2,2- dimethylbenzopyran derivatives containing pyridone structural fragments as selective dual-targeting inhibitors of HIF-1α and EZH2 for the treatment of lung cancer.

We formerly reported that EZH2 inhibitors sensitized HIF-1 inhibitor-resistant cells and inhibited HIF-1α to promote SUZ12 transcription, leading to enhanced EZH2 enzyme activity and elevated H3K27me3 levels, and conversely, inhibition of EZH2 promoted HIF-1α transcription. HIF-1α and EZH2 interacted to form a negative feedback loop that reinforced each other's activity. In this paper, a series of 2,2- dimethylbenzopyran derivatives containing pyridone structural fragments were designed and synthesized with DYB-03, a HIF-1α inhibitor previously reported by our group, and Tazemetostat, an EZH2 inhibitor approved by FDA, as lead compounds. Among these compounds, D-01 had significant inhibitory activities on HIF-1α and EZH2. In vitro experiments showed that D-01 significantly inhibited the migration of A549 cells, clone, invasion and angiogenesis. Moreover, D-01 had good pharmacokinetic profiles. All the results about compound D-01 could lay a foundation for the research and development of HIF-1α and EZH2 dual-targeting compounds.

Photodynamic anticancer activity evaluation of novel 5-aminolevulinic acid and 3-hydroxypyridinone conjugates.

5-Aminolevulinic acid (ALA) and its derivatives, serving as the endogenous precursor of the photosensitizer (PS) protoporphyrin IX (PpIX), successfully applied in tumor imaging and photodynamic therapy (PDT). ALA and its derivatives have been used to treat actinic keratosis (AK), basal cell carcinoma (BCC), and improve the detection of superficial bladder cancer. However, the high hydrophilicity of ALA and the conversion of PpIX to heme have limited the accumulation of PpIX, hindering the efficiency and potential application of ALA-PDT. This study aims to evaluate the PDT activity of three rationally designed series of ALA-HPO prodrugs, which were based on enhancing the lipophilicity of the prodrugs and reducing the labile iron pool (LIP) through HPO iron chelators to promote PpIX accumulation. Twenty-four ALA-HPO conjugates, incorporating amide, amino acid, and ester linkages, were synthesized. Most of the conjugates, exhibited no dark-toxicity to cells, according to bioactivity evaluation. Ester conjugates 19a-g showed promoted phototoxicity when tested on tumor cell lines, and this increased phototoxicity was strongly correlated with elevated PpIX levels. Among them, conjugate 19c emerged as the most promising (HeLa, IC50 = 24.25 ± 1.43 µM; MCF-7, IC50 = 43.30 ± 1.76 µM; A375, IC50 = 28.03 ± 1.00 µM), displaying superior photodynamic anticancer activity to ALA (IC50 > 100 µM). At a concentration of 80 µM, the fluorescence intensity of PpIX induced by compound 19c in HeLa, MCF-7, and A375 cells was 18.9, 5.3, and 2.8 times higher, respectively, than that induced by ALA. In conclusion, cellular phototoxicity showed a strong correlation with intracellular PpIX fluorescence levels, indicating the potential application of ALA-HPO conjugates in ALA-PDT.

Discovery of novel pyridone-benzamide derivatives possessing a 1-methyl-2-benzimidazolinone moiety as potent EZH2 inhibitors for the treatment of B-cell lymphomas.

Enhancer of zeste homolog 2 (EZH2) is a promising therapeutic target for diffuse large B-cell lymphoma. In this study, based on the binding model of 1 (tazemetostat) with polycomb repressive complex 2 (PRC2), we designed and synthesized a series of tazemetostat analogs bearing a 1-methyl-2-benzimidazolinone moiety to improve the inhibitory activity of EZH2 wild-type (WT) and Y641 mutants and enhance metabolic stability. After the assessment of the structure-activity relationship at enzymatic and cellular levels, compound N40 was identified. Biochemical assays showed that compound N40 (IC50 = 0.32 nM) exhibited superior inhibitory activity against EZH2 WT, compared with 1 (IC50 = 1.20 nM), and high potency against EZH2 Y641 mutants (EZH2 Y641F, IC50 = 0.03 nM; EZH2 Y641N, IC50 = 0.08 nM), which were approximately 10-fold more active than those of 1 (EZH2 Y641F, IC50 = 0.37 nM; EZH2 Y641N, IC50 = 0.85 nM). Furthermore, compound N40 (IC50 = 3.52 ±â€¯1.23 nM) effectively inhibited the proliferation of Karpas-422 cells and was more potent than 1 (IC50 = 35.01 ±â€¯1.28 nM). Further cellular experiments showed that N40 arrested Karpas-422 cells in the G1 phase and induced apoptosis in a dose-dependent manner. Moreover, N40 inhibited the trimethylation of lysine 27 on histone H3 (H3K27Me3) in Karpas-422 cells bearing the EZH2 Y641N mutant. Additionally, N40 (T1/2 = 177.69 min) showed improved metabolic stability in human liver microsomes compared with 1 (T1/2 = 7.97 min). Our findings suggest N40 as a promising EZH2 inhibitor; further investigation remains warranted to confirm our findings and further develop N40.

Discovery of Dolutegravir Derivative against Liver Cancer via Inducing Autophagy and DNA Damage.

We introduced a terminal alkyne into the core structure of dolutegravir, resulting in the synthesis of 34 novel dolutegravir-1,2,3-triazole compounds through click chemistry. These compounds exhibited remarkable inhibitory activities against two hepatocellular carcinoma cell lines, Huh7 and HepG2. Notably, compounds 5e and 5p demonstrated exceptional efficacy, particularly against Huh7 cells, with IC50 values of 2.64 and 5.42 µM. Additionally, both compounds induced apoptosis in Huh7 cells, suppressed tumor cell clone formation, and elevated reactive oxygen species (ROS) levels, further promoting tumor cell apoptosis. Furthermore, compounds 5e and 5p activated the LC3 signaling pathway, inducing autophagy, and triggered the γ-H2AX signaling pathway, resulting in DNA damage in tumor cells. Compound 5e exhibited low toxicity, highlighting its potential as a promising anti-tumor drug.

Discovery, Optimization, and Evaluation of Novel Pyridin-2(1H)-one Analogues as Potent TRK Inhibitors for Cancer Treatment.

Tropomyosin receptor kinase (TRK) fusion, an oncogenic form of kinase with pan-tumor occurrence, is a clinically validated important antitumor target. In this study, we screened our in-house kinase inhibitor library against TRK and identified a promising hit compound 4 with a novel pyridin-2(1H)-one scaffold. Through a combination of structure-based drug design and structure-activity relationship (SAR) study, compound 14q was identified as a potent TRK inhibitor with good kinase selectivity. It also blocked cellular TRK signaling, thereby inhibiting TRK-dependent cell viability. Additionally, 14q displayed acceptable pharmacokinetic properties with 37.8% oral bioavailability in mice. Strong in vivo tumor growth inhibition of 14q was observed in subcutaneous M091 and KM12 tumor xenograft models with TRK fusion, causing significant tumor inhibition or even complete tumor regression.

Identification of 4-amino-2-Pyridones as new potent PCSK9 inhibitors: From phenotypic hit discovery to in vivo tolerability.

Among the strategies to overcome the underperformance of statins in cardiovascular diseases (CVDs), the development of drugs targeting the Proprotein Convertase Subtilisin-like Kexin type 9 (PCSK9) is considered one of the most promising. However, only anti-PCSK9 biological drugs have been approved to date, and orally available small-molecules for the treatment of hypercholesterolemic conditions are still missing on the market. In the present work, we describe the application of a phenotypic approach to the identification and optimization of 4-amino-2-pyridone derivatives as a new chemotype with anti-PCSK9 activity. Starting from an in-house collection of compounds, functional assays on HepG2 cells followed by a chemistry-driven hit optimization campaign, led to the potent anti-PCSK9 candidate 5c. This compound, at 5 µM, totally blocked PCSK9 secretion from HepG2 cells, significantly increased LDL receptor (LDLR) expression, and acted cooperatively with simvastatin by reducing its induction of PCSK9 expression. Finally, compound 5c also proved to be well tolerated in C57BL/6J mice at the tested concentration (40 mg/kg) with no sign of toxicity or behavior modifications.

Reduction-Responsive Cationic Vesicles from Bolaamphiphiles with Ionizable Amino Acid or Dipeptide Polar Heads.

This paper presents a study of the aggregation of cationic bolaamphiphilic molecules into vesicles. These molecules are based on a cystamine core with protonated terminal dipeptide groups. The study found that vesicles can be formed at pH 4 for all of the dipeptide-terminated bolaamphiphiles containing different combinations of l-valine, l-phenylalanine, and l-tryptophan. The concentration for aggregation onset was determined by using pyrene as a fluorescent probe or light dispersion for compounds with tryptophan. Dynamic light scattering (DLS) studies and transmission electron microscopy (TEM) reveal that the vesicles have diameters ranging from 140 to 500 nm and show the capability of loading hydrophobic cargos, such as Nile red, and their liberation in reductive environments. Furthermore, the bolaamphiphiles are only fully protonated and prone to vesicle formation at acidic pH, making them a promising alternative for gastrointestinal delivery.

Unexpected Cascade Sequence Forming the C(sp3)-N/C(sp2)-C(sp2) Bond: Direct Access to γ-Lactam-Fused Pyridones with Anticancer Activity.

An unexpected Ugi cascade reaction was developed for the facile construction of γ-lactam-fused pyridone derivatives with high tolerance of substrates. A C(sp3)-N bond and a C(sp2)-C(sp2) bond were formed together, accompanied by a chromone ring-opening in Ugi adducts, under the basic conditions without any metal catalyst for the whole process. Screening data of several difficult-to-inhibit cancer cell lines demonstrated that 7l displayed a high cytotoxicity against HCT116 cells (IC50 = 5.59 ± 0.78 µM). Taken together, our findings revealed new insights into the molecular mechanisms underlying compound 7l and provided potential usage of this scaffold for cancer therapeutics.

Cytotoxic pyridine alkaloids from a marine-derived fungus Arthrinium arundinis exhibiting apoptosis-inducing activities against small cell lung cancer.

Small cell lung cancer (SCLC) is a kind of high-grade neuroendocrine carcinoma, which is characterized by a higher proliferative rate, earlier metastasis and more poor outcomes compared to non-small cell lung cancer (NSCLC). Under the guidance of MS/MS based molecular networking, three undescribed pyridone alkaloids, namely, arthpyrones M-O (1-3), together with two known pyridone derivatives, arthpyrones C (4) and G (5), were isolated from a sponge-derived Arthrinium arundinis. Their structures were determined through extensive spectroscopic analysis, ECD calculations, and X-ray single-crystal diffraction. Arthpyrone M (1) possessed a novel cage structure bearing an ether bridge functionality rarely reported in this class of metabolites. All isolated compounds were evaluated for their cytotoxicities against five cancer cell lines. As a result, compounds 1-5 showed cytotoxicity against some or all of the five cancer cell lines with IC50 values ranging from 0.26 to 6.43 µM. Among them, arthpyrone O (3) not only exhibited potent efficacy against the proliferative activity of SCLC cells and induced apoptosis in vitro, but also significantly inhibited the growth of xenograft tumor based on SCLC cells in vivo, which indicated 4-hydroxy-2-pyridone alkaloids might been revised as privileged scaffolds in drug discovery.

Implications of Protein Interaction in the Speciation of Potential VIVO-Pyridinone Drugs.

Vanadium complexes (VCs) are promising agents for the treatment, among others, of diabetes and cancer. The development of vanadium-based drugs is mainly limited by a scarce knowledge of the active species in the target organs, which is often determined by the interaction of VCs with biological macromolecules like proteins. Here, we have studied the binding of [VIVO(empp)2] (where Hempp is 1-methyl-2-ethyl-3-hydroxy-4(1H)-pyridinone), an antidiabetic and anticancer VC, with the model protein hen egg white lysozyme (HEWL) by electrospray ionization-mass spectrometry (ESI-MS), electron paramagnetic resonance (EPR), and X-ray crystallography. ESI-MS and EPR techniques reveal that, in aqueous solution, both the species [VIVO(empp)2] and [VIVO(empp)(H2O)]+, derived from the first one upon the loss of a empp(-) ligand, interact with HEWL. Crystallographic data, collected under different experimental conditions, show covalent binding of [VIVO(empp)(H2O)]+ to the side chain of Asp48, and noncovalent binding of cis-[VIVO(empp)2(H2O)], [VIVO(empp)(H2O)]+, [VIVO(empp)(H2O)2]+, and of an unusual trinuclear oxidovanadium(V) complex, [VV3O6(empp)3(H2O)], with accessible sites on the protein surface. The possibility of covalent and noncovalent binding with different strength and of interaction with various sites favor the formation of adducts with the multiple binding of vanadium moieties, allowing the transport in blood and cellular fluids of more than one metal-containing species with a possible amplification of the biological effects.

Discovery of a Novel Covalent EZH2 Inhibitor Based on Tazemetostat Scaffold for the Treatment of Ovarian Cancer.

Enhancer of zeste homologue 2 (EZH2) is the enzymatic catalytic subunit of polycomb repressive complex 2 (PRC2), which plays an important role in post-translational modifications of histones. In this study, we designed and synthesized a new series EZH2 covalent inhibitors that have rarely been reported. Biochemical studies and mass spectrometry provide information that SKLB-03220 could covalently bind to the S-adenosylmethionine (SAM) pocket of EZH2. Besides, SKLB-03220 was highly potent for EZH2MUT, while exhibiting weak activities against other tested histone methyltransferases (HMTs) and kinases. Moreover, SKLB-03220 displayed noteworthy potency against ovarian cancer cell lines and continuously abolished H3K27me3 after washing out. Furthermore, oral administration of SKLB-03220 significantly inhibited tumor growth in PA-1 xenograft model without obvious adverse effects. Taken together, SKLB-03220 is a potent, selective EZH2 covalent inhibitor with noteworthy anticancer efficacy both in vitro and in vivo.

Antitumor potential of tricyclic pyridone analogues from an entomopathogenic fungus, Fusarium avenaceum SYKC02-P-1.

Two new tricyclic pyridone analogues, fusapyridons C (1) and D (2), were isolated along with structurally related known compounds 3 - 5 from the entomopathogenic fungus, F. avenaceum SYKC02-P-1. The structures of compounds 1 and 2 were elucidated by analyzing the spectral data of UV, 1 D and 2 D NMR as well as HRESIMS. The absolute configurations of fusapyridons C and D were established by means of single crystal X-ray diffraction and electronic circular dichroism calculation. And antitumor testing of all the isolates showed that compounds 4 and 5 exhibited significant inhibitory activity against the human prostate cancer cells (PC-3 cell lines) with IC50 values of 2.76 and 1.86 µM, respectively.

3,4-Dihydro-2(1H)-Pyridones as Building Blocks of Synthetic Relevance.

3,4-Dihydro-2(1H)-pyridones (3,4-DHPo) and their derivatives are privileged structures, which has increased their relevance due to their biological activity in front of a broad range of targets, but especially for their importance as synthetic precursors of a variety of compounds with marked biological activity. Taking into account the large number of contributions published over the years regarding this kind of heterocycle, here, we presented a current view of 3,4-dihydro-2(1H)-pyridones (3,4-DHPo). The review includes general aspects such as those related to nomenclature, synthesis, and biological activity, but also highlights the importance of DHPos as building blocks of other relevant structures. Additional to the conventional multicomponent synthesis of the mentioned heterocycle, nonconventional procedures are revised, demonstrating the increasing efficiency and allowing reactions to be carried out in the absence of the solvent, becoming an important contribution to green chemistry. Biological activities of 3,4-DHPo, such as vasorelaxant, anti-HIV, antitumor, antibacterial, and antifungal, have demonstrated this heterocycle's potential in medicinal chemistry.

Effective mitigation of gadolinium deposition using the bidentate hydroxypyridinone ligand Me-3,2-HOPO.

With the extensive usage of gadolinium-based contrast agents (GBCAs) in magnetic resonance imaging (MRI), gadolinium deposition has been observed in the brain, kidneys, liver, etc., and this is also closely related to the development of nephrogenic systemic fibrosis (NSF) in patients with renal dysfunction. Chelation, thereby promoting the elimination of deposited Gd(III), seems to be promising for alleviating these problems. Despite many ligands suitable for chelation therapy having been studied, the decorporation of transition metals (e.g. iron, copper, lead, etc.) and actinides (e.g. uranium, plutonium, etc.) has long been a primary concern, whereas the study of Gd(III) has been extremely limited. Due to their excellent metal binding abilities in vivo and therapeutic effects toward neurodegenerative diseases, bidentate hydroxypyridinone ligands are expected to be able to remove Gd(III) from the brain, kidneys, bones, and liver. Herein, the Gd(III) decorporation efficacy of a bidentate hydroxypyridinone ligand (Me-3,2-HOPO) has been evaluated. The complexation behavior between Me-3,2-HOPO and Gd(III) in solution and solid states was characterized with the assistance of potentiometric titration and X-ray diffraction techniques, respectively. Solution-based thermodynamic studies illustrate that the dominant species of complex between Gd(III) and Me-3,2-HOPO (HL) is GdL2+ (log ß120 = 11.8 (3)) at pH 7.4. The structure of the Gd-Me-3,2-HOPO crystal obtained from a room temperature reaction reveals the formation of a Gd(III) dimer that is chelated by four ligands as a result of metal ion hydration and ligand complexation. Cellular Gd(III) removal assays illustrate that Me-3,2-HOPO could effectively reduce final amounts of gadolinium by 77.6% and 66.1% from rat renal proximal tubular epithelial (NRK-52E) cells and alpha mouse liver 12 (AML-12) cells, respectively. Our current results suggest the potential of bidentate HOPO ligands as an effective approach to treat patients suffering from Gd(III) toxicity.

Design, synthesis, in silico studies, and antiproliferative evaluations of novel indolin-2-one derivatives containing 3-hydroxy-4-pyridinone fragment.

Keeping in view the pharmacological properties of indolinones as promising scaffold as kinase inhibitors, herein, a novel series of 3-hydrazonoindolin-2-one derivatives bearing 3-hydroxy-4-pyridinone moiety were synthesized, studied by molecular docking, and fully characterized by spectroscopic techniques. All the prepared compounds were evaluated for their cytotoxicity attributes against a panel of tumor cell lines, including non-small cell lung cancer (A549), breast carcinoma (MCF-7), acute myeloid leukemia (AML), and chronic myeloid leukemia (CML). They displayed moderate to promising antiproliferative effects toward A549 and MCF-7 cells but remarkable results against AML and CML. Especially, compound 10k was found to be more potent against AML (EC50 = 0.69 µM) compare to the other halogen-substituted derivatives. FMS-like tyrosine kinase 3 (FLT3) is known to be expressed in AML cancer cells. The molecular docking studies demonstrated that our prepared compounds were potentially bound to AML active site through essential H-bond and other vital interactions with critical binding residues.

Development of dihydropyrrolopyridinone-based PKN2/PRK2 chemical tools to enable drug discovery.

The Protein Kinase N proteins (PKN1, PKN2 and PKN3) are Rho GTPase effectors. They are involved in several biological processes such as cytoskeleton organization, cell mobility, adhesion, and cell cycle. Recently PKNs have been reported as essential for survival in several tumor cell lines, including prostate and breast cancer. Here, we report the development of dihydropyrrolopyridinone-based inhibitors for PKN2 and its closest homologue, PKN1, and their associated structure-activity relationship (SAR). Our studies identified a range of molecules with high potency exemplified by compound 8 with Ki = 8 nM for PKN2 and 14x selectivity over PKN1. Membrane permeability and target engagement for PKN2 were assessed by a NanoBRET cellular assay. Importantly, good selectivity across the wider human kinome and other kinase family members was achieved. These compounds provide strong starting points for lead optimization to PKN1/2 development compounds.

A score years' update in the synthesis and biological evaluation of medicinally important 2-pyridones.

2-Pyridone core structure has attracted much attention due to its abundance in natural products of biological importance. 2-Pyridone derivatives display diverse biological activities. From being antimicrobial, antimalarial, antitumor, cardiotonic and anti-fibrotic agents to the induction of neurite outgrowth, they affect many biological processes. They find significant role in medicines, agriculture, pharmacophore designing and are also used as synthones for other heterocyclic compounds. Therefore, the main purpose of this review is to assess the biological pursuits of 2-pyridone compounds. In addition, this review presents the overview of synthesis of medicinally active 2-pyridones along with their biological activity done in the past two decades.

Design, synthesis, and evaluation of novel pyridone derivatives as potent BRD4 inhibitors for the potential treatment of prostate cancer.

Since androgen receptor (AR) can bind to BRD4 protein and this binding can be blocked by BRD4 inhibitors, targeting BRD4 has emerged as a promising approach for the treatment of prostate cancer (PC). Herein, we designed and synthesized a series of 5-(1-benzyl-1H-indazol-6-yl)-4-ethoxy-1-methylpyridin-2(1H)-one derivatives as novel BRD4 inhibitors for prostate cancer. Among them, compound 13 displayed the most robust BRD4 inhibitory activity with an IC50 value of 18 nM. Furthermore, 13 showed potent anti-proliferative activity against enzalutamide-resistant 22RV1 cells. The mechanism of action studies demonstrated that 13 induced cell apoptosis by regulating Bcl-2/Bax proteins and activating caspase-3 signaling pathway. In addition, the c-Myc level was significantly reduced in 22RV1 cells on the western blot assay. These findings collectively suggested that compound 13 might find potential use for the treatment of prostate cancer.

Virus-Mimicking Polymer Nanoparticles Targeting CD169+ Macrophages as Long-Acting Nanocarriers for Combination Antiretrovirals.

Monosialodihexosylganglioside (GM3)-presenting lipid-coated polymer nanoparticles (NPs) that recapitulate the sequestration of human immunodeficiency virus-1 (HIV-1) particles in CD169+ virus-containing compartments (VCCs) of macrophages were developed as carriers for delivery and sustained release of a combination of two antiretrovirals (ARVs), rilpivirine (RPV) and cabotegravir (CAB). RPV and CAB were co-loaded into GM3-presenting lipid-coated polylactic acid (PLA) and poly(lactic-co-glycolic acid) (PLGA) NPs without loss in potency of the drugs. GM3-presenting PLA NPs demonstrated the most favorable release properties and achieved inhibition of HIV-1 infection of primary human macrophages for up to 35 days. Intracellular localization of GM3-presenting PLA NPs in VCCs correlated with retention of intracellular ARV concentrations and sustained inhibition of HIV-1 infection. This work elucidates the design criteria of lipid-coated polymer NPs to utilize CD169+ macrophages as cellular drug depots for eradicating the viral reservoir sites or to achieve long-acting prophylaxis against HIV-1 infection.

Identification of new halogen-containing 2,4-diphenyl indenopyridin-5-one derivative as a boosting agent for the anticancer responses of clinically available topoisomerase inhibitors.

Based on previous reports on the significance of halogen moieties and the indenopyridin-5-one skeleton, we designed and synthesized a novel series of halogen (F-, Cl-, Br-, CF3- and OCF3-)-containing 2,4-diphenyl indenopyridin-5-ones and their corresponding -5-ols. Unlike indenopyridin-5-ols, most of the prepared indenopyridin-5-ones with Cl-, Br-, and CF3- groups at the 2-phenyl ring conferred a strong dual topoisomerase I/IIα inhibitory effect. Among the series, para-bromophenyl substituted compound 9 exhibited the most potent topoisomerase inhibition and antiproliferative effects, which showed dependency upon the topoisomerase gene expression level of diverse cancer cells. In particular, as a DNA minor groove-binding non-intercalative topoisomerase I/IIα catalytic inhibitor, compound 9 synergistically promoted the anticancer efficacy of clinically applied topoisomerase I/IIα poisons both in vitro and in vivo, having the great advantage of alleviating poison-related toxicities.