cell or tissues, to obtain the interaction between the immobilized compound (bait) and its protein targets. After several washing steps, proteins tightly bound to the beads are eluted and subjected to electrophoresis or gel free separation, followed by enzymatic digestion. The obtained peptide mixtures are then submitted to MS analyses and data base search for protein identification. This study allows the description of all potential macromolecular targets of a small bioactive molecules in a single experiment, leading to a complete and selective target mapping of a drug candidate. We have recently applied this approach to the study of cellular targets of some bioactive plant small molecules showing interesting protein targets; achieved results will be described in this communication.8,9 Koch, A.M., Schuffenhaue, A., Scheck, M., Wetzel, S., Casaulta M., Odermatt A., Ert P., Waldmann E., (2005) PNSA, 102:17272–17277. Clatdy, J., Walsh, C., (2004) Nature, 432:829–837. Li, J.W., Vederas, J.C. (2009) Scienze, 325: 161.166 Rix, U., Superti-Furga G., (2009) Nat. Chem. Biol., 5: 616–624. Bantscheff, M., Scholten, A., Heck. A. J., (2009) Drug Discov. Today14: 1021–1029. Dal Piaz, F.,Malafronte, N., Romano, A.,Gallotta, D., Belisario, M.A., Bifulco, G., Gualtieri, M.J., Sanogo, R., De Tommasi, N., Pisano C., (2012) Phytochemistry 75: 78–89 Dal Piaz, F.,Vassallo, A., Lepore, L., Tosco, A., Bader, A., De Tommasi, N., (2009)J. Med Chem, 52:3814–3828. Nigro, P., Dal Piaz, F., Gallotta, D., De Tommasi, N., Belisario, M. A., (2008) Free Rad Biol Med 45: 875–884. Tarallo, V., Lepore, L., Marcellini, M., Dal Piaz, F., Tudisco, L., Ponticelli, S., Lund, F.W.; Roepstoff., P., Orlandi, A., Pisano, C., De Tommasi, N., De Falco, S., (2011) JBC 286: 19641–19651.

Analysis of Binding Interaction between the Natural Apocarotenoid Bixin and Human Serum Albumin by Circular Dichroism and Fluorescence Spectroscopy

Bixin is an important, pharmacologically active dietary cis-carotenoid, but its interaction with potential macromolecular targets is completely unexplored. This work was aimed to study the binding of bixin to human serum albumin (HSA), the most abundant protein in blood plasma. Circular dichroism (CD) spectroscopy in combination with UV/VIS absorption spectroscopy and fluorescence quenching techniques were applied. Appearance of induced CD bands in the UV- and VIS-absorption spectral regions indicated the formation of non-covalent carotenoid-albumin complexes. Shape and spectral position of the extrinsic Cotton effects suggested the binding of a single bixin molecule to HSA in chiral conformation. Scatchard and non-linear regression analyses of CD titration data resulted in similar values for the association constant (Ka = 6.6 and 4.6x10(5) M(-1), resp.) and for the number of binding sites (n = 1). The binding interaction was independently confirmed by fluorescence-quenching experiment from which the binding parameters were also calculated. CD Displacement measurements performed with marker ligands established that the main drug binding sites of HSA are not involved in binding of bixin. Palmitic acid decreased the amplitude of the induced CD bands suggesting a common albumin binding site for bixin and long-chain fatty acids. The above data indicate that HSA plays a significant role in the plasma transportation of bixin and related dietary carboxylic acid carotenoids.

Human Ro ribonucleoprotein particles: characterization of native structure and stable association with the La polypeptide.

Anti-Ro autoantibodies, found in sera of patients with systemic lupus erythematosus, Sjogren's syndrome, and related diseases, target the Ro ribonucleoprotein particles (RNPs). Although the polypeptide and RNA components of the Ro RNPs have been characterized, much less is known about the native structure of these particles. We have now characterized by biochemical techniques intact Ro ribonucleoprotein particles from cultured HeLa cells. These particles segregated in three discrete subpopulations with characteristic physicochemical properties: one containing hY5 RNA (RohY5 particles), one containing only hY4 RNA (RohY4 particles) and one with hY1, hY3, and hY4 RNAs (RohY1-hY4 particles). The RohY5 particles were purified free of contaminating ribonucleoproteins; both the La and the 60-kD Ro polypeptides were stable components of this portion of the Ro RNPs. The La RNPs co-purified with the RohY4 particles and contaminated the RohY1-hY4 RNPs. The stable association between the La and the 60-kD Ro polypeptides provides a potential macromolecular target for the linked set of anti-Ro and anti-La antibodies, and suggests a possible functional association of these polypeptides.