8-Mercaptoguanine Derivatives as Inhibitors of Dihydropteroate Synthase

In Silico Drug Repurposing Endorse Amprenavir, Darunavir and Saquinavir to Target Enzymes of Multidrug Resistant Uropathogenic E. Coli

Multidrug resistance is a paramount impediment to successful treatment of most hospital acquired bacterial infections. A plethora of bacterial genera exhibit differential levels of resistance to the existing antibiotics. Prevalent Uropathogenic Escherichia coli or UPEC conduce high mortality among them. Multi-Drug Resistant bacterial strains utilize precise mechanisms to bypass effects of antibiotics. This is probably due to their familiar genomic origin. In this article drug repositioning method have been utilised to target 23 enzymes of UPEC strains viz. CFT073, 536 and UTI89. 3-D drug binding motifs have been predicted using SPRITE and ASSAM servers that compare amino acid side chain similarities. From the hit results anti-viral drugs have been considered for their uniqueness and specificity. Out of 14 anti-viral drugs 3 anti-HIV drugs viz. Amprenavir, Darunavir and Saquinavir have selected for maximum binding score or drug targetability. Finally, active sites of the enzymes were analyzed using GASS-WEB for eloquent drug interference. Further analyses with the active sites of all the enzymes showed that the three selected anti-HIV drugs were very much potent to inhibit their active sites. Combination or sole application of Amprenavir, Darunavir and Saquinavir to MDR-UPEC infections may leads to cure and inhibition of mortality.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-024-01282-x.

The aminosalicylate - folate connection

Two aminosalicylate isomers have been found to possess useful pharmacological behavior: p-aminosalicylate (PAS, 4AS) is an anti-tubercular agent that targets M. tuberculosis, and 5-aminosalicylate (5AS, mesalamine, mesalazine) is used in the treatment of ulcerative colitis (UC) and other inflammatory bowel diseases (IBD). PAS, a structural analog of pABA, is biosynthetically incorporated by bacterial dihydropteroate synthase (DHPS), ultimately yielding a dihydrofolate (DHF) analog containing an additional hydroxyl group in the pABA ring: 2'-hydroxy-7,8-dihydrofolate. It has been reported to perturb folate metabolism in M. tuberculosis, and to selectively target M. tuberculosis dihydrofolate reductase (mtDHFR). Studies of PAS metabolism are reviewed, and possible mechanisms for its mtDHFR inhibition are considered. Although 5AS is a more distant structural relative of pABA, multiple lines of evidence suggest a related role as a pABA antagonist that inhibits bacterial folate biosynthesis. Structural data support the likelihood that 5AS is recognized by the DHPS pABA binding site, and its effects probably range from blocking pABA binding to formation of a dead-end dihydropterin-5AS adduct. These studies suggest that mesalamine acts as a gut bacteria-directed antifolate, that selectively targets faster growing, more folate-dependent species.

Antibacterial Effect of Sesame Protein-Derived Peptides against Escherichia coli and Staphylococcus aureus: In Silico and In Vitro Analysis

This study aimed to screen out antibacterial peptides derived from sesame (Sesamum indicum L.) through in silico and in vitro methods. In silico proteolysis of sesame proteins with pepsin, trypsin, and chymotrypsin was performed with the online server BIOPEP-UWM. The CAMPR3 online server was used to predict the antimicrobial effect of peptides. The ToxinPred, PepCalc, and AllergenFP tools were utilized to forecast the physicochemical properties, toxicity, and allergen of the peptides. Molecular docking analysis showed that six cationic antimicrobial peptides could directly interact with the key sites of dihydropteroate synthase, whereas Ala-Gly-Gly-Val-Pro-Arg and Ser-Thr-Ile-Arg exhibited the strongest binding affinity. In vitro antibacterial experiment showed the minimum inhibitory concentration (MIC) of Ser-Thr-Ile-Arg against Escherichia coli and Staphylococcus aureus was 1024 and 512 µg/mL, respectively. Meanwhile, MIC of Ala-Gly-Gly-Val-Pro-Arg against both bacterial species was 512 µg/mL. Our results suggest that peptides from sesame possess the ability to potentially hinder bacterial activity.

Efficient Samarium-Grafted-C3N4-Doped α-MoO3 Used as a Dye Degrader and Antibacterial Agent: In Silico Molecular Docking Study

This study was used to evaluate the catalytic activity (CA) and bactericidal activity of α-MoO3 and Sm-g-C3N4-doped α-MoO3 composites prepared through an efficient, cost-effective coprecipitation route. Their characteristic studies verify the formation of α-MoO3 and its composites (3, 6, and 9 mL Sm-g-C3N4-doped α-MoO3), which showed high crystallinity, as confirmed by X-ray diffraction (XRD) analysis. The production of superoxide and hydroxyl radicals due to charge transfer through α-MoO3 and g-C3N4 eventually forms electrons in g-C3N4 and holes around α-MoO3. CA against Rhodamine B (RhB) in basic medium provides maximum results compared to acidic and neutral media. The bactericidal efficacy of the (9 mL) doped sample represents a greater inhibition zone of 6.10 mm against the negative bacterial strain Escherichia coli. Furthermore, in silico studies showed that the generated nanorods may inhibit DNA gyrase and dihydropteroate synthase (DHPS) enzymes.

Molecular mechanism of plasmid-borne resistance to sulfonamide antibiotics

The sulfonamides (sulfas) are the oldest class of antibacterial drugs and inhibit the bacterial dihydropteroate synthase (DHPS, encoded by folP), through chemical mimicry of its co-substrate p-aminobenzoic acid (pABA). Resistance to sulfa drugs is mediated either by mutations in folP or acquisition of sul genes, which code for sulfa-insensitive, divergent DHPS enzymes. While the molecular basis of resistance through folP mutations is well understood, the mechanisms mediating sul-based resistance have not been investigated in detail. Here, we determine crystal structures of the most common Sul enzyme types (Sul1, Sul2 and Sul3) in multiple ligand-bound states, revealing a substantial reorganization of their pABA-interaction region relative to the corresponding region of DHPS. We use biochemical and biophysical assays, mutational analysis, and in trans complementation of E. coli ΔfolP to show that a Phe-Gly sequence enables the Sul enzymes to discriminate against sulfas while retaining pABA binding and is necessary for broad resistance to sulfonamides. Experimental evolution of E. coli results in a strain harboring a sulfa-resistant DHPS variant that carries a Phe-Gly insertion in its active site, recapitulating this molecular mechanism. We also show that Sul enzymes possess increased active site conformational dynamics relative to DHPS, which could contribute to substrate discrimination. Our results reveal the molecular foundation for Sul-mediated drug resistance and facilitate the potential development of new sulfas less prone to resistance.

Facile Synthesis of Vanadium Oxide/Carbon Spheres-Doped Nickel Oxide Functioned as a Nanocatalyst and Bactericidal Behavior with Molecular Docking Analysis

Vanadium oxide (V₂O₅) and carbon spheres (Cs)-doped NiO₂ nanostructures (NSs) were prepared using the co-precipitation approach. Several spectroscopic and microscopic techniques, including X-ray diffraction (XRD), UV-vis, FTIR, TEM, and HR-TEM investigations, were used to describe the as-synthesized NSs. The XRD pattern exhibited the hexagonal structure, and the crystallite size of pristine and doped NSs was calculated as 29.3, 32.8, 25.79, and 45.19 nm, respectively. The control sample (NiO₂) showed maximum absorption at 330 nm, and upon doping, a redshift was observed, leading to decreased band gap energy from 3.75 to 3.59 eV. TEM of NiO₂ shows agglomerated nonuniform nanorods exhibited with various nanoparticles without a specific orientation; a higher agglomeration was observed upon doping. The (4 wt %) V₂O₅/Cs-doped NiO₂ NSs served as superior catalysts with a 94.21% MB reduction in acidic media. The significant antibacterial efficacy was estimated against Escherichia coli by measuring the zone of inhibition (3.75 mm). Besides their bactericidal analysis, V₂O₅/Cs-doped NiO₂ was shown to have a binding score of 6.37 for dihydrofolate reductase and a binding score of 4.31 for dihydropteroate synthase in an in silico docking study of E. coli.

In-vitro synergistic microbicidal and catalytic evaluation of polyvinylpyrrolidone/chitosan doped tungsten trioxide nanoplates with evidential in-silico analysis

In this research, hydrothermally synthesized tungsten trioxide (WO₃) nanocomposites doped polyvinylpyrrolidone (PVP) and chitosan (CS) were studied. Various concentrations (3, 6, and 9 wt%) of PVP were doped into a fixed amount of binary system (CS-WO₃) nanocomposites. PVP/CS polymers showed attractive attention because of their different structure, functionality, and architecture control as dopant to WO₃. The PVP/CS encapsulates the WO₃ (ternary composite), which controls crystallite size (band gap reduction), rapidly overcomes the recombination electron-hole pairs issues, and generates the active sites, resulting in improved catalytic and antimicrobial activity. The synthesized nanocomposites revealed significant catalytic efficiency and methylene blue (MB) dye depletion of 99.9 % in the presence of reducing agent (NaBH₄) in neutral and acidic media. Antimicrobial effectiveness of produced nanostructures towards Escherichia coli (E. coli) pathogen at low and high concentrations were investigated by Vernier caliper in mm. Furthermore, to their microbicidal action, docking experiments of CS-doped WO₃ and PVP/CS-doped WO₃ nanostructures for DHFR and FabI of Escherichia coli suggested blockage of aforesaid enzymes as the plausible pathway.

Molybdenum-doped iron oxide nanostructures synthesized via a chemical co-precipitation route for efficient dye degradation and antimicrobial performance: in silico molecular docking studies

In this research, various concentrations of molybdenum (2, 4 and 6 wt%) doped Fe₃O₄ nanostructures (Mo-Fe₃O₄ NSs) were prepared via a co-precipitation technique. Various techniques were then used to investigate the optical, morphological and structural properties of the NSs in the presence of the dopant materials. X-ray diffraction (XRD) was used to investigate the crystalline nature of the prepared NSs and confirm the orthorhombic and tetragonal structure of Fe₃O₄, with a decrease in crystallinity and crystallite sizes of 36.11, 38.45, 25.74 and 24.38 nm with increasing concentration of Mo (2, 4 and 6%). Fourier-transform infrared (FTIR) spectroscopy analysis was carried out to examine the functional groups in the NSs. Structure, surface morphology and topography were examined via field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), which confirmed the fabrication of nanoparticles and nanorods and a floccule-like morphology with a higher doping concentration and the interlayer d-spacing was calculated using high-resolution (HR)TEM, the results of which were a good match to the XRD data. The presence of Mo, Fe and O in a lattice of Mo (2, 4 and 6%) doped Fe₃O₄ was confirmed by energy dispersive X-ray spectroscopy (EDS) analysis. The energy band gap (E _g) was measured via the optical analysis of pure and doped samples, showing a decrease from 2.76 to 2.64 eV. The photoluminescence (PL) spectra exhibit a higher charge combination rate of electron-hole pairs with a higher concentration of doping. The NSs exhibited excellent catalytic activity (CA) in degrading methylene blue (MB) dye in a basic medium by around 86.25%. Additionally, the antimicrobial activity was tested against Escherichia coli (E. coli) bacteria. Pairs of electrons and holes are the fundamental basis for generating reactive oxygen species that kill bacteria. The significant inhibition zones were calculated against E. coli bacteria at around 3.45 mm compared to ciprofloxacin. In silico docking investigations of the Mo-Fe₃O₄ NSs for dihydropteroate synthase (DHPS, binding score: 6.16 kcal mol^-1), dihydrofolate reductase (DHFR, binding score: 6.01 kcal mol^-1), and β-ketoacyl-acyl carrier protein synthase III (FabH, binding score: 5.75 kcal mol^-1) of E. coli show the suppression of the aforementioned enzymes as a potential mechanism besides their microbicidal assay.

Antimicrobial activity and molecular docking screening of bioactive components of Antirrhinum majus (snapdragon) aerial parts

Background

Antirrhinum majus (Snapdragon) is a perennial Mediterranean-native plant that is commonly used for mass display. Few reports acknowledged the traditional use of A. majus for its medicinal and therapeutic effects. Herein, we assess the impact of A. majus’s sample preparation and extraction methods on the plant-aerial parts’ phytochemical contents and antimicrobial activity. Furthermore, the microbial targets of the extracts’ secondary metabolites are inspected using molecular docking simulations.

Methods

The leaves and flowers of A. majus were prepared as fresh and air-dried samples, then extracted using cold maceration and hot reflux, respectively. Extracts with the best phytochemical profiles were selected to test their antimicrobial activities against Bacillus subtilis, Staphylococcus aureus, Enterobacter aerogenes, Escherichia coli and Candida albicans. Besides, molecular docking of 66 reported isolated compounds was conducted against various microbial targets.

Results

The dried-refluxed samples revealed a massive deterioration in their phytochemical profiles, whereas the macerated flowers extract exhibited the highest total phenolic content and antimicrobial activity against all tested bacterial strains. However, both flowers and leaves extracts showed similar minimum inhibitory and lethal concentrations against C. albicans. Molecular docking studies revealed that chlorogenic acid, chalcononaringenin 4’-glucoside, 3,4,2’,4’,6’-pentahydroxy-chalcone 4’-glucoside, apigenin-7-glucuronide, and luteolin-7-glucuronide were the lead compounds in expressing the antimicrobial activity. Yet, A. majus’s compounds could neither inhibit the 30S ribosomal subunit nor muramyl ligase E.

Conclusion

Our results suggest that cold maceration of A. majus fresh aerial parts gave higher flavonoid and phenolic content contributing to its antimicrobial properties. These flavonoids and phenolic compounds are predicted to have a crucial role in inhibiting fungal sterol 14-demethylase, and bacterial dihydropteroate synthase and gyrase B subunit proteins.

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Air-drying of A. majus’s aerial parts deteriorates its phytochemical composition, affecting its antimicrobial activity.

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A. majus’s fresh-flowers macerate exhibited the highest total phenolic content and antibacterial activity.

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The antimycotic activity of A. majus was the same for flowers and leaves macerates.

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In-silico results showed that some phenolics, chalcones, and flavonoids are responsible for the antimicrobial activity.

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A.majus’s components act on fungal sterol 14-demethylase, and bacterial dihydropteroate synthase and gyrase B enzymes.

Crystal structure of Arabidopsis thaliana HPPK/DHPS, a bifunctional enzyme and target of the herbicide asulam

Herbicides are vital for modern agriculture, but their utility is threatened by genetic or metabolic resistance in weeds, as well as regulatory barriers. Of the known herbicide modes of action, 7,8-dihydropterin synthase (DHPS), which is involved in folate biosynthesis, is targeted by just one commercial herbicide, asulam. A mimic of the substrate para-aminobenzoic acid, asulam is chemically similar to sulfonamide antibiotics, and although it is still in widespread use, asulam has faced regulatory scrutiny. With an entire mode of action represented by just one commercial agrochemical, we sought to improve the understanding of its plant target. Here we solve a 2.3 Å resolution crystal structure for Arabidopsis thaliana DHPS that is conjoined to 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK), and we reveal a strong structural conservation with bacterial counterparts at the sulfonamide-binding pocket of DHPS. We demonstrate that asulam and the antibiotic sulfamethoxazole have herbicidal as well as antibacterial activity, and we explore the structural basis of their potency by modeling these compounds in mitochondrial HPPK/DHPS. Our findings suggest limited opportunity for the rational design of plant selectivity from asulam and indicate that pharmacokinetic or delivery differences between plants and microbes might be the best ways to safeguard this mode of action.

Assay Development and Identification of the First Plasmodium falciparum 7,8-dihydro-6-hydroxymethylpterin-pyrophosphokinase Inhibitors

In the fight towards eradication of malaria, identifying compounds active against new drug targets constitutes a key approach. Plasmodium falciparum 7,8-dihydro-6-hydroxymethylpterin-pyrophosphokinase (PfHPPK) has been advanced as a promising target, as being part of the parasite essential folate biosynthesis pathway while having no orthologue in the human genome. However, no drug discovery efforts have been reported on this enzyme. In this study, we conducted a three-step screening of our in-house antifolate library against PfHPPK using a newly designed PfHPPK-GFP protein construct. Combining virtual screening, differential scanning fluorimetry and enzymatic assay, we identified 14 compounds active against PfHPPK. Compounds’ binding modes were investigated by molecular docking, suggesting competitive binding with the HMDP substrate. Cytotoxicity and in vitro ADME properties of hit compounds were also assessed, showing good metabolic stability and low toxicity. The most active compounds displayed low micromolar IC₅₀ against drug-resistant parasites. The reported hit compounds constitute a good starting point for inhibitor development against PfHPPK, as an alternative approach to tackle the malaria parasite.

Phytochemical study: molecular docking of eugenol derivatives as antioxidant and antimicrobial agents

Abstract:

Eugenol (4-allyl-2-methoxyphenol) is a natural phenolic compound present in certain aromatic plants; however, it is generally extracted from essential oil of Eugenia caryophyllata (Syzygiumaromaticum) (L.) Merr. and L.M. Perry. This bioactive natural compound has generated considerable biological interest with well-known antimicrobial and antioxidant actions. The authors have aimed to the evaluations of eugenol derivatives and their as antimicrobial and antioxidant agent with the aid of molecular dynamic simulation. The starting material was extracted from cloves using hydrodistillation. Two eugenol derivatives, acetyleugenol (4-allyl-2-methoxyphenylacetate) and epoxyeugenol (4-allyl-2-methoxyphenol) were prepared and tested against two strains Escherichia coli (E. Coli) and Staphylococcus aureus (S. Aureus). The results have revealed that the three compounds (Eugenol, acetyleugenol and epoxyeugenol) possess important potentials of inhibition against E. coli and S. Aureus. The antioxidant activity of eugenol derivatives was evaluated by the reaction with DPPH (1,1-diphenyl-2-picrylhydrazyl), showed that the epoxyeugenol was the most active compound. The molecular docking scores of three compounds and the amino acids in the active site pockets of the selected proteins of the two bacteria have approved and explain the biological experimental outcomes.

MoS2/cellulose-doped ZnO nanorods for catalytic, antibacterial and molecular docking studies

Cellulose nanocrystals (CNCs) and molybdenum disulphide (MoS₂) incorporated into ZnO nanorods (NRs) were synthesized via a chemical precipitation route at room temperature. All concerned samples were characterized to examine their optical properties, elemental composition, phase formation, surface morphology and functional group presence. The aim of this research was to enhance the catalytic properties of ZnO by co-doping with various concentrations of CNCs and MoS₂ NRs. It was renowned that doped ZnO NRs showed superior catalytic activity compared to bare ZnO NRs. Statistically significant (p < 0.05) inhibition zones for samples were recorded for E. coli and S. aureus at low and high concentrations, respectively. The in vitro bactericidal potential of ZnO-CNC and ZnO-CNC-MoS₂ nanocomposites was further confirmed through in silico molecular docking predictions against the DHFR and DHPS enzymes of E. coli and S. aureus. Molecular docking studies suggested the inhibition of these enzyme targets by CNC nanocomposites as a possible mechanism governing their bactericidal activity.

Identification of a transcription factor, PunR, that regulates the purine and purine nucleoside transporter punC in E. coli

Many genes in bacterial genomes are of unknown function, often referred to as y-genes. Recently, the analytic methods have divided bacterial transcriptomes into independently modulated sets of genes (iModulons). Functionally annotated iModulons that contain y-genes lead to testable hypotheses to elucidate y-gene function. The inversely correlated expression of a putative transporter gene, ydhC, relative to purine biosynthetic genes, has led to the hypothesis that it encodes a purine-related transporter and revealed a LysR-family regulator, YdhB, with a predicted 23-bp palindromic binding motif. RNA-Seq analysis of a ydhB knockout mutant confirmed the YdhB-dependent activation of ydhC in the presence of adenosine. The deletion of either the ydhC or the ydhB gene led to a substantially decreased growth rate for E. coli in minimal medium with adenosine, inosine, or guanosine as the nitrogen source. Taken together, we provide clear evidence that YdhB activates the expression of the ydhC gene that encodes a purine transporter in E. coli. We propose that the genes ydhB and ydhC be re-named as punR and punC, respectively.

Rodionova et al. find that the putative transporter gene, ydhC and its regulator ydhB are involved in purine transportation and that the expression of the ydhC gene is activated by the YdhB in E. coli. The authors suggest renaming the regulator PunR and the transporter PunC, respectively.

8-Mercaptoguanine-based inhibitors of Mycobacterium tuberculosis dihydroneopterin aldolase: synthesis, in vitro inhibition and docking studies

The dihydroneopterin aldolase (DHNA, EC 4.1.2.25) activity of FolB protein is required for the conversion of 7,8-dihydroneopterin (DHNP) to 6-hydroxymethyl-7,8-dihydropterin (HP) and glycolaldehyde (GA) in the folate pathway. FolB protein from Mycobacterium tuberculosis (MtFolB) is essential for bacilli survival and represents an important molecular target for drug development. S8-functionalized 8-mercaptoguanine derivatives were synthesised and evaluated for inhibitory activity against MtFolB. The compounds showed IC₅₀ values in the submicromolar range. The inhibition mode and inhibition constants were determined for compounds that exhibited the strongest inhibition. Additionally, molecular docking analyses were performed to suggest enzyme-inhibitor interactions and ligand conformations. To the best of our knowledge, this study describes the first class of MtFolB inhibitors.

Doping of Mg on ZnO Nanorods Demonstrated Improved Photocatalytic Degradation and Antimicrobial Potential with Molecular Docking Analysis

Various concentrations of Mg-doped ZnO nanorods (NRs) were prepared using co-precipitation technique. The objective of this study was to improve the photocatalytic properties of ZnO. The effect of Mg doping on the structure, phase constitution, functional groups presence, optical properties, elemental composition, surface morphology and microstructure of ZnO was evaluated with XRD, FTIR, UV-Vis spectrophotometer, EDS, and HR-TEM, respectively. Optical absorption spectra obtained from the prepared samples showed evidence of blueshift upon doping. XRD results revealed hexagonal wurtzite phase of nanocomposite with a gradual decrease in crystallite size with Mg addition. PL spectroscopy showed trapping efficiency and migration of charge carriers with electron-hole recombination behavior, while HR-TEM estimated interlayer d-spacing. The presence of chemical bonding, vibration modes and functional groups at the interface of ZnO was revealed by FTIR and Raman spectra. In this study, photocatalytic, sonocatalytic and sonophotocatalytic performance of prepared NRs was systematically investigated by degrading a mixture of methylene blue and ciprofloxacin (MBCF). Experimental results suggested that improved degradation performance was shown by Mg-doped ZnO NRs. We believe that the product synthesized in this study will prove to be a beneficial and promising photocatalyst for wastewater treatment. Conclusively, Mg-doped ZnO exhibited substantial (p < 0.05) efficacy against gram-negative (G-ve) as compared to gram-positive (G+ve) bacteria. In silico molecular docking studies of Mg-doped ZnO NRs against DHFR (binding score: - 7.518 kcal/mol), DHPS (binding score: - 6.973 kcal/mol) and FabH (- 6.548 kcal/mol) of E. coli predicted inhibition of given enzymes as possible mechanism behind their bactericidal activity.

Dapsone is not a Pharmacodynamic Lead Compound for its Aryl Derivatives

BACKGROUND

The relatedness between the linear equations of thermodynamics and QSAR was studied thanks to the recently elucidated crystal structure complexes between sulfonamide pterin conjugates and dihydropteroate synthase (DHPS) together with a published set of thirty- six synthetic dapsone derivatives with their reported entropy-driven activity data. Only a few congeners were slightly better than dapsone.

OBJECTIVE

Our study aimed at demonstrating the applicability of thermodynamic QSAR and to shed light on the mechanistic aspects of sulfone binding to DHPS.

METHODS

To this end ligand docking to DHPS, quantum mechanical properties, 2D- and 3D-QSAR as well as Principle Component Analysis (PCA) were carried out.

RESULTS

The short aryl substituents of the docked pterin-sulfa conjugates were outward oriented into the solvent space without interacting with target residues which explains why binding enthalpy (ΔH) did not correlate with potency. PCA revealed how chemically informative descriptors are evenly loaded on the first three PCs (interpreted as ΔG, ΔH and ΔS), while chemically cryptic ones reflected higher dimensional (complex) loadings.

CONCLUSION

It is safe to utter that synthesis efforts to introduce short side chains for aryl derivatization of the dapsone scaffold have failed in the past. On theoretical grounds we provide computed evidence why dapsone is not a pharmacodynamic lead for drug profiling because enthalpic terms do not change significantly at the moment of ligand binding to target.

Structure based design, synthesis, and biological evaluation of imidazole derivatives targeting dihydropteroate synthase enzyme

In this study, we have designed and synthesized 2-((5-acetyl-1-(phenyl)-4-methyl-1H-imidazol-2-yl)thio)-N-(4-((benzyl)oxy)phenyl) acetamide derivatives. Antimicrobial activities of all the imidazole derivatives have been examined against Gram-positive and Gram-negative bacteria and results showed that the conjugates have appreciable antibacterial activity. Besides, several analogous were evaluated for their in vitro antiresistant bacterial strains such as Extended-spectrum beta-lactamases (ESBL), Vancomycin-resistant Enterococcus (VRE), and Methicillin-resistant Staphylococcus aureus (MRSA). The SAR revealed that the 12l compound resulted in potency against all bacterial strains as well as ESBL, VRE, and MRSA strains. Lipinski's rule of five, and ADME studies were preformed for all the synthesized compounds with Staphylococcus aureus dihydropteroate synthase (saDHPS) protein (PDB ID: 6CLV) and were found standard drug-likeness properties of conjugates. Moreover, the binding mode of the ligands with the protein study has been examined by molecular docking and results are quite promising. Besides, all the analogous were tested for their in vitro antituberculosis, antimalarial, and antioxidant activity.

Photocatalytic and bactericidal properties and molecular docking analysis of TiO2 nanoparticles conjugated with Zr for environmental remediation

Despite implementing several methodologies including a combination of physical, chemical and biological techniques, aquatic and microbial pollution remains a challenge to this day. Recently, nanomaterials have attracted considerable attention due to their extraordinary prospective for utilization toward environmental remediation. Among several probable candidates, TiO2 stands out due to its potential for use in multifaceted applications. One way to improve the catalytic and antimicrobial potential of TiO2 is to dope it with certain elements. In this study, Zr-doped TiO2 was synthesized through a sol-gel chemical method using various dopant concentrations (2, 4, 6, and 8 wt%). Surface morphological, microstructural and elemental analysis was carried out using FESEM and HR-TEM along with EDS to confirm the formation of Zr-TiO2. XRD spectra showed a linear shift of the (101) anatase peak to lower diffraction angles (from 25.4° to 25.08°) with increasing Zr4+ concentration. Functional groups were examined via FTIR, an ample absorption band appearing between 400 and 700 cm-1 in the acquired spectrum was attributed to the vibration modes of the Ti-O-Ti linkage present within TiO2 nanoparticles, which denotes the formation of TiO2. Experimental results indicated that with increasing dopant concentrations, photocatalytic potential was enhanced significantly. In this respect, TiO2 doped with 8 wt% Zr (sample 0.08 : 1) exhibited outstanding performance by realizing 98% elimination of synthetic MB in 100 minutes. This is thought to be due to a decreased rate of electron-hole pair recombination that transpires upon doping. Therefore, it is proposed that Zr-doped TiO2 can be used as an effective photocatalyst material for various environmental and wastewater treatment applications. The good docking scores and binding confirmation of Zr-doped TiO2 suggested doped nanoparticles as a potential inhibitor against selected targets of both E. coli and S. aureus. Hence, enzyme inhibition studies of Zr-doped TiO2 NPs are suggested for further confirmation of these in silico predictions.

Crystal structure of 4-methyl-N-(4-methyl-benz-yl)benzene-sulfonamide

The title compound, C15H17NO2S, was synthesized via a substitution reaction between 4-methyl-benzyl-amine and p-toluene-sulfonyl chloride. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules, forming ribbons running along the b-axis direction. One of the aromatic rings hosts two inter-molecular C-H⋯π inter-actions that link these hydrogen-bonded ribbons into a three-dimensional network.

Folic Acid Antagonists: Antimicrobial and Immunomodulating Mechanisms and Applications

: Bacterial, protozoan and other microbial infections share an accelerated metabolic rate. In order to ensure a proper functioning of cell replication and proteins and nucleic acids synthesis processes, folate metabolism rate is also increased in these cases. For this reason, folic acid antagonists have been used since their discovery to treat different kinds of microbial infections, taking advantage of this metabolic difference when compared with human cells. However, resistances to these compounds have emerged since then and only combined therapies are currently used in clinic. In addition, some of these compounds have been found to have an immunomodulatory behavior that allows clinicians using them as anti-inflammatory or immunosuppressive drugs. Therefore, the aim of this review is to provide an updated state-of-the-art on the use of antifolates as antibacterial and immunomodulating agents in the clinical setting, as well as to present their action mechanisms and currently investigated biomedical applications.

Bioassay Directed Isolation, Biological Evaluation and in Silico Studies of New Isolates from Pteris cretica L

Members of genus Pteris have their established role in the traditional herbal medicine system. In the pursuit to identify its biologically active constituents, the specie Pteris cretica L. (P. cretica) was selected for the bioassay-guided isolation. Two new maleates (F9 and CB18) were identified from the chloroform extract and the structures of the isolates were elucidated through their spectroscopic data. The putative targets, that potentially interact with both of these isolates, were identified through reverse docking by using in silico tools PharmMapper and ReverseScreen3D. On the basis of reverse docking results, both isolates were screened for their antioxidant, acetylcholinesterase (AChE) inhibition, α-glucosidase (GluE) inhibition and antibacterial activities. Both isolates depicted moderate potential for the selected activities. Furthermore, docking studies of both isolates were also studied to investigate the binding mode with respective targets followed by molecular dynamics simulations and binding free energies. Thereby, the current study embodies the poly-pharmacological potential of P. cretica.

Revitalizing antifolates through understanding mechanisms that govern susceptibility and resistance

In prokaryotes and eukaryotes, folate (vitamin B9) is an essential metabolic cofactor required for all actively growing cells. Specifically, folate serves as a one-carbon carrier in the synthesis of amino acids (such as methionine, serine, and glycine), N-formylmethionyl-tRNA, coenzyme A, purines and thymidine. Many microbes are unable to acquire folates from their environment and rely on de novo folate biosynthesis. In contrast, mammals lack the de novo folate biosynthesis pathway and must obtain folate from commensal microbiota or the environment using proton-coupled folate transporters. The essentiality and dichotomy between mammalian and bacterial folate biosynthesis and utilization pathways make it an ideal drug target for the development of antimicrobial agents and cancer chemotherapeutics. In this minireview, we discuss general aspects of folate biosynthesis and the underlying mechanisms that govern susceptibility and resistance of organisms to antifolate drugs.