Azaadamantanes, a New Promising Scaffold for Medical Chemistry.

Azaadamantanes are nitrogen-containing analogs of adamantane, which contain one or more nitrogen atoms instead of carbon atoms. This substitution leads to several specific chemical and physical properties. The azaadamantane derivatives have less lipophilicity compared to their adamantane analogs, which affects both their interaction with biological targets and bioavailability. The significant increase in the number of publications during the last decade (2009-2020) concerning the study of reactivity and biological activity of azaadamantanes and their derivatives indicates a great theoretical and practical interest in these compounds. Compounds with pronounced biological activity have been already discovered among azaadamantane derivatives. The review is devoted to the biological activity of azaadamantanes and their derivatives. It presents the main methods for the synthesis of di- and triazaadamantanes and summarizes the accumulated data on studying the biological activity of these compounds. The prospects for the use of azaadamantanes in medical chemistry and pharmacology are discussed.

Identification of novel inhibitors for the tyrosyl-DNA-phosphodiesterase 1 (Tdp1) mutant SCAN1 using virtual screening.

Spinocerebellar ataxia syndrome with axonal neuropathy (SCAN1) is a debilitating neurological disease that is caused by the mutation the Tyrosyl-DNA phosphodiesterase 1 (TDP1) DNA repair enzyme. The crucial His493 in TDP1's binding site is replaced with an arginine amino acid residue rendering the enzyme dysfunctional. A virtual screen was performed against the homology model of SCAN1 and seventeen compounds were identified and tested in a novel SCAN1 specific biochemical assay. Six compounds showed activity with IC50 values between 3.5 and 25.1 µM. The most active ligand 5 (3.5 µM) is a dicoumarin followed by a close structural analogue 6 at 6.0 µM. A less potent series of ß-carbolines (14 and 15) was found with potency in the mid-teens. According to molecular modelling an excellent fit for the active ligands into the binding pocket is predicted. To the best of our knowledge, data on inhibitors of the mutant form of TDP1 has not been reported previously. The virtual hits were also tested for wild type TDP1 activity and all six SCAN1 inhibitors are potent for the former, e.g., ligand 5 has a measured IC50 at 99 nM. In the last decade, TDP1 is considered as a promising target for adjuvant therapy against cancer in combination with Topoisomerase 1 poisons. The active ligands are mostly non-toxic to cancer cell lines A-549, T98G and MCF-7 as well as the immortalized WI-38 human fetal lung cells. Furthermore, ligands 5 and 7, show promising synergy in conjunction with topotecan, a clinically used topoisomerase 1 anticancer drug. The active ligands 5, 7, 14 and 15 have a good balance of the physicochemical properties required for oral bioavailability making the excellent candidates for further development.

Novel tyrosyl-DNA phosphodiesterase 1 inhibitors enhance the therapeutic impact of topoteсan on in vivo tumor models.

The druggability of the tyrosyl-DNA phosphodiesterase 1 (Tdp1) enzyme was investigated in conjunction with topoisomerase 1 inhibition. A novel class of thiazole, aminothiazole and hydrazonothiazole usnic acid derivatives was synthesized and evaluated as Tdp1 inhibitors and their ability to sensitize tumors to topotecan, a topoisomerase inhibitor in clinical use. Of all the compounds tested, four hydrazinothiazole derivatives, 20c, 20d, 20h and 20i, inhibited the enzyme in the nanomolar range. The activity of the compounds was verified by affinity experiments as well as supported by molecular modelling. The most effective Tdp1 inhibitor, 20d, was ton-toxic and increased the effect of topotecan both in vitro and in vivo in the Lewis lung carcinoma model. Furthermore, 20d showed significant increase in the antitumor and antimetastatic effect of topotecan in mice. The results presented here justify compound 20d to be considered as a drug lead for antitumor therapy.

Inhibitor of Striatal-Enriched Protein Tyrosine Phosphatase, 8-(Trifluoromethyl)-1,2,3,4,5-Benzopentathiepin-6-Amine hydrochloride (TC-2153), Produces Antidepressant-Like Effect and Decreases Functional Activity and Protein Level of 5-HT2A Receptor in the Brain.

The serotoninergic 5-HT2A receptor is involved in the mechanism of depression and antidepressant drugs action. Earlier we showed that striatal-enriched protein tyrosine phosphatase (STEP) inhibitor - 8-(trifluoromethyl)-1,2,3,4,5-benzopentathiepin-6-amine hydrochloride (TC-2153) affects both the brain serotoninergic system and the brain-derived neurotropic factor that are known to be involved in the psychopathology of depression. In the present study we investigated the effects of chronic TC-2153 administration on behavior in the standard battery of tests as well as the effects of acute and chronic TC-2153 treatment on the brain 5-HT2A receptors in mice. We obtained a prominent antidepressant-like effect of chronic TC-2153 treatment in the forced swim test without any adverse side effects on locomotor activity, anxiety, exploration, motor skill and obsessive-compulsive-like behavior. Moreover, both acute and chronic TC-2153 administration inhibited the functional activity of 5-HT2A receptors estimated by the number of 2,5-dimethoxy-4-iodoamphetamine (DOI, agonist of 5-HT2A receptors)-induced head-twitches. TC-2153 treatment also attenuated the DOI-induced c-fos expression in cortical and hippocampal neurons and reduced the 5-HT2A receptor protein level in the hippocampus and frontal cortex, but not in the striatum. Taken together, our combined data demonstrate that the antidepressant effect of STEP inhibitor TC-2153 could be mediated by its inhibitory properties towards the 5-HT2A receptor-mediated signaling.

[Comparison of behavioral effects of fluoxetine, imipramine and new psychotropic drug TC-2153 on mice with hereditary predisposition to catalepsy].

Behavioral effects of classic antidepressants, fluoxetine and imipramine, and new psychotropic benzopentathiepin TC-2153 (20 mg/kg, per os) were studied on mice differing in the predisposition to catalepsy-noncataleptic AKR strain and cataleptic strains CBA and AKR.CBA-D13Mit76 (D13). Mice of D13 strain was created by transferring the CBA-allele of major locus of catalepsy to AKR genome. In the forced swim test (FST) fluoxetine showed antidepressant effect on mice of all three strains, imipramine was effective only in D13 mice, while TC-2153 produced antidepressant effect on AKR and D13 mice. Unlike to imipramine and fluoxetine, TC-2153 did not produce negative side effects in the open field and elevated plus-maze tests. Thus, TC-2153 produces antidepressant effects similar to imipramine and fluoxetine, without any visible negative side effect on locomotory activity and anxiety. The D13 mice in the FST showed high sensitivity to the studied drugs in comparison to the parent strains and can be used as new genetic model for investigation of the mechanism of antidepressant effects.

[Inhibitory Properties of Nitrogen-Containing Adamantane Derivatives with Monoterpenoid Fragments Against Tyrosyl-DNA Phosphodiesterase I].

It was found that compounds combining diazaadamantane and monoterpenoid fragments are potent inhibitors of new structural type of human recombinant DNA repair enzyme Tyrosyl-DNA phosphodiesterase I (Tdp1). It was demonstrated that the inhibition efficiency depended on the length and flexibility of the aliphatic chain of the substituent.

Effect of 2-aminoadamantane derivatives on behavior of mice in a modified light/dark test.

The effects of two derivatives of 2-aminoadamantane, enantiomers J447H and J579, on the behavior of male and female C57Bl/6J mice were studied using a modified light/dark test. The substances differed by their effects on the behavior of male mice. J579 reduced the number of rearings. J447H in a dose of 1 mg/kg affected more parameters: it reduced exploratory activity 1 h after administration and stimulated exploratory and motor activity in 2 h. In female mice, J447H significantly reduced the number of peepings into holes in 2 h after administration. The results indicate that further analysis of the effects of J579 and especially J447H is required.

[Effect of new potential psychotropic drug, 8-(trifluoromethyl)-1,2,3,4,5-benzopentathiepin-6-amine hydrochloride, on the expression of serotonin-related genes in mouse brain].

Study of molecular mechanisms of psychotropic drug action is the main aim of molecular psychopharmacology. New synthetic analog of variacin 8-(Trifluoromethyl)-1,2,3,4,5-benzopentathiepin-6-amine (TX-2153) was shown to produce anxiolytic and anticonvulsant effects on mice. Here the effect of chronic administration of TX-2153 on expression of some serotonin-related genes in mouse brain was investigated. The drug (10 mg/kg, per os, 16 days) was administered to adult males of ASC (Antidepressant Sensitive Catalepsy) mouse strain characterizing by alterations in behavior and brain serotonin system. The expression of genes encoding 1) the key enzyme of serotonin synthesis, tryptophan hydroxylase 2 (TPH2), 2) main enzyme of serotonin degradation, monoamine oxydase A (MAOA), 3) 5-HT transporter (SERT) and 4) 5-HT(1A) receptor was studied using quantitative RT-PCR. TX-2153 significantly reduced m-RNA level of 5-HT(1A) receptor and MAOA genes in the midbrain without any effect on expression of these genes in the frontal cortex and hippocampus. The drug failed to affect expression of TPH2 and SERT genes in the midbrain. The result indicates involvement of the brain 5-HT system in the molecular mechanism underlying the effect of TX-2153.