Synthesis and biological assessment of diversely substituted furo[2,3-b]quinolin-4-amine and pyrrolo[2,3-b]quinolin-4-amine derivatives, as novel tacrine analogues

The synthesis and pharmacological analyses of a number of furo[2,3-b]quinolin-4-amine, and pyrrolo[2,3-b]quinolin-4-amine derivatives are reported. Thus, we synthesized diversely substituted tacrine analogues 1–11 and 12–16 by Friedländer-type reaction of readily available o-amino(furano/pyrrolo)nitriles with suitable and selected cycloalkanones. The biological evaluation of furanotacrines1–11 and pyrrolotacrine13 showed that these are good, in the micromolar range, and highly selective inhibitors of BuChE. In the furanotacrine group, the most interesting inhibitor was 2-(p-tolyl)-5,6,7,8-tetrahydrofuro[2,3-b]quinolin-4-amine (3) [IC₅₀ (eqBuChE) = 2.9 ± 0.4 μM; IC₅₀ (hBuChE) = 119 ± 15 μM]. Conversely, pyrrolotacrines12 and 14 proved moderately equipotent for both cholinesterases, being 1,2-diphenyl-5,6,7,8-tetrahydro-1H-pyrrolo[2,3-b]quinolin-4-amine (12) the most potent for the inhibition of both enzymes [IC₅₀ (EeAChE) = 0.61 ± 0.04 μM; IC₅₀ (eqBuChE) = 0.074 ± 0.009 μM]. Moreover, pyrrolotacrine 12, at concentrations as low as 300 nM can afford significant neuroprotective effects against Aβ-induced toxicity. Docking studies show that compounds 3 and 12 bind in the middle of the AChE active site gorge, but are buried deeper inside BuChE active site gorge, as a consequence of larger BuChE gorge void. All these data suggest that these new tacrine analogues could be used for the potential treatment of Alzheimer’s disease.     

Cholinergic modulation of the urethro genital reflex in spinal cord-transected rats

The aim of this study was to determine which of the muscarinic receptor subtypes are involved in the modulation of the urethrogenital reflex (UGR) in male, spinal cord-transected rats. The electromyographic (EMG) responses of the bulbospongiosus muscle (BS) to the topical spinal application of muscarine and the combination of muscarine and the selective muscarine receptor antagonists methoctramine (M2), AFDX (M2), 4DAMP (M3) and tropicamide (M4) were determined before and after the elicitation of UGR by way of the mechanical stimulation of the urethra. When 50- and 100-mug doses of muscarine were applied without urethral stimulation, a rhythmic activity of the BS was observed, similar to the one found when UGR was evoked. The M3 and M4 - but not the M2 - antagonists prevented BS response to muscarine when urethral stimulation was not performed. When UGR was elicited following urethral stimulation muscarine produced an increase in burst duration and a decrease in burst frequency. The M2 antagonist reverted the effects of muscarine on the UGR, while the M3 and M4 antagonists produced a significant increase in the frequency and in the bursts number, when compared to the control muscarine response. The differences observed in BS responses to muscarine and muscarine antagonists before and after UGR elicitation were probably linked to the intrinsic effects of the endogenous acethylcholine (Ach) released after urethral stimulation. The present results suggest a cholinergic modulation of UGR in spinal cord-transected rats mediated by the M2, M3 and M4 muscarinic receptor subtypes.     

Identification and partial characterisation of hyaluronidases in Lonomia obliqua venom.

By studying Lonomia obliqua (caterpillar) venom we were able to detect a lytic activity on purified hyaluronic acid. The venom hydrolyses purified chondroitin sulphate, but was unable to degrade either heparan sulphate or dermatan sulphate. Moreover, through purified hyaluronic acid-degrading kinetic assays, we observed that this lytic activity was caused by a hydrolase rather than lyase enzyme. In addition, by using the Reissig colorimetric reaction, we detected this hyaluronic acid hydrolase action as a beta-endohexosaminidase enzyme originating terminal N-acetylglucosamine residues rather than beta-endoglucuronidase, which may originate glucuronic acid residues. Zymogram analysis of the venom detected 49 and 53 kDa molecules with hyaluronic acid lytic activity. An examination of these hyaluronic acid degrading activities as a function of pH showed that these hydrolases had no apparent activities at a pH below 5.0 and higher than 8.0 and displayed their optimal activities at pH ranging from 6.0 to 7.0. Finally, through a fluorescence reaction to hyaluronic acid and confocal microscopy, we confirmed this cleaving action upon hyaluronic acid organised on the extracellular matrix of the dermis of rabbit. The data provide experimental evidence of the presence of hyaluronidases in the L. obliqua venom, probably involved in the harmful effects of the venom.     

Serotonin1A-receptor antagonism blocks psychostimulant properties of diethylpropion in marmosets (Callithrix penicillata)

Diethylpropion (1-phenyl-2-diethylamine-1-propanone hydrochloride) is a stimulant drug with reinforcing properties that is used to treat obesity in humans. While the anorectic properties of diethylpropion are mediated by a noradrenergic mechanism, stimulant properties depend on its effects on the serotonergic (5-HT) and/or dopaminergic systems. In this study we investigated the role of the 5-HT1A-receptor in the acute behavioral effects of diethylpropion in marmosets (Callithrix penicillata). Animals were pretreated with the selective 5-HT1A-receptor antagonist, N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl) cyclohexane-carboxamide trihydrochloride (WAY 100635; 0.2, 0.4, 0.8 mg/kg, i.p.) or saline (i.p.) and received a treatment with diethylpropion (10 mg/kg, i.p) or saline (i.p.). Diethylpropion induced an increase in locomotor activity in 60% of the monkeys, which were classified as diethylpropion sensitive, but did not affect locomotion in 40% of the monkeys (diethylpropion insensitive). Sensitivity analysis revealed two types of responders to diethylpropion. In the sensitive animals (type A) diethylpropion increased locomotor activity and anxiogenic-like behavior, but decreased bodycare activities. In the insensitive animals (type B) diethylpropion did not affect locomotor and bodycare activity after diethylpropion, but led to a strong increase in anxiogenic-like behavioral responses. Selective 5-HT1A-receptor antagonism modulated the acute diethylpropion effects responder type specifically. In the sensitive (type A) monkeys WAY 100635 blocked the diethylpropion-induced increase in locomotor activity, while not affecting anxiogenic-like behavioral responses or the suppression of bodycare activities. In the insensitive monkeys, WAY 100635 had no effect on locomotor activity after diethylpropion, but blocked diethylpropion effects on some anxiogenic-like behavioral responses. In conclusion, these results suggest an essential contribution of the 5-HT1A-receptor to the stimulant effects of diethylpropion, which is responder type specific. It also suggests the 5-HT1A-receptor to be a source of the interindividual variance in the acute behavioral response to the stimulant diethylpropion in monkeys.     

Spasmolytic effects, mode of action, and structure-activity relationships of stilbenoids from Nidema boothii

A CH(2)Cl(2)-MeOH (1:1) extract prepared from the whole plant of Nidema boothii inhibited spontaneous contractions (IC(50) = 6.26 +/- 2.5 microg/mL) of the guinea-pig ileum. Bioassay-guided fractionation of the active extract led to the isolation of the novel spiro compound 1, which was given the trivial name nidemone, and the new dihydrophenanthrene 3, characterized as 1,5,7-trimethoxy-9,10-dihydrophenanthrene-2,6-diol. In addition, the known stilbenoids aloifol II (2), 1,5,7-trimethoxyphenanthrene-2,6-diol (4), ephemeranthoquinone (5), gigantol (6), ephemeranthol B (7), 2,4-dimethoxyphenanthrene-3,7-diol (8), lusianthridin (9), and batatasin III (10) were obtained. The isolates were characterized structurally by spectroscopic data interpretation. Compounds 2-6, 9, and 10 induced notable concentration-dependent inhibition of the spontaneous contractions of the guinea-pig ileum with IC(50) values that ranged between 0.14 and 2.36 microM. Bibenzyl analogues 23-35 were synthesized and tested pharmacologically. The results indicated that for maximum spasmolytic activity the bibenzyls should have oxygenated substituents on both aromatic rings; on the other hand, methylation of free hydroxyl groups as well as the increment of oxygenated groups in relation to compounds 6 and 10 decreased the smooth muscle relaxant activity. It was also demonstrated that bibenzyls 6 and 10 might exert their spasmolytic action not only by a nitrergic mechanism but also by inhibiting CaM-mediated processes.     

Correlates of depressive symptoms among Latino and Non-Latino White adolescents: Findings from the 2003 California Health Interview Survey

Background  

The prevalence of depression is increasing not only among adults, but also among adolescents. Several risk factors for depression in youth have been identified, including female gender, increasing age, lower socio-economic status, and Latino ethnic background. The literature is divided regarding the role of acculturation as risk factor among Latino youth. We analyzed the correlates of depressive symptoms among Latino and Non-Latino White adolescents residing in California with a special focus on acculturation.     

Carpal tunnel syndrome: under-recognition of occupational risk factors by clinicians

This study was performed in order to demonstrate that non-occupational physicians are often unaware of the possible role of occupational risk factors in the multifactorial etiology of carpal tunnel syndrome (CTS). Study participants consisted of 229 individuals, 127 cases of CTS matched with 102 controls. In only 41% of the cases did family or attending physicians in the hospital asked the concerned patients about their occupation or specific job tasks, and less than 10% of the cases were referred for further evaluation to an occupational physician. Occupational risk factors that were identified were: work with repeated movements of the wrist (OR=2.15, 95% CI=1.14-4.07) and work in a cold environment (OR=3.52, 95% CI=1.08-11.47). By improving the awareness of clinicians (and patients) to the possible role of work-related factors in the etiology of CTS, appropriate preventive measures can be introduced in order to reduce the burden of this syndrome.     

Ajoene,a garlic compound,inhibits protein prenylation and arterial smooth muscle cell proliferation

(1) Ajoene is a garlic compound with anti-platelet properties and, in addition, was shown to inhibit cholesterol biosynthesis by affecting 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase and late enzymatic steps of the mevalonate (MVA) pathway. (2) MVA constitutes the precursor not only of cholesterol, but also of a number of non-sterol isoprenoids, such as farnesyl and geranylgeranyl groups. Covalent attachment of these MVA-derived isoprenoid groups (prenylation) is a required function of several proteins that regulate cell proliferation. We investigated the effect of ajoene on rat aortic smooth muscle cell proliferation as related to protein prenylation. (3) Cell counting, DNA synthesis, and cell cycle analysis showed that ajoene (1-50 micro M) interfered with the progression of the G1 phase of the cell cycle, and inhibited rat SMC proliferation. (4) Similar to the HMG-CoA reductase inhibitor simvastatin, ajoene inhibited cholesterol biosynthesis. However, in contrast to simvastatin, the antiproliferative effect of ajoene was not prevented by the addition of MVA, farnesol (FOH), and geranylgeraniol (GGOH). Labelling of smooth muscle cell cellular proteins with [3H]-FOH and [3H]-GGOH was significantly inhibited by ajoene. (5) In vitro assays for protein farnesyltransferase (PFTase) and protein geranylgeranyltransferase type I (PGGTase-I) confirmed that ajoene inhibits protein prenylation. High performance liquid chromatography (HPLC) and mass spectrometry analyses also demonstrated that ajoene causes a covalent modification of the cysteine SH group of a peptide substrate for protein PGGTase-I. (6) Altogether, our results provide evidence that ajoene interferes with the protein prenylation reaction, an effect that may contribute to its inhibition of SMC proliferation.     

Hemorrhagic activity of Bothrops venoms determined by two different methods and relationship with proteolytic activity on gelatin and lethality

The changes in hemorrhagic activity, proteolytic activity on gelatin and the lethal potency of four Bothrops venoms treated at different pH values or with EDTA were studied. Venoms from B. alternatus, B. jararaca, B. moojeni and B. neuwiedii of Argentina were preincubated at pH 5.8, 5.1 or 3.8 or with EDTA and the hemorrhagic activity expressed as size of the hemorrhagic lesion or as the amount of hemoglobin extracted, the proteolytic activity on gelatin and the lethal potency were determined. Although the MHDs recorded in rats were 19–56 fold higher than those recorded in mice, the A₅₅₀ extracted per gram of hemorrhagic haloes was very similar in rats or mice independent of the venom dose. Inhibition of proteolytic activity after preincubation at pH 5.1 or 3.8, agrees with the decreased amount of hemoglobin extracted from the hemorrhagic haloes, and with the increase in mean survival time after the i.p. injection to mice. Preincubation with EDTA resulted in 80% inhibition of hemorrhagic activity of B. jararaca venom and complete inhibition with the other Bothrops venoms tested. Measurement of the amount of hemoglobin extracted gives significant information in comparative studies, not available by measurement of the size of hemorrhagic haloes.