The Current Landscape in the Development of Small-molecule Modulators Targeting Sphingosine-1-phosphate Receptors to Treat Neurodegenerative Diseases.

Sphingosine 1-phosphate (S1P) is extensively researched as a lysophospholipid and is crucial in various physiological and pathological processes. It achieves this via signalling through five different subtypes of G protein-coupled receptors (GPCRs), namely S1PR1 to S1PR5. S1PR modulators possess the ability to traverse the blood-brain barrier, potentially leading to direct ac-tions within the Central Nervous System (CNS). S1PR modulators specifically bind to receptors located on the surface of naive and central memory lymphocytes, causing these cells to be trapped or confined within the lymph node. The investigation of the S1P pathway has resulted in the ap-proval of three S1PR modulators, namely fingolimod, siponimod, and ozanimod, as medications for the treatment of patients suffering from Multiple Sclerosis (MS). Additionally, new S1PR modulators, such as ponesimod and etrasimod, are currently being developed and tested in clini-cal trials. Research on the creation of S1P modulators in neurodegenerative illnesses is ongoing as scientists continue to explore novel possibilities for selective S1P modulators. This study provides a concise overview of sphingolipid metabolism, the mechanism by which S1P receptors are af-fected, and the structural characteristics of several small molecule S1P modulators, with a particu-lar focus on their structure-activity connections.

Metal-free synthesis of selenoesters directly from carboxylic acids using bifunctional selenoureas under batch and continuous-flow conditions.

A new metal-free method for the synthesis of selenoesters directly from carboxylic acids in a flow reactor is reported. The carboxylic acids, Michael acceptors, and bifunctional selenoureas (source of selenium and nucleophile, activator of carbonyl group) were reacted to obtain selenoesters (up to 70% yield). An evidence-backed plausible mechanism is also presented.

Recent Developments in the Design of New Water-Soluble Boron Dipyrromethenes and Their Applications: An Updated Review.

Boron-dipyrromethene (BODIPY) and its derivatives play an important role in the area of organic fluorophore chemistry. Recently, the water-soluble boron-dipyrromethene dyes have increasingly received interest. The structural modification of the BODIPY core by incorporating different neutral and ionic hydrophilic groups makes it water-soluble. The important hydrophilic groups, such as quaternary ammonium, sulfonate, oligoethylene glycol, dicarboxylic acid, and sugar moieties significantly increase the solubility of these dyes in water while preserving their photophysical properties. As a result, these fluorescent dyes are utilized in aqueous systems for applications such as chemosensors, cell imaging, anticancer, biolabeling, biomedicine, metal ion detection, and photodynamic treatment. This review covers the most current developments in the design and synthesis of water-soluble BODIPY derivatives and their wide applications since 2014.

Mechanistic Study of Triazole Based Aminodiol Derivatives in Leukemic Cells-Crosstalk between Mitochondrial Stress-Involved Apoptosis and Autophagy.

Various derivatives that mimic ceramide structures by introducing a triazole to connect the aminodiol moiety and long alkyl chain have been synthesized and screened for their anti-leukemia activity. SPS8 stood out among the derivatives, showing cytotoxic selectivity between leukemic cell lines and human peripheral blood mononuclear cells (about ten times). DAPI nuclear staining and H&E staining revealed DNA fragmentation under the action of SPS8. SPS8 induced an increase in intracellular Ca2+ levels and mitochondrial stress in HL-60 cells identified by the loss of mitochondrial membrane potential, transmission electron microscopy (TEM) examination, and altered expressions of Bcl-2 family proteins. SPS8 also induced autophagy through the detection of Atg5, beclin-1, and LC3 II protein expression, as well as TEM examination. Chloroquine, an autophagy inhibitor, promoted SPS8-induced apoptosis, suggesting the cytoprotective role of autophagy in hindering SPS8 from apoptosis. Furthermore, SPS8 was shown to alter the expressions of a variety of genes using a microarray analysis and volcano plot filtering. A further cellular signaling pathways analysis suggested that SPS8 induced several cellular processes in HL-60, including the sterol biosynthesis process and cholesterol biosynthesis process, and inhibited some cellular pathways, in which STAT3 was the most critical nuclear factor. Further identification revealed that SPS8 inhibited the phosphorylation of STAT3, representing the loss of cytoprotective activity. In conclusion, the data suggest that SPS8 induces both apoptosis and autophagy in leukemic cells, in which autophagy plays a cytoprotective role in impeding apoptosis. Moreover, the inhibition of STAT3 phosphorylation may support SPS8-induced anti-leukemic activity.

Imidazolidinones and Imidazolidine-2,4-diones as Antiviral Agents.

Imidazolidinones and imidazolidine-2,4-diones are important classes of heterocyclic compounds that possess potent activities against several viruses such as dengue virus, enterovirus, hepatitis C virus (HCV), and human immunodeficiency virus (HIV). The first imidazolidinone derivative as an anti-HIV agent was reported in 1996. Imidazolidinones inhibit HIV aspartic protease activity, and also act as CCR5 co-receptor antagonists. Significant effort has been devoted to the design of various imidazolidinone analogues that are active against drug-resistant HIV strains, with fewer side effects. Different scaffolds have been designed through both rational drug design strategies and computer-aided drug design. Imidazolidinones have been found to be potent against HIV, and preclinical studies are currently in progress. There are some reports of imidazolidinones as having both anti-HCV and anti-dengue virus activity, and more research has yet to be done along these lines. These compounds inhibit NS3 serine protease of HCV, and NS2B-NS3 protease of dengue virus. Pyridyl-imidazolidinones possess very specific and potent activity against human enterovirus 71 (EV71) by targeting the EV71 capsid protein VP1, and inhibiting viral adsorption and/or viral RNA uncoating.

Microwave-Assisted Direct Thioesterification of Carboxylic Acids.

A one-pot synthesis of thioesters directly from carboxylic acids, N,N'-diphenylthiourea, triethylamine, and primary alkyl halides is described. Microwave-assisted heating and a catalytic amount of 4-(dimethylamino)pyridine (DMAP) further improved the yields. Both aromatic and aliphatic carboxylic acids were converted to the corresponding thioesters, and many functional groups were compatible with this reaction. Several possible reaction intermediates were investigated, and the quaternary ammonium salts, derived from alkyl halides and tertiary amines, were the intermediates to yield thioesters. A new reaction mechanism for this thioesterification is proposed.

Non-immunosuppressive triazole-based small molecule induces anticancer activity against human hormone-refractory prostate cancers: the role in inhibition of PI3K/AKT/mTOR and c-Myc signaling pathways.

A series of triazole-based small molecules that mimic FTY720-mediated anticancer activity but minimize its immunosuppressive effect have been produced. SPS-7 is the most effective derivative displaying higher activity than FTY720 in anti-proliferation against human hormone-refractory prostate cancer (HRPC). It induced G1 arrest of cell cycle and subsequent apoptosis in thymidine block-mediated synchronization model. The data were supported by a decrease of cyclin D1 expression, a dramatic increase of p21 expression and an associated decrease in RB phosphorylation. c-Myc overexpression replenished protein levels of cyclin D1 indicating that c-Myc was responsible for cell cycle regulation. PI3K/Akt/mTOR signaling pathways through p70S6K- and 4EBP1-mediated translational regulation are critical to cell proliferation and survival. SPS-7 significantly inhibited this translational pathway. Overexpression of Myr-Akt (constitutively active Akt) completely abolished SPS-7-induced inhibitory effect on mTOR/p70S6K/4EBP1 signaling and c-Myc protein expression, suggesting that PI3K/Akt serves as a key upstream regulator. SPS-7 also demonstrated substantial anti-tumor efficacy in an in vivo xenograft study using PC-3 mouse model. Notably, FTY720 but not SPS-7 induced a significant immunosuppressive effect as evidenced by depletion of marginal zone B cells, down-regulation of sphingosine-1-phosphate receptors and a decrease in peripheral blood lymphocytes. In conclusion, the data suggest that SPS-7 is not an immunosuppressant while induces anticancer effect against HRPC through inhibition of Akt/mTOR/p70S6K pathwaysthat down-regulate protein levels of both c-Myc and cyclin D1, leading to G1 arrest of cell cycle and subsequent apoptosis. The data also indicate the potential of SPS-7 since PI3K/Akt signalingis responsive for the genomic alterations in prostate cancer.