Bioactivity-based analysis and chemical characterization of hypoglycemic and antioxidant components from Artemisia argyi.

Diabetes is one of the metabolic disorders in the world. It is the prime reason of mortality and morbidity owing to hyperglycemia which is link with numerus obstacles. Artemisia argyi is commonly used as an ingredient in healthy foods as well as an herbal medicine in Asian countries. The present research aims to evaluate the hypoglycemic effects of A. argyi and reveal its the potentially active constituents. The chemical composition was identified by HPLC-DAD-Q-TOF-MS, and fractionation was performed by extraction. The fractions were assessed by the blood glucose level, oral glucose tolerance and small intestinal α-glucosidase inhibitory tests, and an analysis of the total phenolic content (TPC), antioxidant and α-glucosidase inhibitory activities. In our efforts to characterize the compounds responsible for hypoglycemic effect, bioactivity-guided fraction of the MeOH extract and chemical investigation of its active EtOAc fraction led to the successful identification of caffeoylquinic acids, which were elucidated by molecular docking, using the crystal structure of S. cerevisiae isomaltase (PD code: 3AXI). In summary, this bio-guided search revealed that caffeoylquinic acids from A. argyi as potential active constituents displayed with hypoglycemic activity, which provided a basis for further study of pharmacological activity.

The recent progress of isoxazole in medicinal chemistry.

Isoxazole compounds exhibit a wide spectrum of targets and broad biological activities. Developing compounds with heterocycle rings has been one of the trends. The integration of isoxazole ring can offer improved physical-chemical properties. Because of the unique profiles, isoxazole ring becomes a popular moiety in compounds design. In this review article, the major focus has been paid to the applications of isoxazole compounds in treating multiple diseases, including anticancer, antimicrobial, anti-inflammatory, etc. Strategies for compounds design for preclinical, clinical, and FDA approved drugs were discussed. Also, the emphasis has been addressed to the future perspectives and trend for the application.

Chemical Constituents of the Seed Cake of Camellia oleifera and Their Antioxidant and Antimelanogenic Activities.

There is a growing interest in the exploitation of agricultural byproducts. This study explored the potential beneficial health effects from the main biowaste, tea seed pomace of Camellia oleifera Abel (Theaceae), produced when tea seed is processed. Eighteen compounds were isolated from the 70% EtOH extract of the seed cake of C. oleifera. Their structures were determined by ESI-MS, 1 H- and 13 C-NMR together with literature data. All fractions and compounds were evaluated for the antioxidant and melanogenesis inhibitory activities. As the result, AcOEt fraction has the best in vitro antioxidant and antimelanogenesis activities, compounds 7 - 12 and 15 showed remarkable antioxidant activity, compounds 4, 6, 8, and 15 - 17 exhibited superior inhibitory activities against melanogenesis. Furthermore, tyrosinase inhibitory activity assay suggested that compound 8 could suppress melanogenesis by inhibiting the expression of tyrosinase.

Dual GSK-3ß/AChE Inhibitors as a New Strategy for Multitargeting Anti-Alzheimer's Disease Drug Discovery.

Designing multitarget-directed ligands (MTDLs) is considered to be a promising approach to address complex and multifactorial maladies such as Alzheimer's disease (AD). The concurrent inhibition of the two crucial AD targets, glycogen synthase kinase-3ß (GSK-3ß) and human acetylcholinesterase (hAChE), might represent a breakthrough in the quest for clinical efficacy. Thus, a novel family of GSK-3ß/AChE dual-target inhibitors was designed and synthesized. Among these hybrids, 2f showed the most promising profile as a nanomolar inhibitor on both hAChE (IC50 = 6.5 nM) and hGSK-3ß kinase activity (IC50 = 66 nM). It also showed good inhibitory effect on ß-amyloid self-aggregation (inhibitory rate = 46%) at 20 µM. Western blot analysis revealed that compound 2f inhibited hyperphosphorylation of tau protein in mouse neuroblastoma N2a-Tau cells. In vivo studies confirmed that 2f significantly ameliorated the cognitive disorders in scopolamine-treated ICR mice and less hepatotoxicity than tacrine. This study provides new leads for assessment of GSK-3ß and AChE pathway dual inhibition as a promising strategy for AD treatment.

G9a - An Appealing Antineoplastic Target.

BACKGROUND: G9a is the primary enzyme for mono- and dimethylation at Lys 9 of histone H3 and forms predominantly the heteromeric complex as a G9a-GLP (G9a-like protein) that is a functional histone lysine methltransferase in vivo. Mounting evidence suggests that G9a catalyzes methylation of histone and nonhistone proteins, which plays a crucial role in diverse biological processes and human diseases. METHODS: In this study, the current knowledge on biological functions of G9a and inhibitors were summarized. RESULTS: we review the current knowledge on biological functions of G9a, with particular emphasis on regulating gene expression and cell processes, and involvement in human diseases. We outline a perspective on various classes of G9a inhibitors to date from both articles and patents with an emphasis on their discovery, activity and the current research status. CONCLUSION: We highlight the key knowledge on potential biological functions and various human diseases. We also reviewed the discovery and characterization of the reported G9a inhibitors. However, we also propose the challenges and future opportunities in study of G9a. This review could make a crucial contribution to the long journey to develop drug-like molecules targeting G9a.

Discovery of novel inhibitors disrupting HIF-1α/von Hippel-Lindau interaction through shape-based screening and cascade docking.

Major research efforts have been devoted to the discovery and development of new chemical entities that could inhibit the protein-protein interaction between HIF-1α and the von Hippel-Lindau protein (pVHL), which serves as the substrate recognition subunit of an E3 ligase and is regarded as a crucial drug target in cancer, chronic anemia, and ischemia. Currently there is only one class of compounds available to interdict the HIF-1α/pVHL interaction, urging the need to discover chemical inhibitors with more diversified structures. We report here a strategy combining shape-based virtual screening and cascade docking to identify new chemical scaffolds for the designing of novel inhibitors. Based on this strategy, nine active hits have been identified and the most active hit, 9 (ZINC13466751), showed comparable activity to pVHL with an IC50 of 2.0 ± 0.14 µM, showing the great potential of utilizing these compounds for further optimization and serving as drug candidates for the inhibition of HIF-1α/von Hippel-Lindau interaction.

NRF2 promotes breast cancer cell proliferation and metastasis by increasing RhoA/ROCK pathway signal transduction.

Nuclear factor erythroid 2-related factor (NRF2) is an important transcription factor in oxidative stress regulation. Overexpression of NRF2 is associated with human breast carcinogenesis, and increased NRF2 mRNA levels predict poor patient outcome for breast cancer. However, the mechanisms linking gain of NRF2 expression and poor prognosis in breast cancer are still unclear. Here, we provide evidence that NRF2 deletion inhibits proliferation and metastasis of breast cancer cells by down-regulating RhoA. Restoration of RhoA in MCF7 and MDA-MB-231 cells induced NRF2 knockdown-suppressed cell growth and metastasis in vitro, and NRF2 silencing suppressed stress fiber and focal adhesion formation leading to decreased cell migration and invasion. Mechanistic studies showed that NRF2 binds to the promoter region of estrogen-related receptor α (ERR1) and may function as a silencer. This may enhance RhoA protein stability and lead to RhoA overexpression in breast cancer cell. Our findings indicate that NRF2 silencing-mediated reduction of RhoA expression contributes, at least in part, to the poor outcome of breast cancer patients with high NRF2 expression.

Synthesis and evaluation of 4-(2-hydroxypropyl)piperazin-1-yl) derivatives as Hsp90 inhibitors.

We previously reported 4-(3-((6-bromonaphthalen-2-yl)oxy)-2-hydroxypropyl)-N,N-dimethylpiperazine-1-sulfonamide (1) as a novel heat shock protein 90 inhibitor with moderate activity. In our ongoing efforts for the discovery of Hsp90 modulators we undertake structural investigations on 1. Series of the titled compound were designed, synthesized and evaluated. We have found that compounds with a hydroxyl group at C-4 of the aryl ring on the piperazine moiety possess Hsp90 inhibition properties. Compound 6f with improved activity could be further developed and optimized as Hsp90 inhibitor.

Discovery and optimization of new benzofuran derivatives against p53-independent malignant cancer cells through inhibition of HIF-1 pathway.

p53-independent malignant cancer is still severe health problem of human beings. HIF-1 pathway is believed to play an important role in the survival and developing progress of such cancers. In the present study, with the aim to inhibit the proliferation of p53-independent malignant cells, we disclose the optimization of 6a, the starting compound which is discovered in the screening of in-house compound collection. The structure-activity relationship (SAR) is summarized. The most potent derivative 8d, inhibits the proliferation of both p53-null and p53-mutated cells through inhibition of HIF-1 pathway. Our findings here provide a new chemotype in designing potent anticancer agent especially against those p53-independent malignant tumors.

Structure-based design and synthesis of small molecular inhibitors disturbing the interaction of MLL1-WDR5.

MLL1 complex catalyzes the methylation of H3K4, and plays important roles in the development of acute leukemia harboring MLL fusion proteins. Targeting MLL1-WDR5 protein-protein interaction (PPI) to inhibit the activity of histone methyltransferase of MLL1 complex is a novel strategy for treating of acute leukemia. WDR5-47 (IC50 = 0.3 µM) was defined as a potent small molecule to disturb the interaction of MLL1-WDR5. Here, we described structure-based design and synthesis of small molecular inhibitors to block MLL1-WDR5 PPI. Especially, compound 23 (IC50 = 104 nM) was the most potent small molecular, and about 3-times more potent than WDR5-47. We also discussed the SAR of these series of compounds with docking study, which may stimulate more potent compounds.

CPUY201112, a novel synthetic small-molecule compound and inhibitor of heat shock protein Hsp90, induces p53-mediated apoptosis in MCF-7 cells.

Heat-shock protein 90 (Hsp90) is highly expressed in many tumor cells and is associated with the maintenance of malignant phenotypes. Targeting Hsp90 has had therapeutic success in both solid and hematological malignancies, which has inspired more studies to identify new Hsp90 inhibitors with improved clinical efficacy. Using a fragment-based approach and subsequent structural optimization guided by medicinal chemistry principles, we identified the novel compound CPUY201112 as a potent Hsp90 inhibitor. It binds to the ATP-binding pocket of Hsp90 with a kinetic dissociation (Kd) constant of 27 ± 2.3 nM. It also exhibits potent in vitro antiproliferative effects in a range of solid tumor cells. In MCF-7 cells with high Hsp90 expression, CPUY201112 induces the degradation of Hsp90 client proteins including HER-2, Akt, and c-RAF. We prove that treating MCF-7 cells with CPUY201112 results in cell cycle arrest and apoptosis through the wild-type (wt) p53 pathway. CPUY201112 also synergizes with Nutlin-3a to induce cancer cell apoptosis. CPUY201112 significantly inhibited the growth of MCF-7 xenografts in nude mice without apparent body weight loss. These results demonstrate that CPUY201112 is a novel Hsp90 inhibitor with potential use in treating wild-type p53 related cancers.

Structure-Activity and Structure-Property Relationship and Exploratory in Vivo Evaluation of the Nanomolar Keap1-Nrf2 Protein-Protein Interaction Inhibitor.

Directly disrupting the Keap1-Nrf2 protein-protein interaction (PPI) is an effective way to activate Nrf2. Using the potent Keap1-Nrf2 PPI inhibitor that was reported by our group, we conducted a preliminary investigation of the structure-activity and structure-property relationships of the ring systems to improve the drug-like properties. Compound 18e, which bore p-acetamido substituents on the side chain phenyl rings, was the best choice for balancing PPI inhibition activity, physicochemical properties, and cellular Nrf2 activity. Cell-based experiments with 18e showed that the Keap1-Nrf2 PPI inhibitor can activate Nrf2 and induce the expression of Nrf2 downstream proteins in an Nrf2-dependent manner. An exploratory in vivo experiment was carried out to further evaluate the anti-inflammatory effects of 18e in a LPS-challenged mouse model. The primary results indicated that 18e could reduce the level of circulating pro-inflammatory cytokines induced by LPS and relieve the inflammatory response.

Discovery of new acetylcholinesterase inhibitors with small core structures through shape-based virtual screening.

Targeting acetylcholinesterase (AChE) using small molecule inhibitors is considered to be the most successful therapeutic strategy in the treatment of Alzheimer's disease (AD). Herein we present a shape-based virtual screening to identify new cores for the designing of AChE inhibitors. Ten active hits are identified and the most active hit, 5169-0032 and T5369186, showed comparable AChE inhibitory activity to tacrine. Prediction of physicochemical properties and ADME/T risk indicates their potential in druggability and safety. The two compounds provide new core and can serve as a promising fragment to design potent AChE inhibitors.

Discovery and Modification of in Vivo Active Nrf2 Activators with 1,2,4-Oxadiazole Core: Hits Identification and Structure-Activity Relationship Study.

Induction of phase II antioxidant enzymes by activation of Nrf2/ARE pathway has been recognized as a promising strategy for the regulation of oxidative stress-related diseases. Herein we report our effort on the discovery and optimization of Nrf2 activators with 1,2,4-oxadiazole core. Screening of an in-house collection containing 7500 compounds by ARE-luciferase reporter assay revealed a moderate Nrf2 activator, 1. Aimed at obtaining more derivatives efficiently, molecular similarity search by the combination of 2D fingerprint-based and 3D shape-based search was applied to virtually screening the Chemdiv collection. Three derivatives with the same core were identified to have better inductivity of Nrf2 than 1. The best hit 4 was selected as starting point for structurally optimization, leading to a much more potent derivative 32. It in vitro upregulated gene and protein level of Nrf2 as well as its downstream markers such as NQO1, GCLM, and HO-1. It remarkably suppressed inflammation in the in vivo LPS-challenged mouse model. Our results provide a new chemotype as Nrf2-ARE activators which deserve further optimization with the aim to obtain active anti-inflammatory agents through Nrf2-ARE pathway.

A sensitive colorimetric strategy for monitoring cerebral ß-amyloid peptides in AD based on dual-functionalized gold nanoplasmonic particles.

A sensitive and selective strategy for the colorimetric visualization of the total monomeric Aß down to 40 pg mL(-1) based on dual-functionalized gold nanoplasmonic particles (GNPs) is developed and applied to evaluate Aß levels in the AD cerebral system.

Investigation of the intermolecular recognition mechanism between the E3 ubiquitin ligase Keap1 and substrate based on multiple substrates analysis.

E3 ubiquitin ligases are attractive drug targets due to their specificity to the ubiquitin machinery. However, the development of E3 ligase inhibitors has proven challenging for the fact that they must disrupt protein-protein interactions (PPIs). The E3 ligase involved in interactome provide new hope for the discovery of the E3 ligase inhibitors. These currently known natural binding partners of the E3 ligase can benefit the discovery of other unknown substrates and also the E3 ligase inhibitors. Herein, we present a novel strategy that using multiple substrates to elucidate the molecular recognition mechanism of E3 ubiquitin ligase. Molecular dynamics simulation, molecular mechanics-generalized born surface area (MM-GBSA) binding energy calculation and energy decomposition scheme were incorporated to evaluate the quantitative contributions of sub-pocket and per-residue to binding. In this case, Kelch-like ECH-associated protein-1 (Keap1), a substrate adaptor component of the Cullin-RING ubiquitin ligases complex, is applied for the investigation of how it recognize its substrates, especially Nrf2, a master regulator of the antioxidant response. By analyzing multiple substrates binding determinants, we found that both the polar sub-pockets (P1 and P2) and the nonpolar sub-pockets (P4 and P5) of Keap1 can make remarkable contributions to intermolecular interactions. This finding stresses the requirement for substrates to interact with the polar and nonpolar sub-pockets simultaneously. The results discussed in this paper not only show the binding determinants of the Keap1 substrates but also provide valuable implications for both Keap1 substrate discovery and PPI inhibitor design.

Insights into targeting NEMO for pharmacological regulation.

NF-κB essential modulator (NEMO), the non-catalytic regulatory subunit of the IκB kinase (IKK) complex, is essential for the canonical NF-κB activation pathway. It has been identified as a molecular platform for assembling the IKK complex and recruiting upstream IKK activators. However, the exact mechanism for regulating IKK activity has still remained elusive. This review describes structural and functional characteristics of NEMO protein, covers the feasible polyubiquitin-mediated NEMO-dependent IKK complex activation mechanism, and briefly summarizes some proteins that bind to NEMO for enhancing or suppressing IKK complex activity. Furthermore, it also discusses several bioactive compounds that disrupt the protein-protein interactions (PPI) involving NEMO, as these PPI may act as alternative routes to develop novel pharmacological agents for inflammation and cancer therapy.

Recent advances in the structure-based and ligand-based design of IKKß inhibitors as anti-inflammation and anti-cancer agents.

NF-κB is a significant transcription factor that regulates the expression of various pro-survival genes. IKK is a crucial protein kinase that activates NF-κB translocating from cytoplasm to nucleus for DNA binding. It is composed of three subunits, IKKα, IKKß, IKKγ (NEMO), where IKKα and IKKß are catalytic subunits, and IKKγ is the regulatory subunit. Many diseases, such as Hodgkin's disease, Hepatitis-associated hepatocellular carcinoma, colorectal cancer, prostate cancer, rheumatoid arthritis and inflammatory bowel disease, are related to IKK and NF-κB. So far, various IKK inhibitors targeting the ATP binding site have been identified through high throughput screening, rational design or in silico methods, however, only three of them (CHS-828, EB-1627 and IMD-1041) have been under clinical studies, indicating the strategy for the design of IKK inhibitors need to be reinspected. Besides ATP-competitive inhibitors, several other inhibitors have also been disclosed recently, which provide novel concepts to the discovery of IKK inhibitors. In this review, we focus on two parts: 1) the chemotypes and binding patterns of the traditional ATP-competitive IKK inhibitors; 2) novel strategies for the identification of non-ATP-competitive IKK inhibitors as NF-κB modulators. Through these discussions we hope to present inspirations for the development of new IKK inhibitors.

[Progress in research of the structural optimization of natural product-like Garcinia caged xanthones].

Designing of natural product-like compounds using natural products as template structures is an important strategy for the discovery of new drugs. Gambogic acid (GA), which is a Garcinia natural product with a unique caged xanthone scaffold, inhibits potent antitumor activity both in vitro and in vivo. This review summarized the researches on the identification of the antitumor pharmacophore of GA, and the design, structural optimization and structure-activity relationship (SAR) of natural product-like caged xanthones based on it.

Identification and optimization of novel Hsp90 inhibitors with tetrahydropyrido[4,3-d]pyrimidines core through shape-based screening.

Rapid Overlay of Chemical Structures (ROCS), which can rapidly identify potentially active compounds by shape comparison, is recognized as a powerful virtual screening tool. By ROCS, a class of novel Hsp90 inhibitors was identified. The calculated binding mode of the most potent hit 36 guided us to design and synthesize a series of analogs (57a-57h). Over 100-fold improvement was achieved in the target-based assay. The most potent compound 57h inhibited Hsp90 with IC50 0.10 ± 0.01 µM. It also showed much improved cell potency and ligand efficiency. Our study showed that ROCS is efficient in the identification of novel cores of Hsp90 inhibitors. 57h can be ideal leads for further optimization.