Highly potent and selective PPARδ agonist reverses memory deficits in mouse models of Alzheimer's disease.

Rationale: Alzheimer's disease (AD) is a progressive neurodegenerative disease accompanied by neurotoxicity, excessive inflammation, and cognitive impairment. The peroxisome proliferator-activated receptor (PPAR) δ is a potential target for AD. However, its regulatory mechanisms and therapeutic potential in AD remain unclear. We aimed to investigate if the activation of PPARδ using a highly selective and potent agonist could provide an effective therapeutic strategy against AD. Methods: We synthesized a novel PPARδ agonist, 5a, containing a selenazole group and determined the X-ray crystal structure of its complex with PPARδ. The drug-like properties of 5a were assessed by analyzing cytochrome P450 (CYP) inhibition, microsomal stability, pharmacokinetics, and mutagenicity. We investigated the anti-inflammatory effects of 5a using lipopolysaccharide (LPS)-stimulated BV-2 microglia and neuroinflammatory mouse model. The therapeutic efficacy of 5a was evaluated in AD mice with scopolamine-induced memory impairment and APP/PS1 by analyzing cognitive function, glial reactivity, and amyloid pathology. Results: Compound 5a, the most potent and selective PPARδ agonist, was confirmed to bind hPPARδ in a complex by X-ray crystallographic analysis. PPARδ activation using 5a showed potent anti-inflammatory effects in activated glial cells and mouse model of neuroinflammation. Administration of 5a inhibited amyloid plaque deposition by suppressing the expression of neuronal beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), and reduced abnormal glial hyperactivation and inflammatory responses, resulting in improved learning and memory in the APP/PS1 mouse model of AD. Conclusion: We identified that specific activation of PPARδ provides therapeutic effects on multiple pathogenic phenotypes of AD, including neuroinflammation and amyloid deposition. Our findings suggest the potential of PPARδ as a promising drug target for treating AD.

Discovery of the therapeutic potential of PPARδ agonist bearing 1,3,4- thiadiazole in inflammatory disorders.

As a defense mechanism against deleterious stimuli, inflammation plays a vital role in the development of many disorders, including atherosclerosis, inflammatory bowel disease, experimental autoimmune encephalomyelitis, septic and non-septic shock, and non-alcoholic fatty liver disease (NAFLD). Despite the serious adverse effects of extended usage, traditional anti-inflammatory medications, such as steroidal and non-steroidal anti-inflammatory medicines (NSAIDs), are commonly used for alleviating symptoms of inflammation. The PPARδ subtype of peroxisome proliferator-activated receptors (PPARs) has attracted interest because of its potential for reducing inflammation and related disorders. In this study, a series of 1,3,4-thiadiazole derivatives were designed, synthesized, and evaluated. Compound 11 exhibited potent PPARδ agonistic activity with EC50 values 20 nM and strong selectivity over PPARα and PPARγ. Furthermore, compound 11 demonstrated favorable in vitro and in vivo pharmacokinetic properties. In vivo experiments using labeled macrophages and paw thickness measurements confirmed compound 11's potential to reduce macrophage infiltration and alleviate inflammation. These findings highlight compound 11 as a potent and promising therapeutic candidate for the treatment of acute inflammatory diseases and warrant further investigation to explore various biological roles.

DN200434 Inhibits Vascular Smooth Muscle Cell Proliferation and Prevents Neointima Formation in Mice after Carotid Artery Ligation.

BACKGRUOUND: Excessive proliferation and migration of vascular smooth muscle cells (VSMCs), which contributes to the development of occlusive vascular diseases, requires elevated mitochondrial oxidative phosphorylation to meet the increased requirements for energy and anabolic precursors. Therefore, therapeutic strategies based on blockade of mitochondrial oxidative phosphorylation are considered promising for treatment of occlusive vascular diseases. Here, we investigated whether DN200434, an orally available estrogen receptor-related gamma inverse agonist, inhibits proliferation and migration of VSMCs and neointima formation by suppressing mitochondrial oxidative phosphorylation. METHODS: VSMCs were isolated from the thoracic aortas of 4-week-old Sprague-Dawley rats. Oxidative phosphorylation and the cell cycle were analyzed in fetal bovine serum (FBS)- or platelet-derived growth factor (PDGF)-stimulated VSMCs using a Seahorse XF-24 analyzer and flow cytometry, respectively. A model of neointimal hyperplasia was generated by ligating the left common carotid artery in male C57BL/6J mice. RESULTS: DN200434 inhibited mitochondrial respiration and mammalian target of rapamycin complex 1 activity and consequently suppressed FBS- or PDGF-stimulated proliferation and migration of VSMCs and cell cycle progression. Furthermore, DN200434 reduced carotid artery ligation-induced neointima formation in mice. CONCLUSION: Our data suggest that DN200434 is a therapeutic option to prevent the progression of atherosclerosis.

DN200434, an orally available inverse agonist of estrogen-related receptor γ, induces ferroptosis in sorafenib-resistant hepatocellular carcinoma.

Sorafenib, originally identified as an inhibitor of multiple oncogenic kinases, induces ferroptosis in hepatocellular carcinoma (HCC) cells. Several pathways that mitigate sorafenib-induced ferroptosis confer drug resistance; thus strategies that enhance ferroptosis increase sorafenib efficacy. Orphan nuclear receptor estrogen-related receptor γ (ERRγ) is upregulated in human HCC tissues and plays a role in cancer cell proliferation. The aim of this study was to determine whether inhibition of ERRγ with DN200434, an orally available inverse agonist, can overcome resistance to sorafenib through induction of ferroptosis. Sorafenib-resistant HCC cells were less sensitive to sorafenibinduced ferroptosis and showed significantly higher ERRγ levels than sorafenib-sensitive HCC cells. DN200434 induced lipid peroxidation and ferroptosis in sorafenib-resistant HCC cells. Mechanistically, DN200434 increased mitochondrial ROS generation by reducing glutathione/glutathione disulfide levels, which subsequently reduced mTOR activity and GPX4 levels. DN200434 induced amplification of the antitumor effects of sorafenib was confirmed in a tumor xenograft model. The present results indicate that DN200434 may be a novel therapeutic strategy to re-sensitize HCC cells to sorafenib. [BMB Reports 2022; 55(11): 547-552].

Antibacterial Bicyclic Fatty Acids from a Korean Colonial Tunicate Didemnum sp.

Five new bicyclic carboxylic acids were obtained by antibacterial activity-guided isolation from a Korean colonial tunicate Didemnum sp. Their structures were elucidated by the interpretation of NMR, MS and CD spectroscopic data. They all belong to the class of aplidic acids. Three of them were amide derivatives (1-3), and the other two were dicarboxylic derivatives (4 and 5). The absolute configurations were determined by a bisignate pattern of CD spectroscopy, which revealed that the absolute configurations of amides were opposite to those of dicarboxylates at every stereogenic centers. Compound 2 exhibited the most potent antibacterial activity (MIC, 2 µg/mL).

Targeting the Nuclear Receptor-Binding SET Domain Family of Histone Lysine Methyltransferases for Cancer Therapy: Recent Progress and Perspectives.

Nuclear receptor-binding SET domain (NSD) proteins are a class of histone lysine methyltransferases (HKMTases) that are amplified, mutated, translocated, or overexpressed in various types of cancers. Several campaigns to develop NSD inhibitors for cancer treatment have begun following recent advances in knowledge of NSD1, NSD2, and NSD3 structures and functions as well as the U.S. FDA approval of the first HKMTase inhibitor (tazemetostat, an EZH2 inhibitor) to treat follicular lymphoma and epithelioid sarcoma. This perspective highlights recent findings on the structures of catalytic su(var), enhancer-of-zeste, trithorax (SET) domains and other functional domains of NSD methyltransferases. In addition, recent progress and efforts to discover NSD-specific small molecule inhibitors against cancer-targeting catalytic SET domains, plant homeodomains, and proline-tryptophan-tryptophan-proline domains are summarized.

Antioxidative and anti-inflammatory activity of psiguadial B and its halogenated analogues as potential neuroprotective agents.

Psiguadial B (8), and its fluoro- (8a), chloro- (8b), and bromo- (8c) derivatives were synthesized using a sodium acetate-catalyzed single step coupling of three components: ß-caryophyllene (5), diformylphloroglucinol (11), and benzaldehyde (12). These compounds efficiently and dose-dependently decreased H2O2-induced cell death, a quantitative marker of cell death, in primary cultures of mouse cortical neurons. Psiguadial B also decreased neuronal death and accumulation of ROS induced by FeCl2 in cortical cultures. The in vitro effects of these compounds in lipopolysaccharide (LPS)-induced expression of nitric oxide (NO), and TNF-α and IL-6 by suppressing the NF-κB pathway in immune cells demonstrated their antioxidative and anti-inflammatory activity. The present findings warrant further research on the development of psiguadial B-based neuroprotective agents for the treatment of neurodegenerative diseases, acute brain injuries and immunological disorders.

Tunicamycin as a Novel Redifferentiation Agent in Radioiodine Therapy for Anaplastic Thyroid Cancer.

The silencing of thyroid-related genes presents difficulties in radioiodine therapy for anaplastic thyroid cancers (ATCs). Tunicamycin (TM), an N-linked glycosylation inhibitor, is an anticancer drug. Herein, we investigated TM-induced restoration of responsiveness to radioiodine therapy in radioiodine refractory ATCs. 125I uptake increased in TM-treated ATC cell lines, including BHT101 and CAL62, which was inhibited by KClO4, a sodium-iodide symporter (NIS) inhibitor. TM upregulated the mRNA expression of iodide-handling genes and the protein expression of NIS. TM blocked pERK1/2 phosphorylation in both cell lines, but AKT (protein kinase B) phosphorylation was only observed in CAL62 cells. The downregulation of glucose transporter 1 protein was confirmed in TM-treated cells, with a significant reduction in 18F-fluorodeoxyglucose (FDG) uptake. A significant reduction in colony-forming ability and marked tumor growth inhibition were observed in the combination group. TM was revealed to possess a novel function as a redifferentiation inducer in ATC as it induces the restoration of iodide-handling gene expression and radioiodine avidity, thereby facilitating effective radioiodine therapy.

Discrimination of Lycium chinense and L. barbarum Based on Metabolite Analysis and Hepatoprotective Activity.

Lycii Fructus is a traditional medicine used to prevent liver and kidney diseases, which commonly derives from Lycium chinense and Lycium barbarum. Here, the extracts and ethyl acetate-soluble fractions of L. chinense fruits exhibited better hepatoprotective effects than those of L. barbarum, which was likely due to differences in their composition. Therefore, GC-MS and HPLC analyses were conducted to characterize the metabolite differences between L. chinense and L. barbarum. Based on amino acid (AA) and phenolic acid (PA) profiling, 24 AAs and 9 PAs were identified in the two species. Moreover, each species exhibited unique and readily distinguishable AA and PA star graphic patterns. HPLC analysis elucidated composition differences between the ethyl acetate-soluble layers of the two compounds. Further, NMR analysis identified their chemical structures as 4-(2-formyl-5-(hydroxymethyl)-1H-pyrrol-1-yl)butanoic acid and p-coumaric acid. The higher content of 4-(2-formyl-5-(hydroxymethyl)-1H-pyrrol-1-yl)butanoic acid was detected in L. chinense, whereas the content of p-coumaric acid was higher in L. barbarum. Therefore, the differences in the relative contents of these two secondary metabolites in the ethyl acetate-soluble layer of Lycii Fructus could be a good marker to discriminate between L. chinense and L. barbarum.

Identification and evaluation of a napyradiomycin as a potent Nrf2 activator: Anti-oxidative and anti-inflammatory activities.

Natural products with antioxidant and anti-inflammatory properties are important sources of therapeutic agents. The nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway is a well-known defense system against oxidative stress. In this study, a panel of extracts of plants, fungi, and bacteria were screened for Nrf2 activation in a cell-based assay and a crude extract of cultured marine Streptomyces sp. YP127 was found to activate Nrf2. Chemical investigation of the extracts led to isolation of a series of napyradiomycins that activate Nrf2. Among them, napyradiomycin, 16Z-19-hydroxynapyradiomycin A1 (1) exhibited the highest Nrf2-activating efficacy. Compound 1 was further confirmed to induce both mRNA and protein levels of Nrf2-dependent antioxidant enzyme genes in BV-2 microglial cells and suppress inflammatory mediators and intracellular reactive oxygen species. Our findings confirm the antioxidant and anti-inflammatory properties of compound 1, making it a promising therapeutic natural compound for various diseases associated with oxidative stress and inflammation.

An orally available inverse agonist of estrogen-related receptor gamma showed expanded efficacy for the radioiodine therapy of poorly differentiated thyroid cancer.

Estrogen-related receptor gamma (ERRγ) is the NR3B subgroup of associated transcription factors. In this report, a new generation of a potent and selective ERRγ inverse agonist (25) with good biocompatibility was proposed. We also explored the potential of the newly developed compound 25 in the PDTC model to expand the original indications from ATC. In addition, an X-ray crystallographic study of the ligand and ERRγ co-complex showed that 25 completely binds to the target protein (PDB 6KNR). Its medicinal chemistry, including a distinctive structural study to in vivo results, denotes that 25 may be directed towards the development of a pivotal treatment for ERRγ-related cancers.

Targeting Peroxisome Proliferator-Activated Receptor Delta (PPARδ): A Medicinal Chemistry Perspective.

One of the three subtypes of the peroxisome proliferator-activated receptor (PPAR) functioning as a transcription factor is the PPARß or PPARδ. PPARδ is crucial to pathophysiological processes, including metabolic disorders, liver diseases, and cardiovascular diseases. In the past, the clinical development of PPARδ-selective agonist drugs has been stalled due to potential safety-related issues. Despite the elusiveness of such a drug, efforts continue in developing drugs that target PPARδ due to advances in the knowledge of the PPARδ receptor's structure and functions. While several preclinical and clinical studies are reported on PPARδ agonists, there is limited data with no clinical evidence available for PPARδ-selective antagonists. In this review, we mainly focus on the challenges of PPARδ selectivity and the medicinal chemistry of most active agonists discovered by different pharmaceutical companies and institutes. With this in mind, we also provide an update on the development status of PPARδ agonists that are undergoing clinical trials and their therapeutic promise for the treatment of various diseases.

Isolation of Unstable Isomers of Lucilactaene and Evaluation of Anti-Inflammatory Activity of Secondary Metabolites Produced by the Endophytic Fungus Fusarium sp. QF001 from the Roots of Scutellaria baicalensis.

The filamentous fungal pathogen Fusarium sp. causes several crop diseases. Some Fusarium sp. are endophytes that produce diverse valuable bioactive secondary metabolites. Here, extensive chemical investigation of the endophytic fungus, Fusarium sp. QF001, isolated from the inner rotten part of old roots of Scutellariae baicalensis resulted in the isolation of two new photosensitive geometrical isomers of lucilactaene (compounds 2 and 3) along with lucilactaene (6) and six other known compounds (fusarubin (1), (+)-solaniol (4), javanicin (5), 9-desmethylherbarine (7), NG391 (8) and NG393 (9)). Newly isolated isomers and lucilactaene were unstable under light at room temperature and tended to be a mixture in equilibrium state when exposed to a polar protic solvent during reversed phase chromatography. Normal phase chromatography under dim light conditions with an aprotic mobile phase led to the successful isolation of the relatively unstable isomers 2 and 3. Their structures were elucidated as 8(Z)-lucilactaene (2) and 4(Z)-lucilactaene (3) based on spectroscopic data. The absolute configuration of 4 was speculated to be R by computer-assisted specific rotation analysis. The isolated compounds could inhibit NO production and suppress pro-inflammatory cytokines expression in LPS-stimulated macrophage cells. These properties of the isolated compounds indicate their potential use as anti-inflammatory drugs.

Medical fluorophore 1 (MF1), a benzoquinolizinium-based fluorescent dye, as an inflammation imaging agent.

Structure-based targeting of fluorescent dyes is essential for their use as imaging agents for disease diagnosis. Here, we describe the development of the benzoquinolizinium compound Medical fluorophore 1 (MF1) as a novel biomedical imaging agent that allows the visualization of inflammation by virtue of its unique chemical structure. Lipopolysaccharide treatment stimulated the uptake of MF1 by bone marrow-derived macrophages, with no adverse effects on cell proliferation. In vivo fluorescence lifetime imaging revealed the accumulation of MF1 in carrageenan-induced acute inflammatory lesions in mice, which peaked at 6 h. MF1-based imaging also allowed monitoring of the response to the anti-inflammatory drugs dexamethasone and sulfasalazine. Thus, MF1 can be used to diagnose diseases characterized by inflammation as well as treatment efficacy.

Quantitative Analysis of Bioactive Phenanthrenes in Dioscorea batatas Decne Peel, a Discarded Biomass from Postharvest Processing.

Dioscorea batatas Decne (Chinese yam) has been widely cultivated in East Asia for the purposes of food and medicinal uses for centuries. Along with its high nutritional value, the medicinal value of D. batatas has been extensively investigated in association with phytochemicals such as allantoin, flavonoids, saponins and phenanthrenes. Phenanthrenes are especially considered the standard marker chemicals of the Chinese yam for their potent bioactivity and availability of analysis with conventional high performance liquid chromatography with ultraviolet detection (HPLC-UV) methods. In order to investigate how much the contents of phenanthrenes are in the actual food products provided for consumers, D. batatas tuber was peeled and separated into its peel and flesh as in the conventional processing method. A quantitative analysis using the HPLC-UV method revealed that phenanthrenes are concentrically present in the D. batatas peel, while phenanthrenes are present in the flesh under the limit of detection. The difference in the contents of phenanthrenes is estimated to have arisen the considerable difference of antioxidant potential between the peel and the flesh. The results from this study suggest the high value of the discarded biomass of the Chinese yam peel and the necessity for the utilization of the Chinese yam peel.

Discovery of BR102375, a new class of non-TZD PPARγ full agonist for the treatment of type 2 diabetes.

As a potential treatment of type 2 diabetes, a novel PPARγ non-TZD full agonist, compound 18 (BR102375) was identified from the original lead BR101549 by the SAR efforts of the labile metabolite control through bioisosteres approach. In vitro assessments of BR102375 demonstrated its activating potential of PPARγ comparable to Pioglitazone as well as the induction of related gene expressions. Further in vivo evaluation of BR102375 in diabetic rodent models successfully proved its glucose lowering effect as a potential antidiabetic agent, but the anticipated suppression of weight gain was not evident. The X-ray co-crystal analysis of BR102375-PPARγ LBD unexpectedly revealed binding modes totally different from those of BR101549, which was found, instead, closely resembled to those of TZD full agonists.

A Novel Orally Active Inverse Agonist of Estrogen-related Receptor Gamma (ERRγ), DN200434, A Booster of NIS in Anaplastic Thyroid Cancer.

PURPOSE: New strategies to restore sodium iodide symporter (NIS) expression and function in radioiodine therapy-refractive anaplastic thyroid cancers (ATCs) are urgently required. Recently, we reported the regulatory role of estrogen-related receptor gamma (ERRγ) in ATC cell NIS function. Herein, we identified DN200434 as a highly potent (functional IC50 = 0.006 µmol/L), selective, and orally available ERRγ inverse agonist for NIS enhancement in ATC. EXPERIMENTAL DESIGN: We sought to identify better ERRγ-targeting ligands and explored the crystal structure of ERRγ in complex with DN200434. After treating ATC cells with DN200434, the change in iodide-handling gene expression, as well as radioiodine avidity was examined. ATC tumor-bearing mice were orally administered with DN200434, followed by 124I-positron emission tomography/CT (PET/CT). For radioiodine therapy, ATC tumor-bearing mice treated with DN200434 were administered 131I (beta ray-emitting therapeutic radioiodine) and then bioluminescent imaging was performed to monitor the therapeutic effects. Histologic analysis was performed to evaluate ERRγ expression status in normal tissue and ATC tissue, respectively. RESULTS: DN200434-ERRγ complex crystallographic studies revealed that DN200434 binds to key ERRγ binding pocket residues through four-way interactions. DN200434 effectively upregulated iodide-handling genes and restored radioiodine avidity in ATC tumor lesions, as confirmed by 124I-PET/CT. DN200434 enhanced ATC tumor radioiodine therapy susceptibility, markedly inhibiting tumor growth. Histologic findings of patients with ATC showed higher ERRγ expression in tumors than in normal tissue, supporting ERRγ as a therapeutic target for ATC. CONCLUSIONS: DN200434 shows potential clinical applicability for diagnosis and treatment of ATC or other poorly differentiated thyroid cancers.

Saccharoquinoline, a Cytotoxic Alkaloidal Meroterpenoid from Marine-Derived Bacterium Saccharomonospora sp.

A cytotoxic alkaloidal meroterpenoid, saccharoquinoline (1), has been isolated from the fermentation broth of the marine-derived bacterium Saccharomonospora sp. CNQ-490. The planar structure of 1 was elucidated by 1D, 2D NMR, and MS spectroscopic data analyzes, while the relative configuration of 1 was defined through the interpretation of NOE spectroscopic data. Saccharoquinoline (1) is composed of a drimane-type sesquiterpene unit in combination with an apparent 6,7,8-trihydroxyquinoline-2-carboxylic acid. This combination of biosynthetic pathways was observed for the first time in natural microbial products. Saccharoquinoline (1) was found to have cytotoxicity against the HCT-116 cancer cell line by inducing G1 arrest, which leads to cell growth inhibition.

Discovery of Potent, Selective, and Orally Bioavailable Estrogen-Related Receptor-γ Inverse Agonists To Restore the Sodium Iodide Symporter Function in Anaplastic Thyroid Cancer.

An inverse agonist of estrogen-related receptor-γ (ERRγ), an orphan nuclear receptor encoded by E srrg, enhances sodium iodide symporter-mediated radioiodine uptake in anaplastic thyroid cancer (ATC) cells, thereby facilitating responsiveness to radioiodine therapy in vitro. We synthesized potent, selective, and orally bioavailable ERRγ-inverse agonists and evaluated their activity by analyzing in vitro pharmacology and absorption, distribution, metabolism, excretion, and toxicity profiles. X-ray crystallographic analysis of the ligand and ERRγ complex showed that 35 completely binds to the target protein (PDB 6A6K ). Our results showed improved radioiodine avidity in ATC cells through compound 35-mediated upregulation of iodide-handling genes, leading to enhanced responsiveness to radioiodine therapy in vitro. Importantly, in vivo 124I-positron emission tomography/computed tomography imaging revealed that 35 increases radioiodine avidity in CAL62 tumors. Collectively, these results demonstrated that 35 can be developed as a promising treatment for ERRγ-related cancer in the future.

Identification of BR101549 as a lead candidate of non-TZD PPARγ agonist for the treatment of type 2 diabetes: Proof-of-concept evaluation and SAR.

The new class of PPARgamma non-TZD agonist originally derived from the backbone of anti-hypertensive Fimasartan, BR101549, was identified as a potential lead for anti-diabetic drug development. The X-ray crystallography of BR101549 with PPARgamma ligand binding domain (LBD) revealed unique binding characteristics versus traditional TZD full agonists. The lead candidate, BR101549, has been found activating PPARgamma to the level of Pioglitazone in vitro and indeed has demonstrated its effects on blood glucose control in mouse proof-of-concept evaluation. The attempts to improve its metabolic stability profile through follow-up SAR including deuterium incorporation have been also described.