Natural Product-Inspired Discovery of Naphthoquinone-Furo-Piperidine Derivatives as Novel STAT3 Inhibitors for the Treatment of Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, and STAT3 has emerged as an effective drug target for TNBC treatment. Herein, we employed a scaffold-hopping strategy of natural products to develop a series of naphthoquinone-furopiperidine derivatives as novel STAT3 inhibitors. The in vitro assay showed that compound 10g possessed higher antiproliferative activity than Cryptotanshinone and Napabucasin against TNBC cell lines, along with lower toxicity and potent antitumor activity in a TNBC xenograft model. Mechanistically, 10g could inhibit the phosphorylation of STAT3 and the binding affinity was determined by the SPR assay (KD = 8.30 µM). Molecule docking studies suggested a plausible binding mode between 10g and the SH2 domain, in which the piperidine fragment and the terminal hydroxy group of 10g played an important role in demonstrating the success of this evolution strategy. These findings provide a natural product-inspired novel STAT3 inhibitor for TNBC treatment.

Highly Potent and Intestine Specific P-Glycoprotein Inhibitor to Enable Oral Delivery of Taxol.

Taxol is widely used in cancer chemotherapy; however, the oral absorption of Taxol remains a formidable challenge. Since the intestinal p-glycoprotein (P-gp) mediated drug efflux is one of the primary causes, the development of P-gp inhibitor is emerging as a promising strategy to realize Taxol's oral delivery. Because P-gp exists in many tissues, the non-selective P-gp inhibitors would lead to toxicity. Correspondingly, a potent and intestine specific P-gp inhibitor would be an ideal solution to boost the oral absorption of Taxol and avoid exogenous toxicity. Herein, we would like to report a highly potent and intestine specific P-gp inhibitor to enable oral delivery of Taxol in high efficiency. Through a multicomponent reaction and post-modification, various benzofuran-fused-piperidine derivatives were achieved and the biological evaluation identified 16c with potent P-gp inhibitory activity. Notably, 16c was intestine specific and showed almost none absorption (F = 0.82%), but possessing higher efficacy than Encequidar to improve the oral absorption of Taxol. In MDA-MB-231 xenograft model, the oral administration of Taxol and 16c showed high therapeutic efficiency and low toxicity, thus providing a valuable chemotherapy strategy.

Selective PI3Kδ inhibitor TYM-3-98 suppresses AKT/mTOR/SREBP1-mediated lipogenesis and promotes ferroptosis in KRAS-mutant colorectal cancer.

Colorectal cancer (CRC) is one of the most common tumors of the digestive system worldwide. KRAS mutations limit the use of anti-EGFR antibodies in combination with chemotherapy for the treatment of CRC. Therefore, novel targeted therapies are needed to overcome the KRAS-induced oncogenesis. Recent evidence suggests that inhibition of PI3K led to ferroptosis, a nonapoptotic cell death closely related to KRAS-mutant cells. Here, we showed that a selective PI3Kδ inhibitor TYM-3-98 can suppress the AKT/mTOR signaling and activate the ferroptosis pathway in KRAS-mutant CRC cells in a concentration-dependent manner. This was evidenced by the lipid peroxidation, iron accumulation, and depletion of GSH. Moreover, the overexpression of the sterol regulatory element-binding protein 1 (SREBP1), a downstream transcription factor regulating lipid metabolism, conferred CRC cells greater resistance to ferroptosis induced by TYM-3-98. In addition, the effect of TYM-3-98 was confirmed in a xenograft mouse model, which demonstrated significant tumor suppression without obvious hepatoxicity or renal toxicity. Taken together, our work demonstrated that the induction of ferroptosis contributed to the PI3Kδ inhibitor-induced cell death via the suppression of AKT/mTOR/SREBP1-mediated lipogenesis, thus displaying a promising therapeutic effect of TYM-3-98 in CRC treatment.

Caspase-1 inhibitor CZL80 protects against acute seizures via amplifying the inhibitory neural transmission.

Current anti-seizure medications (ASDs) primarily target ion channels or neurotransmissions; however, their practicability is limited by unwanted side-effects and pharmacoresistance. Cumulative evidence has proposed pro-inflammatory caspase-1 as a potential target for developing ASDs. In this study, we showed that the small-molecular caspase-1 inhibitor CZL80 can prevent seizures in various models including the maximal electroshock (MES), the pentylenetetrazol (PTZ), and the amygdaloid kindled models. Specifically, we discovered that CZL80 prevented death, reduced the duration of generalized seizures, and increased the threshold of generalized seizures in a dose-dependent manner in the MES model. In the PTZ model, CZL80 decreased the seizure stages, prolonged the latency to stage 4 seizures, and decreased the death rate. And in amygdaloid kindled rats, CZL80 inhibited the seizure stages, shortened the durations of both generalized seizures and after-discharges. And the anti-seizure efficacy of CZL80 was diminished in caspase-1 knockout mice. In vitro electrophysiology recordings revealed that CZL80 was able to decreased the excitability of glutamatergic pyramidal neurons, as denoted by reducing the spontaneous neuronal firings and increasing the rheobase injected currents to elicit action potentials. Furthermore, CZL80 was able to increase the amplitudes of inhibitory post-synaptic currents (IPSC), while the excitatory post-synaptic currents (EPSC) were not influenced. Lastly, daily administration of CZL80 for 3 weeks did not influence the normal locomotor functions in mice. In sum, our results highlighted CZL80 as a potential anti-seizure therapy with therapeutic significance.

Discovery of Novel Azaindoles as Potent and Selective PI3Kδ Inhibitors for Treatment of Multiple Sclerosis.

Multiple sclerosis (MS) is a chronic autoimmune disorder of the central nervous system and the unmet need for MS treatment demands new therapeutic development. Particularly, PI3Kδ is a high-value target for autoimmune disease, while the investigation of PI3Kδ inhibitors for MS therapy is relatively scarce. Herein, we report a novel class of azaindoles as PI3Kδ inhibitors for MS treatment. Compound 31, designed via nitrogen bioisosterism, displayed excellent PI3Kδ inhibitory activity and selectivity. In vitro assay showed that 31 exhibited superior activity on T lymphocytes to inhibit the proliferation of CD4+, CD8+, and CD3+ T cells. In the experimental autoimmune encephalomyelitis (EAE) model, 31 showed a comparable therapeutical efficacy with Dexamethasone to significantly ameliorate EAE symptoms. Mechanistic studies showed that compound 31 could significantly inhibit the PI3K/AKT/mTOR signaling pathway and inhibited T-cell proliferation and differentiation. Overall, this work provides a new structural PI3Kδ inhibitor and a new vision for MS therapy.

A multicomponent reaction for modular assembly of indole-fused heterocycles.

Indoles are privileged chemical entities in natural products and drug discovery. Indole-fused heterocycles, particularly seven-membered ones, have received increasing attention due to their distinctive chemical characteristics and wide spectrum of bioactivities. However, the synthetic access to these compounds is highly limited. Herein, we report a unique multicomponent reaction (MCR) for modular assembly of indole-fused seven-membered heterocycles. In this process, indole, formaldehyde and amino hydrochloride could assemble rapidly to yield indole-fused oxadiazepines, and another addition of sodium thiosulphate would furnish indole-fused thiadiazepines. The biological evaluation disclosed the promising anticancer activity of these compounds. Furthermore, this MCR could be applicable in the late-stage and selective modifications of peptides. Therefore, this work provides a powerful strategy for indole functionalization and valuable tool for construction of seven-membered heterocycles.

Discovery of Potent and Selective PI3Kδ Inhibitors for the Treatment of Acute Myeloid Leukemia.

PI3Kδ is an essential target correlated to the occurrence and development of acute myeloid leukemia (AML). Herein, we investigated the pyrazolo[3,4-d]pyrimidine derivatives as potent and selective PI3Kδ inhibitors with high therapeutic efficacy toward AML. There were 44 compounds designed and prepared in a four-round optimization, and the biological evaluation showed that (S)-36 exhibited potent PI3Kδ inhibitory activity, high selectivity, and high antiproliferative activities against MV-4-11 and MOLM-13 cells, coupled with high oral bioavailability (F = 59.6%). In the MOLM-13 subcutaneous xenograft model, (S)-36 could significantly suppress the tumor progression with a TGI of 67.81% at an oral administration dosage of 10 mg/kg without exhibiting obvious toxicity. Mechanistically, (S)-36 could robustly inhibit the PI3K/AKT pathway for significant suppression of cell proliferation and remarkable induction of apoptosis both in vitro and in vivo. Thus, compound (S)-36 represents a promising PI3Kδ inhibitor for the treatment of acute myeloid leukemia with high efficacy.

TYM-3-98, a novel selective inhibitor of PI3Kδ, demonstrates promising preclinical antitumor activity in B-cell lymphomas.

AIMS: PI3Kδ is expressed predominately in leukocytes and is commonly found to be aberrantly activated in human B-cell lymphomas. Although PI3Kδ has been intensively targeted for discovering anti-lymphoma drugs, the application of currently approved PI3Kδ inhibitors has been limited due to unwanted systemic toxicities, thus warranting the development of novel PI3Kδ inhibitors with new scaffolds. MAIN METHODS: We designed TYM-3-98, an indazole derivative, and evaluated its selectivity for all four PI3K isoforms, as well as its efficacy against various B-cell lymphomas both in vitro and in vivo. KEY FINDINGS: We identified TYM-3-98 as a highly selective PI3Kδ inhibitor over other PI3K isoforms at both molecular and cellular levels. It showed superior antiproliferative activity in several B-lymphoma cell lines compared with the approved first-generation PI3Kδ inhibitor idelalisib. TYM-3-98 demonstrated a concentration-dependent PI3K/AKT/mTOR signaling blockage followed by apoptosis induction. In vivo, TYM-3-98 showed good pharmaceutical properties and remarkably reduced tumor growth in a human lymphoma xenograft model and a mouse lymphoma model. SIGNIFICANCE: Our findings establish TYM-3-98 as a promising PI3Kδ inhibitor for the treatment of B-cell lymphoma.

Small-molecule caspase-1 inhibitor CZL80 terminates refractory status epilepticus via inhibition of glutamatergic transmission.

Status epilepticus (SE), a serious and often life-threatening medical emergency, is characterized by abnormally prolonged seizures. It is not effectively managed by present first-line anti-seizure medications and could readily develop into drug resistance without timely treatment. In this study, we highlight the therapeutic potential of CZL80, a small molecule that inhibits caspase-1, in SE termination and its related mechanisms. We found that delayed treatment of diazepam (0.5 h) easily induces resistance in kainic acid (KA)-induced SE. CZL80 dose-dependently terminated diazepam-resistant SE, extending the therapeutic time window to 3 h following SE, and also protected against neuronal damage. Interestingly, the effect of CZL80 on SE termination was model-dependent, as evidenced by ineffectiveness in the pilocarpine-induced SE. Further, we found that CZL80 did not terminate KA-induced SE in Caspase-1-/- mice but partially terminated SE in IL1R1-/- mice, suggesting the SE termination effect of CZL80 was dependent on the caspase-1, but not entirely through the downstream IL-1ß pathway. Furthermore, in vivo calcium fiber photometry revealed that CZL80 completely reversed the neuroinflammation-augmented glutamatergic transmission in SE. Together, our results demonstrate that caspase-1 inhibitor CZL80 terminates diazepam-resistant SE by blocking glutamatergic transmission. This may be of great therapeutic significance for the clinical treatment of refractory SE.

Targeting NLRP3 Inflammasome: Structure, Function, and Inhibitors.

Inflammasomes are multimeric protein complexes that can detect various physiological stimuli and danger signals. As a result, they perform a crucial function in the innate immune response. The NLRP3 inflammasome, as a vital constituent of the inflammasome family, is significant in defending against pathogen invasion and preserving cellhomeostasis. NLRP3 inflammasome dysregulation is connected to various pathological conditions, including inflammatory diseases, cancer, and cardiovascular and neurodegenerative diseases. This profile makes NLRP3 an applicable target for treating related diseases, and therefore, there are rising NLRP3 inhibitors disclosed for therapy. Herein, we summarized the updated advances in the structure, function, and inhibitors of NLRP3 inflammasome. Moreover, we aimed to provide an overview of the existing products and future directions for drug research and development.

Chemical Evolution and Biological Evaluation of Natural Products for Efficient Therapy of Acute Lung Injury.

Acute lung injury (ALI) is one of the most common complications in COVID-19 and also a syndrome of acute respiratory failure with high mortality rates, but lacks effective therapeutic drugs. Natural products provide inspiration and have proven to be the most valuable source for bioactive molecule discovery. In this study, the chemical evolution of the natural product Tanshinone IIA (Tan-IIA) to achieve a piperidine-fused scaffold through a synthetic route of pre-activation, multi-component reaction, and post-modification is presented. Through biological evaluation, it is pinpointed that compound 8b is a standout candidate with remarkable anti-inflammation and anti-oxidative stress properties, coupled with low toxicity. The mechanistic study unveils a multifaceted biological profile of 8b and shows that 8b is highly efficient in vivo for the treatment of ALI. Therefore, this work not only provides an effective strategy for the treatment of ALI, but also offers a distinctive natural product-inspired drug discovery.

Discovery of Highly Selective and Orally Bioavailable PI3Kδ Inhibitors with Anti-Inflammatory Activity for Treatment of Acute Lung Injury.

PI3Kδ is a promising target for the treatment of inflammatory disease; however, the application of PI3Kδ inhibitors in acute respiratory inflammatory diseases is rarely investigated. In this study, through scaffold hopping design, we report a new series of 1H-pyrazolo[3,4-d]pyrimidin-4-amine-tethered 3-methyl-1-aryl-1H-indazoles as highly selective and potent PI3Kδ inhibitors with significant anti-inflammatory activities for treatment of acute lung injury (ALI). There were 29 compounds designed, prepared, and subjected to PI3Kδ inhibitory activity evaluation and anti-inflammatory activity evaluation in macrophages. (S)-29 was identified as a candidate with high PI3Kδ inhibitory activity, isoform selectivity, and high oral bioavailability. The in vivo administration of (S)-29 at 10 mg/kg dosage could significantly ameliorate histopathological changes and attenuate lung inflammation in lung tissues of LPS-challenged mice. Molecular docking demonstrated the success of scaffold hopping design. Overall, (S)-29 is a potent PI3Kδ inhibitor which might be a promising candidate for the treatment of ALI.

Modular assembly of indole alkaloids enabled by multicomponent reaction.

Indole alkaloids are one of the largest alkaloid classes, proving valuable structural moiety in pharmaceuticals. Although methods for the synthesis of indole alkaloids are constantly explored, the direct single-step synthesis of these chemical entities with broad structural diversity remains a formidable challenge. Herein, we report a modular assembly of tetrahydrocarboline type of indole alkaloids from simple building blocks in a single step while showing broad compatibility with medicinally relevant functionality. In this protocol, the 2-alkylated or 3-alkylated indoles, formaldehyde, and amine hydrochlorides could undergo a one-pot reaction to deliver γ-tetrahydrocarbolines or ß-tetrahydrocarbolines directly. A wide scope of these readily available starting materials is applicable in this process, and numerous structural divergent tetrahydrocarbolines could be achieved rapidly. The control reaction and deuterium-labelling reaction are conducted to probe the mechanism. And mechanistically, this multicomponent reaction relies on a multiple alkylamination cascade wherein an unusual C(sp3)-C(sp3) connection was involved in this process. This method could render rapid access to pharmaceutically interesting compounds, greatly enlarge the indole alkaloid library and accelerate the lead compound optimization thus facilitating drug discovery.

Multicomponent Reactions for Expeditious Construction of ß-Indole Carboxamide Amino Amides.

A multicomponent reaction of N-indole carboxylic acids, aldehydes, amines, and C2 building blocks can be transformed to structurally diverse ß-indole carboxamide amino amides. In this multicomponent reaction, the ynamides and triazenyl alkynes act as the C2 building block, and this protocol features readily available starting materials, high atom economy, and mild reaction conditions. Besides, the acyl triazene group in the product can be easily transformed to differential groups to expand the structural diversity.

Discovery of Novel 1,2,3,4-Tetrahydrobenzofuro[2,3-c]pyridine Histone Deacetylase Inhibitors for Efficient Treatment of Hepatocellular Carcinoma.

The development of histone deacetylase (HDAC) inhibitors for treating hematologic malignancies has been widely investigated, while their role in hepatocellular carcinoma (HCC) remains unexplored. In this study, we employed a scaffold-hopping design and a multicomponent synthesis approach to develop a novel series of 1,2,3,4-tetrahydrobenzofuro[2,3-c]pyridines as HDAC inhibitors. There were a total of 29 compounds achieved with flexible linkers and zinc-binding groups, wherein compound 12k was identified as a promising candidate with good HDAC inhibitory activity, pharmacokinetic profiles, and potency. It exhibited significant therapeutic efficacy in HCC cell lines (IC50 = 30 nM for Bel-7402) and xenograft models (76% inhibition for Bel-7402 xenografts, P.O. at 20 mg/kg, QOD, for 14 days) and was found to upregulate the acetylation of histone H3 and α-tubulin, leading to apoptosis and autophagy in HCC models. Molecular docking studies indicated a unique T-shaped conformation of 12k with the catalytic domain of HDAC1. Therefore, this work provides a new structure design for HDAC inhibitors and also offers a promising treatment for HCC.

Scaffold Hybrid of the Natural Product Tanshinone I with Piperidine for the Discovery of a Potent NLRP3 Inflammasome Inhibitor.

Natural products provide inspiration and have proven to be the most valuable source for drug discovery. Herein, we report a scaffold hybrid strategy of Tanshinone I for the discovery of NLRP3 inflammasome inhibitors. 36 compounds were designed and synthesized, and the cheminformatic analyses showed that these compounds occupy a unique chemical space. The biological evaluation identified compounds 5j, 12a, and 12d as NLRP3 inflammasome inhibitors with significant potency, selectivity, and drug-likeness. Mechanistic studies revealed that these Tanshinone I derivatives could inhibit the degradation of the protein NLRP3 and block the oligomerization of NLRP3-induced apoptosis-associated speck-like proteins, thus inhibiting NLRP3 inflammasome activation. In addition, the water solubility, in vitro metabolic stability, and oral bioavailability of these compounds were also greatly improved compared to Tanshinone I. Therefore, this protocol provides a new structural evolution of Tanshinone I and a new class of potent NLRP3 inflammasome inhibitors.

Small Molecular Mimetics of Antimicrobial Peptides as a Promising Therapy To Combat Bacterial Resistance.

Clinically, antibiotics are widely used to treat infectious diseases; however, excessive drug abuse and overuse exacerbate the prevalence of drug-resistant bacterial pathogens, making the development of novel antibiotics extremely difficult. Antimicrobial peptide (AMP) is one of the most promising candidates for overcoming bacterial resistance owing to its unique structure and mechanism of action. This study examines the development of small molecular mimetics of AMPs over the past two decades. These mimetics can selectively disrupt membranes, which are the characteristic antibacterial mechanism of AMPs. In addition, the advantages and disadvantages of small AMP mimetics are discussed. The small molecular mimetics of AMPs are anticipated to garner interest and investment in discovering new antibiotics. This Perspective will assist in revitalizing the golden age of antibiotics in the current era of combating bacterial resistance.

Construction of Axial Chirality via Click Chemistry: Rh-Catalyzed Enantioselective Synthesis of 1-Triazolyl-2-Naphthylamines.

A modular and practical click chemistry for atroposelective synthesis of 1-triazolyl-2-naphthylamines is developed. In this protocol, a variety of aromatic or aliphatic azides, and 1-alkynyl-2-naphthylamines could be assembled into valuable 1-triazlyl-2-naphthylamine scaffolds via a [3 + 2] cycloaddition under Rh-catalysis. This asymmetric click technology features easily accessible starting materials, mild reaction conditions, facile scalability, and good enantioselectivity. The good thermostability of products showcases great applicable potential, and the synthetic transformations further expand the molecular diversity of atropisomers.

Discovery and Optimization of N-Acyl-6-sulfonamide-tetrahydroquinoline Derivatives as Novel Non-Steroidal Selective Glucocorticoid Receptor Modulators.

Selective glucocorticoid receptor modulators (SGRMs), which can dissociate the transactivation from the transrepression of the glucocorticoid receptor (GR), are regarded as very promising therapeutics for inflammatory and autoimmune diseases. We previously discovered a SGRM HP-19 based on the passive antagonistic conformation of GR and bioassays. In this study, we further analyzed the dynamic changes of the passive antagonistic state upon the binding of HP-19 and designed and synthesized 62 N-acyl-6-sulfonamide-tetrahydroquinoline derivatives by structural optimization of HP-19. Therein, compound B53 exhibits the best transrepression activity (IC50 NF-κB = 0.009 ± 0.001 µM) comparable with dexamethasone (IC50 NF-κB = 0.005 ± 0.001 µM) and no transactivation activity. B53 can efficiently reduce the expression of inflammatory factors IL-6, IL-1ß, TNF-α, and so on and makes a milder adverse effect and is highly specific to GR. Furthermore, B53 is able to significantly relieve dermatitis on a mouse model via oral drug intervention.