Reinvestigation of diphenylmethylpiperazine analogues of pyrazine as new class of Plasmodial cysteine protease inhibitors for the treatment of malaria.

Malaria eradication is still a global challenge due to the lack of a broadly effective vaccine and the emergence of drug resistance to most of the currently available drugs as part of the mainline artemisinin-based combination therapy. A variety of experimental approaches are quite successful in identifying and synthesizing new promising pharmacophore hybrids with distinct mechanisms of action. Based on our recent findings, the current study demonstrates the reinvestigation of a series of diphenylmethylpiperazine and pyrazine-derived molecular hybrids. Pyrazine-derived molecular hybrids were screened to investigate the antiplasmodial activity on drug-susceptible Pf3D7 and drug-resistant PfW2 strains. The selected compounds were shown to be potent dual inhibitors of cysteine protease PfFP2 and PfFP3. Time-course parasitic development study demonstrated that compounds were able to arrest the growth of the parasite at the early trophozoite stage. The compounds did not show hemolysis of red blood cells and showed selectivity to the parasite compared with the mammalian Vero and A5489 cell lines. The study underlined HR5 and HR15 as a new class of Plasmodial falcipain inhibitors with an IC50 of 6.2 µM and 5.9 µM for PfFP2 and 6.8 µM and 6.4 µM for PfFP3, respectively. Both compounds have antimalarial efficacy with IC50 values of 3.05 µM and 2.80 µM for the Pf3D7 strain, and 4.35 µM and 3.39 µM for the PfW2 strain, respectively. Further structural optimization may turn them into potential Plasmodial falcipain inhibitors for malaria therapeutics.

Naphthyl bearing 1,3,4-thiadiazoleacetamides targeting the parasitic folate pathway as anti-infectious agents: in silico, synthesis, and biological approach.

Malaria is still a complex and lethal parasitic infectious disease, despite the availability of effective antimalarial drugs. Resistance of malaria parasites to current treatments necessitates new antimalarials targeting P. falciparum proteins. The present study reported the design and synthesis of a series of a 2-(4-substituted piperazin-1-yl)-N-(5-((naphthalen-2-yloxy)methyl)-1,3,4-thiadiazol-2-yl)acetamide hybrids for the inhibition of Plasmodium falciparum dihydrofolate reductase (PfDHFR) using computational biology tools followed by chemical synthesis, structural characterization, and functional analysis. The synthesized compounds were evaluated for their in vitro antimalarial activity against CQ-sensitive PfNF54 and CQ-resistant PfW2 strain. Compounds T5 and T6 are the most active compounds having anti-plasmodial activity against PfNF54 with IC50 values of 0.94 and 3.46 µM respectively. Compound T8 is the most active against the PfW2 strain having an IC50 of 3.91 µM. Further, these active hybrids (T5, T6, and T8) were also evaluated for enzyme inhibition assay against PfDHFR. All the tested compounds were non-toxic against the Hek293 cell line with good selectivity indices. Hemolysis assay also showed non-toxicity of these compounds on normal uninfected human RBCs. In silico molecular docking studies were carried out in the binding pocket of both the wild-type and quadruple mutant Pf-DHFR-TS to gain further insights into probable modes of action of active compounds. ADME prediction and physiochemical properties support their drug-likeness. Additionally, they were screened for antileishmanial activity against L. donovani promastigotes to explore broader applications. Thus, this study provides molecular frameworks for developing potent antimalarials and antileishmanial agents.

Development of ADS051, an oral, gut-restricted, small molecule neutrophil modulator for the treatment of neutrophil-mediated inflammatory diseases.

Neutrophils are an essential component of the innate immune system; however, uncontrolled neutrophil activity can lead to inflammation and tissue damage in acute and chronic diseases. Despite inclusion of neutrophil presence and activity in clinical evaluations of inflammatory diseases, the neutrophil has been an overlooked therapeutic target. The goal of this program was to design a small molecule regulator of neutrophil trafficking and activity that fulfilled the following criteria: (a) modulates neutrophil epithelial transmigration and activation, (b) lacks systemic exposure, (c) preserves protective host immunity, and (d) is administered orally. The result of this discovery program was ADS051 (also known as BT051), a low permeability, small molecule modulator of neutrophil trafficking and activity via blockade of multidrug resistance protein 2 (MRP2)- and formyl peptide receptor 1 (FPR1)-mediated mechanisms. ADS051, based on a modified scaffold derived from cyclosporine A (CsA), was designed to have reduced affinity for calcineurin with low cell permeability and, thus, a greatly reduced ability to inhibit T-cell function. In cell-based assays, ADS051 did not inhibit cytokine secretion from activated human T cells. Furthermore, in preclinical models, ADS051 showed limited systemic absorption (<1% of total dose) after oral administration, and assessment of ADS051 in human, cell-based systems demonstrated inhibition of neutrophil epithelial transmigration. In addition, preclinical toxicology studies in rats and monkeys receiving daily oral doses of ADS051 for 28 days did not reveal safety risks or ADS051-related toxicity. Our results to date support the clinical development of ADS051 in patients with neutrophil-mediated inflammatory diseases.

Development of diphenylmethylpiperazine hybrids of chloroquinoline and triazolopyrimidine using Petasis reaction as new cysteine proteases inhibitors for malaria therapeutics.

Malaria is a widespread infectious disease, causing nearly 247 million cases in 2021. The absence of a broadly effective vaccine and rapidly decreasing effectiveness of most of the currently used antimalarials are the major challenges to malaria eradication efforts. To design and develop novel antimalarials, we synthesized a series of 4,7-dichloroquinoline and methyltriazolopyrimidine analogues using a multi-component Petasis reaction. The synthesized molecules (11-31) were screened for in-vitro antimalarial activity against drug-sensitive and drug-resistant strains of Plasmodium falciparum with an IC50 value of 0.53 µM. The selected compounds were screened to evaluate in-vitro and in-silico enzyme inhibition efficacy against two cysteine proteases, PfFP2 and PfFP3. The compounds 15 and 17 inhibited PfFP2 with an IC50 = 3.5 and 4.8 µM, respectively and PfFP3 with an IC50 = 4.9 and 4.7 µM, respectively. Compounds 15 and 17 were found equipotent against the Pf3D7 strain with an IC50 value of 0.74 µM, whereas both were displayed IC50 values of 1.05 µM and 1.24 µM for the PfW2 strain, respectively. Investigation of effect of compounds on parasite development demonstrated that compounds were able to arrest the growth of the parasites at trophozoite stage. The selected compounds were screened for in-vitro cytotoxicity against mammalian lines and human red-blood-cell (RBC), which demonstrated no significant cytotoxicity associated with the molecules. In addition, in silico ADME prediction and physiochemical properties supported the drug-likeness of the synthesized molecules. Thus, the results highlighted the diphenylmethylpiperazine group cast on 4,7-dichloroquinoline and methyltriazolopyrimidine using Petasis reaction may serve as models for the development of new antimalarial agents.

Design and synthesis of leucine-linked quinazoline-4(3H)-one-sulphonamide molecules distorting malarial reductase activity in the folate pathway.

Optimization of a modified Grimmel's method for N-heterocyclization of a leucine-linked sulfonamide side-arm at position 2 leading to 2,3-disustituted-4-quinazolin-(3H)-ones was accomplished. Further, 22 hybrid quinazolinone motifs (4a-v) were synthesized by N-heterocyclization reaction under microwave irradiation using the ionic liquid [Bmim][BF4 ]-H2 O as green solvent as well as the catalyst. The in vitro screening of the hybrid entities against the malarial species Plasmodium falciparum yielded five potent molecules 4l, 4n, 4o, 4t, and 4u owning antimalarial activity comparable to those of the reference drugs. In continuation, an in silico study was carried out to obtain a pharmacophoric model and quantitative structure-activity relationship. We also built a 3D-QSAR model to procure more information that could be applied to design new molecules with more potent Pf-DHFR inhibitory activity. The designed pharmacophore was recognized to be more potent for the selected molecules, exhibiting five pharmacophoric features. The active scaffolds were further evaluated for enzyme inhibition efficacy against alleged receptor Pf-DHFR computationally and in vitro, proving their candidature as lead dihydrofolate reductase inhibitors, and the selectivity of the test candidates was ascertained by toxicity study against Vero cells. Good oral bioavailability was also proved by studying pharmacokinetic properties.

Green synthesis, biological evaluation, molecular docking studies and 3D-QSAR analysis of novel phenylalanine linked quinazoline-4(3H)-one-sulphonamide hybrid entities distorting the malarial reductase activity in folate pathway.

A modified Grimmel's method for N-heterocyclization of phenylalanine linked sulphonamide side arm at position-2 was optimized leading to 2,3-disustituted-4-quinazolin-(3H)-ones. Further, [Bmim][BF4]-H2O (IL) was used as green solvent as well as catalyst for the synthesis of twenty two hybrid quinazolinone motifs (4a-4v) by N-heterocyclization reaction using microwave irradiation technique. The in vitro screening of the hybrid entities against the malarial species Plasmodium falciparum yielded five potent molecules 4l, 4n, 4r, 4t & 4u owing comparable antimalarial activity to the reference drugs. In continuation, anin silicostudy was carried out to obtain a pharmacophoric model and quantitative structure activity relationship. We also built a 3D-QSAR model to procure more information that could be applied to design new molecules with more potent Pf-DHFR inhibitory activity. The designed pharmacophore was recognized to be more potent for the selected molecules, exhibiting five pharmacophoric features. The active scaffolds were further evaluated for enzyme inhibition efficacy against alleged receptor Pf-DHFR computationally and in vitro, proving their candidature as lead dihydrofolate reductase inhibitors as well as the selectivity of the test candidates was ascertained by toxicity study against vero cells. The perception of good oral bioavailability was also proved by study of pharmacokinetic properties.

Ionic liquid mediated stereoselective synthesis of alanine linked hybrid quinazoline-4(3H)-one derivatives perturbing the malarial reductase activity in folate pathway.

Grimmel's method was optimized as well as modified leading to the cyclization and incorporation of alanine linked sulphonamide in 4-quinazolin-(3H)-ones. Further, the generation of heterocyclic motif at position-3 of 4-quinazolinones was explored by synthesis of imines, which unfortunately led to an isomeric mixture of stereoisomers. The hurdle of diastereomers encountered on the path was eminently rectified by development of new rapid and reproducible methodology involving the use of imidazolium based ionic liquid as solvents as well as catalyst for cyclization as well as synthesis of imines in situ at position-3 leading to procurement of single E-isomer as the target hybrid heterocyclic molecules. The purity and presence of single isomer was also confirmed by HPLC and spectroscopic techniques. Further, the synthesized sulphonamide linked 4-quinazolin-(3H)-ones hybrids were screened for their antimalarial potency rendering potent entities (4b, 4c, 4 l, 4 t and 4u). The active hybrids were progressively screened for enzyme inhibitory efficacy against presumed receptor Pf-DHFR and h-DHFR computationally as well as in vitro, proving their potency as dihydrofolate reductase inhibitors. The ADME properties of these active molecules were also predicted to enhance the knowhow of the oral bioavailability, indicating good bioavailability of the active entities.

Novel 2,3-disubstituted quinazoline-4(3H)-one molecules derived from amino acid linked sulphonamide as a potent malarial antifolates for DHFR inhibition.

An optimization of a modified Grimmel's method for N-heterocyclization of Leucine linked sulphonamide leading to 2,3-disustituted-4-quinazolin-(3H)-ones was accomplished. Further, nineteen hybrid quinazolinone motifs (5a-5s) were synthesized by N-heterocyclization reaction under microwave irradiation using TEAA (IL) as green solvent as well as catalyst. The in vitro screening of the hybrid entities against the plasmodium species P. falciparum yielded five antimalarial potent molecules 5g, 5l, 5m, 5n &5p owing comparable activity to the reference drugs. The active scaffolds were further evaluated for enzyme inhibition efficacy against alleged receptor Pf-DHFR computationally as well as in vitro, proving their candidature as lead dihydrofolate reductase inhibitors. The prediction of the ADMET properties of the potent molecules also indicated their good oral bioavailability.

Formulation and In Vitro Evaluation of Ofloxacin Tablets using Natural Gums as Binders.

Natural gums are economical, easily available, and useful as tablet binders. In the present investigation, an attempt was made to formulate Ofloxacin tablets using three natural binders, namely Acacia arabica, Hibiscus esculentus, and xanthan gum. Such six batches of Ofloxacin tablets were prepared by using different types and amounts of the natural binders by the wet granulation method. The tablets were analyzed for their hardness, friability, and weight variation, and in vitro release was performed in a phosphate buffer at pH 6.8. The prepared tablets were also evaluated for their various release kinetics and similarity factors f2. The physical properties of the tablets containing the natural binders showed sufficient hardness, desirable disintegration time, and low friability. Their better percentage of drug release was observed as compared to the marketed formulation showing more than 85% drug release within 45 minutes. The in vitro release data was well-fitted into zero-order and the values of release exponent 'n' were between 0.303 and 0.514. The high similarity factor f2 of 64.50 was achieved with the best batch in comparison to the marketed tablets. The results obtained indicated that the gum Acacia arabica performed as well as gelatin compared to the other binders for the Ofloxacin tablet formulation.

Toll-like receptor 2-dependent protection against pneumococcal carriage by immunization with lipidated pneumococcal proteins.

Infections with Streptococcus pneumoniae cause substantial morbidity and mortality, particularly in children in developing nations. Polysaccharide-conjugate vaccines provide protection against both invasive disease and colonization, but their use in developing countries is limited by restricted serotype coverage and expense of manufacture. Using proteomic screens, we recently identified several antigens that protected mice from pneumococcal colonization in a CD4(+) T cell- and interleukin-17A (IL-17A)-dependent manner. Since several of these proteins are lipidated, we hypothesized that their immunogenicity and impact on colonization are in part due to activation of Toll-like receptor 2 (TLR2), a receptor for lipoproteins. Here we show that lipidated versions of the antigens elicited significantly higher activation of both human embryonic kidney cells engineered to express TLR2 (HEK-TLR2) and wild-type (WT) murine macrophages than nonlipidated mutant antigens. Lipoprotein-stimulated secretion of proinflammatory cytokines was ∼10× to ∼100× lower in murine TLR2-deficient macrophages than in WT macrophages. Subcutaneous immunization of C57BL/6 mice with protein subunit vaccines containing one or two of these lipoproteins or protein fusion constructs bearing N-terminal lipid adducts elicited a robust IL-17A response and a significant reduction in colonization compared with immunization with alum alone. In contrast, immunization of Tlr2(-/-) mice elicited no detectable IL-17A response and no protection against pneumococcal colonization. These experiments suggest that the lipid moieties enhance the immunogenicity and protective efficacy of pneumococcal TH17 antigens through activation of TLR2. Thus, triggering TLR2 with an antigen-specific protein subunit formulation is a possible strategy for the development of a serotype-independent pneumococcal vaccine that would reduce pneumococcal carriage.

DNA-Binding Interaction Studies of Microwave Assisted Synthesized Sulfonamide Substituted 8-Hydroxyquinoline Derivatives.

Sulfonamide substituted 8-hydroxyquinoline derivatives were prepared using a microwave synthesizer. The interaction of sulfonamide substituted 8-hydroxyquinoline derivatives and their transition metal complexes with Plasmid (pUC 19) DNA and Calf Thymus DNA were investigated by UV spectroscopic studies and gel electrophoresis measurements. The interaction between ligand/metal complexes and DNA was carried out by increasing the concentration of DNA from 0 to 12 µl in UV spectroscopic study, while the concentration of DNA in gel electrophoresis remained constant at 10 µl. These studies supported the fact that, the complex binds to DNA by intercalation via ligand into the base pairs of DNA. The relative binding efficacy of the complexes to DNA was much higher than the binding efficacy of ligands, especially the complex of Cu-AHQMBSH had the highest binding ability to DNA. The mobility of the bands decreased as the concentration of the complex was increased, indicating that there was increase in the interaction between the metal ion and DNA. Complexes of AHQMBSH were excellent for DNA binding as compared to HQMABS.

Development and evaluation of cefadroxil drug loaded biopolymeric films based on chitosan-furfural schiff base.

Cefadroxil drug loaded biopolymeric films of chitosan-furfural schiff base were prepared by reacting chitosan with furfural in presence of acetic acid and perchloric acid respectively for the external use. Prepared films were evaluated for their strength, swelling index, thickness, drug content, uniformity, tensile strength, percent elongation, FTIR spectral analysis and SEM. The results of in vitro diffusion studies revealed that the films exhibited enhanced drug diffusion as compared to the films prepared using untreated chitosan. The films also demonstrated good to moderate antibacterial activities against selective gram positive and gram negative bacteria.

Synthesis, Characterization and Antimicrobial Study of Novel 4-{[(8-Hydroxyquinolin-5-yl)methyl]amino}benzenesulfonamide and Its Oxinates.

A novel 4-[(8-hydroxyquinolin-5-yl)methyl]aminobenzenesulfonamide (HQMABS) was synthesized by optimized reaction of 4-aminobenzenesulfonamide with 5-chloromethyl-8-hydroxyquinoline hydrochloride (CMHQ). Various oxinates of HQMABS were also prepared using Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) metal salts. All compounds were analyzed by physicochemical, thermogravimetric and spectroscopic techniques. Antimicrobial activity was carried out using agar-plate method against various strains of bacteria (Staphylococcus aureus, Bacillus subtillis, Pseudomonas aerugionsa, and Escherichia coli) and spores of fungi (Aspergillus niger and Aspergillus flavous). The results showed significantly higher antimicrobial activity of HQMABS compared to the parent 8-hydroxyquinoline and sulfonamide, while oxinates of HQMABS showed milder activity.

Functional conservation of the human EXT1 tumor suppressor gene and its Drosophila homolog tout velu.

Heparan sulfate proteoglycans play a vital role in signaling of various growth factors in both Drosophila and vertebrates. In Drosophila, mutations in the tout velu (ttv) gene, a homolog of the mammalian EXT1 tumor suppressor gene, leads to abrogation of glycosaminoglycan (GAG) biosynthesis. This impairs distribution and signaling activities of various morphogens such as Hedgehog (Hh), Wingless (Wg), and Decapentaplegic (Dpp). Mutations in members of the exostosin (EXT) gene family lead to hereditary multiple exostosis in humans leading to bone outgrowths and tumors. In this study, we provide genetic and biochemical evidence that the human EXT1 (hEXT1) gene is conserved through species and can functionally complement the ttv mutation in Drosophila. The hEXT1 gene was able to rescue a ttv null mutant to adulthood and restore GAG biosynthesis.

Identification of direct DAF-16 targets controlling longevity, metabolism and diapause by chromatin immunoprecipitation.

DAF-16, a forkhead transcription factor, is a key regulator of longevity, metabolism and dauer diapause in Caenorhabditis elegans. The precise mechanism by which DAF-16 regulates multiple functions, however, is poorly understood. Here, we used chromatin immunoprecipitation (ChIP) to identify direct targets of DAF-16. We cloned 103 target sequences containing consensus DAF-16 binding sites and selected 33 targets for further analysis. Expression of most of these genes is regulated in a DAF-16-dependent manner, and inactivation of more than half of these genes significantly altered DAF-16-dependent functions, including life span, fat storage and dauer formation. Our results show that the ChIP-based cloning strategy leads to greater enrichment for DAF-16 target genes than previous screening strategies. We also demonstrate that DAF-16 is recruited to multiple promoters to coordinate regulation of its downstream targets. The large number of target genes discovered provides insight into how DAF-16 controls diverse biological functions.

TRF3, a TATA-box-binding protein-related factor, is vertebrate-specific and widely expressed.

TATA-box-binding protein (TBP) is a highly conserved RNA polymerase II general transcription factor that binds to the core promoter and initiates assembly of the preinitiation complex. Two proteins with high homology to TBP have been found: TBP-related factor 1 (TRF1), described only in Drosophila melanogaster, and TRF2, which is broadly distributed in metazoans. Here, we report the identification and characterization of an additional TBP-related factor, TRF3. TRF3 is virtually identical to TBP in the C-terminal core domain, including all residues involved in DNA binding and interaction with other general transcription factors. Like other TBP family members, the N-terminal region of TRF3 is divergent. The TRF3 gene is present and expressed in vertebrates, from fish through humans, but absent from the genomes of the urochordate Ciona intestinalis and the lower eukaryotes D. melanogaster and Caenorhabditis elegans. TRF3 is a nuclear protein that is present in all human and mouse tissues and cell lines examined. Despite the highly homologous TBP-like C-terminal core domain, gel filtration analysis indicates that the native molecular weight of TRF3 is substantially less than that of TFIID. Interestingly, after mitosis, reimport of TRF3 into the nucleus occurs subsequent to TBP and other basal transcription factors. In summary, TRF3 is a highly conserved vertebrate-specific TRF whose phylogenetic conservation, expression pattern, and other properties are distinct from those of TBP and all other TRFs.

Selective recruitment of TAFs by yeast upstream activating sequences. Implications for eukaryotic promoter structure.

The general transcription factor TFIID is composed of the TATA box binding protein (TBP) and multiple TBP-associated factors (TAFs). In yeast, promoters can be grouped into two classes based on the involvement of TAFs. TAF-dependent (TAF(dep)) promoters require TAFs for transcription, and TBP and TAFs are present at comparable levels on these promoters. TAF-independent (TAF(ind)) promoters do not require TAFs for activity, and TAFs are either absent or present at levels far below those of TBP on these promoters. Here, we demonstrate that the upstream activating sequence (UAS) mediates the selective recruitment of TAFs to TAF(dep) promoters. A TAF(ind) UAS fails to recruit TAFs and to direct efficient transcription when inserted upstream of a TAF(dep) core promoter. This transcriptional defect can be overcome by a potent activator, indicating that a strong activation domain can compensate for the absence of TAFs on a TAF(dep) core promoter. Our results reveal a requirement for compatibility between the UAS and core promoter and thus help explain previous reports that only certain yeast UAS-core promoter combinations and mammalian enhancer-promoter combinations are efficiently transcribed. The differential recruitment of TAFs by UASs provides strong evidence for the proposal that in vivo TAFs are the targets of some, but not all, activators.