A rhodamine-labeled citalopram analogue as a high-affinity fluorescent probe for the serotonin transporter

A novel fluorescent ligand was synthesized as a high-affinity, high specificity probe for visualizing the serotonin transporter (SERT). The rhodamine fluorophore was extended from an aniline substitution on the 5-position of the dihydroisobenzofuran ring of citalopram (2, 1-(3-(dimethylamino)propyl)-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-carbonitrile), using an ethylamino linker. The resulting rhodamine-labeled ligand 8 inhibited [³H]5-HT uptake in COS-7 cells (K_i = 225 nM) with similar potency to the tropane-based JHC 1-064 (1), but with higher specificity towards the SERT relative to the transporters for dopamine and norepinephrine. Visualization of the SERT with compound 8 was demonstrated by confocal microscopy in HEK293 cells stably expressing EGFP–SERT.     

Synthesis and antitumor activity of 1,3,4-oxadiazole possessing 1,4-benzodioxan moiety as a novel class of potent methionine aminopeptidase type II inhibitors

A series of 1,3,4-oxadiazole derivatives containing 1,4-benzodioxan moiety (7a–7q) have been designed, synthesized and evaluated for their antitumor activity. Most of the synthesized compounds were proved to have potent antitumor activity and low toxicity. Among them, compound 7a showed the most potent biological activity against Human Umbilical Vein Endothelial cells, which was comparable to the positive control. The results of apoptosis and flow cytometry (FCM) demonstrated that compound 7a induce cell apoptosis by the inhibition of MetAP2 pathway. Molecular docking was performed to position compound 7a into MetAP2 binding site in order to explore the potential target.     

Discovery of aryl ureas and aryl amides as potent and selective histamine H3 receptor antagonists for the treatment of obesity (Part I)

A series of structurally novel aryl ureas was derived from optimization of the HTS lead as selective histamine H₃ receptor (H₃R) antagonists. The SAR was explored and the data obtained set up the starting point and foundation for further optimization. The most potent tool compounds, as exemplified by compounds 2l, 5b, 5d, and 5e, displayed antagonism potencies in the subnanomolar range in in vitro human-H₃R FLIPR assays and rhesus monkey H₃R binding assays.     

Synthesis and antitumor-evaluation of 1,3-selenazole-containing 1,3,4-thiadiazole derivatives

A series of novel 1,3-selenazole-containing 1,3,4-thiadiazole derivatives bearing Schiff base moieties were synthesized and evaluated for their in vitro antiproliferative activities against human breast cancer cell MCF-7 and mouse lymphocyte leukemia cell L1210 by CCK-8 assay. The majority of the compounds showed better activity against MCF-7 cell, compared with lead compound PCS. In particular, compound 6c was the most potent compound with IC₅₀ value of 4.02 μM.     

Azetidines and spiro azetidines as novel P2 units in hepatitis C virus NS3 protease inhibitors

Herein, we report the synthesis and structure–activity relationship studies of new analogs of boceprevir 1 and telaprevir 2. Introduction of azetidine and spiroazetidines as a P2 substituent that replaced the pyrrolidine moiety of 1 and 2 led to the discovery of a potent hepatitis C protease inhibitor 37c (EC₅₀ = 0.8 μM).     

Discovery of natural estrogen receptor modulators with structure-based virtual screening

Eleven compounds were identified as estrogen receptor modulators from an in-house natural product database (NPD) by structure-based virtual screening for ERα and ERβ. Among them, 3 compounds were confirmed as ER agonists and 8 compounds were confirmed as ER antagonists by yeast two-hybrid (Y2H) assay, with EC₅₀ values ranging from several micromolar to 100 micromolar. In this study, a novel series of cycloartane triterpenoids isolated from Schisandra glaucescens Diels was found to have ER antagonistic effect, the most potent antagonist of which exhibited activity with EC₅₀ value of 2.55 and 4.68 μM for ERα and ERβ, respectively. Moreover, the types of modulation and subtype selectivity were also investigated through molecular docking simulation.     

Increased ��-tocotrienol content in seeds of transgenic rice overexpressing Arabidopsis ��-tocopherol methyltransferase

Vitamin E comprises a group of eight lipid soluble antioxidant compounds that are an essential part of the human diet. The ??-isomers of both tocopherol and tocotrienol are generally considered to have the highest antioxidant activities. ??-tocopherol methyltransferase (??-TMT) catalyzes the final step in vitamin E biosynthesis, the methylation of ??- and ??-isomers to ??- and ??-isomers. In present study, the Arabidopsis ??-TMT (AtTMT) cDNA was overexpressed constitutively or in the endosperm of the elite japonica rice cultivar Wuyujing 3 (WY3) by Agrobacterium-mediated transformation. HPLC analysis showed that, in brown rice of the wild type or transgenic controls with empty vector, the ??-/??-tocotrienol ratio was only 0.7, much lower than that for tocopherol (~19.0). In transgenic rice overexpressing AtTMT driven by the constitutive Ubi promoter, most of the ??-isomers were converted to ??-isomers, especially the ??- and ??-tocotrienol levels were dramatically decreased. As a result, the ??-tocotrienol content was greatly increased in the transgenic seeds. Similarly, over-expression of AtTMT in the endosperm also resulted in an increase in the ??-tocotrienol content. The results showed that the ??-/??-tocopherol ratio also increased in the transgenic seeds, but there was no significant effect on ??-tocopherol level, which may reflect the fact that ??-tocopherol is present in very small amounts in wild type rice seeds. AtTMT overexpression had no effect on the absolute total content of either tocopherols or tocotrienols. Taken together, these results are the first demonstration that the overexpression of a foreign ??-TMT significantly shift the tocotrienol synthesis in rice, which is one of the world??s most important food crops.     

Midgut aminopeptidase N isoforms from Ostrinia nubilalis: Activity characterization and differential binding to Cry1Ab and Cry1Fa proteins from Bacillus thuringiensis

Aminopeptidase N (APN) isoforms from Lepidoptera are known for their involvement in the mode of action of insecticidal Cry proteins from Bacillus thuringiensis. These enzymes belong to a protein family with at least eight different members that are expressed simultaneously in the midgut of lepidopteran larvae. Here, we focus on the characterization of the APNs from Ostrinia nubilalis (OnAPNs) to identify potential Cry receptors. We expressed OnAPNs in insect cells using a baculovirus system and analyzed their enzymatic activity by probing substrate specificity and inhibitor susceptibility. The interaction with Cry1Ab and Cry1Fa proteins (both found in transgenic insect-resistant maize) was evaluated by ligand blot assays and immunocytochemistry. Ligand blots of brush border membrane proteins showed that both Cry proteins bound mainly to a 150 kDa-band, in which OnAPNs were greatly represented. Binding analysis of Cry proteins to the cell-expressed OnAPNs showed that OnAPN1 interacted with both Cry1Ab and Cry1Fa, whereas OnAPN3a and OnAPN8 only bound to Cry1Fa. Two isoforms, OnAPN2 and OnAPN3b, did not interact with any of these two proteins. This work provides the first evidence of a differential role of OnAPN isoforms in the mode of action of Cry proteins in O. nubilalis.     

Synthesis and evaluation of quinazoline derivatives as phosphodiesterase 7 inhibitors

The latest scientific findings concerning PDE7 and PDE4 inhibition suggest that selective small-molecule inhibitors of both enzymes could provide a novel approach to treat a variety of immunological diseases. In this context, we describe a new series of quinazoline derivatives from quinazolin-4-thiones which include a substituted biphenyl fragment. Some of these compounds show inhibitory potencies at sub-micromolar levels against the catalytic domain of PDE7.