Platinum(II) metal complexes as potential anti-Trypanosoma cruzi agents

In the search for new therapeutic tools against Chagas’ disease (American Trypanosomiasis) two series of new platinum(II) complexes with bioactive 5-nitrofuryl containing thiosemicarbazones as ligands were synthesized, characterized and in vitro evaluated. Most of the complexes showed IC₅₀ values in the μM range against two different strains of Trypanosoma cruzi, causative agent of the disease, being as active as the anti-trypanosomal drug Nifurtimox. In particular, the coordination of L3 (4-ethyl-1-(5-nitrofurfurylidene)thiosemicarbazide) to Pt(II) forming [Pt(L3)₂] lead to almost a five-fold activity increase in respect to the free ligand. Trying to get an insight into the trypanocidal mechanism of action of these compounds, DNA and redox metabolism (intra-parasite free radical production) were evaluated as potential parasite targets. Results suggest that the complexes could inhibit parasite growth through a dual mechanism of action involving production of toxic free radicals by bioreduction and DNA interaction.     

GABA(A) signalling is involved in N/OFQ anxiolytic-like effects but not in nocistatin anxiogenic-like action as evaluated in the mouse elevated plus maze

Nociceptin/orphanin FQ (N/OFQ) and nocistatin are two neuropeptides originated from the same precursor prepronociceptin/orphanin FQ (ppN/OFQ). N/OFQ is the endogenous ligand of the NOP receptor, while the target of action of nocistatin is still unknown. N/OFQ modulates various biological functions, including anxiety. Conversely, nocistatin either behaves as a functional N/OFQ antagonist or evokes per se effects opposite to those of N/OFQ. Here we investigated the interaction between the anxiolytic-like effects of N/OFQ and the anxiogenic-like action of nocistatin with those evoked by GABA_A receptor ligands in the mouse elevated plus maze. The anxiogenic-like effects of the GABA_A receptor antagonist pentylenetetrazol (20 mg/kg; intraperitoneal, i.p.) were abolished by the co-treatment with N/OFQ (10 pmol; intracerebroventricular, i.c.v.) while potentiated by the administration of nocistatin (0.01 pmol; i.c.v.). The anxiolytic-like effects of the benzodiazepine receptor agonist diazepam (0.75 mg/kg, i.p.) were reversed by nocistatin (0.1 pmol; i.c.v.), whereas signs of sedation were observed when mice were co-treated with diazepam and N/OFQ (3 pmol). Interesting enough, the i.p. treatment with flumazenil (1 mg/kg) blocked the anxiolytic-like effects of N/OFQ (10 pmol; i.c.v.), but not the anxiogenic effect elicited by nocistatin. Collectively, our findings suggest that the effects on anxiety elicited by pentylenetetrazol and diazepam can be counteracted or potentiated in the presence of N/OFQ and nocistatin. In addition, the effects on anxiety of N/OFQ, but not nocistatin, appear to be dependent on the benzodiazepine site of the GABA_A receptor.     

Structure-activity relationships of bifunctional cyclic disulfide peptides based on overlapping pharmacophores at opioid and cholecystokinin receptors

Prolonged opioid exposure increases the expression of cholecystokinin (CCK) and its receptors in the central nervous system (CNS), where CCK may attenuate the antinociceptive effects of opioids. The complex interactions between opioid and CCK may play a role in the development of opioid tolerance. We designed and synthesized cyclic disulfide peptides and determined their agonist properties at opioid receptors and antagonist properties at CCK receptors. Compound 1 (Tyr-c[d-Cys-Gly-Trp-Cys]-Asp-Phe-NH(2)) showed potent binding and agonist activities at delta and mu opioid receptors but weak binding to CCK receptors. The NMR structure of the lead compound displayed similar conformational features of opioid and CCK ligands.     

指数富集配基的系统进化原理及应用进展

过去十几年,指数富集配基的系统进化（SELEX）技术得到了充分的发展,目前已经成为在数量众多的靶分子中,高亲和性和特异性地确定适配子的一种崭新的方法.SELEX的流程即是人工合成随机寡核苷酸序列、适配子筛选、扩增、再循环的过程.在这一过程中,适配子修饰基团文库的应用使得SELEX流程更加经济、快捷、高通量.回顾了SELEX的研究和应用,期待着这一方法能够在理论和实践上得到进一步的发展.     

Apoptosis of adherent cells by recruitment of caspase-8 to unligated integrins.

Integrin-mediated adhesion promotes cell survival in vitro, whereas integrin antagonists induce apoptosis of adherent cells in vivo. Here, we demonstrate that cells adherent within a three-dimensional extracellular matrix undergo apoptosis due to expression of unligated integrins, the beta subunit cytoplasmic domain, or its membrane proximal sequence KLLITIHDRKEF. Integrin-mediated death requires initiator, but not stress, caspase activity and is distinct from anoikis, which is caused by the loss of adhesion per se. Surprisingly, unligated integrin or beta integrin tails recruit caspase-8 to the membrane, where it becomes activated in a death receptor-independent manner. Integrin ligation disrupts this integrin-caspase containing complex and increases survival, revealing an unexpected role for integrins in the regulation of apoptosis and tissue remodeling.     

Antimicrobial metal-based thiophene derived compounds

A novel series of thiophene derived Schiff bases and their transition metal- [Co(II), Cu(II), Zn(II), Ni(II)] based compounds are reported. The Schiff bases act as tridentate ligands toward metal ions via azomethine-N, deprotonated-N of ammine substituents and S-atom of thienyl moiety. The synthesized ligands along with their metal complexes were screened for their in vitro antibacterial activity against six bacterial pathogens (Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus and Bacillus subtilis) and for antifungal activity against six fungal pathogens (Trichophytonlongifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata). The results of antimicrobial studies revealed the free ligands to possess potential activity which significantly increased upon chelation.     

Sgβ1, a novel locust (Schistocerca gregaria) non-α nicotinic acetylcholine receptor-like subunit with homology to the Drosophila melanogaster Dβ1 subunit

The cloning, sequencing and functional expression of Sgβ1, a novel locust (Schistocerca gregaria) non-α nicotinic acetylcholine receptor (nAChR) subunit is described. This subunit shows 80% identity with the Drosophila melanogaster Dβ1 and 92% identity with the Locusta migratoria β1, non-α subunits but only 38% identity to Sgα1 (also referred to as αL1), a previously cloned S. gregaria nAChR α-subunit. When expressed in Xenopus laevis oocytes, Sgβ1 does not respond to nicotine. Responses to nicotine are observed, however, in oocytes co-expressing Sgα1 and Sgβ1, but the pharmacology is indistinguishable from that of currents produced by expressing Sgα1 alone. We conclude that either Sgβ1 does not co-assemble with Sgα1, or that it is unable to contribute to the functional properties of the receptor, in the Xenopus oocyte expression system.     

CCR7 ligand-enhanced phagocytosis of various antigens in mature dendritic cells-time course and antigen distribution different from phagocytosis in immature dendritic cells

CC chemokine receptor 7 (CCR7) is selectively expressed on mature dendritic cells (DC). The CCR7 ligands, CC chemokine ligand (CCL) 19 and CCL21, facilitate migration of mature DC from the peripheral tissues to regional lymph nodes. We previously demonstrated that CCR7 ligands induced rapid receptor-mediated endocytosis of dextran in mature DC. In the present study, we further examined the effects of CCR7 ligands on endocytosis of other kinds of antigen, mannosilated bovine serum albumin (Mann-BSA), Escherichia coli(E. coli), or ovalbumin-containing immune complex (OVA-IC), by mature DC. We found that CCR7 ligands enhanced the endocytosis of Mann BSA, E. coli, and OVA-IC in mature DC but not in immature DC. The endocytosis of BSA was not enhanced by CCR7 ligands. Furthermore, the phagocytosis of OVA-IC was significantly inhibited by anti-Fcgamma receptor III/II antibody. These results demonstrate that CCR7 ligands enhance only receptor-mediated endocytosis by mature DC. When rapidly phagocytosed E. coli were traced in CCL19-treated mature DC, most of the phagocytosed E. coli did not colocalize with the lysosomal marker: lysosome-associated membrane protein-1 (Lamp-1), whereas most of E. coli taken up relatively slowly by immature DC colocalized with Lamp-1. These results suggest that phagocytosis of antigens by immature and mature DC plays different functional roles.