Protective effects of 10,11-dihydro-5H-dibenzo[b,f]azepine hydroxamates on vascular cognitive impairment

Seven-membered N-heterocycles as approved drugs and promising leads in medicinal chemistry as well as the metal-free domino access to their scaffolds

Azepanes or azepines are structural motifs of many drugs, drug candidates and evaluated lead compounds. Even though compounds having N-heterocyclic 7-membered rings are often found in nature (e.g. alkaloids), the natural compounds of this group are rather rare as approved therapeutics. Thus, recently studied and approved azepane or azepine-congeners predominantly consist of semi-synthetically or synthetically-obtained scaffolds. In this review a comparison of approved drugs and recently investigated leads was proposed taking into regard their structural aspects (stereochemistry), biological activities, pharmacokinetic properties and confirmed molecular targets. The 7-membered N-heterocycles reveal a wide range of biological activities, not only against CNS diseases, but also as e.g. antibacterial, anticancer, antiviral, antiparasitic and against allergy agents. As most of the approved or investigated potential drugs or lead structures, belonging to 7-membered N-heterocycles, are synthetic scaffolds, this report also reveals different and efficient metal-free cascade approaches useful to synthesize both simple azepane or azepine-containing congeners and those of oligocyclic structures. Stereochemistry of azepane/azepine fused systems, in view of biological data and binding with the targets, is discussed. Apart from the approved drugs, we compare advances in SAR studies of 7-membered N-heterocycles (mainly from 2018 to 2023), whereas the related synthetic part concerning various domino strategies is focused on the last ten years.

Identification of differentially expressed exosome proteins in serum as potential biomarkers for cognitive impairments in cerebral small vessel disease

BACKGROUND

Cognitive impairment arising from cerebral small vessel disease (CSVD) represents a critical subtype of vascular cognitive impairments (VCI) and is the primary cause of vascular dementia. However, identifying reliable clinical and laboratory indicators for this disease remain elusive. We hypothesize that plasma exosome proteins hold the potential to serve as biomarkers for the onset of cognitive dysfunction associated with cerebrovascular diseases.

METHODS

We employed TMT-based proteomics to discern variations in serum exosome proteomes between individuals with cognitive impairments due to CSVD and healthy volunteers.

RESULTS

Each group comprised 18 subjects, and through differential expression analysis, we identified 22 down-regulated and 8 up-regulated proteins between the two groups. Our research revealed 30 differentially expressed plasma exosome proteins, including histone, proteasome, clusterin and coagulation factor XIII, in individuals with cognitive impairments caused by CSVD.

CONCLUSION

The 30 differentially expressed plasma exosome proteins identified in our study are promising as biomarkers for diagnosing cognitive impairments resulting from CSVD. These findings may help us better understand the underlying pathological mechanisms involved in the diseases.

Fatty Acids Support the Fitness and Functionality of Tumor-Resident CD8+ T Cells by Maintaining SCML4 Expression

CD8+ tissue-resident memory T (Trm) cells and tumor-infiltrating lymphocytes (TIL) regulate tumor immunity and immune surveillance. Characterization of Trm cells and TILs could help identify potential strategies to boost antitumor immunity. Here, we found that the transcription factor SCML4 was required for the progression and polyfunctionality of Trm cells and was associated with a better prognosis in patients with cancer. Moreover, SCML4 maintained multiple functions of TILs. Increased expression of SCML4 in CD8+ cells significantly reduced the growth of multiple types of tumors in mice, while deletion of SCML4 reduced antitumor immunity and promoted CD8+ T-cell exhaustion. Mechanistically, SCML4 recruited the HBO1-BRPF2-ING4 complex to reprogram the expression of T cell-specific genes, thereby enhancing the survival and effector functions of Trm cells and TILs. SCML4 expression was promoted by fatty acid metabolism through mTOR-IRF4-PRDM1 signaling, and fatty acid metabolism-induced epigenetic modifications that promoted tissue-resident and multifunctional gene expression in Trm cells and TILs. SCML4 increased the therapeutic effect of anti-PD-1 treatment by elevating the expression of effector molecules in TILs and inhibiting the apoptosis of TILs, which could be further enhanced by adding an inhibitor of H3K14ac deacetylation. These results provide a mechanistic perspective of functional regulation of tumor-localized Trm cells and TILs and identify an important activation target for tumor immunotherapy.

SIGNIFICANCE

SCML4 upregulation in CD8+ Trm cells and tumor-infiltrating lymphocytes induced by fatty acid metabolism enhances antitumor immune responses, providing an immunometabolic axis to target for cancer treatment. See related commentary by Chakraborty et al., p. 3321.

Accommodation of ring C expanded deoxyvasicinone in the HDAC inhibitory pharmacophore culminates into a tractable anti-lung cancer agent and pH-responsive nanocarrier

A fragment recruitment process was conducted to pinpoint a suitable fragment for installation in the HDAC inhibitory template to furnish agents endowed with the potential to treat lung cancer. Resultantly, Ring C expanded deoxyvasicinone was selected as an appropriate surface recognition part that was accommodated in the HDAC three-component model. Delightfully, fused quinazolinone 6 demonstrating a magnificent anticancer profile against KRAS and EGFR mutant lung cancer cell lines (IC₅₀ = 0.80-0.96 μM) was identified. Results of the mechanistic studies confirmed that the cell growth inhibitory effects of compound 6 stems for HDAC6 (IC₅₀ = 12.9 nM), HDAC1 (IC₅₀ = 49.9 nM) and HDAC3 inhibition (IC₅₀ = 68.5 nM), respectively. Compound 6 also suppressed the colony formation ability of A549 cells, induced apoptosis, and increased autophagic flux. Key interactions of HDAC inhibitor 6 within the active site of HDAC isoforms were figured out through molecular modeling studies. Furthermore, a pH-responsive nanocarrier (Hyaluronic acid - fused quinazolinone 6 nanoparticles) was designed and assessed using a dialysis bag approach under both normal and acidic circumstances that confirmed the pH-sensitive nature of NPs. Delightfully, the nanoparticles demonstrated selective cell viability reduction potential towards the lung cancer cell lines (A549 lung cancer cell lines) and were found to be largely devoid of cell growth inhibitory effects under normal settings (L929, mouse fibroblast cells).

Effect and Mechanism of Yisui Fuyongtang (YSFYT) Decoction on Cognitive Function and Synaptic Plasticity in Rats with Vascular Cognitive Impairment

Vascular cognitive impairment (VCI) has emerged as the second major disease responsible for dementia, and there is still a lack of effective treatment methods for this disorder to date. Clinical medications have found that Yisui Fuyongtang (YSFYT) Decoction is effective in improving neurological signs and learning-memory functions in patients who develop white matter lesions and whole brain atrophy. To clarify the effect and molecular regulation mechanism of YSFYT Decoction on model rats, this research analyzed the influence of YSFYT Decoction on the learning-memory ability and lipid metabolism of rats based on behavioral and biochemical analysis. Further pathology and protein detection methods were adopted to investigate the action of YSFYT Decoction on the neurons in the hippocampus of model rats and the regulation of the brain derived neurotrophic factor (BDNF)-tyrosine protein kinase receptor B (TrkB) signaling pathway. Compared with the VCI group, after YSFYT Decoction administration, the ratio of swimming time in the platform, number of crossing the platform, number of active avoidance, and proportion of active avoidance of the rats were markedly increased, whereas the response latency was substantially reduced (p < 0.05). Biochemical tests indicated that contents of lipoprotein lipase (LPL), triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) of the model rats in YSFYT Decoction treatment group were greatly reduced, whereas those of total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-PX), catalase (CAT), malondialdehyde (MDA), and superoxide dismutase (SOD) were elevated (p < 0.05). Additionally, Bcl-2 expression in YSFYT Decoction treatment group was significantly increased, but neuron apoptosis of the hippocampus tissue was reduced. Meanwhile, neuron number was apparently higher than that in VCI model group. Following Yisui Decoction treatment, expressions of growth-associated protein 43 (GAP43), synaptophysin (SYP), postsynaptic density 95 (PSD95), NMDAR subunit 2B (NR2B), BDNF, TrkB, phospho-mitogen-activated protein kinase (p-MAPK), extracellular signal-regulated kinase (ERK), phosphatidylinositol 3-kinase (PI3K), and phospho-protein kinase B (p-AKT) were markedly elevated. Taken together, YSFYT Decoction could activate the BDNF-TrkB signaling pathway, elevate Bcl-2 expression, and minimize neuronal apoptosis in hippocampus, thereby improving the behavioral characteristics and biochemical indicators of the VCI rat model.

Theoretical Study of the Geometry of Dibenzoazepine Analogues

The geometry of dibenzoazepine analogues—typical multifunctional drugs—was investigated to find the geometrical parameters sensitive to the substitution of the central seven-membered ring. Exploration of the crystal structure database (CSD) shows that the geometrical parameter sensitive to the substitution of the carbon atom distance of the central ring not included in the aromatic rings to the plane through the carbon atoms common for the central ring and the aromatic side rings. Presence of the double bond in the central ring was reflected in its partial aromaticity expressed by the HOMED parameter. Some derivatives of 5H-dibenzo[b,f]azepine with flat conformation of the central ring are characterized by mobility of the electron density comparable to the mobility in the aromatic side rings. Influence of the surrounding on the investigated compounds was confirmed by comparison of the optimized molecules and the molecules in the crystal state where the packing forces can influence the molecular geometry.

Medicinal chemistry updates of novel HDACs inhibitors (2020 to present)

Epigentic enzymes histone deacetylases (HDACs) catalyze the removal of acetyl groups from the ε-N-acetylated lysine residues of various protein substrates including both histone and non-histone proteins. Different HDACs have distinct biological functions and are recruited to specific regions of the genome. Due to their important biological functions, HDACs have been validated in clinics for anticancer therapy, and are being explored for potential treatment of several other diseases such as Alzheimer disease (AD), metabolic disease, viral infection, and multiple sclerosis, etc. Besides five approved drugs, there are more than thirty HDACs inhibitors currently being investigated in clinical trials. Centering on the advances of drug discovery programs in this field since 2020, this review discusses HDACs inhibitors from the aspects of the structure-based rational design, isoform selectivity, pharmacology, and toxicology of the compounds of interest. The hope is to provide the medicinal chemistry community with up-to-date information and to accelerate the drug discovery programs in this area.

HDACi protects against vascular cognitive impairment from CCH injury via induction of BDNF-related AMPA receptor activation

We previously showed a hydroxamic acid‐based histone deacetylase inhibitor (HDACi), compound 13, provides neuroprotection against chronic cerebral hypoperfusion (CCH) both in vitro under oxygen‐glucose deprivation (OGD) conditions and in vivo under bilateral common carotid artery occlusion (BCCAO) conditions. Intriguingly, the protective effect of this HDACi is via H3K14 or H4K5 acetylation–mediated differential BDNF isoform activation. BDNF is involved in cell proliferation and differentiation in development, synaptic plasticity and in learning and memory related with receptors or synaptic proteins. B6 mice underwent BCCAO and were randomized into 4 groups; a sham without BCCAO (sham), BCCAO mice injected with DMSO (DMSO), mice injected with HDACi‐compound 13 (compound 13) and mice injected with suberoylanilide hydroxamic acid (SAHA). The cortex and hippocampus of mice were harvested at 3 months after BCCAO, and levels of BDNF, AMPA receptor and dopamine receptors (D1, D2 and D3) were studied using Western blotting analysis or immunohistochemistry. We found that the AMPA receptor plays a key role in the molecular mechanism of this process by modulating HDAC. This protective effect of HDACi may be through BDNF; therefore, activation of this downstream signalling molecule, for example by AMPA receptors, could be a therapeutic target or intervention applied under CCH conditions.

CAP rigidification of MS-275 and chidamide leads to enhanced antiproliferative effects mediated through HDAC1, 2 and tubulin polymerization inhibition

The study focuses on the prudent design and synthesis of anilide type class I HDAC inhibitors employing a functionalized pyrrolo[2,3-d]pyrimidine skeleton as the surface recognition part. Utilization of the bicyclic aromatic ring to fabricate the target compounds was envisioned to confer rigidity to the chemical architecture of MS-275 and chidamide. In-vitro enzymatic and cellular assays led to the identification of compound 7 as a potent inhibitor of HDAC1 and 2 isoform that exerted substantial cell growth inhibitory effects against human breast MDA-MB-231, cervical HeLa, breast MDA-MB-468, colorectal DLD1, and colorectal HCT116 cell lines with an IC₅₀ values of 0.05-0.47 μM, better than MS-275 and chidamide. In addition, the anilide 7 was also endowed with a superior antiproliferative profile than MS275 and chidamide towards the human cutaneous T cell lymphoma (HH and HuT78), leukemia (HL60 and KG-1), and HDACi sensitive/resistant gastric cell lines (YCC11 and YCC3/7). Exhaustive exploration of the construct 7 confirmed it to be a microtubule-targeting agent that could trigger the cell-cycle arrest in mitosis. In pursuit of extracting the benefits of evidenced microtubule-destabilizing activity of the anilide 7, it was further evaluated against non-small-cell lung cancer cell lines as well as the multiple-drug resistant uterine cancer cell line (MES-SA/Dx5) and overwhelmingly positive results in context of inhibitory effects were attained. Furthermore, molecular modelling studies were performed and some key interactions of the anilide 7 with the amino acid residues of the active site of HDAC1 isoform and tubulin were figured out.