Search

The authors report the synthesis of three new derivatives of gallic acid with L-thiazolidine-4-carboxylic acid. The new compounds were tested for radical scavenger activity against doxorubicin toxicity in mice and for antitoxic activity against acetaldehyde and formaldehyde toxicities in rats. Unlike the utilized standards, the new compounds show no activity.

6-Substituted 5-hydroxymethylimidazo[2.1-b]thiazoles and 2,3-dihydro-5-hydroxymethylimidazo[2,1-b]thiazoles (VII - XII) were prepared by reducing the corresponding aldehydes (I - VI) with NaBH4. Among the acetic (VII a - XII a), methylcarbamic (VII b - XII b) and ethylcarbamic esters (VII c - XII c), compound (VII a) was active in a preliminary P388 leukemia test.

A new series of 3-methoxy-1,2-benzisothiazol-5-ylacetic acid analogs and some of their functional derivatives were synthesized and tested for their analgesic, antipyretic and anti-inflammatory activities. From an analysis of the relationship between structure and pharmacological activity, it was observed that modifications in the acid group induced useful variations in the parameters studied.

We have prepared a group of ethyl imidazo [2,1-b]thiazole-6- and imidazo[2,1-b]benzothiazole-2-acetates, starting from some substituted 2-aminothiazoles and 2-aminobenzothiazoles, by reaction with ethyl 4-bromoacetoacetate. From these esters we have obtained the corresponding acetic acids, and we have tested their anti-inflammatory activity.

The synthesis of 2,3-dihydro-5-formylimidazo[2,1-b]thiazoles with different substituents at position 6 (CH3, C6H5, Cl, Br) is reported; thiosemicarbazones and tosylhydrazones were prepared from these aldehydes and from the 2,3-unsaturated analogues: these derivatives, submitted to a preliminary test, did not show significant antileukemic activity.

Reaction of 2-aminothiazole with the N,N-dialkyl or (N-alkyl, N-phenyl) ethoxycarbonylacetamide/POCl3 reactant (I), in refluxing 1,2-dichloroethane, yielded the corresponding N,N-disubstituted 5-amino-7H-thiazolo[3,2-a]pyrimidin-7-ones (VII) along with lower quantities of isomeric N,N-disubstituted 7-amino-5H-thiazolo[3,2-a]pyrimidin-5-ones (VIII). Structures attributed to isomeric compounds (VII) and (VIII) were supported both by spectroscopic and chemical evidences. Some compounds (VII) were submitted to pharmacological investigation and results are described: only (N-alkyl, N-phenyl)derivatives (VII f,g) showed a significant, even if mild, activity as peripheral analgesics.

The synthesis and chemical and pharmacological properties of 3-benzyl-1,2-benzisothiazoleaminoalkyl derivatives are reported. These compounds were studied because 4-dimethyl-2-phenyl-2-(1,2-benzisotiazol-3-yl)-butyramide and N,N-dimethyl-3-phenyl-3-(1,2-benzisothiazol-3-yl)propylamine were recently found to have antispasmodic properties. Most of the compounds studied aspecifically inhibited the contracturant effects of acetylcholine, histamine and BaCl2. Three of them showed mixed antagonism (competitive and non-competitive) versus acetylcholine and histamine, showing both antimuscarinic and antihistaminic properties. However the antimuscarinic action prevailed over the others, as shown by pA2 and pD'2 calculated values. On the basis of the results obtained, the structure-activity relationships is discussed.

The synthesis and chemical behaviour of N-(benzothiazolyl-2-carbonyl)-N-1-(2-thiazolyl)hydrazines is described. All the products were screened in vitro for antimicrobial activity. Some of them were found to give positive results.

The synthesis of a series of 2-substituted 3-[2-(1,3,4-thiadiazolyl)]-4-thiazolidinones is described. Evaluation of these derivatives against P 388 lymphocytic leukemia growth in mice revealed that no compound shows significant activity. 2-(2-Thienyl)-3-[2-(1,3,4-thiadiazolyl)]-4-thiazolidinone (I) whose significant activity on P 388 leukemia was reported in a previous paper, was tested against other experimental tumors: it exhibits slight activity also against L 1210 leukemia and M 5076 ascitic sarcoma.

2-Substituted 3-(2-thiazolyl) and 3-[2-(1,3,4-thiadiazolyl)]-4-thiazolidinones were prepared and tested for their activity against the leukemic P 388 tumor system in mice. The thiadiazolyl derivatives are generally more active than the thiazolyl ones and some of them showed significant activity.

Some di-N-(20-aminothiazolyl)derivatives were synthesized and then cyclyzed to give the thiazolidin-4-ones (II) and (III). All compounds were tested for their activity against the leukemic P 388 tumor system in mice.

This paper describes the synthesis of 3-benzyl-1,2-benzisothiazole derivatives, structurally related to benzylisoquinolines, and their analgesic activity studied using writhing technique in the mouse. The presence of lipophilic substituents in position 3, 4 of the benzyl group give substances with analgesic activity, although their "potency" is lower than that shown by papaverine.

The synthesis of a new series of 4-(3-oxo-1,2-benzisothiazolin-2-yl)phenylalkanoic compounds and some of their functional derivatives is described. The compounds, on the basis of data obtained from 1,2-benzisothiazolin-3-one derivatives, were biologically examined mainly for their antiphlogistic and analgesic actions. Results obtained, in analyzing the relationship between structure and pharmacological actions, suggest that both 4-(3-oxo-1,2-benzisothiazolin-2-yl)-phenyalkanoic acids and o-sulphobenzimido alkanoic esters are endowed with pain-killing effects comparable in potency and efficacy with phenylbutazone.

Based on previous observations, the preparation, some physicochemical (partition coefficient, pKa) and pharmacological properties of 4-(3-oxo-1,2-benzisothiazolin-2-yl)alkanoic, benzoic, phenyl, phenoxyalkanoic acids and of some of their functional derivatives are reported. All new compounds were biologically examined for their antiphlogistic, analgesic and antipiretic actions, in comparison with those of 1,2-benzisothiazolin-2-one and with those of ibuprofen as the antiphlogistic, analgesic, antipyretic arylalkanoic prototype. Structure-activity relationships showed that the 1,2-benzisothiazolin-2-one and its new alkanoic and arylalkanoic derivatives have strong actions which are however specific for some of the tested pharmacological properties. From this point of view, the synthesized substances have a narrow spectrum of activity, if compared with ibuprofen which is at the same time an antiphlogistic, analgesic and antipiretic substance. The antiphlogistic and antipyretic activities of 4-(3-oxo-1,2-benzisothiazolin-2-yl)benzoic, phenylacetic and phenylmethylacetic acids and the antipyretic and analgesic actions of 3-oxo-1,2-benzisothiazolin-2-ylacetic acid, which are comparable or higher in "potency" than those of ibuprofen, are noteworthy.

The synthesis of some phthalimido-derivatives of the pyrimidine and thiazole ring systems is described. The functional groups have been suitably selected to enhance structural analogy with the pairs of pyrimidine and purine bases present in nucleic acids. In preliminary tests some of these compounds have shown inhibitory activity towards RNA polymerase reaction in vitro.

A new series of 5-(4-halobenzoyl)-4-amino-3-(2-dialkylamino-ethylthio)thieno [2,3-c] and [3,2-d] isothiazole derivatives has been synthetized. The compounds were evaluated for antifungal activity on yeast and dermatophytes. The compound (VI b) resulted about thirty times less potent than miconazole on dermatophytes.

Tetrazole analogs of a series of known 1,2-benzisothiazolalkanoic acids were synthesized and tested for anti-inflammatory, antipyretic and analgesic activities in comparison with their corresponding carboxylic acids. The benzisothiazoliltetrazoles showed high antipyretic activity and each tetrazole, except one, was appreciably more potent than the corresponding acid. The examined tetrazoles are generally inactive as anti-inflammatory agents and weakly active in the mouse writhing test, with effect comparable with those of the corresponding carboxylic acids.

As a part of a study on H2-agonists, the preparations and properties are reported for a representative group of 2-aminothiazolethylamine derivatives which contain the gastric secretion stimulating S-aminoalkylisothiourea moiety. The test compounds were obtained by known methods or from 2-(2-amino-5-thiazolyl)ethyl chloride and were tested for their possible histamine-like activities on different biological substrates. From the biological results it appears that the behaviour of the substances is rather complex, but the following general observations can be pointed out: the contracturant properties, sometimes quite marked, do not derive from direct H1-specific activities; the effects, particularly evident in stimulating in vitro or in vivo gastric secretion, in relaxing gall-bladder smooth muscle, on auriculae and/or on blood pressure, are not competitively antagonized by cimetidine; none of the tested compounds proved to be an antagonist of histamine H2-receptors, while one of them is found to inhibit competitively the H1-receptors. On the basis of structure-activity relationships it can be excluded that the iuxta-nuclear NH2 group of 2-aminothiazolethylamines reacts, in some way, with the H2-receptors, since, in this case, the 2-aminothiazole group is not a pharmacophore like the 2-aminoimidazole or isothiurea group. Consequently the hypotheses, that the flexibility of the molecule is a fundamental requirement for the H2-stimulating properties of S-(3-dimethylaminopropyl)isothiurea and that the different activities of 2-aminohistamine, in comparison with those of 2-methylhistamine, are due to the existence of a hydrophilic area suitable for the allocation of the iuxta-nuclear NH2 group in the H2-receptor, are strengthened.

A series of 5-acyl-4-amino-3-(2-dialkylaminoethyl)thieno-[2,3-c] and [3,2-d]isothiazole derivatives was synthesized. The compounds were evaluated for antifungal activity.

Starting from 3-aryl-4-amino-5-mercapto-4H-1,2,4-triazoles (II), two series of 3,6-disubstituted 7H-1,2,4-triazol [3,4-b] [1,3,4] thiadiazines (III) and their 5-carboxymethylthio derivatives (IV) were prepared. From the mercapto-amino-triazoles (II) because of their reactivity in some oxidising media, were obtained the triazole derivatives (V), (VI) and (VII). The synthesis of the alpha-thioketones (VIII) of 3-aryl-5-mercapto-1,3,4-oxadiazoles (I), used in alternative synthesis of triazole-thiadiazines (III), is also reported. All the substances described were subjected to biological screening. In the tests, the carboxymethylthiotriazole (IV) showed weak antiinflammatory activity (carrageenin edema) and more consistent scavanger activity, in vitro, on superoxide anions. The triazole-thiadiazines (III) and triazoles (II), (V) and (VI) showed moderate antimycotic activity.

Two new series of 2-aryletenylthiazolo-4-acetic (IV-XII) and 4-carboxylic (XIII-XXI) acids substituted with alkoxy groups in the benzene ring were synthesized. The compounds were subjected to comparative tests of antiinflammatory, analgesic and antipyretic activity.