Pharmacophore elucidation of phosphoiodyn A - Potent and selective peroxisome proliferator-activated receptor β/δ agonists with neuroprotective activity

Targeting Peroxisome Proliferator-Activated Receptor-β/δ, Reactive Oxygen Species and Redox Signaling with Phytocompounds for Cancer Therapy

Significance: Peroxisome proliferator-activated receptors (PPARs) have a moderately preserved amino-terminal domain, an extremely preserved DNA-binding domain, an integral hinge region, and a distinct ligand-binding domain that are frequently encountered with the other nuclear receptors. PPAR-β/δ is among the three nuclear receptor superfamily members in the PPAR group. Recent Advances: Emerging studies provide an insight on natural compounds that have gained increasing attention as potential anticancer agents due to their ability to target multiple pathways involved in cancer development and progression. Critical Issues: Modulation of PPAR-β/δ activity has been suggested as a potential therapeutic strategy for cancer management. This review focuses on the ability of bioactive phytocompounds to impact reactive oxygen species (ROS) and redox signaling by targeting PPAR-β/δ for cancer therapy. The rise of ROS in cancer cells may play an important part in the initiation and progression of cancer. However, excessive levels of ROS stress can also be toxic to the cells and cancer cells with increased oxidative stress are likely to be more vulnerable to damage by further ROS insults induced by exogenous agents, such as phytocompounds and therapeutic agents. Therefore, redox modulation is a way to selectively kill cancer cells without causing significant toxicity to normal cells. However, use of antioxidants together with cancer drugs may risk the effect of treatment as both act through opposite mechanisms. Future Directions: It is advisable to employ more thorough and detailed methodologies to undertake mechanistic explorations of numerous phytocompounds. Moreover, conducting additional clinical studies is recommended to establish optimal dosages, efficacy, and the impact of different phytochemicals on PPAR-β/δ.

Marine Natural and Nature-Inspired Compounds Targeting Peroxisome Proliferator Activated Receptors (PPARs)

Peroxisome proliferator-activated receptors α, γ and β/δ (PPARα, PPARγ, and PPARβ/δ) are a family of ligand-activated transcriptional factors belonging to the superfamily of nuclear receptors regulating the expression of genes involved in lipid and carbohydrate metabolism, energy homeostasis, inflammation, and the immune response. For this reason, they represent attractive targets for the treatment of a variety of metabolic diseases and, more recently, for neurodegenerative disorders due to their emerging neuroprotective effects. The degree of activation, from partial to full, along with the selectivity toward the different isoforms, greatly affect the therapeutic efficacy and the safety profile of PPAR agonists. Thus, there is a high interest toward novel scaffolds with proper combinations of activity and selectivity. This review intends to provide an overview of the discovery, optimization, and structure-activity relationship studies on PPAR modulators from marine sources, along with the structural and computational studies that led to their identification and/or elucidation, and rationalization of their mechanisms of action.

Development of Heterocyclic PPAR Ligands for Potential Therapeutic Applications

The family of nuclear peroxisome proliferator-activated receptors (PPARα, PPARβ/δ, and PPARγ) is a set of ligand-activated transcription factors that regulate different functions in the body. Whereas activation of PPARα is known to reduce the levels of circulating triglycerides and regulate energy homeostasis, the activation of PPARγ brings about insulin sensitization and increases the metabolism of glucose. On the other hand, PPARβ when activated increases the metabolism of fatty acids. Further, these PPARs have been claimed to be utilized in various metabolic, neurological, and inflammatory diseases, neurodegenerative disorders, fertility or reproduction, pain, and obesity. A series of different heterocyclic scaffolds have been synthesized and evaluated for their ability to act as PPAR agonists. This review is a compilation of efforts on the part of medicinal chemists around the world to find novel compounds that may act as PPAR ligands along with patents in regards to PPAR ligands. The structure-activity relationship, as well as docking studies, have been documented to better understand the mechanistic investigations of various compounds, which will eventually aid in the design and development of new PPAR ligands. From the results of the structural activity relationship through the pharmacological and in silico evaluation the potency of heterocycles as PPAR ligands can be described in terms of their hydrogen bonding, hydrophobic interactions, and other interactions with PPAR.

Discovery of First-in-Class Peptidomimetic Neurolysin Activators Possessing Enhanced Brain Penetration and Stability

Peptidase neurolysin (Nln) is an enzyme that functions to cleave various neuropeptides. Upregulation of Nln after stroke has identified the enzyme as a critical endogenous cerebroprotective mechanism and validated target for the treatment of ischemic stroke. Overexpression of Nln in a mouse model of stroke results in dramatic improvement of stroke outcomes, while pharmacological inhibition aggravates them. Activation of Nln has therefore emerged as an intriguing target for drug discovery efforts for ischemic stroke. Herein, we report the discovery and hit-to-lead optimization of first-in-class Nln activators based on histidine-containing dipeptide hits identified from a virtual screen. Adopting a peptidomimetic approach provided lead compounds that retain the pharmacophoric histidine moiety and possess single-digit micromolar potency over 40-fold greater than the hit scaffolds. These compounds exhibit 5-fold increased brain penetration, significant selectivity over highly homologous peptidases, greater than 65-fold increase in mouse brain stability, and 'drug-like' fraction unbound in the brain.

Phosphorus Compounds of Natural Origin: Prebiotic, Stereochemistry, Application

Organophosphorus compounds play a vital role as nucleic acids, nucleotide coenzymes, metabolic intermediates and are involved in many biochemical processes. They are part of DNA, RNA, ATP and a number of important biological elements of living organisms. Synthetic compounds of this class have found practical application as agrochemicals, pharmaceuticals, bioregulators, and othrs. In recent years, a large number of phosphorus compounds containing P-O, P-N, P-C bonds have been isolated from natural sources. Many of them have shown interesting biological properties and have become the objects of intensive scientific research. Most of these compounds contain asymmetric centers, the absolute configurations of which have a significant effect on the biological properties of the products of their transformations. This area of research on natural phosphorus compounds is still little-studied, that prompted us to analyze and discuss it in our review. Moreover natural organophosphorus compounds represent interesting models for the development of new biologically active compounds, and a number of promising drugs and agrochemicals have already been obtained on their basis. The review also discusses the history of the development of ideas about the role of organophosphorus compounds and stereochemistry in the origin of life on Earth, starting from the prebiotic period, that allows us in a new way to consider this most important problem of fundamental science.

An iPSC-Derived Neuron Model of CLN3 Disease Facilitates Small Molecule Phenotypic Screening

The neuronal ceroid lipofuscinoses (NCLs) are a family of rare lysosomal storage disorders. The most common form of NCL occurs in children harboring a mutation in the CLN3 gene. This form is lethal with no existing cure or treatment beyond symptomatic relief. The pathophysiology of CLN3 disease is complex and poorly understood, with current in vivo and in vitro models failing to identify pharmacological targets for therapeutic intervention. This study reports the characterization of the first CLN3 patient-specific induced pluripotent stem cell (iPSC)-derived model of the blood-brain barrier and establishes the suitability of an iPSC-derived neuron model of the disease to facilitate compound screening. Upon differentiation, hallmarks of CLN3 disease are apparent, including lipofuscin and subunit c of mitochondrial ATP synthase accumulation, mitochondrial dysfunction, and attenuated Bcl-2 expression. The model led to the identification of small molecules that cleared subunit c accumulation by mTOR-independent modulation of autophagy, conferred protective effects through induction of Bcl-2 and rescued mitochondrial dysfunction.

Melatonin Alleviates Neuronal Damage After Intracerebral Hemorrhage in Hyperglycemic Rats

Background

This study sought to investigate a novel effect of melatonin in reducing brain injury in an in vivo hyperglycemic intracerebral hemorrhage (ICH) model and further explore the mechanisms of protection.

Methods

Hyperglycemia ICH was induced in Sprague-Dawley rats by streptozocin injection followed by autologous blood injection into the striatum. A combined approach including RNA-specific depletion, electron microscopy, magnetic resonance, Western blots, and immunohistological staining was applied to quantify the brain injuries after ICH.

Results

Hyperglycemia resulted in enlarged hematoma volume, deteriorated brain edema, and aggravated neuronal mitochondria damage 3 days after ICH. Post-treatment with melatonin 2 hours after ICH dose-dependently improved neurological behavioral performance lasting out to 14 days after ICH. This improved neurological function was associated with enhanced structural and functional integrity of mitochondria. Mechanistic studies revealed that melatonin alleviated mitochondria damage in neurons via activating the PPARδ/PGC-1α pathway. Promisingly, melatonin treatment delayed until 6 hours after ICH still reduced brain edema and improved neurological functions. Melatonin supplementation reduces neuronal damage after hyperglycemic ICH by alleviating mitochondria damage in a PPARδ/PGC-1α-dependent manner.

Conclusion

Melatonin may represent a therapeutic strategy with a wide therapeutic window to reduce brain damage and improve long-term recovery after ICH.

Emerging targets and potential therapeutic agents in non-alcoholic fatty liver disease treatment

Nonalcoholic Fatty Liver Disease (NAFLD) is the most common chronic liver disease in the world, which is characterized by liver fat accumulation unrelated to excessive drinking. Indeed, it attracts growing attention and becomes a global health problem. Due to the complexity of the NAFLD pathogenic mechanism, no related drugs were approved by Food and Drug Administration (FDA) till now. However, it is encouraging that a series of candidate drugs have entered the clinical trial stage with expectation to treat NAFLD. In this review, we summarized the main pathways and pathogenic mechanisms of NAFLD, as well as introduced the main potential therapeutic targets and the corresponding compounds involved in metabolism, inflammation and fibrosis. Furthermore, we also discuss the progress of these compounds, such as drug design and optimization, the choice of pharmacological properties and druglikeness, and the analysis of structure-activity relationship. This review offers a medium on future drug design and development, to be beneficial to relevant studies.

Bergenin Exerts Hepatoprotective Effects by Inhibiting the Release of Inflammatory Factors, Apoptosis and Autophagy via the PPAR-γ Pathway

Objective

Hepatic ischemia reperfusion (IR) limits the development of liver transplantation technology. The aim of this study was to explore the protective effects of Bergenin on hepatic IR, particularly the elimination of reactive oxygen species (ROS) and activation of the peroxisome proliferators activated receptor γ (PPAR-γ) pathway.

Methods

Initial experiments were performed to confirm the non-toxicity of Bergenin. Mice were randomly divided into sham, IR, and IR + Bergenin (10, 20 and 40 mg/kg) groups, and serum and tissue samples were obtained at 2, 8 and 24 h for detection of liver enzymes (ALT and AST), inflammatory factors (TNF-α, IL-6 and IL-1β), ROS, cell death markers (Bcl-2, Bax, Beclin-1 and LC3) and related important pathways (PPAR-γ, P38 MAPK, NF-κB p65 and JAK2/STAT1).

Results

Bergenin reduced the release of ROS, down-regulated inflammatory factors, and inhibited apoptosis and autophagy. Additionally, expression of PPAR-γ-related genes was increased and phosphorylation of P38 MAPK, NF-κB p65 and JAK2/STAT1-related proteins was decreased in Bergenin pre-treatment groups in a dose-dependent manner.

Conclusion

Bergenin exerts hepatic protection by eliminating ROS, affecting the release of inflammatory factors, and influencing apoptosis- and autophagy-related genes via the PPAR-γ pathway in this model of hepatic IR injury.

Rational approaches, design strategies, structure activity relationship and mechanistic insights for therapeutic coumarin hybrids

Hybrid molecules, furnished by combining two or more pharmacophores is an emerging concept in the field of medicinal chemistry and drug discovery that has attracted substantial traction in the past few years. Naturally occurring scaffolds such as coumarins display a wide spectrum of pharmacological activities including anticancer, antibiotic, antidiabetic and others, by acting on multiple targets. In this view, various coumarin-based hybrids possessing diverse medicinal attributes were synthesized in the last five years by conjugating coumarin moiety with other therapeutic pharmacophores. The current review summarizes the recent development (2014 and onwards) of these pharmacologically active coumarin hybrids and demonstrates rationale behind their design, structure-activity relationships (SAR) and mechanistic studies performed on these hybrid molecules. This review will be beneficial for medicinal chemist and chemical biologist, and in general to the drug discovery community and will facilitate the synthesis and development of novel, potent coumarin hybrid molecules serving as lead molecules for the treatment of complex disorders.

Discovery of Aromatic Carbamates that Confer Neuroprotective Activity by Enhancing Autophagy and Inducing the Anti-Apoptotic Protein B-Cell Lymphoma 2 (Bcl-2)

Neurodegenerative diseases share certain pathophysiological hallmarks that represent common targets for drug discovery. In particular, dysfunction of proteostasis and the resultant apoptotic death of neurons represent common pathways for pharmacological intervention. A library of aromatic carbamate derivatives based on the clinically available drug flupirtine was synthesized to determine a structure-activity relationship for neuroprotective activity. Several derivatives were identified that possess greater protective effect in human induced pluripotent stem cell-derived neurons, protecting up to 80% of neurons against etoposide-induced apoptosis at concentrations as low as 100 nM. The developed aromatic carbamates possess physicochemical properties desirable for CNS therapeutics. The primary known mechanisms of action of the parent scaffold are not responsible for the observed neuroprotective activity. Herein, we demonstrate that neuroprotective aromatic carbamates function to increase the Bcl-2/Bax ratio to an antiapoptotic state and activate autophagy through induction of beclin 1.