Evolution of a 4-Benzyloxy-benzylamino Chemotype to Provide Efficacious, Potent, and Isoform Selective PPARα Agonists as Leads for Retinal Disorders

One-pot synthesis of tetrahydropyrimidinecarboxamides enabling in vitro anticancer activity: a combinative study with clinically relevant brain-penetrant drugs

In this study, we describe a one-pot three-component synthesis of bioactive tetrahydopyrimidinecarboxamide derivatives employing lanthanum triflate as a catalyst. Out of the synthesized compounds, 4f had the most potent anti-cancer activity and impeded cell cycle progression effectively. Anti-cancer bioactivity was observed in 4f against liver, breast, and lung cancers as well as primary patient-derived glioblastoma cell lines. Compound 4f effectively inhibited the 3D neurosphere formation in primary patient-derived glioma stem cells. Specifically, 4f exhibited synergistic cytotoxicity with the EGFR inhibitor that is the clinical epidermal growth factor receptor inhibitor osimertinib. 4f does not exhibit anti-kinase activity and is cytostatic in nature, and further work is needed to understand the true molecular target of 4f and its derivatives. Through our current work, we establish a promising tetrahydopyrimidinecarboxamide-based lead compound with anti-cancer activity, which may exhibit potent anti-cancer activity in combination with specific clinically relevant small molecule kinase inhibitors.

Design and Assessment of First-Generation Heterobifunctional PPARα/STING Modulators

Inflammatory retinal diseases such as diabetic retinopathy (DR) and age-related macular degeneration (AMD) are prominent causes of blindness in industrialized countries. The complexity of these diseases, involving diverse cell types and pathways that give rise to a multifactorial pathogenesis, complicates drug discovery. As such, therapies exhibiting polypharmacology are expected to improve outcomes through broader disease stage coverage and beneficial spatiotemporal effects. We report herein the first dual modulator of PPARα and STING, two targets tied to disparate pathologies in retinal diseases. Recognizing structural similarities between a reported STING inhibitor SN-013 and our previously described PPARα agonist A229, we designed BH400, which agonizes PPARα (EC50 = 1.2 μM) and inhibits STING (IC50 = 8.1 μM). BH400 demonstrates superior protection over single-target PPARα or STING modulation in microglial and photoreceptor cells. These findings provide compelling evidence for the potential benefit of polypharmacology in common retinal diseases through dual PPARα/STING modulation, motivating further studies.

Design, Synthesis, and Structure-Activity Relationships of Biaryl Anilines as Subtype-Selective PPAR-alpha Agonists

The role of peroxisome proliferator-activated receptor alpha (PPARα) in retinal biology is clarifying, and evidence demonstrates that novel PPARα agonists hold promising therapeutic utility for diseases like diabetic retinopathy and age-related macular degeneration. Herein, we disclose the design and initial structure-activity relationships for a new biaryl aniline PPARα agonistic chemotype. Notably, this series exhibits subtype selectivity for PPARα over other isoforms, a phenomenon postulated to be due to the unique benzoic acid headgroup. This biphenyl aniline series is sensitive to B-ring functionalization but allows isosteric replacement, and provides an opportunity for C-ring extension. From this series, 3g, 6j, and 6d were identified as leads with <90 nM potency in a cell-based luciferase assay cell and exhibited efficacy in various disease-relevant cell contexts, thereby setting the stage for further characterization in more advanced in vitro and in vivo models.

1,2,4‐Triazole and benzimidazole fused dihydropyrimidine derivatives: Design, green synthesis, antibacterial, antitubercular, and antimalarial activities

This study reports the design and synthesis of novel 1,2,4-triazolo/benzimidazolo-pyrimidine linked 1-benzyl-4-[(p-tolyloxy)methyl]-1,2,3-triazole derivatives as potent antimicrobial agents according to their in vitro antibacterial, antifungal, antitubercular as well as antimalarial activities. An efficient, ecologically benign, and facile multicomponent synthesis was employed to synthesize these derivatives. The synthesis is accelerated with the mild and eco-friendly organocatalyst tetrabutylammonium bromide, providing a yield of 82%-96% within the short reaction time of 0.5-1.5 h. Compared with the MIC values of ciprofloxacin and ampicillin on the respective strains, compound d2 showed better activity against Escherichia coli and Streptococcus pyogenes and compound d8 showed better MIC against Staphylococcus aureus. Additionally, compounds d3, d4, and d5 showed potent MIC values against Pseudomonas aeruginosa. All triazolo-pyrimidine derivatives d1-d8 showed potent inhibitory action against Gram-positive strains. Compound e3 showed good potency against Mycobacterium tuberculosis H37Rv. The IC₅₀ values of d3 and e2 indicated better activity against Plasmodium falciparum. Collectively, these derivatives depict potent multifaceted activity and provide promising access for further antimicrobial and antimalarial investigations.

Design and synthesis of novel quinazolinone-based fibrates as PPARα agonists with antihyperlipidemic activity

Aiming to discover new antihyperlipidemic agents, a new set of quinazolinone-fibrate hybrids 9a-r bearing the essential features for peroxisome proliferator-activated receptor-α (PPARα) agonistic activity was synthesized and the structures were confirmed by different spectral data. All the target compounds were screened for their PPARα agonistic activity. Compounds 9o and 9q exhibited potent activity, with EC₅₀ values better than that of fenofibrate by 8.7- and 27-fold, respectively. Molecular docking investigations were performed for all the newly synthesized compounds in the active site of the PPARα receptor to study their interactions and energies in the receptor. Moreover, the antihyperlipidemic and antioxidant activities of compounds 9o and 9q were determined using Triton WR-1339-induced hyperlipidemic rats. Compound 9q exhibited effective hypolipidemic activity in a dose-dependent manner, where it significantly reduced the serum levels of total cholesterol, triglycerides, low-density lipoprotein cholesterol, and very-low-density lipoprotein cholesterol and increased the level of high-density lipoprotein cholesterol. Furthermore, it possesses a powerful antioxidant profile where it significantly elevated the levels of reduced glutathione as well as the total antioxidant capacity and significantly decreased the malondialdehyde level. The histopathological studies revealed that compound 9q improved the aortic architecture and hepatic steatosis. These findings support that compound 9q could be a promising lead compound for the development of new antihyperlipidemic agents.

Discovery of 4-benzyloxy and 4-(2-phenylethoxy) chalcone fibrate hybrids as novel PPARα agonists with anti-hyperlipidemic and antioxidant activities: Design, synthesis and in vitro/in vivo biological evaluation

In the current work, a series of novel 4-benzyloxy and 4-(2-phenylethoxy) chalcone fibrate hybrids (10a-o) and (11a-e) were synthesized and evaluated as new PPARα agonists in order to find new agents with higher activity and fewer side effects. The 2-propanoic acid derivative 10a and the 2-butanoic acid congener 10i showed the best overall PPARα agonistic activity showing E_max% values of 50.80 and 90.55%, respectively, and EC₅₀ values of 8.9 and 25.0 μM, respectively, compared to fenofibric acid with E_max = 100% and EC₅₀ = 23.22 μM, respectively. These two compounds also stimulated carnitine palmitoyltransferase 1A gene transcription in HepG2 cells and PPARα protein expression. Molecular docking simulations were performed for the newly synthesized compounds to study their predicted binding pattern and energies in PPARα active site to rationalize their promising activity. In vivo, compounds 10a and 10i elicited a significant hypolipidemic activity improving the lipid profile in triton WR-1339-induced hyperlipidemic rats, including serum triglycerides, total cholesterol, LDL, HDL and VLDL levels. Compound 10i possessed better anti-hyperlipidemic activity than 10a. At a dose of 200 mg/kg, it demonstrated significantly lower TC, TG, LDL and VLDL levels than that of fenofibrate at the same dose with similar HDL levels. Compounds 10i and 10a possessed atherogenic indices (CRR, AC, AI, CRI-II) like that of fenofibrate. Additionally, a promising antioxidant activity indicated by the increased tissue reduced glutathione and plasma total antioxidant capacity with decreased plasma malondialdehyde levels was demonstrated by compounds 10a and 10i. No histopathological alterations were recorded in the hepatic tissue of compound 10i (200 mg/kg).

Small-Molecule Modulation of PPARs for the Treatment of Prevalent Vascular Retinal Diseases

Vascular-related retinal diseases dramatically impact quality of life and create a substantial burden on the healthcare system. Age-related macular degeneration, diabetic retinopathy, and retinopathy of prematurity are leading causes of irreversible blindness. In recent years, the scientific community has made great progress in understanding the pathology of these diseases and recent discoveries have identified promising new treatment strategies. Specifically, compelling biochemical and clinical evidence is arising that small-molecule modulation of peroxisome proliferator-activated receptors (PPARs) represents a promising approach to simultaneously address many of the pathological drivers of these vascular-related retinal diseases. This has excited academic and pharmaceutical researchers towards developing new and potent PPAR ligands. This review highlights recent developments in PPAR ligand discovery and discusses the downstream effects of targeting PPARs as a therapeutic approach to treating retinal vascular diseases.

Genotypic variability in radial resistance to water flow in olive roots and its response to temperature variations

As radial root resistance (Rp) represents one of the key components of the soil-plant-atmosphere continuum resistance catena modulating water transport, understanding its control is essential for physiologists, modelers and breeders. Reports of Rp, however, are still scarce and scattered in the scientific literature. In this study, we assessed genetic variability in Rp and its dependence on temperature in five widely used olive cultivars. In a first experiment, cultivar differences in Rp at 25 °C were evaluated from flow-pressure measurements in excised roots and subsequent analysis of root traits. In a second experiment, similar determinations were performed continually over a 5-h period in which temperature was gradually increased from 12 to 32 °C, enabling the assessment of Rp response to changing temperature. Despite some variability, our results did not show statistical differences in Rp among cultivars in the first experiment. In the second, cultivar differences in Rp were not significant at 12 °C, but they became so as temperature increased. Furthermore, the changes in Rp between 12 and 32 °C were higher than those expected by the temperature-driven decrease in water viscosity, with the degree of that change differing among cultivars. Also, Rp at 25 °C reached momentarily in the second experiment was consistently higher than in the first at that same, but fixed, temperature. Overall, our results suggest that there is limited variability in Rp among the studied cultivars when plants have been exposed to a given temperature for sufficient time. Temperature-induced variation in Rp might thus be partly explained by changes in membrane permeability that occur slowly, which explains why our values at 25 °C differed between experiments. The observed cultivar differences in Rp with warming also indicate faster acclimation of Rp to temperature changes in some cultivars than others.

Recent Developments in Diabetic Retinal Neurodegeneration: A Literature Review

Neurodegeneration plays a significant role in the complex pathology of diabetic retinopathy. Evidence suggests the onset of neurodegeneration occurs early on in the disease, and so a greater understanding of the process is essential for prompt detection and targeted therapies. Neurodegeneration is a common pathway of assorted processes, including activation of inflammatory pathways, reduction of neuroprotective factors, DNA damage, and apoptosis. Oxidative stress and formation of advanced glycation end products amplify these processes and are elevated in the setting of hyperglycemia, hyperlipidemia, and glucose variability. These key pathophysiologic mechanisms are discussed, as well as diagnostic modalities and novel therapeutic avenues, with an emphasis on recent discoveries. The aim of this article is to highlight the crucial role of neurodegeneration in diabetic retinopathy and to review the molecular basis for this neuronal dysfunction, its diagnostic features, and the progress currently made in relevant therapeutic interventions.