Development of selective class I protein arginine methyltransferase inhibitors through fragment-based drug design approach.

Protein arginine methyltransferases (PRMTs) catalyze the methylation of the terminal nitrogen atoms of the guanidino group of arginine of protein substrates. The aberrant expression of these methyltransferases is linked to various diseases, making them promising therapeutic targets. Currently, PRMT inhibitors are at different stages of clinical development, which validated their significance as drug targets. Structural Genomics Consortium (SGC) has reported several small fragment inhibitors as Class I PRMT inhibitors, which can be the starting point for rational drug development. Herein, we report the successful application of a fragment-based approach toward the discovery of selective Class I PRMT inhibitors. Structure-based ligand optimization was performed by strategic incorporation of fragment hits on the drug-like quinazoline core and subsequent fragment growth in the desired orientation towards identified hydrophobic shelf. A clear SAR was established, and the lead compounds 55 and 56 displayed potent inhibition of Class I PRMTs with IC50 values of 92 nM and 37 nM against PRMT4. We report the systematic development of potent Class I PRMT inhibitors with good potency and about 100-fold selectivity when tested against a panel of 31 human DNA, RNA, and protein lysine and arginine methyltransferases. These improved small molecules will provide new options for the development of novel potent and selective PRMT4 inhibitors.

Molecular mechanisms regulating wound repair: Evidence for paracrine signaling from corneal epithelial cells to fibroblasts and immune cells following transient epithelial cell treatment with Mitomycin C.

In this paper, we use RNAseq to identify senescence and phagocytosis as key factors to understanding how mitomyin C (MMC) stimulates regenerative wound repair. We use conditioned media (CM) from untreated (CMC) and MMC treated (CMM) human and mouse corneal epithelial cells to show that corneal epithelial cells indirectly exposed to MMC secrete elevated levels of immunomodulatory proteins including IL-1α and TGFß1 compared to cells exposed to CMC. These factors increase epithelial and macrophage phagocytosis and promote ECM turnover. IL-1α supplementation can increase phagocytosis in control epithelial cells and attenuate TGFß1 induced αSMA expression by corneal fibroblasts. Yet, we show that epithelial cell CM contains factors besides IL-1α that regulate phagocytosis and αSMA expression by fibroblasts. Exposure to CMM also impacts the activation of bone marrow derived dendritic cells and their ability to present antigen. These in vitro studies show how a brief exposure to MMC induces corneal epithelial cells to release proteins and other factors that function in a paracrine way to enhance debris removal and enlist resident epithelial and immune cells as well as stromal fibroblasts to support regenerative and not fibrotic wound healing.

Integration of Ligand-Based and Structure-Based Methods for the Design of Small-Molecule TLR7 Antagonists.

Toll-like receptor 7 (TLR7) is activated in response to the binding of single-stranded RNA. Its over-activation has been implicated in several autoimmune disorders, and thus, it is an established therapeutic target in such circumstances. TLR7 small-molecule antagonists are not yet available for therapeutic use. We conducted a ligand-based drug design of new TLR7 antagonists through a concerted effort encompassing 2D-QSAR, 3D-QSAR, and pharmacophore modelling of 54 reported TLR7 antagonists. The developed 2D-QSAR model depicted an excellent correlation coefficient (R2training: 0.86 and R2test: 0.78) between the experimental and estimated activities. The ligand-based drug design approach utilizing the 3D-QSAR model (R2training: 0.95 and R2test: 0.84) demonstrated a significant contribution of electrostatic potential and steric fields towards the TLR7 antagonism. This consolidated approach, along with a pharmacophore model with high correlation (Rtraining: 0.94 and Rtest: 0.92), was used to design quinazoline-core-based hTLR7 antagonists. Subsequently, the newly designed molecules were subjected to molecular docking onto the previously proposed binding model and a molecular dynamics study for a better understanding of their binding pattern. The toxicity profiles and drug-likeness characteristics of the designed compounds were evaluated with in silico ADMET predictions. This ligand-based study contributes towards a better understanding of lead optimization and the future development of potent TLR7 antagonists.

Highly Thiolated Dendritic Mesoporous Silica Nanoparticles with High-Content Gold as Nanozymes: The Nano-Gold Size Matters.

Thiolated dendritic mesoporous silica nanoparticles (T-DMSNs) with ultrahigh density of thiol groups (284.6 ± 9 µmol g-1) are synthesized and used to load gold nanoparticles with tunable sizes (1.2-2.7 nm) and high content (34.0 wt %). It is demonstrated that the size of gold nanoparticles has a significant impact on their peroxidase-mimicking activity. At an optimized size of 1.9 nm, T-DMSNs@Au exhibits the highest activity. Our contribution provides new insights into the rational design of nanozymes for future applications.

Mesoporous carbon hollow spheres: carbonisation-temperature-dependent delivery of therapeutic proteins.

Protein therapeutics have received significant recognition due to their potential in the treatment of diseases and cancer, thanks to the rapid development of efficient nanocarriers. In this work, we for the first time report the influence of the carbonisation temperature of mesoporous carbon hollow spheres (MCHS) on their delivery performance of therapeutic proteins. Samples MHCS-500, MHCS-700 and MHCS-900 were prepared at carbonisation temperatures of 500, 700 and 900 °C, respectively. It was found that MHCS-900 displayed the highest inherent hydrophobicity among all samples. As a result, MHCS-900 demonstrated the highest loading amount and most sustained release of RNase A (a therapeutic protein). The hydrophobicity also facilitated the cellular uptake and endo/lysosome escape of RNase A delivered by MHCS-900. Consequently, RNase A delivered by MHCS-900 significantly improved the therapeutic efficacy tested in human squamous carcinoma cells (SCC25) compared with free RNase A or those delivered by the other MHCS carriers. This work optimises the carbonisation temperature on porous carbon spheres for highly efficient intracellular delivery of therapeutic proteins.

Characterization and relative sonocatalytic efficiencies of a new MWCNT and CdS modified TiO2 catalysts and their application in the sonocatalytic degradation of rhodamine B.

TiO(2) nanoparticles modified with MWCNTs and CdS were synthesized by the sol-gel method followed by solvothermal treatment at low temperature. The chemical composition and surface structure of the CdS/CNT-TiO(2) composites were investigated by X-ray diffraction, specific surface area measurements, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and scanning electron microscopy. Then a series of sonocatalytic degradation experiments were carried out under ultrasonic irradiation in the presence of CNT/TiO(2) and the CdS/CNT-TiO(2) composites. It was found that RhB was quickly and effectively degraded under different ultrasonic conditions. As expected, the nanosized CdS/CNT-TiO(2) photocatalyst showed enhanced activity compared with the non CdS treated CNT/TiO(2) material in the sonocatalytic degradation of RhB. The sonocatalyst CCTb with 34.68% contents of Ti heat treated at 500 °C for 1h showed the highest sonocatalytic activity. The synergistic effect of the greater surface area and catalytic activities of the composite catalysts was examined in terms of their strong adsorption ability and interphase interaction by comparing the effects of different amounts of MWCNTs and CdS in the catalysts and their roles. The mechanism of sonocatalytic degradation over the CdS/CNT modified TiO(2) composites under different ultrasonic conditions was also discussed.

The characteristic study and sonocatalytic performance of CdSe-graphene as catalyst in the degradation of azo dyes in aqueous solution under dark conditions.

The sonocatalytic degradation of azo dyes; methyl orange (MO) and rhodamine B (RhB) were studied catalyzed by cadmium selenide (CdSe)-graphene in dark ambiance. The CdSe-graphene composites were prepared by simple hydrothermal method. The characterizations of composites were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), specific surface area (BET) and with energy dispersive X-ray (EDX). The UV-spectroscopic analysis of the dyes was done by measuring the change in absorbance. The degradation of the organic dyes was calculated based on the decrease in concentration of the dyes with respect to regular time intervals. The rate coefficients for the sonocatalytic process were successfully established and the reusability tests were done to test the stability of the used catalysts.