Synthesis and evaluation of a thio analogue of duocarmycin SA

The design, synthesis, and preliminary evaluation of methyl 1,2,8,8a-tetrahydrocyclopropa[c]thieno[3,2-e]indol-4-one-6-carboxylate (CTI) derivatives are detailed representing a single atom change (N to S) embedded in the duocarmycin SA alkylation subunit.     

Alterations of GABA-A and dopamine D-2 brain receptors in dogs with portal-systemic encephalopathy.

The binding characteristics of gamma-aminobutyric acid-A (GABA-A) receptors and the kinetic characteristics of the target enzyme of GABA synthesis in nerve terminals, glutamic acid decarboxylase (GAD), were studied in a dog model of portal-systemic encephalopathy obtained by porta-caval shunt performed in dimethylnitrosamine pretreated animals. Furthermore the properties of dopamine receptors and the levels of catecholamines of encephalopathic dogs were investigated. The mild stage of encephalopathy was characterized by an up-regulation of the inhibitory GABA-A receptors probably related to a decrese of GABA in nerve terminals since GAD was decreased and by a slight decrease of catecholamines and by an increased synthesis of octopamine associated with a decreased affinity of dopamine receptors. In the severe stage there was a selection of high affinity GABA-A receptors with an increased number of benzodiazepine recognition sites which were supersensitive to GABA stimulation, a decreased number of Dopamine D-2 receptors and a marked reduction of catecholamines. These data seem to suggest that the neurological disturbances of experimental portal-systemic encephalopathy might be the result of an imbalance between inhibitory and excitatory systems leading to a prevalence of the first one.     

Physiological and structural changes in response to altered precipitation regimes in a Mediterranean macchia ecosystem

Significant decrease in precipitation up to 15–20% has been observed in the Mediterranean area in the last two decades as a consequence of climate change. To simulate an analogous scenario, the precipitation regime was altered in replicated experimental plots in a Mediterranean macchia dominated by Arbutus unedo L. species. Two different levels of soil water content (SWC) were obtained during the summer: a mean value of 7% was obtained in water-depleted (D) plots by a partial (−20%) rain exclusion treatment using rain gutters; while a mean value of 14% in SWC was obtained in watered (W) plots supplying water by a sprinkler net. The physiological and structural changes were investigated over the course of two consecutive years by measurement of water potential, gas exchange leaf carbon isotopes, leaf pigments and growth. Apart from short-term responses, mainly related to the elastic response of stomatal conductance to soil water, a more long-lasting and significant acclimation to water availability was observed as a result of the increase in hydraulic resistance in the soil–plant continuum, which persisted even after the return to full water availability during the fall and winter. This response involved the permanent down-regulation of stomatal conductance and photosynthesis, accumulation of photo-protective pigments, as well as a reduction in shoot growth, leaf area index and an increase in shoot-bearing flowers in D plots. This acclimation response prevented the onset of any run-away damage thereby reducing the forest vulnerability to drought. Furthermore, the imposed drought induced a slight increase or no change in intrinsic water-use efficiency (WUE_int), as a result of the parallel increase in stomatal and non-stomatal limitations; conversely integrated WUE (i.e., estimated from leaf carbon isotopes) was not affected by drought.     

Synthesis of novel antimitotic agents based on 2-amino-3-aroyl-5-(hetero)arylethynyl thiophene derivatives

Microtubules are dynamic structures that play a crucial role in cellular division and are recognized as an important target for cancer therapy. In search of new compounds with strong antiproliferative activity and simple molecular structure, a new series of 2-amino-3-(3′,4′,5′-trimethoxybenzoyl)-5-(hetero)aryl ethynyl thiophene derivatives was prepared by the Sonogashira coupling reaction of the corresponding 5-bromothiophenes with several (hetero)aryl acetylenes. When these compounds were analyzed in vitro for their inhibition of cell proliferation, the 2- and 3-thiophenyl acetylene derivatives were the most powerful compounds, both of which exerted cytostatic effects at submicromolar concentrations. In contrast, the presence of a more flexible ethyl chain between the (hetero)aryl and the 5-position of the thiophene ring resulted in significant reduction in activity relative to the 5-(hetero)aryl acetylene substituted derivatives. The effects of a selected series of compounds on cell cycle progression correlated well with their strong antiproliferative activity and inhibition of tubulin polymerization. We found that the antiproliferative effects of the most active compounds were associated with increase of the proportion of cells in the G₂/M and sub-G₁ phases of the cell cycle.     

Structure-activity relationships of 2-amino-3-aroyl-4-[(4-arylpiperazin-1-yl)methyl]thiophenes. Part 2: Probing the influence of diverse substituents at the phenyl of the arylpiperazine moiety on allosteric enhancer activity at the A₁ adenosine receptor

In a preliminary article, we reported the potent allosteric enhancer activity at the A(1) adenosine receptor of a small series of 2-amino-3-(4-chlorobenzoyl)-4-[4-(aryl)piperazin-1-yl)methyl]thiophene derivatives bearing electron-withdrawing or electron-releasing groups at the para-position of the phenylpiperazine moiety. In the present study, we report the development of the compounds previously studied by modifying both the number and position of substituents on the phenylpiperazine moiety, aimed at establishing a structure-activity relationship identifying additional compounds with improved activity. The nature and the position of substituents on the phenyl ring tethered to the piperazine seemed to exert a fundamental influence on the allosteric enhancer activity, with the 3,4-difluoro 4i, 3-chloro-4-fluoro 4o, and 4-trifluoromethoxy 4ak derivatives being the most active compounds in binding (saturation and competition experiments) and functional cAMP studies. This study shows that it is also possible to obtain a good separation between allosteric enhancement and antagonistic activity at the A(1) adenosine receptor.     

Synthesis and biological evaluation of 2-substituted-4-(3′,4′,5′-trimethoxyphenyl)-5-aryl thiazoles as anticancer agents

Antitumor agents that bind to tubulin and disrupt microtubule dynamics have attracted considerable attention in the last few years. To extend our knowledge of the thiazole ring as a suitable mimic for the cis-olefin present in combretastatin A-4, we fixed the 3,4,5-trimethoxyphenyl at the C4-position of the thiazole core. We found that the substituents at the C2- and C5-positions had a profound effect on antiproliferative activity. Comparing compounds with the same substituents at the C5-position of the thiazole ring, the moiety at the C2-position influenced antiproliferative activities, with the order of potency being NHCH₃ > Me ? N(CH₃)₂. The N-methylamino substituent significantly improved antiproliferative activity on MCF-7 cells with respect to C2-amino counterparts. Increasing steric bulk at the C2-position from N-methylamino to N,N-dimethylamino caused a 1–2 log decrease in activity. The 2-N-methylamino thiazole derivatives 3b, 3d and 3e were the most active compounds as antiproliferative agents, with IC₅₀ values from low micromolar to single digit nanomolar, and, in addition, they are also active on multidrug-resistant cell lines over-expressing P-glycoprotein. Antiproliferative activity was probably caused by the compounds binding to the colchicines site of tubulin polymerization and disrupting microtubule dynamics. Moreover, the most active compound 3e induced apoptosis through the activation of caspase-2, -3 and -8, but 3e did not cause mitochondrial depolarization.     

Reproductive status is associated with the severity of fibrosis in women with hepatitis C

Introduction

Chronic hepatitis C is the main cause of death in patients with end-stage liver disease. Prognosis depends on the increase of fibrosis, whose progression is twice as rapid in men as in women. Aim of the study was to evaluate the effects of reproductive stage on fibrosis severity in women and to compare these findings with age-matched men.

Materials and Methods

A retrospective study of 710 consecutive patients with biopsy-proven chronic hepatitis C was conducted, using data from a clinical database of two tertiary Italian care centers. Four age-matched groups of men served as controls. Data about demographics, biochemistry, liver biopsy and ultrasonography were analyzed. Contributing factors were assessed by multivariate logistic regression analysis.

Results

Liver fibrosis was more advanced in the early menopausal than in the fully reproductive (P<0.0001) or premenopausal (P = 0.042) group. Late menopausal women had higher liver fibrosis compared with the other groups (fully reproductive, P<0.0001; premenopausal, P = <0.0001; early menopausal, P = 0.052). Multivariate analyses showed that male sex was independently associated with more severe fibrosis in the groups corresponding to premenopausal (P = 0.048) and early menopausal (P = 0.004) but not late menopausal pairs. In women, estradiol/testosterone ratio decreased markedly in early (vs. reproductive age: P = 0.002 and vs. premenopausal: P<0.0001) and late menopause (vs. reproductive age: P = 0.001; vs. premenopausal: P<0.0001). In men age-matched with menopausal women, estradiol/testosterone ratio instead increased (reproductive age group vs. early: P = 0.002 and vs. late M: P = 0.001).

Conclusions

The severity of fibrosis in women worsens in parallel with increasing estrogen deprivation and estradiol/testosterone ratio decrease. Our data provide evidence why fibrosis progression is discontinuous in women and more linear and severe in men, in whom aging-associated estradiol/testosterone ratio increase occurs too late to noticeably influence the inflammatory process leading to fibrosis.     

Synthesis and antiplatelet activity of gemfibrozil chiral analogues

The chiral analogues of gemfibrozil 5-(2,5-dimethylphenoxy)-2-methylpentanoic acid and 5-(2,5-dimethylphenoxy)-2-ethylpentanoic acid were synthesized in optically active form using (S)-4-(1-methylethyl)-2-oxazolidinone as chiral auxiliary. All compounds inhibit human platelet aggregation. From these data, one can surmise that all tested compounds and gemfibrozil act at the platelet level with different mechanism than that of ASA, even if with a different potency.