Andrew Tsotinis

Synthesis, lipophilicity and biological evaluation of indole-containing derivatives of 1,3,4-thiadiazole and 1,2,4-triazole

3-[(2-Methyl-1H-3-indolyl) methyl]-4-aryl-4, 5-dihydro-1H-1,2,4-triazole-5-thiones 6a-c and their respective N-¿5-[2-methyl-1H-3-indolyl) methyl]-1,3,4-thiadiazol-2-yl¿-N-arylamines 7a,b have been prepared. The antidepressant profile of 6a,c and 7a was studied on mice with respect to that of the analogous 3-(1H-1-indolylmethyl)-4-aryl-4,5-dihydro-1H-1,2,4-triazole-5-thio nes 1a-c and the respective N-¿5-[(2-methyl-1H-3-indolyl) methyl]-1,3,4-thiadiazole-2-yl¿-N-arylamines 2a-c, the synthesis and antimicrobial potency of which we have recently reported. Behavioral effects, induced by the members of both series, in conjunction with their activity in some specific tests (forced swim, pentetrazole convulsions) on mice, show that these derivatives cross the blood-brain barrier and could develop an antidepressant activity comparable to that of imipramine. Blood-brain barrier penetration is also supported by the lipophilicity data obtained for all analogs.

Mapping the melatonin receptor. 6. Melatonin agonists and antagonists derived from 6H-isoindolo[2,1-a]indoles, 5,6-dihydroindolo[2,1-a]isoquinolines, and 6,7-dihydro-5H-benzo[c]azepino[2,1-a]indoles.

6H-Isoindolo[2,1-a]indoles (5, 7, 10, 13), 5,6-dihydroindolo[2, 1-a]isoquinolines (20, 21), and 6,7-dihydro-5H-benzo[c]azepino[2, 1-a]indoles (23, 25, 27, 30) have been prepared as melatonin analogues to investigate the nature of the binding site of the melatonin receptor. The affinity of analogues was determined in a radioligand binding assay using cloned human mt(1) and MT(2) receptor subtypes expressed in NIH 3T3 cells. Agonist and antagonist potency was measured using the pigment aggregation response of a clonal line of Xenopus laevis melanophores. The 2-methoxyisoindolo[2, 1-a]indoles (7a-d) showed much higher binding affinities than the parent isoindoles (5a-e), and whereas 7a-c were agonists in the functional assay, 7d and 5a-e were antagonists. The 2-ethoxyisoindolo[2,1-a]indoles (10a-d) showed reduced binding affinities compared to their methoxy analogues, while the 5-chloro derivative 13 showed a considerable reduction in binding affinity and potency compared to 7a. The 10-methoxy-5,6-dihydroindolo[2, 1-a]isoquinolines (21a-c) had higher binding affinities than the corresponding parent indoloisoquinolines (20a-c) in the human receptor subtypes, and the parent compounds were antagonists whereas the 10-methoxy derivatives were agonists in the functional assay. The N-cyclobutanecarbonyl derivatives of both the parent (20d) and 10-methoxyl (21d) series had similar binding affinities and were both antagonists with similar potencies. The 11-methoxy-6, 7-5H-benzo[c]azepino[2,1-a]indoles (25a-d) had higher binding affinities than the corresponding parent compounds (23a-d) at the MT(2) receptor but similar affinities at the mt(1) site; all of the compounds were antagonists in the functional assay. Changing 11-methoxy for 11-ethoxy decreased the binding affinity slightly, and this was more evident at the MT(2) receptor. All of the derivatives investigated had either the same or a greater affinity for the human MT(2) receptor compared to the mt(1) receptor (range 1:1-1:132). This suggests that the mt(1) and MT(2) receptor pockets differ in their ability to accommodate alkyl groups in the indole nitrogen region of the melatonin molecule. Two compounds (7c and 25c) were tested in functional assays on recombinant mt(1) and MT(2) melatonin receptors. Compound 7c is a potent agonist with some selectivity (44-fold) for the MT(2) receptor, while 25c is an MT(2)-preferring antagonist. Increasing the carbon chain length between N-1 of indole and the 2-phenyl group from n = 1 through n = 3 leads to a fairly regular decrease in the binding affinity, but, remarkably, when n = 3, it converts the methoxy compounds from melatonin agonists to antagonists. The Xenopus melatonin receptor thus cannot accommodate an N-n-alkyl chain attached to a 2-phenyl substituent with n > 2 in the required orientation to induce or stabilize the active receptor conformation.

Design, Synthesis, and Trypanocidal Activity of New Aminoadamantane Derivatives

To develop functionalized adamantanes for treating African trypanosomiasis, we report on the synthesis of new 1-alkyl-2-aminoadamantanes 1a- i, 1-alkyltricyclo[3.3.1.1 (3,7)]decan-2-guanylhydrazones 2a- g, and their congeneric thiosemicarbazones 3a, b. The potency of these compounds against Trypanosoma brucei was compared to that of amantadine and rimantadine and found to be substantially higher. The most active analogues, 1c, 1d, 2c, 2g, and 3b, illustrate the synergistic effect of the lipophilic character of the C1 side chain and the C2 functionality on trypanocidal activity.

Design and synthesis of bioactive 1,2-annulated adamantane derivatives

Adamantanopyrrolidines 8, 9 and 10, adamantanopyrrolidines 16 and 18, adamantanoxazolone 20, adamantanopyrazolone 23, adamantanopyrazolothione 24 and adamantanocyclopentanamine 32 were synthesized and tested for anti-influenza A virus and trypanocidal activity. The stereoelectronic requirements for optimal antiviral and trypanocidal potency were investigated. Pyrrolidine 16 proved to be the most active of the compounds tested against influenza A virus, being 4-fold more active than amantadine, equipotent to rimantadine and 19-fold more potent than ribavirin. Oxazolone 20 showed significant trypanocidal activity against bloodstream forms of the African trypanosome, Trypanosoma brucei, being approximately 3 times more potent than rimantadine and almost 50-fold more active than amantadine.

Synthesis of Compounds as Melatonin Agonists and Antagonists

The functions of melatonin, the hormone of the pineal gland, are of considerable current interest. Synthetic melatonin analogues as agonists and antagonists have been explored in some detail and the molecule can be considered as consisting of an indole core, acting mainly as a spacer, and the 5-methoxyl and 3-amidoethyl side chains acting as the functional components, as originally proposed by Heward and Hadley. This review focuses on the synthetic routes to these melatonin analogues, first of the core, then of the substituents that have been attached to the core, and finally those compounds with restricted conformations and those that are chiral. The importance of the various factors involved in the activity of the compounds as agonist or antagonists is indicated, as is the difference in activity of enantiomers.

Alternative syntheses and Diels-Alder reactions of 2,3-bis(trimethylsilyl)buta-1,3-diene

Abstract The title compound has been prepared by two routes and some Diels-Alder reactions of it investigated.

A Facile Synthesis of C2-Substituted Pyrrolo[2,3-f]quinolines with Cytotoxic Activity

An expeditious four-step synthesis of the 1H-pyrrolo[2,3-f]quinoline-2- carboxamides (5a-h) is described. Readily available 6-quinolinecarboxaldehyde is converted to the parent acid (6) by nucleophilic attack of the azido-ester (9) and intramolecular cyclization of (10) followed by hydrolysis of the methyl ester (11). The cytotoxicity of the target molecules (5a-h) was evaluated in four tumour cell lines in vitro. One compound (5d) showed sufficient activity (IC50 = 10.2 ?M) in the human non-small cell lung cell line NSCLC-N16-L16 to be worthy of further study.

Synthesis, σ1, σ2-receptors binding affinity and antiproliferative action of new C1-substituted adamantanes

The synthesis of N-{4-[a-(1-adamantyl)benzyl]phenyl}piperazines 2a-e is described. The in vitro antiproliferative activity of most compounds against main cancer cell lines is significant. The σ(1), σ(2)-receptors and sodium channels binding affinity of compounds 2 were investigated. One of the most active analogs, 2a, had an interesting in vivo anticancer profile against the BxPC-3 and Mia-Paca-2 pancreas cancer cell lines with caspase-3 activation, which was associated with an anagelsic activity against the neuropathic pain.

Alternative pharmacological interventions that limit myocardial infarction.

Despite current optimal treatment, the morbidity and mortality of coronary heart disease remain significant worldwide and open the way for the development of novel cardioprotective therapies. In the last two decades, a remarkable scientific effort has focused on the limitation of infarct size. Important input from experimental studies has led the way in this direction. However, clinical and preclinical results using various cardioprotective strategies to attenuate reperfusion injury have generally not been applicable for every day clinical practice. Protection of the ischemic myocardium is known to occur as a result of ischemic preconditioning (PC), in which repetitive brief periods of ischemia protect the heart from a subsequent prolong ischemic insult. Although PC is a powerful form of protection, it is of limited clinical application for obvious ethical and practical reasons. Another endogenous form of cardioprotection, similar to PC but applicable at the time of reperfusion, termed postconditioning (PostC), has been recently described. Short series of repetitive cycles of brief reperfusion and re-occlusion of the coronary artery applied at the onset of reperfusion, reduce the infarct size and coronary artery endothelial dysfunction. At present, pharmacological PC and PostC are possible alternative methods that may substitute pharmaceutical treatments the short ischemic insults. Adenosine, nicorandil and other agents have been already used as pharmacological mimetics of ischemic PC in multicenter trials. We summarize the recent research efforts on novel therapeutic strategies and on the design of new compounds, based on the accumulated knowledge of the ligands, receptors and intracellular signaling pathways of PC and PostC.

A New Ring-forming Methodology for the Synthesis of Bioactive Pyrroloquinoline Derivatives

A new, efficient, two-step method for the synthesis of bioactive pyrroloquinolines is described. Readily available nitroquinolines, bearing the nitro moiety in the carbocyclic ring, are treated with 4-chlorophenoxyacetonitrile in the presence of potassium tert-butoxide/THF to give the analogous vicarious nucleophilic substitution products (5, 8 and 11). These, in turn, are subjected to catalytic hydrogenation to produce 1H-pyrrolo[2,3-f]quinoline (6), 3H-pyrrolo[3,2-f]quinoline (9) and 1H-pyrrolo[3,2-h]quinoline (12) in good yields and relatively short reaction times. The differential activity of two N-alkylated 1H-pyrrolo[2,3-f]quinolines (1) in cisplatin resistant cell lines compared to the corresponding parent lines suggests that these might be useful leads for developing agents for use in drug resistant diseases.