Ammonium release in synthetic and human urine by a urease immobilized nanoconstruct

In this work, we have studied the ability of urease immobilized on glutaraldehyde crosslinked chitosan coated magnetic iron oxide nanoparticles (Urease/GA/CS/MIONPs), for the hitherto unreported comparative hydrolysis of urea in synthetic (SUr) and real human urine (HUr). The prepared Urease/GA/CS/MIONPs were characterized by a combination of Fourier transform infrared spectroscopy (FTIR), field emission-scanning-electron-microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and dynamic light scattering (DLS). The nanoconstructs display the highest ammonium ion liberation post-urea hydrolysis in 1/20 or 1/24-fold dilutions of SUr and HUr, respectively. The optimum activity of immobilized urease is observed at pH 7, and the nanoconstructs facilitate efficient urea-hydrolysis till at least 45 °C. Kinetic analysis of the immobilized urease shows km and vmax of 14.81 mM, 12.36 mM, and 18.55 μM min-1 and 10.10 μM min-1, towards SUr and HUr, respectively. The magnetization of the immobilized urease is suitable for reuse across multiple cycles of urea hydrolysis in SUr and HUr. The robust performance of Urease/GA/CS/MIONPs in SUr and HUr is promising for generating ammonium as a useable source of nitrogen from human urine, and underscores the suitability of SUr as a urine mimic for such interventions.

Emergent antibacterial activity of N-(thiazol-2-yl)benzenesulfonamides in conjunction with cell-penetrating octaarginine

Hybrid antimicrobials that combine the effect of two or more agents represent a promising antibacterial therapeutic strategy. In this work, we have synthesized N-(4-(4-(methylsulfonyl)phenyl)-5-phenylthiazol-2-yl)benzenesulfonamide derivatives that combine thiazole and sulfonamide, groups with known antibacterial activity. These molecules are investigated for their antibacterial activity, in isolation and in complex with the cell-penetrating peptide octaarginine. Several of the synthesized compounds display potent antibacterial activity against both Gram-negative and Gram-positive bacteria. Compounds with 4-tert-butyl and 4-isopropyl substitutions exhibit attractive antibacterial activity against multiple strains. The isopropyl substituted derivative displays low MIC of 3.9 μg mL⁻¹ against S. aureus and A. xylosoxidans. The comparative antibacterial behaviour of drug–peptide complex, drug alone and peptide alone indicates a distinctive mode of action of the drug–peptide complex, that is not the simple sum total of its constituent components. Specificity of the drug–peptide complex is evident from comparison of antibacterial behaviour with a synthetic intermediate–peptide complex. The octaarginine–drug complex displays faster killing-kinetics towards bacterial cells, creates pores in the bacterial cell membranes and shows negligible haemolytic activity towards human RBCs. Our results demonstrate that mere attachment of a hydrophobic moiety to a cell penetrating peptide does not impart antibacterial activity to the resultant complex. Conversely, the work suggests distinctive modes of antibiotic activity of small molecules when used in conjunction with a cell penetrating peptide.

Hybrid antimicrobials that combine the effect of two or more agents represent a promising antibacterial therapeutic strategy.

Small Molecule Soluble Epoxide Hydrolase Inhibitors in Multitarget and Combination Therapies for Inflammation and Cancer

The enzyme soluble epoxide hydrolase (sEH) plays a central role in metabolism of bioactive lipid signaling molecules. The substrate-specific hydrolase activity of sEH converts epoxyeicosatrienoic acids (EETs) to less bioactive dihydroxyeicosatrienoic acids. EETs exhibit anti-inflammatory, analgesic, antihypertensive, cardio-protective and organ-protective properties. Accordingly, sEH inhibition is a promising therapeutic strategy for addressing a variety of diseases. In this review, we describe small molecule architectures that have been commonly deployed as sEH inhibitors with respect to angiogenesis, inflammation and cancer. We juxtapose commonly used synthetic scaffolds and natural products within the paradigm of a multitarget approach for addressing inflammation and inflammation induced carcinogenesis. Structural insights from the inhibitor complexes and novel strategies for development of sEH-based multitarget inhibitors are also presented. While sEH inhibition is likely to suppress inflammation-induced carcinogenesis, it can also lead to enhanced angiogenesis via increased EET concentrations. In this regard, sEH inhibitors in combination chemotherapy are described. Urea and amide-based architectures feature prominently across multitarget inhibition and combination chemotherapy applications of sEH inhibitors.

Design and Development of Novel Urea, Sulfonyltriurea, and Sulfonamide Derivatives as Potential Inhibitors of phingosine Kinase 1

Sphingosine kinase 1 (SphK1) is one of the well-studied drug targets for cancer and inflammatory diseases. Recently discovered small-molecule inhibitors of SphK1 have been recommended in cancer therapeutics; however, selectivity and potency of first-generation inhibitors are great challenge. In search of effective SphK1 inhibitors, a set of small molecules have been designed and synthesized bearing urea, sulfonylurea, sulfonamide, and sulfonyltriurea groups. The binding affinity of these inhibitors was measured by fluorescence-binding assay and isothermal titration calorimetry. Compounds 1, 5, 6, and 7 showed an admirable binding affinity to the SphK1 in the sub-micromolar range and significantly inhibited SphK1 activity with admirable IC50 values. Molecular docking studies revealed that these compounds fit well into the sphingosine binding pocket of SphK1 and formed significant number of hydrogen bonds and van der Waals interactions. These molecules may be exploited as potent and selective inhibitors of SphK1 that could be implicated in cancer therapeutics after the required in vivo validation.

Template-free H-dimer and H-aggregate formation by dimeric carbocyanine dyes

Dimeric cyanine dyes self-assemble into H-dimers and H-aggregates, which experience de-aggregation with specific biomolecules.