Identification of Novel Artemisinin Hybrids Induce Apoptosis and Ferroptosis in MCF-7 Cells.

A series of novel 1,3,4-oxadiazole-artemisinin hybrids have been designed and synthesized. An MTT assay revealed that most of tested hybrids showed more enhanced anti-proliferative activities than artemisinin, among which A8 had the superior potency with IC50 values ranging from 4.07 µM to 9.71 µM against five tested cancer cell lines. Cell colony formation assays showed that A8 could inhibit significantly more cell proliferation than artemisinin and 5-fluorouracil. Further mechanism studies reveal that A8 induces apoptosis and ferroptosis in MCF-7 cells in a dose-dependent manner, and CYPs inhibition assays reveal that A8 has a moderate inhibitory effect on CYP1A2 and CYP3A4 in the human body at 10 µM. The present work indicates that hybrid A8 may merit further investigation as a potential therapeutic agent.

Recent progress on betulinic acid and its derivatives as antitumor agents: a mini review.

Natural products are one of the important sources for the discovery of new drugs. Betulinic acid (BA), a pentacyclic triterpenoid widely distributed in the plant kingdom, exhibits powerful biological effects, including antitumor activity against various types of cancer cells. A considerable number of BA derivatives have been designed and prepared to remove their disadvantages, such as poor water solubility and low bioavailability. This review summarizes the current studies of the structural diversity of antitumor BA derivatives within the last five years, which provides prospects for further research on the structural modification of betulinic acid.

Novel carbohydrate-based sulfonamide derivatives as selective carbonic anhydrase II inhibitors: Synthesis, biological and molecular docking analysis.

A series of sulfonamides containing glucosamine moieties had been prepared and investigated for the inhibition of the zinc enzyme carbonic anhydrases (CAs, EC 4.2.1.1). Compared to their parent compound p-sulfamoylbenzoic acid, target compounds showed two order of magnitude improvement in their binding affinities against hCA II in vitro. Moreover, they also showed great selectivity toward hCA II enzyme with the ratios for inhibiting hCA II over hCA I in the range 20-96 and for inhibiting hCA II over hCA IX in the range 4.3-9. Due to the introduction of glucosamine moieties, all of compounds displayed good water solubility (in the range of 2.0-2.5%) and the pH values of the obtained solutions is neutral (7.0-7.2). Compared to the clinically available and relatively highly acidic dorzolamide (pH 5.5), target compounds are more likely to be less irritating to the eye when applied to topical glaucomatous drugs. Then, cytotoxicity evaluation suggested that all target compounds did not display any appreciable toxicity against human cornea epithelial cell. In addition, molecular docking studies elucidated the binding modes of those compounds toward hCA II. Collectively, these results suggest that target compounds represented a promising scaffold to treat glaucoma without major topical side effects.

Synthesis, Molecular Docking Analysis and Biological Evaluations of Saccharide-Modified Thiadiazole Sulfonamide Derivatives.

A series of saccharide-modified thiadiazole sulfonamide derivatives has been designed and synthesized by the "tail approach" and evaluated for inhibitory activity against carbonic anhydrases II, IX, and XII. Most of the compounds showed high topological polar surface area (TPSA) values and excellent enzyme inhibitory activity. The impacts of some compounds on the viability of HT-29, MDA-MB-231, and MG-63 human cancer cell lines were examined under both normoxic and hypoxic conditions, and they showed certain inhibitory effects on cell viability. Moreover, it was found that the series of compounds had the ability to raise the pH of the tumor cell microenvironment. All the results proved that saccharide-modified thiadiazole sulfonamides have important research prospects for the development of CA IX inhibitors.

Synthesis and antitumor activity evaluation of oleanolic acid saponins bearing an acetylated l-arabinose moiety.

A series of oleanolic acid derivatives bearing acetyl-substituted l-arabinose moiety has been synthesized and screened in vitro for cytotoxicity against ten cancer cell lines and four normal cell lines. The antiproliferative evaluation indicated that synthetic derivatives showed excellent selectivity, as they were toxic against only A431 cell line. Among them, the compound 6 possesses the best inhibitory activity. A series of pharmacology experiments showed that compound 6 significantly induced A431 cells apoptosis and cell cycle arrest, which could serve as a promising lead candidate for further study.

Recent Advances in ß2-Agonists for Treatment of Chronic Respiratory Diseases and Heart Failure.

ß2-Adrenoceptor (ß2-AR) agonists are widely used as bronchodilators. The emerge of ultralong acting ß2-agonists is an important breakthrough in pulmonary medicine. In this review, we will provide mechanistic insights into the application of ß2-agonists in asthma, chronic obstructive pulmonary disease (COPD), and heart failure (HF). Recent studies in ß-AR signal transduction have revealed opposing functions of the ß1-AR and the ß2-AR on cardiomyocyte survival. Thus, ß2-agonists and ß-blockers in combination may represent a novel strategy for HF management. Allosteric modulation and biased agonism at the ß2-AR also provide a theoretical basis for developing drugs with novel mechanisms of action and pharmacological profiles. Overlap of COPD and HF presents a substantial clinical challenge but also a unique opportunity for evaluation of the cardiovascular safety of ß2-agonists. Further basic and clinical research along these lines can help us develop better drugs and innovative strategies for the management of these difficult-to-treat diseases.

Precise design of highly isoform-selective p21-activated kinase 4 inhibitors: computational insights into the selectivity mechanism through molecular dynamics simulation and binding free energy calculation.

Understanding the selectivity mechanisms of inhibitors towards highly similar protein kinases is the first step in discovering new selective candidate for satisfactory safety profile. P21-activated kinases (PAKs) are pertain to a family of serine/threonine (Ser/Thr) protein kinases, which are the first Rho family GTPase-regulated kinases identified and served as important downstream mediators of Ras-Rac and Cdc42 function. Among PAKs, PAK4 is emerging as a promising target for cancer treatment. Since the PAK2 inhibition correlates with increased acute cardiovascular toxicity, which may be enhanced by PAK1 inhibitor, selective inhibition of PAK4 over PAK1 is crucial in discovering safe anticancer candidates with optimal therapeutic efficacy. While the conserved ATP-binding pockets of both PAK1/4 make it challenging to discriminating selective inhibitors between PAK1 and PAK4, thus the selectivity mechanism of PAK1/4 inhibitors will be explored in this present study through, computational strategies which combine molecular docking, structural comparison, molecular dynamics simulation and molecular mechanics/generalized Born surface area calculation. The research would provide valuable insight into the selectivity mechanism of PAK4 inhibitors over PAK1 and thus be helpful for designing selective PAK4 inhibitors.Communicated by Ramaswamy H. Sarma.

Molecular determinants for ligand binding at Nav1.4 and Nav1.7 channels: Experimental affinity results analyzed by molecular modeling.

Here, we focused on exploring the selectivity mechanism against Nav1.7 over Nav1.4 due to different binding modes of two selected inhibitors. By the superposition of Nav1.7 and Nav1.4 proteins, we selected the most homologous chain of Nav1.7 with Nav1.4, defining the active site of Nav1.4-VSD4 based on the aryl sulfonamide binding site of Nav1.7-VSD4. Comparison of the conformations exhibited by Tyr1386 (Nav1.4) and Tyr1537 (Nav1.7) suggested that the steric hindrance caused by Tyr1386 owned primary influence on inhibition selectivity, which was further verified through molecular docking and MD simulation of two representative inhibitors. Our finding would be helpful for discovery of selective Nav1.7 inhibitors over Nav1.4.

Design, Synthesis and Molecular Docking Analysis of Flavonoid Derivatives as Potential Telomerase Inhibitors.

Based on the structural scaffolds of natural products, two series of flavonoid derivatives, for a total of twelve compounds, were designed and synthesized as potential human telomerase inhibitors. Using a modified TRAP-PCR assay, compound 5c exhibited the most potent inhibitory activity against human telomerase with an IC50 value of less than 50 µM. In vitro, the results demonstrated that compound 5c had potent anticancer activity against five classes of tumor cell lines. The molecular docking and molecular dynamics analyses binding to the human telomerase holoenzyme were performed to elucidate the binding mode of active compound 5c. This finding helps the rational design of more potent telomerase inhibitors based on the structural scaffolds of natural products.

Strategy and validation of a structure-based method for the discovery of selective inhibitors of PAK isoforms and the evaluation of their anti-cancer activity.

p21 activated kinase 4 (PAK4), which belongs to the serine/threonine (Ser/Thr) protein kinase family, is a representative member of the PAK family and plays a significant role in multiple processes associated with cancer development. In this study, structure-based virtual screening was performed to discover novel and selective small molecule scaffolds, and a 6-hydroxy-2-mercapto-3-phenylpyrimidin-4(3H)-one-based compound (SPU-106, 14#) was identified as an effective PAK4 inhibitor. By combining both a molecular docking study and molecular dynamics (MD) simulation strategies, the binding mode was determined in the PAK4 site. The SPU-106 compound could efficiently and selectively bind to the PAK4 kinase domain at an IC50 of 21.36 µM according to the kinase analysis. The designed molecular probe demonstrated that SPU-106 binds to the kinase domain in the C-terminus of PAK4. Further investigation revealed that the SPU-106 had a strong inhibitory effect on the invasion of SGC7901 cells but without any cytotoxicity. The western blot analysis indicated that the compound potently inhibited the PAK4/LIMK1/cofilin and PAK4/SCG10 signaling pathways. Thus, our work shows the successful application of computational strategies for the discovery of selective hits, and SPU-106 may be an effective PAK4 inhibitor for further development as an antitumor agent.

Synthesis, Molecular Docking Analysis, and Carbonic Anhydrase Inhibitory Evaluations of Benzenesulfonamide Derivatives Containing Thiazolidinone.

To find novel human carbonic anhydrase (hCA) inhibitors, we synthesized thirteen compounds by combining thiazolidinone with benzenesulfonamide. The result of the X-ray single-crystal diffraction experiment confirmed the configuration of this class of compounds. The enzyme inhibition assays against hCA II and IX showed desirable potency profiles, as effective as the positive controls. The docking studies revealed that compounds (2) and (7) efficiently bound in the active site cavity of hCA IX by forming sufficient interactions with active site residues. The fragment of thiazolidinone played an important role in the binding of the molecules to the active site.

Identification of 10-dehydrooxyglycyuralin E as a selective human estrogen receptor alpha partial agonist.

Selective estrogen receptor modulators (SERMs) act as either agonist or antagonist of estrogen receptor (ER) in a tissue selective manner and have been used in several diseases such as breast cancer, postmenopausal syndrome, osteoporosis, and cardiovascular diseases. However, current SERMs may also increase the risk of serious side effects and trigger drug resistance. Herein, a screening program, that was designed to search for novel SERMs, resulted in the identification of a series of 2-arylbenzofuran-containing compounds that are ligands for ERα, when applying the Gaussia-luciferase reporter assay. One of these compounds, 10-dehydrooxyglycyuralin E (T9) was chemically synthesized. T9 showed anti-estrogenic/proliferative activity in ERα-positive breast cancer cells. Pretreatment of T9 prevented the mRNA expression of GREB1, which is an estrogen response gene. Furthermore, by an in silico docking simulation study we demonstrated that T9 showed interactions directly to ERα. Taken together, these results demonstrated that T9 is a candidate of SERMs and a useful seed compound for the foundation of the selective activity of SERMs.

Targeting PAK1 with the Small Molecule Drug AK963/40708899 Suppresses Gastric Cancer Cell Proliferation and Invasion by Downregulation of PAK1 Activity and PAK1-Related Signaling Pathways.

PAK1 (p21-activated kinase 1) is a serine/threonine protein kinase which has been initially identified as downstream effector of the Rho GTPase family. In previous research, PAK1 has been involved in the regulation of diverse cellular processes, such as cell motility, cell proliferation, gene transcription, cytoskeletal rearrangement, and cell invasion. Hyper-activation of PAK1 was constantly observed in a variety of human cancer which make it a potential target of novel anti-tumor drugs. To date, a great number of attentions focus on identifying the PAK1 inhibitors in medical and pharmaceutical fields. In this article, we found that a novel and potent PAK1 inhibitor, AK963/40708899, suppressed the proliferation of human gastric cancer cells significantly by downregulation of PAK1-NF-κB-cyclinB1 pathway. In addition, AK963/40708899 inhibited the formation of filopodia and promoted cell adhesion which in turn inhibited invasive potential of gastric cells by negatively regulating PAK1-LIMKl-cofilin and PAK1-ERK-FAK pathways. Considering our result, AK963/40708899 would be a possible candidate for PAK1 targeted anti-tumor drug. Anat Rec, 302:1571-1579, 2019. © 2019 American Association for Anatomy.

Protein tyrosine phosphatase 1B inhibitory activities of ursane-type triterpenes from Chinese raspberry, fruits of Rubus chingii.

Protein tyrosine phosphatase 1B (PTP1B) has led to an intense interest in developing its inhibitors as anti-diabetes, anti-obesity and anti-cancer agents. The fruits of Rubus chingii (Chinese raspberry) were used as a kind of dietary traditional Chinese medicine. The methanolic extract of R. chingii fruits exhibited significant PTP1B inhibitory activity. Further bioactivity-guided fractionation resulted in the isolation of three PTP1B inhibitory ursane-type triterpenes: ursolic acid (1), 2-oxopomolic acid (2), and 2α, 19α-dihydroxy-3-oxo-urs-12-en-28-oic acid (3). Kinetics analyses revealed that 1 was a non-competitive PTP1B inhibitor, and 2 and 3 were mixed type PTP1B inhibitors. Compounds 1-3 and structurally related triterpenes (4-8) were further analyzed the structure-activity relationship, and were evaluated the inhibitory selectivity against four homologous protein tyrosine phosphatases (TCPTP, VHR, SHP-1 and SHP-2). Molecular docking simulations were also carried out, and the result indicated that 1, 3-acetoxy-urs-12-ene-28-oic acid (5), and pomolic acid-3ß-acetate (6) bound at the allosteric site including α3, α6, and α7 helix of PTP1B.

Discovery of ß-arrestin-biased ß2-adrenoceptor agonists from 2-amino-2-phenylethanol derivatives.

ß-Arrestins are a small family of proteins important for signal transduction at G protein-coupled receptors (GPCRs). ß-Arrestins are involved in the desensitization of GPCRs. Recently, biased ligands possessing different efficacies in activating the G protein- versus the ß-arrestin-dependent signals downstream of a single GPCR have emerged, which can be used to selectively modulate GPCR signal transduction in such a way that desirable signals are enhanced to produce therapeutic effects while undesirable signals of the same GPCR are suppressed to avoid side effects. In the present study, we evaluated agonist bias for compounds developed along a drug discovery project of ß2-adrenoceptor agonists. About 150 compounds, including derivatives of fenoterol, 2-amino-1-phenylethanol and 2-amino-2-phenylethanol, were obtained or synthesized, and initially screened for their ß-adrenoceptor-mediated activities in the guinea pig tracheal smooth muscle relaxation assay or the cardiomyocyte contractility assay. Nineteen bioactive compounds were further assessed using both the HTRF cAMP assay and the PathHunter ß-arrestin assay. Their concentration-response data in stimulating cAMP synthesis and ß-arrestin recruitment were applied to the Black-Leff operational model for ligand bias quantitation. As a result, three compounds (L-2, L-4, and L-12) with the core structure of 5-(1-amino-2-hydroxyethyl)-8-hydroxyquinolin-2(1H)-one were identified as a new series of ß-arrestin-biased ß2-adrenoceptor agonists, whereas salmeterol was found to be Gs-biased. These findings would facilitate the development of novel drugs for the treatment of both heart failure and asthma.

Synthesis, antitumor activity evaluation and mechanistic study of novel hederacolchiside A1 derivatives bearing an aryl triazole moiety.

In an attempt to arrive at a more potent antitumor agent than the parent natural saponin hederacolchiside A1, 23 hederacolchiside A1 derivatives (4a-4w) were synthesized via Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition and screened in vitro for cytotoxicity against six human cancer cell lines. The structure-activity relationship of these compounds was elucidated, and the biological screening results showed that most of the compounds exhibited moderate to high levels of antitumor activities against the tested cell lines and some of them displayed more potent inhibitory activities compared with hederacolchiside A1. Compound 4f showed a 2- to 7-fold more potent activity than hederacolchiside A1. The mechanistic study of 4f revealed that this compound can induce cell apoptosis in HepG2 cells via mitochondrial-mediated intrinsic pathways.

Synthesis, biological evaluation and structure-activity relationship studies of hederacolchiside E and its derivatives as potential anti-Alzheimer agents.

Inspired by the previously reported neuroprotective activity of hederacolchiside E (1), we synthesized hederacolchiside E for the first time along with eleven of its derivatives. The neuroprotective effects of these compounds were further evaluated against H2O2- and Aß1-42-induced injury using cell-based assays. The derivatives showed obvious differences in activity due to structural variations, and two of them exhibited better neuroprotective effects than 1 in the Aß1-42-induced injury model. Compound 7 was the most active derivative and had a relatively simple chemical structure. Moreover, 1 and 7 can significantly reduce the release of lactate dehydrogenase (LDH), level of intracellular reactive oxygen species (ROS) and extent of malondialdehyde (MDA) increase resulting from Aß1-42 treatment, which demonstrated that these kinds of compounds show neuroprotective effects in Alzheimer's disease (AD) models via modulating oxidative stress. Compound 7 could be used as promising lead for the development of a new type of neuroprotective agent against AD.

LC-0882 targets PAK4 and inhibits PAK4-related signaling pathways to suppress the proliferation and invasion of gastric cancer cells.

Gastric cancer is the most common malignant tumor and globally the third leading cause of cancer-related deaths. Therefore, there exists an urgent need to identify new effective gastric cancer treatments. Given the important roles in tumorigenesis and progression, p21-activated kinase 4 (PAK4) has been regarded as an attractive high-value druggable target. In this study, we examined the effects and molecular mechanisms of action of the small molecular compound LC-0882 on gastric cancer cells in vitro. LC-0882 was found to significantly inhibit the proliferation of human gastric cancer cells by repressing phospho-PAK4/cyclin D1 and CDK4/6 expression. In addition, LC-0882 was found to attenuate cell invasion by blocking the PAK4/LIMK1/cofilin signaling pathway. Finally, analysis of immunofluorescence revealed that LC-0882 exposure decreased filopodia formation and induced cell elongation in BGC823 and SGC7901 gastric cancer cells. These findings suggest that targeting PAK4 with the novel compound LC-0882 may provide a new chemotherapeutic approach in gastric cancer treatment.

Design, Synthesis, Molecular Docking Analysis, and Carbonic Anhydrase IX Inhibitory Evaluations of Novel N-Substituted-ß-d-Glucosamine Derivatives that Incorporate Benzenesulfonamides.

A series of novel N-substituted-ß-d-glucosamine derivatives that incorporate benzenesulfonamides were designed using a fragment-based drug design strategy. Each derivative was synthesized and evaluated in vitro for its inhibitory activity against human carbonic anhydrase (hCA) IX; several derivatives displayed desirable potency profiles against this enzyme. The molecular docking studies provided the design rationale and predicted potential binding modes for carbonic anhydrase (CA) IX and three target compounds, including the most potent inhibitor, compound 7f (IC50 = 10.01 nM). Moreover, the calculated Log P (cLog P) values showed that all the compounds tended to be hydrophilic. In addition, topological polar surface area (TPSA) value-based predictions highlighted the selectivity of these carbohydrate-based inhibitors for membrane-associated CA IX.

Dual-tail approach to discovery of novel carbonic anhydrase IX inhibitors by simultaneously matching the hydrophobic and hydrophilic halves of the active site.

Dual-tail approach was employed to design novel Carbonic Anhydrase (CA) IX inhibitors by simultaneously matching the hydrophobic and hydrophilic halves of the active site, which also contains a zinc ion as part of the catalytic center. The classic sulfanilamide moiety was used as the zinc binding group. An amino glucosamine fragment was chosen as the hydrophilic part and a cinnamamide fragment as the hydrophobic part in order to draw favorable interactions with the corresponding halves of the active site. In comparison with sulfanilamide which is largely devoid of the hydrophilic and hydrophobic interactions with the two halves of the active site, the compounds so designed and synthesized in this study showed 1000-fold improvement in binding affinity. Most of the compounds inhibited the CA effectively with IC50 values in the range of 7-152 nM. Compound 14e (IC50: 7 nM) was more effective than the reference drug acetazolamide (IC50: 30 nM). The results proved that the dual-tail approach to simultaneously matching the hydrophobic and hydrophilic halves of the active site by linking hydrophobic and hydrophilic fragments was useful for designing novel CA inhibitors. The effectiveness of those compounds was elucidated by both the experimental data and molecular docking simulations. This work laid a solid foundation for further development of novel CA IX inhibitors for cancer treatment.