Synthesis and cytotoxic activity of some novel N-pyridinyl-2-(6-phenylimidazo[2,1-b]thiazol-3-yl)acetamide derivatives

A series of novel compounds bearing imidazo[2,1-b]thiazole scaffolds were designed and synthesized based on the optimization of the virtual screening hit compound N-(6-morpholinopyridin-3-yl)-2-(6-phenylimidazo[2,1-b]thiazol-3-yl)acetamide (5a), and tested for their cytotoxicity against human cancer cell lines, including HepG2 and MDA-MB-231. The results indicated that the compound 2-(6-(4-chlorophenyl)imidazo[2,1-b]thiazol-3-yl)-N-(6-(4-(4-methoxybenzyl)piperazin-1-yl)pyridin-3-yl)acetamide (5l), with slightly higher inhibition on VEGFR2 than 5a (5.72% and 3.76% inhibitory rate at 20 μM, respectively), was a potential inhibitor against MDA-MB-231 (IC(50) = 1.4 μM) compared with sorafenib (IC(50) = 5.2 μM), and showed more selectivity against MDA-MB-231 than HepG2 cell line (IC(50) = 22.6 μM).     

Commercial Copper Foam as an Effective 3D Porous Electrode for Nonenzymatic Glucose Detection

Commercially available copper foam (CF) was used as a 3D porous electrochemical sensing platform for nonenzymatic glucose detection. CF shows high electrocatalytic activity towards glucose oxidation and can be used directly for glucose electrochemical sensing without any pretreatment. The sensor exhibits high performance towards glucose in 0.1 M NaOH solution with the linear range from 1 μM to 0.5 mM, the sensitivity of 5.85 mA mM^?1 cm^?2 and the detection limit of 0.5 μM (S/N=3) simultaneously. Furthermore, the sensor shows a high selectivity for glucose against the common interferences and good reliability for glucose detection in human serum samples.     

Evaluation of the effects of Mitragyna speciosa alkaloid extract on cytochrome P450 enzymes using a high throughput assay

The extract from Mitragyna speciosa has been widely used as an opium substitute, mainly due to its morphine-like pharmacological effects. This study investigated the effects of M. speciosa alkaloid extract (MSE) on human recombinant cytochrome P450 (CYP) enzyme activities using a modified Crespi method. As compared with the liquid chromatography-mass spectrometry method, this method has shown to be a fast and cost-effective way to perform CYP inhibition studies. The results indicated that MSE has the most potent inhibitory effect on CYP3A4 and CYP2D6, with apparent half-maximal inhibitory concentration (IC(50)) values of 0.78 μg/mL and 0.636 μg/mL, respectively. In addition, moderate inhibition was observed for CYP1A2, with an IC(50) of 39 μg/mL, and weak inhibition was detected for CYP2C19. The IC(50) of CYP2C19 could not be determined, however, because inhibition was <50%. Competitive inhibition was found for the MSE-treated CYP2D6 inhibition assay, whereas non-competitive inhibition was shown in inhibition assays using CYP3A4, CYP1A2 and CYP2C19. Quinidine (CYP2D6), ketoconazole (CYP3A4), tranylcypromine (CYP2C19) and furafylline (CYP1A2) were ACCESSused as positive controls throughout the experiments. This study shows that MSE may contribute to an herb-drug interaction if administered concomitantly with drugs that are substrates for CYP3A4, CYP2D6 and CYP1A2.     

Identification of novel PfDHODH inhibitors as antimalarial agents via pharmacophore-based virtual screening followed by molecular docking and in vivo antimalarial activity

Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) catalyses the fourth reaction of de novo pyrimidine biosynthesis in parasites, and represents an important target for the treatment of malaria. In this study, we describe pharmacophore-based virtual screening combined with docking study and biological evaluation as a rational strategy for identification of novel hits as antimalarial agents. Pharmacophore models were established from known PfDHODH inhibitors using the GALAHAD module with IC₅₀ values ranging from 0.033 μM to 142 μM. The best pharmacophore model consisted of three hydrogen bond acceptor, one hydrogen bond donor and one hydrophobic features. The pharmacophore models were validated through receiver operating characteristic and Günere–Henry scoring methods. The best pharmacophore model as a 3D search query was searched against the IBS database. Several compounds with different structures (scaffolds) were retrieved as hit molecules. Among these compounds, those with a Q_FIT value of more than 81 were docked in the PfDHODH enzyme to further explore the binding modes of these compounds. In silico pharmacokinetic and toxicities were predicted for the best docked molecules. Finally, the identified hits were evaluated in vivo for their antimalarial activity in a parasite inhibition assay. The hits reported here showed good potential to become novel antimalarial agents.     

Selective cytotoxicity of goniothalamin against hepatoblastoma HepG2 cells

Liver cancer has become one of the major types of cancer with high mortality and liver cancer is not responsive to the current cytotoxic agents used in chemotherapy. The purpose of this study was to examine the in vitro cytotoxicity of goniothalamin on human hepatoblastoma HepG2 cells and normal liver Chang cells. The cytotoxicity of goniothalamin against HepG2 and liver Chang cell was tested using MTT cell viability assay, LDH leakage assay, cell cycle flow cytometry PI analysis, BrdU proliferation ELISA assay and trypan blue dye exclusion assay. Goniothalamin selectively inhibited HepG2 cells [IC?? = 4.6 (±0.23) μM in the MTT assay; IC?? = 5.20 (±0.01) μM for LDH assay at 72 hours], with less sensitivity in Chang cells [IC?? = 35.0 (±0.09) μM for MTT assay; IC?? = 32.5 (±0.04) μM for LDH assay at 72 hours]. In the trypan blue dye exclusion assay, the Viability Indexes were 52 ± 1.73% for HepG2 cells and 62 ± 4.36% for Chang cells at IC?? after 72 hours. Cytotoxicity of goniothalamin was related to inhibition of DNA synthesis, as revealed by the reduction of BrdU incorporation. At 72 hours, the lowest concentration of goniothalamin (2.3 μL) retained 97.6% of normal liver Chang cells proliferation while it reduced HepG2 cell proliferation to 19.8% as compared to control. Besides, goniothalamin caused accumulation of hypodiploid apoptosis and different degree of G2/M arrested as shown in cell cycle analysis by flow cytometry. Goniothalamin selectively killed liver cancer cell through suppression of proliferation and induction of apoptosis. These results suggest that goniothalamin shows potential cytotoxicity against hepatoblastoma HepG2 cells.     

Tandem allylic oxidation-condensation/esterification catalyzed by silica gel: an expeditious approach towards antimalarial diaryldienones and enones from natural methoxylated phenylpropenes

A new one-pot strategy has been developed, wherein abundantly available methoxylated phenylpropenes are directly transformed into corresponding dienones (1,5-diarylpenta-2,4-dien-1-ones) and enones (chalcones and cinnamic esters) via allylic oxidation-condensation or allylic oxidation-esterification sequences. Preliminary antimalarial activity studies of the above synthesized diaryldienones and enones against Plasmodium falciparum (Pf3D7) have shown them to be promising lead candidates for developing newer and economical antimalarial agents. In particular, two enones (12b and 13b) were found to possess comparatively better activity (IC(50) = 4.0 and 3.4 μM, respectively) than licochalcone (IC(50) = 4.1 μM), a well known natural antimalarial compound.     

Chemical and biological analyses of the essential oils and main constituents of Piper species

The essential oils obtained from leaves of Piper duckei and Piper demeraranum by hydrodistillation were analyzed by gas chromatography-mass spectrometry. The main constituents found in P. demeraranum oil were limonene (19.3%) and β-elemene (33.1%) and in P. duckei oil the major components found were germacrene D (14.7%) and trans-caryophyllene (27.1%). P. demeraranum and P. duckei oils exhibited biological activity, with IC(50) values between 15 to 76 μg mL(-1) against two Leishmania species, P. duckei oil being the most active. The cytotoxicity of the essential oils on mice peritoneal macrophage cells was insignificant, compared with the toxicity of pentamidine. The main mono- and sesquiterpene, limonene (IC(50) = 278 μM) and caryophyllene (IC(50) = 96 μM), were tested against the strains of Leishmania amazonensis, and the IC(50) values of these compounds were lower than those found for the essential oils of the Piper species. The HET-CAM test was used to evaluate the irritation potential of these oils as topical products, showing that these oils can be used as auxiliary medication in cases of cutaneous leishmaniasis, with less side effects and lower costs.     

Ion channel drug potency assay with an artificial bilayer chip

The potency of pharmaceutical compounds acting on ion channels can be determined through measurements of ion channel conductance as a function of compound concentration. We have developed an artificial lipid bilayer chip for simple, fast, and high-yield measurement of ion channel conductance with simultaneous solution perfusion. Here we show the application of this chip to the measurement of the mammalian cold and menthol receptor TRPM8. Ensemble measurements of TRPM8 as a function of concentration of menthol and 2-aminoethoxydiphenyl borate (2-APB) enabled efficient determination of menthol's EC(50) (111.8 μM ± 2.4 μM) and 2-APB's IC(50) (4.9 μM ± 0.2 μM) in agreement with published values. This validation, coupled with the compatibility of this platform with automation and parallelization, indicates significant potential for large-scale pharmaceutical ion channel screening.     

Design, synthesis, and anti-proliferative evaluation of [1,1'-biphenyl]-4-ols as inhibitor of HUVEC migration and tube formation

Allylated biphenol neolignans contain a variety of chemopreventive entities that have been used as anti-tumor drug leads. Herein, 37 allylated biphenols were evaluated for anti-proliferative activity by the MTT assay and inhibitory effect on the migration and tube formation of HUVECs featuring anti-angiogenic properties. 3-(2-Methylbut-3-en-2-yl)-3′,5′-bis(trifluoromethyl)-[1,1′-biphenyl]-4-ol (5c) exerted an inhibitory effect on HUVECs compared to honokiol (IC?? = 47.0 vs. 52.6 μM) and showed significant blocking effects on the proliferation of C26, Hela, K562, A549, and HepG2 (IC?? = 15.0, 25.0, 21.2, 29.5, and 13.0 μM, respectively), superior to those of honokiol (IC?? = 65.1, 62.0, 42.0, 75.0, and 55.4 μM, respectively). Importantly, compound 5c inhibited the migration and capillary-like tube formation of HUVECs in vitro.     

PdFe Ultrathin Nanosheets for Highly Sensitive Detection of Nitrite

PdFe ultrathin nanosheets (NSs) were prepared by one‐step hydrothermal route. PdFe NSs showed superior catalytic activity towards the oxidation of nitrite due to the large surface area of 2 dimensional (2D) nanostructure and the synergetic effect between Pd and Fe. A sensitive and selective electrochemical nitrite sensing platform was designed base on PdFe NSs and the amperometric technique. The limit of detection (LOD) was found to be 0.12 μM (S/N=3), with a linear relationship between nitrite concentration and response current in the range of 1–160 μM. The nitrite sensor was applied to analysis of nitrite in tap water and sausage successfully.     

Synthesis of Novel 3-(5-(Alkyl/arylthio)-1,3,4-Oxadiazol-2-yl)-8-Phenylquinolin-4(1H)-One Derivatives as Anti-HIV Agents

Novel quinolone derivatives featuring an 1,3,4-oxadiazole ring as a metal-chelating component and a benzyl group base on HIV-1 integrase inhibitors pharmacophore were designed and synthesized. An antiviral assay revealed that most analogues inhibited HIV-1 replication in the cell culture. Our results showed that compounds bearing small alkyl groups as R group were inactive in anti-HIV-1 assay, whereas compounds possessing benzyl or substituted benzyl at the same position showed good anti-HIV activity with the range of 20–57% at 100 μM concentration. Among them, 3-(5-((2-fluorobenzyl)thio)-1,3,4-oxadiazol-2-yl)-8-phenylquinolin-4-(1H)-one (compound 13) showed reasonable cell-based antiviral activity (EC₅₀ = 50 μM) with no considerable cytotoxicity (CC₅₀ > 100 μM) in the cell viability assay, suggesting that it may be amenable to further development for identifying new anti-HIV-1 agents. Docking studies using the later crystallographic data available for PFV integrase corroborate favorable binding to the active site of HIV integrase, providing a basis for the design of more potent analogues.     

β分泌酶抑制剂的药效团模型研究

选择活性跨越0.002至25 μmol&#8226;L－1的4类共25个β分泌酶抑制剂作为训练集, 使用Catalyst软件包构建出药效团模型, 并通过对药效团的有效性分析, 筛选得到的最佳模型(correlCorrel＝0.969, Config＝16.32, Δcost＝62.422)由一个环芳香性、一个疏水中心、一个正电荷中心和一个氢键供体组成. 并用其它209个抑制剂组成测试集对模型进行验证, 结果表明该模型显示出较强的预测能力, 能够为进一步的数据库搜索, 寻找新型的β分泌酶抑制剂先导物提供依据.     

New serotonin 5-HT(6) ligands from common feature pharmacophore hypotheses

Serotonin 5-HT6 receptor antagonists are thought to play an important role in the treatment of psychiatry, Alzheimer's disease, and probably obesity. To find novel and potent 5-HT6 antagonists and to provide a new idea for drug design, we used a ligand-based pharmacophore to perform the virtual screening of a commercially available database. A three-dimensional common feature pharmacophore model was developed by using the HipHop program provided in Catalyst software and was used as a query for screening the database. A recursive partitioning (RP) model which can separate active and inactive compounds was used as a filtering system. Finally a sequential virtual screening procedure (SQSP) was conducted, wherein both the common feature pharmacophore and the RP model were used in succession to improve the results. Some of the hits were selected based on druglikeness, ADME properties, structural diversity, and synthetic accessibility for real biological evaluation. The best hit compound showed a significant IC50 value of 9.6 nM and can be used as a lead for further drug development.     

A novel cyclopentene derivative and a polyhydroxylated steroid from a South China Sea gorgonian Menella sp

A chemical investigation on a South China Sea gorgonian, Menella sp. resulted in the isolation and elucidation of menellin A (1), a highly oxygenated racemate with C(8) skeleton, and a polyhydroxylated steroid, menellsteroid C (2), along with eight known compounds (3-10). The structures of the new compounds were elucidated by means of MS, 1D and 2D NMR spectra, and the relative stereochemistry of 1 was determined by X-ray single-crystal diffraction analysis. In addition, compound 7 was isolated as a new natural product. Compounds 1-3 and 7 were selected to test the anti-inflammatory inhibition against lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 macrophages. 1 and 3 exhibited modest inhibitory effects with IC(50) of 71.3, 33.9 μM, respectively, compared to the positive control aminoguanidine (IC(50) 25.0 μM).     

Design of a heterobivalent ligand to inhibit IgE clustering on mast cells

We describe the design, synthesis, and characterization of a heterobivalent ligand (HBL) system that competitively inhibits allergen binding to mast cell bound IgE antibody, thereby inhibiting mast cell degranulation. HBLs are composed of a hapten conjugated to a nucleotide analog allowing simultaneous targeting of the antigen-binding site as well the "unconventional nucleotide binding site" on IgE Fab domains. Simultaneous bivalent binding to both sites provides HBLs with over 100-fold enhancement both in avidity for IgE(DNP) (K(d) = 0.33 μM) and in inhibition of allergen binding to IgE(DNP) (IC(50) = 0.45 μM) than the monovalent hapten (K(d)(mono) = 41 μM; IC(50)(mono) = 55.4 μM, respectively). In cellular assays, HBL2 effectively inhibits mast cell degranulation (IC(50) = 15 μM), whereas no inhibition is detected by the monovalent hapten. In conclusion, this study establishes the use of multivalency in a novel HBL design to inhibit mast cell degranulation.     

Determination of vitamins A, D and E in a small volume of human plasma by a high-throughput method based on liquid chromatography/tandem mass spectrometry

We have developed an automated high-throughput assay for the determination of vitamin A (retinol), ergocalciferol (25-OH D2), cholecalciferol (25-OH D3) and vitamin E (α-tocopherol) in a small volume of human plasma. Sample preparation involved mixing 50 μL of plasma with 100 μL of ethanol containing isotope-labelled internal standards, followed by mixing with isooctane/chloroform (3:1, 300 μL). The organic phase was evaporated, and the sample reconstituted in 50 μL methanol. The analysis was performed using reversed-phase liquid chromatography with a gradient mobile phase containing water, methanol and ammonium formate. Chromatographic run-time was 5 min, and positive mode electrospray tandem mass spectrometry (MS/MS) was used for detection. The limits of detection were 0.10 μM for all-trans retinol and 3.3 nM for 25-OH D2 and 25-OH D3. Recoveries were 91.9-105.0%, and within- and between-day coefficients of variance (CVs) 2.4-5.3 and 3.1-8.2, respectively. The assay is presently being used in large-scale studies.     

Absolute configuration and total synthesis of a novel antimalarial lipopeptide by the de novo preparation of chiral nonproteinogenic amino acids

The absolute configuration (via degradation and Marfey's derivatization studies) and the total synthesis of a novel antimalarial lipid-peptide isolated from Streptomyces sp. (IC(50) = 0.8 μM, Plasmodium falciparum 3D7) is disclosed. To this end, versatile stereocontrolled routes to nonproteinogenic amino acids (via catalytic Mannich, Sharpless methods) and enantiomeric trans fatty acids (via Evans alkylation, Kocienski-Julia olefination) have been developed.     

Surrogate AutoShim: predocking into a universal ensemble kinase receptor for three dimensional activity prediction, very quickly, without a crystal structure

"Ensemble surrogate AutoShim" is a kinase specific extension of the AutoShim docking method that solves the three traditional limitations of conventional docking: (1) it gives good correlations with affinity, (2) does not require a target protein structure, and (3) for a preprocessed company archive of 1.5 million compounds, is as fast as traditional 2D QSAR. It does require several hundred experimental IC 50 values for each new target. Original AutoShim adds pharmacophore "shims" to a crystal structure binding site. An iterative partial least squares (PLS) procedure selects the best pose, while adjusting the shim weights to reproduce IC 50 data. Surrogate AutoShim adjusts shims in one crystal structure to reproduce IC 50 data for a different kinase target. Ensemble surrogate AutoShim uses 16 structurally diverse kinase crystal structures as a "universal ensemble kinase receptor", suitable for any kinase target. The 1.5 million member Novartis screening collection has been predocked into the shimmed ensemble, so new kinase models can be built, and the entire corporate archive virtually screened, in hours rather than weeks. A kinase-biased set of 10,000 compounds, that samples the entire corporate archive, has been designed for lead discovery by iterative kinase screening.     

Rational design of new class of BH3-mimetics as inhibitors of the Bcl-xL protein

The Bcl-2 family of proteins plays an important role in the intrinsic pathway of cell apoptosis. Overexpression of pro-survival members of this family of proteins is often associated with the development of many types of cancer and confers resistance against conventional therapeutic treatments. Accordingly, antagonism of its protective function has emerged as an encouraging anticancer strategy. In the present work, we use a pharmacophore for describing interaction between the BH3 domain of different pro-apoptotic members and the pro-survival protein Bcl-x(L) in order to identify new lead compounds. In the strategy followed in the present work, the pharmacophore was derived from molecular dynamics studies of different Bcl-x(L)/BH3 complexes. This pharmacophore was later used as query for 3D database screening. Hits obtained from the search were computationally assessed, and a subset proposed for in vitro testing. Two of the 15 compounds assayed were found able to disrupt the Bcl-x(L)/Bak(BH3) complex with IC(50) values in the lower micromolar range. Finally, docking studies were performed to explore the binding mode of these compounds to Bcl-x(L) for further modifications.     

Studying the interaction of carbohydrate-protein on the dendrimer-modified solid support by microarray-based plasmon resonance light scattering assay

Here, a three-dimensional (3D) carbohydrate microarray-based plasmon resonance light scattering (RLS) assay has been established for studying carbohydrate-lectin binding with high selectivity. The 3D carbohydrate microarray is fabricated by immobilizing amino-modified carbohydrates on the home-made fourth-generation (G4) NH(2)-terminated poly(amidoamine) dendrimers (PAMAM)-modified substrate. After marking the carbohydrate-lectin binding events by 13 nm peptide-stabilized gold nanoparticles through the biotin-avidin reaction, the 3D microarray can be directly detected by the RLS scanner without the conventional silver enhancement step. The well defined recognition systems: three monosaccharides (Man-α, Glc-α and Gal-β) with two lectins (Con A and RCA 120), have been chosen here to establish the RLS assay, respectively. Quantitative determination of the surface dissociation constants (K(D,surf)) for surface carbohydrates and lectins has been achieved. In addition, inhibition values (i.e. the inhibition constants (K(i)) and the concentrations of inhibitors required to produce 50% inhibition (IC(50))) for inhibitors in solution are also demonstrated by the saccharide competing assays.