Synthesis of 2-amino-5-sulfanyl-1,3,4-thiadiazole derivatives and evaluation of their antidepressant and anxiolytic activity.

Recently a series of 2-amino-5-sulfanyl-1,3,4-thiadiazole derivatives bearing different substituents were synthesized and screened pharmacologically in order to evaluate their central nervous system activity. The purpose of this study was to evaluate the effects of the title compounds on CNS activity by varying the substituents in the thiadiazole moiety. It was found that some of these compounds possess marked antidepressant and anxiolytic properties comparable in efficiency to the reference drugs Imipramine and Diazepam. The most potent compound 3k was further investigated to complete its pharmacological profile with respect to undesired side effects. Behavioral results showed that 3k is a very promising compound, characterized by a mixed antidepressant-anxiolytic activity accompanied by a therapeutic dose range that is essentially 2 orders of magnitude less than that at which side effects such as sedation and amnesia are evident.

N-deacetyl-N-aminoacylthiocolchicine derivatives: synthesis and biological evaluation on MDR-positive and MDR-negative human cancer cell lines.

A new series of N-deacetyl-N-(N-trifluoroacetylaminoacyl)thiocolchicine derivatives 9-15 have been synthesized starting from the corresponding N-deacetylthiocolchicine (3) and the N-trifluoroacetylamino acids 5-8 which were used as a racemic mixture. The trifluoroacetyl protecting group has been removed easily, giving the corresponding N-deacetyl-N-aminoacylthiocolchicines 16-22. Optical pure compounds 9-22 were isolated from the diastereoisomeric mixture or were prepared starting from compound 3 and an optical pure amino acid derivative; the configuration of each compound was assigned unequivocally. The diastereoisomeric couples of amino acids synthesized were tested, and their antiproliferative activity on MDR-positive and MDR-negative human cancer cell lines was evaluated.

A Novel Class of Conformationally Constrained, Masked Cysteines: Synthesis of 2-Alkyl- and 2-Arylsulfanyl-1-aminocyclopropanecarboxylic Acids.

A convenient synthesis of 4-sulfanylmethylene-5(4H)-oxazolones 3 was realized starting from 4-(chloromethylene)oxazolone 1 and mercaptans 2. Oxazolones 3 were used as starting materials for the preparation of unknown 2-sulfanyl-1-aminocyclopropanecarboxylic acid derivatives 5 and7. Oxazolones 3 were cyclopropanated at the exocyclic double bond with diazomethane, giving a mixture of the two (Z)- and (E)-spirocyclopropane oxazolones 4 with good diastereoselectivity. These were then treated with ethanol and DMAP to produce the corresponding carboxylates 5. The trityl derivative 5d was converted into a mixture of diastereoisomeric disulfides 6 using iodine in ethanol solution. Disulfides 6 are convenient synthons for the preparation of 3-sulfanyl-substituted 2,3-methanoamino acids 7.

Antiproliferative activity of colchicine analogues on MDR-positive and MDR-negative human cancer cell lines.

In this study the in vitro antitumor activity of a series of 20 colchicine analogues was tested and compared with colchicine and thiocolchicine on three different human cancer cell lines, two of which express the multidrug-resistance (MDR) phenotype. At concentrations from 1 nM to 100 microM, all compounds tested inhibited cancer cell proliferation. The IC50 values indicate that the three fluorinated analogues were the most active compounds, with a similar decreasing order of potency (IDN 5005 > IDN 5079 > IDN 5080) on the two MDR-expressing cell lines, whereas thiocolchicine was the most effective compound on the MDR-negative MDA-MB 231 cells. A strong correlation (r = 0.94; P = 0.004) was found between IC50 values obtained using the two MDR-positive cell lines. Conversely, IC50 values obtained in MDA-MB 231 cells did not show a significant correlation with MDR-positive cell lines, thereby suggesting some difference in the antiproliferative mechanism(s) of colchicine analogues. Cell cycle analysis of the most active analogues in breast cancer cells showed a relationship between cell cycle blocking activity and growth inhibition. The most active agents on the MDR-positive MCF7 ADRr cell line, after 24 h of culture, in terms of cell cycle blocking activity were the three fluorinated analogues. Interestingly, after 72 h, when the cell cycle block subsided, a consistent amount of DNA fragmentation was evident. The extent of cell cycle block, measured as the G2/G1 ratio, was significantly correlated with the apoptosis rate expressed as a percentage of DNA fragmentation on both cell lines, thereby suggesting that a large number of blocked cells underwent the apoptotic pathway.

2-[N'-(3-arylallylidene)hydrazino]adenosines showing A2a adenosine agonist properties and vasodilation activity.

A series of 2-[N'-(3-arylallylidene)hydrazino]adenosines were prepared and studied in binding and functional assays to assess their potency for the A2a compared with the A1 adenosine receptor. These analogs possess A2a receptor affinity in the low nanomolar range associated with weak interaction with the A1 receptor. Among the compounds, in rat tissues, 2-[N'-[3-(4-nitrophenyl)allylidene] hydrazinoadenosine (5g) had the most potent affinity for the A2a receptor, the K(i) value being 23 nM. The type and position of substituents on the phenyl ring show a moderate influence on biological activity, allowing the conclusion that the latter is mostly due to the allylidenehydrazino side chain. From functional experiments 2-[N'-(2-furylmethylidene)hydrazino]adenosine (4b), 2-[N'-(3-phenylallylidene)hydrazino]adenosine (5a) and 2-[N'-[3-(2-furyl)allylidene]hydrazino]adenosine (5b) appeared to be potent in inducing vasorelaxation (an A2a-mediated response) without appreciable effects on the heart rate (an A1-mediated action). While the lack of effects on heart rate is clearly explained by the poor affinity for A1 receptors, more difficult appears the interpretation of vasorelaxant properties displayed by some compounds. Affinity for A2a has a major role, but other types of interactions, yet to be identified, may play a part.