AM-18002, a derivative of natural anmindenol A, enhances radiosensitivity in mouse breast cancer cells.

Natural anmindenol A isolated from the marine-derived bacteria Streptomyces sp. caused potent inhibition of inducible nitric oxide synthase without any significant cytotoxicity. This compound consists of a structurally unique 3,10-dialkylbenzofulvene skeleton. We previously synthesized and screened the novel derivatives of anmindenol A and identified AM-18002, an anmindenol A derivative, as a promising anticancer agent. The combination of AM-18002 and ionizing radiation (IR) improved anticancer effects, which were exerted by promoting apoptosis and inhibiting the proliferation of FM3A mouse breast cancer cells. AM-18002 increased the production of reactive oxygen species (ROS) and was more effective in inducing DNA damage. AM-18002 treatment was found to inhibit the expansion of myeloid-derived suppressor cells (MDSC), cancer cell migration and invasion, and STAT3 phosphorylation. The AM-18002 and IR combination synergistically induced cancer cell death, and AM-18002 acted as a potent anticancer agent by increasing ROS generation and blocking MDSC-mediated STAT3 activation in breast cancer cells.

Development of Oxadiazolone Activity-Based Probes Targeting FphE for Specific Detection of Staphylococcus aureus Infections.

Staphylococcus aureus (S. aureus) is a major human pathogen that is responsible for a wide range of systemic infections. Since its propensity to form biofilms in vivo poses formidable challenges for both detection and treatment, tools that can be used to specifically image S. aureus biofilms are highly valuable for clinical management. Here, we describe the development of oxadiazolone-based activity-based probes to target the S. aureus-specific serine hydrolase FphE. Because this enzyme lacks homologues in other bacteria, it is an ideal target for selective imaging of S. aureus infections. Using X-ray crystallography, direct cell labeling, and mouse models of infection, we demonstrate that oxadiazolone-based probes enable specific labeling of S. aureus bacteria through the direct covalent modification of the FphE active site serine. These results demonstrate the utility of the oxadizolone electrophile for activity-based probes and validate FphE as a target for the development of imaging contrast agents for the rapid detection of S. aureus infections.

Optimization of 3-aminotetrahydrothiophene 1,1-dioxides with improved potency and efficacy as non-electrophilic antioxidant response element (ARE) activators.

Activating NRF2-driven transcription with non-electrophilic small molecules represents an attractive strategy to therapeutically target disease states associated with oxidative stress and inflammation. In this study, we describe a campaign to optimize the potency and efficacy of a previously identified bis-sulfone based non-electrophilic ARE activator 2. This work identifies the efficacious analog 17, a compound with a non-cytotoxic profile in IMR32 cells, as well as ARE activators 18 and 22, analogs with improved cellular potency. In silico drug-likeness prediction suggested the optimized bis-sulfones 17, 18, and 22 will likely be of pharmacological utility.

Development of Oxadiazolone Activity-Based Probes Targeting FphE for Specific Detection of S. aureus Infections.

Staphylococcus aureus is a major human pathogen responsible for a wide range of systemic infections. Since its propensity to form biofilms in vivo poses formidable challenges for both detection and treatment, tools that can be used to specifically image S. aureus biofilms are highly valuable for clinical management. Here we describe the development of oxadiazolonebased activity-based probes to target the S. aureus-specific serine hydrolase FphE. Because this enzyme lacks homologs in other bacteria, it is an ideal target for selective imaging of S. aureus infections. Using X-ray crystallography, direct cell labeling and mouse models of infection we demonstrate that oxadiazolone-based probes enable specific labeling of S. aureus bacteria through the direct covalent modification of the FphE active site serine. These results demonstrate the utility of the oxadizolone electrophile for activity-based probes (ABPs) and validate FphE as a target for development of imaging contrast agents for the rapid detection of S. aureus infections.

A bioisosteric approach to the discovery of novel N-aryl-N'-[4-(aryloxy)cyclohexyl]squaramide-based activators of eukaryotic initiation factor 2 alpha (eIF2α) phosphorylation.

Inhibition of translation initiation has emerging implications for the development of mechanism-based anticancer therapeutics. Phosphorylation of eIF2α is recognized as a key target that regulates the translation initiation cascade. Based on the bioisosteric replacement of urea-derived eIF2α phosphorylation activator 1, a novel series of N-aryl-N'-[4-(aryloxy)cyclohexyl]squaramide derivatives was designed and synthesized; their effects on the activation of eIF2α phosphorylation was assessed systematically. A brief structure-activity relationship analysis was established by stepwise structural optimization of the squaramide series. Subsequently, the antiproliferative activities of the selected analogues were determined in human leukemia K562 cells. We then identified 10 potent eIF2α phosphorylation activators with considerable anticancer activity. The most promising analogues 19 and 40 possessed higher cancer cell selectivity (SI = 6.16 and 4.83, respectively) than parent 1 (SI = 2.20). Finally, protein expression analysis revealed that compounds 19 and 40 induced eIF2α phosphorylation and its downstream effectors ATF4 and CHOP.

Recent advances in development of hetero-bivalent kinase inhibitors.

Identifying a pharmacological agent that targets only one of more than 500 kinases present in humans is an important challenge. One potential solution to this problem is the development of bivalent kinase inhibitors, which consist of two connected fragments, each bind to a dissimilar binding site of the bisubstrate enzyme. The main advantage of bivalent (type V) kinase inhibitors is generating more interactions with target enzymes that can enhance the molecules' selectivity and affinity compared to single-site inhibitors. Earlier type V inhibitors were not suitable for the cellular environment and were mostly used in in vitro studies. However, recently developed bivalent compounds have high kinase affinity, high biological and chemical stability in vivo. This review summarized the hetero-bivalent kinase inhibitors described in the literature from 2014 to the present. We attempted to classify the molecules by serine/threonine and tyrosine kinase inhibitors, and then each target kinase and its hetero-bivalent inhibitor was assessed in depth. In addition, we discussed the analysis of advantages, limitations, and perspectives of bivalent kinase inhibitors compared with the monovalent kinase inhibitors.

Discovery and optimization of novel 3-benzyl-N-phenyl-1H-pyrazole-5-carboxamides as bifunctional antidiabetic agents stimulating both insulin secretion and glucose uptake.

A novel series of 3-benzyl-N-phenyl-1H-pyrazole-5-carboxamides was designed, synthesized and evaluated for their biological activities on glucose-stimulated insulin secretion (GSIS). The cytotoxicity of all 41 novel compounds was screened to assess their pharmacological safety in pancreatic ß-cells. A two-step optimization process was carried out to establish the structure-activity relationship for this class and subsequently we identified the most active analogue 26. Further modification study of 26 evidenced the necessity of N-hydrogens in the core architecture. Protein expression analysis suggested that 26 increases insulin secretion via the activation of the upstream effector of pancreatic and duodenal homeobox 1 (PDX-1), which is an important factor promoting GSIS. Moreover, the administration of 26 effectively augmented glucose uptake in C2C12 myotube cells via the suppression of Mitsugumin 53 (MG53), an insulin receptor substrate 1 (IRS-1) ubiquitination E3 ligase.

Discovery and SAR studies of 3-amino-4-(phenylsulfonyl)tetrahydrothiophene 1,1-dioxides as non-electrophilic antioxidant response element (ARE) activators.

The transcription factor NRF2 controls resistance to oxidative insult and is thus a key therapeutic target for treating a number of disease states associated with oxidative stress and aging. We previously reported CBR-470-1, a bis-sulfone which activates NRF2 by increasing the levels of methylglyoxal, a metabolite that covalently modifies NRF2 repressor KEAP1. Here, we report the design, synthesis, and structure activity relationship of a series of bis-sulfones derived from this unexplored chemical template. We identify analogs with sub-micromolar potencies, 7f and 7g, as well as establish that efficacious NRF2 activation can be achieved by non-toxic analogs 7c, 7e, and 9, a key limitation with CBR-470-1. Further efforts to identify non-covalent NRF2 activators of this kind will likely provide new insight into revealing the role of central metabolism in cellular signaling.

SAR optimization studies on a novel series of 2-anilinopyrimidines as selective inhibitors against triple-negative breast cancer cell line MDA-MB-468.

Triple-negative breast cancers (TNBCs) account for approximately 15% of breast cancer cases and exhibit an aggressive clinical behavior. In this study, we designed and synthesized two series of 2-anilinopyrimidines based on the structure of our previously reported compound 1 that act as a selective inhibitor of the basal-like TNBC cell line MDA-MB-468. Through the fine-tuning of 1, cyclic and acyclic amines at 4-position of the pyrimidine core were turned out to be crucial for the selectivity. An extensive analysis of structure-activity relationships of the analogs revealed that aminoalkyl groups at the end of the propyl chain are amenable to modification. Among the newly synthesized analogs, compound 38, bearing 4-chloropiperidinyl and cyclohexyl groups, was found to be the most potent and selective, and was about three times more potent and selective than 1 was against the TNBC cells.

Total Synthesis of Anmindenol A and Its Application to the Design, Synthesis, and Biological Evaluation of Derivatives Thereof.

The first total synthesis of anmindenol A is described in four steps. A notable feature of the synthetic route includes the efficient construction of the 3,10-dialkylsubstituted benzofulvene core via a stereoselective vinylogous Stork enamine aldol condensation. The strategy provided a blueprint for the practical preparation of derivatives with modifications in the C-10 alkyl substituents. The novel derivatives inhibited nitric oxide production in stimulated RAW 264.7 macrophage cells.

Dual effects of isoflavonoids from Pueraria lobata roots on estrogenic activity and anti-proliferation of MCF-7 human breast carcinoma cells.

Pueraria lobata root (PLR), well known as Kudzu root, has recently become commercially available in Western dietary supplements for menopausal symptoms. The scientific basis for its action has been attributed to the action of phytoestrogens. This study aimed to investigate the estrogen-like activity of isoflavonoids isolated from P. lobata root and their safety with respect to their effect on breast cancer cell proliferation. In an E-screen assay, crude MeOH extract of PLR significantly increased the proliferation of MCF-7 cells in a concentration-dependent manner. Among the four fractions obtained by solvent fractionation of MeOH extract, the n-BuOH fraction had significant estrogen-like activities at all concentrations tested. Phytochemical analysis of the n-BuOH fraction led to the isolation of 10 isoflavones (1-10), among which genistein (10) had significant estrogen-like activities at all concentrations tested. These activities were significantly enhanced by treatment with genistein and 17ß-estradiol compared with 17ß-estradiol alone, and this effect was mediated by decreased expression of estrogen receptor (ER)α and phospho-ERα in MCF-7 cells. In a cell cytotoxicity assay, genistein (10) exhibited significant cytotoxicity in both ER-positive MCF-7 and ER-negative MDA-MB-231 breast cancer cells. This cytotoxicity was characterized by the induction of apoptotic cells stained with annexin V conjugated with Alexa Fluor 488 and involved activation of mitochondria-independent and -dependent apoptosis pathways in MCF-7 cells. Our results demonstrated that genistein (10) has estrogen-like effects dependent on ER pathway activation and anti-proliferative effects mediated by the apoptosis pathway rather than the ER pathway in MCF-7 breast cancer cells.

Discovery and SAR studies of novel 2-anilinopyrimidine-based selective inhibitors against triple-negative breast cancer cell line MDA-MB-468.

Triple-negative breast cancers (TNBCs) are characterized as an invasive and intractable subtype of breast cancers. Overexpression of epidermal growth factor receptor (EGFR) has been considered to be an important target for TNBC therapy, but efficacies of EGFR inhibitors in clinical trials are elusive. In this study, novel series of 2-anilinopyrimidines were synthesized in an effort to identify selective inhibitors against an EGFR-overexpressing TNBC cell line. Biological evaluation demonstrated that compounds 21 and 38, with a 4-methylpiperidine group and a high ClogP value, exhibited good potency and selectivity for the TNBC cell line. This study has provided evidence to support further development of 2-anilinopyrimidine-based TNBC selective inhibitors and investigation of the targets of compounds 21 and 38.

Beneficial effects of Cirsium japonicum var. maackii on menopausal symptoms in ovariectomized rats.

In women, menopause refers to a series of physiological and mental symptoms of distress that result from a decrease in 17ß-estradiol. In addition to the loss of fertility, the symptoms include facial flushing, depression, osteoporosis, sexual dysfunction, and genitourinary atrophy. Cirsium japonicum var. maackii is a perennial herbaceous species found in the mountains and fields of Korea, China, and Japan. The medicinal uses of C. japonicum include antioxidant, antidiabetic, antitumor, antifungal, and anti-inflammatory activities. We investigated the effect of C. japonicum extract in a rat model of menopause that exhibited rapid estrogen decline induced by ovariectomy (OVX rats). The rats were treated with C. japonicum extract for 10 weeks and the following parameters were measured: food intake, feed efficiency, body weight, total cholesterol, triglyceride, LDL-cholesterol, HDL-cholesterol, liver weight, 17ß-estradiol, uterus weight, AST, ALT, bone mineral density (BMD), bone alkaline phosphatase, calcitonin, and osteocalcin. In OVX rats, the administration of 50 and 100 mg kg-1C. japonicum extract significantly decreased body weight, total cholesterol, triglyceride, HDL-cholesterol, and LDL-cholesterol and significantly increased 17ß-estradiol and BMD. During the light/dark box test, the C. japonicum treatment group (100 mg kg-1) spent more time in the light chamber than in the dark area, which was reflective of their diurnal nature. Using a molecular docking simulation, we predicted the plausible binding mode of the active compounds of C. japonicum with the ligand binding domain of estrogen receptor (ER)-α and ER-ß. These results showed that C. japonicum extract can treat the symptoms before and after the menopause.

Recent Advances in Substrate-Controlled Asymmetric Cyclization for Natural Product Synthesis.

Asymmetric synthesis of naturally occurring diverse ring systems is an ongoing and challenging research topic. A large variety of remarkable reactions utilizing chiral substrates, auxiliaries, reagents, and catalysts have been intensively investigated. This review specifically describes recent advances in successful asymmetric cyclization reactions to generate cyclic architectures of various natural products in a substrate-controlled manner.

Recent Advances in Substrate-Controlled Asymmetric Induction Derived from Chiral Pool α-Amino Acids for Natural Product Synthesis.

Chiral pool α-amino acids have been used as powerful tools for the total synthesis of structurally diverse natural products. Some common naturally occurring α-amino acids are readily available in both enantiomerically pure forms. The applications of the chiral pool in asymmetric synthesis can be categorized prudently as chiral sources, devices, and inducers. This review specifically examines recent advances in substrate-controlled asymmetric reactions induced by the chirality of α-amino acid templates in natural product synthesis research and related areas.