Iron Chelators and Antioxidants Regenerate Neuritic Tree and Nigrostriatal Fibers of MPP+/MPTP-Lesioned Dopaminergic Neurons.

Neuronal death in Parkinson's disease (PD) is often preceded by axodendritic tree retraction and loss of neuronal functionality. The presence of non-functional but live neurons opens therapeutic possibilities to recover functionality before clinical symptoms develop. Considering that iron accumulation and oxidative damage are conditions commonly found in PD, we tested the possible neuritogenic effects of iron chelators and antioxidant agents. We used three commercial chelators: DFO, deferiprone and 2.2'-dypyridyl, and three 8-hydroxyquinoline-based iron chelators: M30, 7MH and 7DH, and we evaluated their effects in vitro using a mesencephalic cell culture treated with the Parkinsonian toxin MPP+ and in vivo using the MPTP mouse model. All chelators tested promoted the emergence of new tyrosine hydroxylase (TH)-positive processes, increased axodendritic tree length and protected cells against lipoperoxidation. Chelator treatment resulted in the generation of processes containing the presynaptic marker synaptophysin. The antioxidants N-acetylcysteine and dymetylthiourea also enhanced axodendritic tree recovery in vitro, an indication that reducing oxidative tone fosters neuritogenesis in MPP+-damaged neurons. Oral administration to mice of the M30 chelator for 14 days after MPTP treatment resulted in increased TH- and GIRK2-positive nigra cells and nigrostriatal fibers. Our results support a role for oral iron chelators as good candidates for the early treatment of PD, at stages of the disease where there is axodendritic tree retraction without neuronal death.

Multivariate SAR/QSAR of 3-aryl-4-hydroxyquinolin-2(1H)-one derivatives as type I fatty acid synthase (FAS) inhibitors.

Two multivariate studies, a PCA-SAR and a PLS-QSAR, of 3-aryl-4-hydroxyquinolin-2(1H)-one derivatives described as type I fatty acid synthase (FAS) inhibitors, are presented in this work. The variable selection was performed with the Fisher's weight and Ordered Predictors Selection (OPS) algorithm, respectively. In the PCA, a separation between active and inactive compounds was obtained by six descriptors (topological and geometrical). The PLS model presented five descriptors and two Latent Variables. Leave-N-out cross validation and y-randomization test showed that the model presented robustness and no chance correlation, respectively, and the descriptors indicated that the FAS inhibition depends on electronic distribution of the investigated compounds. The model obtained in this study may provide a guidance for proposition of new FAS inhibitors.

Suppression of survival in human SKBR3 breast carcinoma in response to metal-chelator complexes is preferential for copper-dithiocarbamate.

Since diethyl dithiocarbamate (DEDTC) forms complexes with either zinc or copper, and 8-hydroxyquinoline (8-OHQ) also complexes with copper, we now compared the cytotoxic activity of Cu[DEDTC]2, Zn[DEDTC]2 and Cu[8-OHQ]2. This report shows that at nanomolar levels, only copper-[DEDTC]2, suppresses proliferation and clonogenicity of SKBR3 human breast carcinoma, concurrently with induction of apoptosis-associated PARP fragmentation. Susceptibility to these agents was paralleled by reactive oxygen generation (ROS) and greater expression of anti-oxidant enzymes like MnSOD and catalase, with no comparable effect on Cu/Zn superoxide dismutase. The lethal effects of Cu[DEDTC]2 manifested when adding the two separate aqueous components or the preformed synthetic complexes in DMSO, was prevented by N-acetyl cysteine or glutathione, with no comparable protection afforded by non-thiol anti-oxidants like mannitol or DMSO. Exogenously added catalase also protected cells from Cu[DEDTC]2, suggesting that this complex may kill after the levels of superoxide anion [O2*-] dismutated by MnSOD increase hydrogen peroxide-related stress. Cu[DEDTC]2 also induced p21WAF1, a cdk inhibitor usually not inducible in mutant p53 tumors like SKBR3 carcinoma, correlating with dephosphorylation of the Sp1 transcription factor. Concentrations of Cu[DEDTC]2 cytotoxic for SKBR3 carcinoma did not induce comparable damage versus normal diploid human WI-38 fibroblasts. In contrast to the cytotoxic effect of nM levels of Cu[DEDTC]2 against SKBRR3 cells, no response was seen in the same cells exposed to 20 microM cis-platin. Since neither DEDTC bound to zinc, nor copper bound to 8-OHQ showed comparable cytotoxicity, our results suggest that the greater activity of copper-DEDTC reflects a specific structure-activity relationship for the active complex. Since Cu[DEDTC]2 shows more effectiveness than other metal-chelator complexes, it may be worth further investigation as an alternative to cancer therapies.

Isolation and structure of ruprechstyril from Ruprechtia tangarana.

Bioassay (P388 lymphocytic leukemia cell line and human cancer cell lines)-guided separation of an extract prepared from the stem bark and twigs of the previously uninvestigated Ruprechtia tangarana led to the isolation of a new isocarbostyril designated ruprechstyril (1), secalonic acid A (2), 2'-O-methylevernic acid (3), 3,3',4-tri-O-methylflavellagic acid (4), lichexanthone (5), methyl asterrate (6), and 3beta,22E,24S-stigmasta-5,22-dien-3-ol (7). Only secalonic acid A exhibited cancer cell and microbial growth inhibition. The structure of ruprechstyril (1) was determined by HRMS and 1D and 2D NMR spectra and confirmed by single-crystal X-ray analysis. The structures and absolute stereochemistry of five of the other compounds were also established by X-ray crystal structure determination.

Pharmacological evidence for beta2-adrenoceptor in right atria from stressed female rats.

The purpose of the present study was to demonstrate a physiological response to TA2005, a potent m-adrenoceptor (beta2-AR) selective agonist, in right atria isolated from stressed female rats under the influence of the estrous cycle. We obtained concentration-response curves to the agonist in the presence and in the absence of selective antagonists in right atria isolated from female rats submitted to three daily foot-shock sessions (30 min duration, 120 pulses of 1.0 mA, 1.0 s, applied at random intervals of 5-25 s) and sacrificed at estrus or diestrus. Our results showed that the pD2 values of TA2005 were not influenced by estrous cycle phase or foot-shock stress. However, in right atria from stressed rats sacrificed during diestrus, the concentration-response curve to TA2005 was biphasic, with a response being obtained at concentrations of 0.1 nM, whereas during estrus no response was observed at doses lower than 3 nM. ICI 1118,551, a beta2-AR antagonist, abolished the response to nanomolar concentrations of TA2005 in right atria from stressed rats at diestrus, with no changes in agonist pD2 values in right atria from control rats (7.47 +/- 0.09, p > 0.05) but a 3-fold decrease in pD2 values of TA2005 in right atria from foot shock stressed rats (7.90 +/- 0.07, p < or = 0.05). Concentration-response curves to TA2005 in the presence of ICI118,551 were best fitted by a one-site model equation. The beta1-AR antagonist, CGP20712A, shifted to the right only the second part of the concentration-response curves to the agonist, unmasking the putative beta2-AR-mediated response to the agonist in tissues isolated from stressed rats at diestrus. Under this condition, concentration-response curves to the agonist were best fitted by a two-site model equation. pD2 and maximum response of TA2005 interaction with beta1- and putative beta2-adrenoceptor components were calculated. Schild analyses gave a pK(B) value for CGP20712A that was typical for the interaction with beta1-AR in each experimental group. pK(B) values for ICI118,551 could not be obtained in stressed rats sacrificed at diestrus since Schild plot slopes were lower than 1.0. In right atria from control rats, ICI118,551 pK(B) values were similar to reported values for the interaction of the antagonist with beta1-AR. These results confirm that a heterogenous beta-AR population mediating the chronotropic response to catecholamines can be demonstrated in right atria from foot shock stressed female rats sacrificed at diestrus. The stress-induced response seems to be mediated by the beta2-AR subtype. Right atria from rats sacrificed during estrus are protected against stress-induced alterations on the homogeneity of beta-AR population.

[Reliability of the PEHPS culture medium for the in vitro evaluation of antiamebic drugs]. / Confiabilidad del medio de cultivo pehps para la evaluación in vitro de drogas antiamibianas.

Monophasic liquid media for axenical cultivation of Entamoeba histolytica, have permitted to define diverse aspects of this parasite's biology, without associated organisms interference. In addition, these media have allowed the in vitro evaluation of new drugs with potential antiamebic properties. PEHPS, a new medium recently developed in our laboratory, was used in order to determine its usefulness in the searching for new antiamebic compounds. The antiamebic potency of currently employed drugs in clinical therapy: emetine, metronidazole and diiodohydroxyquinoline on E. histolytica, strain HM-1, trophozoites grown in PEHPS was tested. The IC50 for each drug was 0.082 microgram/ml, 0.10 micrograms/ml and 5.84 micrograms/ml respectively. Results obtained with each drug are statistically reliable and reproducible, and agree with the species sensibility reported by several other authors. Accordingly, we propose PEHPS as a useful medium for new antiamebic drug research.