Advanced Glycation End Products: Formation, Role in Diabetic Complications, and Potential in Clinical Applications

Hyperglycemic conditions and disruptions to glucose-regulating pathways lead to increased formation of highly reactive aldehydes, methylglyoxal and glyoxal, which react with certain arginine and lysine residues in proteins to form advanced glycation end products (AGEs). These AGEs damage the integrity of the retinal vasculature predominantly through two mechanisms: non-receptor-mediated damage, which pertains to the interaction with extracellular matrix and its functional properties, and receptor-mediated damage through AGE interactions with their receptors (RAGE) on pericytes and Muller cells. Damage occurring between AGE and RAGE potentially generates reactive oxygen species, inflammatory cytokines, and growth factors. Both mechanisms result in increased permeability of endothelial tight junctions, and this increased permeability can lead to leaking and eventually ischemia. Once this ischemia becomes significant, neovascularization can occur, the hallmark of proliferative diabetic retinopathy. Current pharmaceutical studies have shown the potential of AGE inhibitors, such as aminoguanidine, in decreasing AGE production, thus minimizing its effects in hyperglycemic conditions. Other pharmaceutical interventions, such as Tanshinone IIA, aim to protect cells from the impacts of AGEs. Future research will not only continue to understand the properties of AGEs and their effects on diabetes and diabetic complications like diabetic retinopathy but will also explore how they impact other diseases

Recent advances on visual cycle protein research and progress on clinical translation

Since the publication of our previous paper, Visual cycle proteins: Structure, function, and roles in human retinal disease (Tsin, et.al, JBC 293:13016, 2018) there has been significant progress on multiple topics discussed in this paper. In the present communication, we further explore research advances on two visual cycle proteins: DES1 and IRBP. In addition, we emphasize the progress of clinical translation of other visual cycle protein research, including the breakthrough of FDA-approved gene therapy for Leber’s congenital amaurosis, and additional gene therapies at different stages of clinical trials for various retinal diseases such as retinitis pigmentosa, diabetic retinopathy, and Stargardt’s disease

The Interplay between Drug and Sorbitol Contents Determines the Mechanical and Swelling Properties of Potential Rice Starch Films for Buccal Drug Delivery

Rice starch is a promising biomaterial for thin film development in buccal drug delivery, but the plasticisation and antiplasticisation phenomena from both plasticisers and drugs on the performance of rice starch films are not well understood. This study aims to elucidate the competing effects of sorbitol (plasticiser) and drug (antiplasticiser) on the physicochemical characteristics of rice starch films containing low paracetamol content. Rice starch films were prepared with different sorbitol (10, 20 and 30% w/w) and paracetamol contents (0, 1 and 2% w/w) using the film casting method and were characterised especially for drug release, swelling and mechanical properties. Sorbitol showed a typical plasticising effect on the control rice starch films by increasing film flexibility and by reducing swelling behaviour. The presence of drugs, however, modified both the mechanical and swelling properties by exerting an antiplasticisation effect. This antiplasticisation action was found to be significant at a low sorbitol level or a high drug content. FTIR investigations supported the antiplasticisation action of paracetamol through the disturbance of sorbitol–starch interactions. Despite this difference, an immediate drug release was generally obtained. This study highlights the interplay between plasticiser and drug in influencing the mechanical and swelling characteristics of rice starch films at varying concentrations

The Interplay between Drug and Sorbitol Contents Determines the Mechanical and Swelling Properties of Potential Rice Starch Films for Buccal Drug Delivery

Rice starch is a promising biomaterial for thin film development in buccal drug delivery, but the plasticisation and antiplasticisation phenomena from both plasticisers and drugs on the performance of rice starch films are not well understood. This study aims to elucidate the competing effects of sorbitol (plasticiser) and drug (antiplasticiser) on the physicochemical characteristics of rice starch films containing low paracetamol content. Rice starch films were prepared with different sorbitol (10, 20 and 30% w/w) and paracetamol contents (0, 1 and 2% w/w) using the film casting method and were characterised especially for drug release, swelling and mechanical properties. Sorbitol showed a typical plasticising effect on the control rice starch films by increasing film flexibility and by reducing swelling behaviour. The presence of drugs, however, modified both the mechanical and swelling properties by exerting an antiplasticisation effect. This antiplasticisation action was found to be significant at a low sorbitol level or a high drug content. FTIR investigations supported the antiplasticisation action of paracetamol through the disturbance of sorbitol–starch interactions. Despite this difference, an immediate drug release was generally obtained. This study highlights the interplay between plasticiser and drug in influencing the mechanical and swelling characteristics of rice starch films at varying concentrations

SAR study of niclosamide derivatives for neuroprotective function in SH-SY5Y neuroblastoma

Neurodegenerative disease is a debilitating and incurable condition that affects millions of people around the world. The loss of functions or malfunctions of neural cells are the causes of mortality. A proteosome inhibitor, MG132, is well known to cause neurodegeneration in vitro when model neuronal-derived cell lines are exposed to it. Niclosamide, an anthelmintic drug, which has been used to treat tapeworm infections for more than 50 years, has recently attracted renewed attention in drug repurposing because it has been found to be a good candidate in many drug development screenings. We recently found that all markers of MG132-induced neuronal cell toxicity, including the accumulation of ubiquitinated proteins, were prevented by the presence of niclosamide. In addition, niclosamide was shown to enhance autophagy induced by MG132. There results suggested that niclosamide could act as a neuroprotective agent. In the present study, niclosamide derivatives were synthesized, and the structure-activity relationship (SAR) were determined with respect to protein ubiquitination induced by MG132 and effect on cell survival signaling pathways for neuroprotective function. Our results indicate that phenol OH plays a significant role in neuroprotective activity while the niclosamide derivatives without Cl (5- or 2\u27-Cl) showed almost the same neuroprotective effect. 4\u27-NO2 can be replaced by N3 or CF3 whereas NH2 significantly decreased activity. These findings provide guidance for the development of new niclosamide analogues against neurodegenerative diseases including Parkinson\u27s disease

SAR study of niclosamide derivatives in the human glioblastoma U-87 MG cells

Glioblastoma is a lethal malignant brain tumor, and the development of efficient chemotherapeutic agents remains an urgent need. Niclosamide, an anthelmintic drug, which has been used to treat tapeworm infections more than 50 years, has recently attracted renewed attention due to its evident anticancer activities. It has been shown that niclosamide induces cytotoxicity in human glioblastoma U-87 MG cells corresponding with increased protein ubiquitination, ER stress, and autophagy. Furthermore, niclosamide showed down regulation of multiple pro-survival signaling pathways including Wnt/β-catenin, PI3K/AKT, MAPK/ERK, and STAT3, which further caused reduction of U87-MG cell viability. However, the molecular mechanisms of niclosimide and its derivatives in cancer are not fully understood. In the present article, 12 niclosamide derivatives were synthesized by the replacement of substituents for the structure-activity relationship (SAR) study of the protein ubiquitination and related signaling pathways. Our approach is to identify which substituents of niclosamide play important roles in inducing cell apoptosis, inhibition of cell growth, and down regulation of cell survival signaling pathways. Our results indicate that phenol OH of niclosamide plays a significant role in the anti-glioblastoma activity, while missing Cl (5- or 2′-Cl) showed almost no such effect. 4′-N3 or CF3 has the similar activity to niclosamide (4′-NO2) whereas NH2 significantly decreased the cytotoxicity in U87 cells. These modified compounds can be tested to determine which are most effective on cancer treatment. These findings are important in the development of multi-functionalized niclosamide and drug design therapy in the future

RNase2 is a possible trigger of acute-on-chronic inflammation leading to mRNA vaccine-associated cardiac complication.

10.1016/j.medj.2023.04.001MedS2666-6340(23)00104-6