Phosphine-initiated general base catalysis: facile access to benzannulated 1,3-diheteroatom five-membered rings via double-Michael reactions of allenes

General base-catalyzed double-Michael reactions of allenes with various dinucleophiles are described. The reactions are facilitated most efficiently by a catalytic amount of trimethylphosphine, affording six types of C2-functionalized benzannulated five-membered heterocycles: benzimidazolines, benzoxazolines, benzothiazolines, 1,3-benzodioxoles, 1,3-benzoxathioles, and 1,3-benzodithioles. This atom-economical reaction is operationally simple and provides the product heterocycles in good to excellent yields. Careful mechanistic studies unveiled the phosphine-triggered general base catalysis pathway. Furthermore, the double-Michael reaction can serve as an alternative method for the selective monoketalization of β-diketones.     

Large-scale synthesis of uniform and extremely small-sized iron oxide nanoparticles for high-resolution T1 magnetic resonance imaging contrast agents

Uniform and extremely small-sized iron oxide nanoparticles (ESIONs) of < 4 nm were synthesized via the thermal decomposition of iron-oleate complex in the presence of oleyl alcohol. Oleyl alcohol lowered the reaction temperature by reducing iron-oleate complex, resulting in the production of small-sized nanoparticles. XRD pattern of 3 nm-sized nanoparticles revealed maghemite crystal structure. These nanoparticles exhibited very low magnetization derived from the spin-canting effect. The hydrophobic nanoparticles can be easily transformed to water-dispersible and biocompatible nanoparticles by capping with the poly(ethylene glycol)-derivatized phosphine oxide (PO-PEG) ligands. Toxic response was not observed with Fe concentration up to 100 μg/mL in MTT cell proliferation assay of POPEG-capped 3 nm-sized iron oxide nanoparticles. The 3 nm-sized nanoparticles exhibited a high r(1) relaxivity of 4.78 mM(-1) s(-1) and low r(2)/r(1) ratio of 6.12, demonstrating that ESIONs can be efficient T(1) contrast agents. The high r(1) relaxivities of ESIONs can be attributed to the large number of surface Fe(3+) ions with 5 unpaired valence electrons. In the in vivo T(1)-weighted magnetic resonance imaging (MRI), ESIONs showed longer circulation time than the clinically used gadolinium complex-based contrast agent, enabling high-resolution imaging. High-resolution blood pool MR imaging using ESIONs enabled clear observation of various blood vessels with sizes down to 0.2 mm. These results demonstrate the potential of ESIONs as T(1) MRI contrast agents in clinical settings.     

Formulation variation and in vitro-in vivo correlation for a rapidly swellable three-layered tablet of tamsulosin HCl

In order to develop a preferable once-a-day oral tablet formulation, various formulations of three-layered tablets containing tamsulosin HCl as a hydrophilic model drug were evaluated and compared with a commercial reference, tamsulosin OCAS?. When the test tablet was exposed to a release medium, the medium quickly permeated to the mid-layer and the two barrier layers swelled surrounding the mid-layer rapidly. Volume expansion showed faster and enough swelling of the three-layered tablet up to 2 h. Larger amount of barrier layers caused reduced release kinetics and a high molecular weight polymer showed more resistance against agitation force. A formulation with water-soluble mid-layer showed fast erosion decreasing its volume significantly. On the pharmacokinetic study, the mean ratio of area under the curve (AUC) and C(max) for the test formulation to the reference was 0.69 and 0.84, respectively, showing that the absorption of the drug was less complete than the reference. Plasma concentration at 24 h of the test formulation was higher than the reference. The Wagner-Nelson method showed that decreased initial dissolution rate might be the cause of the less complete absorption. On considering in vitro-in vivo correlation (IVIVC), level A, the reference (R2=0.981) showed more linear relationship than the test (R2=0.918) due to the decreased dissolution and absorption rate of the formulation. This result suggests that the in vitro dissolution profiles and release kinetics might be useful in correlating absorption kinetics as well as overall plasma drug concentration-time profiles for formulation studies.     

Dithienothiophene (DTT)-based dyes for dye-sensitized solar cells: synthesis of 2,6-dibromo-DTT

A one-pot synthesis of 2,6-dibromodithieno[3,2-b;2',3'-d]thiophene (dibromo-DTT, 4) was developed. A key step was bromodecarboxylation of DTT-2,6-dicarboxylic acid, obtained by saponification of the diester 1. The donor-acceptor dye DAHTDTT (13), based on a central 2,6-bis[2'-(3'-hexylthienyl)]dithieno[3,2-b;2',3'-d]thiophene core (9), was prepared and incorporated in a dye-sensitized solar cell (DSC), which exhibited an energy conversion efficiency of 7.3% with V(oc) of 697 mV, J(sc) of 14.4 mA/cm(2), and ff of 0.73 at 1 sun.     

Suppression of hepatic tumor growth and metastasis by metronomic therapy in a rat model of hepatocellular carcinoma

Although continuous low-dose (metronomic [MET]) therapy exerts anti-cancer efficacy in various cancer models, the effect of long-term MET therapy for hepatocellular carcinoma (HCC) remains unknown. This study assessed the long-term efficacy of MET on suppression of tumor growth and spontaneous metastasis in a rat model of HCC induced by administration of diethylnitrosamine for 16 wk. The rats were divided into 3 groups: MTD group received intraperitoneal (i.p.) injections of 40 mg/kg cyclophosphamide on days 1, 3, and 5 of a 21-day cycle; Control and MET groups received i.p. injections of saline and 20 mg/kg cyclophosphamide twice a week, respectively. Anti-tumor and anti-angiogenic effects and anti-metastatic mechanisms including matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) were evaluated. Twelve wk of MET therapy resulted in a significant reduction in intrahepatic tumors than control or MTD therapy. The MET group had fewer proliferating cell nuclear antigen-positive cells and decreased hypoxia-inducible factor-1α levels and microvessel density. Lung metastases were detected in 100%, 80%, and 42.9% in the control, MTD, and MET groups, respectively. MET therapy significantly decreased expression of TIMP-1, MMP-2 and -9. For mediators of pro-MMP-2 activation, MET therapy induced significant suppression in the TIMP-2 and MMP-14 level. The survival in the MET group was significantly prolonged compared to the control and MTD groups. Long-term MET scheduling suppresses tumor growth and metastasis via its potent anti-angiogenic properties and a decrease in MMPs and TIMPs activities. These results provide a rationale for long-term MET dosing in future clinical trials of HCC treatment.     

5-(4-Hydroxy-2,3,5-trimethylbenzylidene) thiazolidine-2,4-dione attenuates atherosclerosis possibly by reducing monocyte recruitment to the lesion

A variety of benzylidenethiazole analogs have been demonstrated to inhibit 5-lipoxygenase (5-LOX). Here we report the anti-atherogenic potential of 5-(4-hydroxy- 2,3,5-trimethylbenzylidene) thiazolidin-2,4-dione (HMB-TZD), a benzylidenethiazole analog, and its potential mechanism of action in LDL receptor-deficient (Ldlr-/-) mice. HMB-TZD Treatment reduced leukotriene B4 (LTB4) production significantly in RAW264.7 macrophages and SVEC4-10 endothelial cells. Macrophages or endothelial cells pre-incubated with HMB-TZD for 2 h and then stimulated with lipopolysaccharide or tumor necrosis factor-alpha (TNF-α) displayed reduced cytokine production. Also, HMB-TZD reduced cell migration and adhesion in accordance with decreased proinflammatory molecule production in vitro and ex vivo. HMB-TZD treatment of 8-week-old male Ldlr-/- mice resulted in significantly reduced atherosclerotic lesions without a change to plasma lipid profiles. Moreover, aortic expression of pro-atherogenic molecules involved in the recruitment of monocytes to the aortic wall, including TNF-α , MCP-1, and VCAM-1, was downregulated. HMB-TZD also reduced macrophage infiltration into atherosclerotic lesions. In conclusion, HMB-TZD ameliorates atherosclerotic lesion formation possibly by reducing the expression of proinflammatory molecules and monocyte/macrophage recruitment to the lesion. These results suggest that HMB-TZD, and benzylidenethiazole analogs in general, may have therapeutic potential as treatments for atherosclerosis.     

Rottlerin enhances IL-1β-induced COX-2 expression through sustained p38 MAPK activation in MDA-MB-231 human breast cancer cells

Cyclooxygenase-2 (COX-2) is an important enzyme in inflammation. In this study, we investigated the underlying molecular mechanism of the synergistic effect of rottlerin on interleukin1β (IL-1β)-induced COX-2 expression in MDA-MB-231 human breast cancer cell line. Treatment with rottlerin enhanced IL-1β-induced COX-2 expression at both the protein and mRNA levels. Combined treatment with rottlerin and IL-1β significantly induced COX-2 expression, at least in part, through the enhancement of COX-2 mRNA stability. In addition, rottlerin and IL-1β treatment drove sustained activation of p38 Mitogen-activated protein kinase (MAPK), which is involved in induced COX-2 expression. Also, a pharmacological inhibitor of p38 MAPK (SB 203580) and transient transfection with inactive p38 MAPK inhibited rottlerin and IL-1β-induced COX-2 upregulation. However, suppression of protein kinase C δ (PKC δ) expression by siRNA or overexpression of dominant-negative PKC δ (DN-PKC-δ) did not abrogate the rottlerin plus IL-1β-induced COX-2 expression. Furthermore, rottlerin also enhanced tumor necrosis factor-α (TNF-α), phorbol myristate acetate (PMA), and lipopolysaccharide (LPS)-induced COX-2 expression. Taken together, our results suggest that rottlerin causes IL-1β-induced COX-2 upregulation through sustained p38 MAPK activation in MDA-MB-231 human breast cancer cells.     

Size dependent macrophage responses and toxicological effects of Ag nanoparticles

The immune-response of macrophages is an important area of investigation since it represents the major pathway by which early-stage defense barriers are established in skin, lungs, and mucosal systems to counteract foreign objects. In this study, we have examined the size-dependent inflammatory and toxicological effects of nanostructured silver particles (nano-Ag) on macrophage immune cells.     

DNA-templated preparation of gold nanoparticles

DNA-mediated gold nanoparticles were prepared by chemical reduction of DNA-Au(III) complex. The DNA-Au(III) was first formed by reacting DNA with HAuCl? at a pH of 5.6. The complex in solution was reacted with hydrazine reducing Au(III) to Au. The reduced Au formed nanodimensional aggregates. The particle distributions were obtained by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). This method resulted in a rather uniform dispersion of Au nanoparticles of near-spherical shape and 45~80 nm in diameter. Gold nanoparticles were embedded and stabilized by DNA.     

Kaempferol and kaempferol rhamnosides with depigmenting and anti-inflammatory properties

The objective of this study was to examine the biological activity of kaempferol and its rhamnosides. We isolated kaempferol (1), a-rhamnoisorobin (2), afzelin (3), and kaempferitrin (4) as pure compounds by far-infrared (FIR) irradiation of kenaf (Hibiscus cannabinus L.) leaves. The depigmenting and anti-inflammatory activity of the compounds was evaluated by analyzing their structure-activity relationships. The order of the inhibitory activity with regard to depigmentation and nitric oxide (NO) production was kaempferol (1) > a-rhamnoisorobin (2) > afzelin (3) > kaempferitrin (4). However, a-rhamnoisorobin (2) was more potent than kaempferol (1) in NF-kB-mediated luciferase assays. From these results, we conclude that the 3-hydroxyl group of kaempferol is an important pharmacophore and that additional rhamnose moieties affect the biological activity negatively.