Carbonic anhydrase inhibitors: Inhibition of cytosolic/tumor-associated carbonic anhydrase isozymes I, II, and IX with benzo[b]thiophene 1,1-dioxide sulfonamides

A series of selected benzo[b]thiophene-5- and 6-sulfonamide derivatives previously reported to show cytotoxic activity and some others newly synthesized has been tested for the interactions with several CA isozymes, some of which are known to be involved in tumorigenesis (hCA IX), whereas others are ubiquitously found in many normal tissues (the cytosolic isoforms hCA I and II). The unsubstituted sulfonamides inhibited hCA I with inhibition constants in the range of 63-138 nM, hCA II with inhibition constants in the range of 6.3-8.8 nM, and hCA IX with inhibition constants in the range of 2.8-15 nM, being thus more active than clinically used inhibitors such as acetazolamide, methazolamide, ethoxzolamide, dichlorophenamide or indisulam (E 7070). Some of these derivatives also showed some selectivity for the inhibition of the tumor-associated (hCA IX) over the cytosolic isozyme hCA II. Although these derivatives may act on many targets other than the CAs (such as the NADH oxidase) or may induce apoptosis by accumulation of reactive oxygen species, it is quite important to try to decipher as many as possible of the potential mechanisms that lead to derivatives with potent antitumor activity in order to develop novel therapeutic strategies for the management of cancer.

Synthesis and cytotoxic activity of lipophilic sulphonamide derivatives of the benzo[ b ]thiophene 1,1-dioxide

In the search of new compounds with antineoplastic activity, we have analysed the effect of several structural modifications on the nucleus 6-benzo[b]thiophenesulphonamide 1,1-dioxide on its cytotoxic activity on tumour cells. Lipophilic substituents on the sulphonamide group significantly increased the cytotoxic activity measured using a panel of human tumour cell lines. Only slight variations on cytotoxicity were obtained when the sulphonamide group occupied the position 5 of the system. The most active compound was the N-4-methoxyphenyl derivative 15, which showed GI(50) values of 1-9 nM against HT-29, CCRF-CEM, K-562 and MEL-AC cells and of 200 nM against HTB-54 cells. Free access to the 3-position of the heterocyclic system seems to be required to obtain cytotoxic derivatives. Derivative 15 was also active at the same level of commercial Doxorubicine against cultured normal human lung fibroblasts.

CoMFA-SIMCA Model for antichagasic nitrofurazone derivatives

The physico-chemical properties of some 5-nitro-2-furaldehyde semicarbazones (nitrofurazones) and thiophene analogues were compared with their in vitro and in vivo trypanocidal activity against Trypanosoma cruzi (Tulahuen strain). 3D-QSAR models were obtained by applying the SIMCA methodology to the electrostatic and steric fields (CoMFA fields) of the molecules. Nitrofurazones bearing N4 substituents. which cover a range of 14-17 A from the nitro group with a thickness of about 6 A when considering the extended conformer. produced complete survival in infected mice. The in vitro model allows larger N4 substituents than the SURVival model, but they must not bear positive centres in the region 15-16 A from the nitro group. Moreover, the in vitro model is in agreement with the active site of trypanothione reductase (TR). Both models can be of use in the design of novel drugs bearing an amide-like group at a distance of 7-9 A from an easily reducible group.

New 5H-[1,3]thiazolo[3,2-a]pyrido[3,2-e]pyrimidin-5-one derivatives as diuretics

A series of new 5H-[1,3]thiazolo[3,2-a]pyrido[3,2-e] pyrimidin-5-ones 3-substituted and/or 8,9-hydrogenated was prepared and tested for their diuretic, natriuretic and kaliuretic activities on male Wistar rats at a dosage of 25 mg/kg or less. Diuretic and saliuretic activities were strongly influenced by substituents in 3-position. Quantitative structure-activity relationships show that electron withdrawn substituents in 3-position enhance both diuretic and saliuretic activities at 25 mg/kg. Global analysis of the variations introduced on pyridine, pyrimidine and thiazole rings of this tricyclic system showed an increases of diuretic and natriuretic activities when the formal charge on N9a and C9b increases. Potassium ion excretion also increases, although not as drastically a in the earlier cases. Regression equations were calculated by partial least squares method (PLS) and validated by the cross-validation (leave-one-out) technique.

New 2-aryl-1,2,3,4-tetrahydropyrido[2,3-d]pyrimidin-4-one derivatives as diuretics

2-Aryl-1,2,3,4-tetrahydropyrido[2,3-d]pyrimidin-4-one derivatives having various substituents at the 4'-position, H or methyl at 1,3-positions and nitro or amino at 6-position were prepared and tested for their diuretic, natriuretic and kaliuretic activities on male Wistar rats at a dosage of 25 mg/kg or less. 2-(3-Pyridyl) derivatives were inactive. 1,3-Dimethyl-6-nitro-2-phenyl derivatives (1) were active depending on the electronic character of the 4'-substituent but at the same time were sodium-sparing. However, 1(H),3(H)-6-nitro-2-phenyl derivatives (2) were generally inactive as diuretics but active as potassium-sparing drugs. 6-Amino-1(H),3(H)-2-phenyl derivatives (4) were active as diuretics depending on dipolar moment of the substituent at the 4'-position, and induced moderate potassium release. The 6-amino-2-(4-trifluoromethylphenyl)-1, 2,3,4-tetrahydropyrido [2,3-d]pyrimidin-4-one (4f) remained active up to a dosage of 3 mg/kg. The structure-activity relationships were carried out in light of the adaptative least squares (ALS) method and discriminant functions for diuretic compounds were established.

Quantitative structure-mutagenic activity relationships of triazino indole derivatives

The mutagenicity of 3-(4'-benzylidenamino)-5H-1,2,3-triazin[5,4-b]-indol-4-one derivatives, new compounds with considerable platelet antiaggregating activity, was assayed with the Ames test using the Salmonella typhimurium strains TA97, TA98, TA100 and TA102. The adaptive least-squares method (ALS method) was used to carry out a quantitative structure-activity relationship (QSAR) analysis. Three equations, based on 10 congeners, were found for strains TA97, TA98 and TA100. The results suggest that lipophilicity of the substituent decreases the mutagenicity of the series.

New 5H-[1,3]thiazolo[3,2-a]pyrido[3,2-e]pyrimidine derivatives as diuretics

New 5H-[1,3]thiazolo[3,2-a]pyrido[3,2-e]pyrimidines 1 and 6,10-dihydro-5H-pyrido[3',2':5,6]pyrimido[2,1-c] [1,2,4]triazines 4 with 5-one, 5-thione or 5-hydrazono substituents and in some cases 1,2,3,4 or 8,9 hydrogenated are synthetized. The diuretic, natriuretic and kaliuretic activities of these compounds in Wistar rats at a dose of 24 mg/kg were estimated. A series of 24 possible derivatives of 1 and 4 possessing diuretic and saliuretic activities are investigated for structure-activity relationships in light of Fujita-Ban model. The Fujita-Ban group contributions have been calculated for different structural variations on the parent ring 1a. It is observed that the hydrogenation of pyridine, [1,3]thiazole or [1,2,4]triazine rings on 1 or 4 decrease the diuretic and saliuretic activities.

Diuretic and hypotensive activities of 4-anilino derivatives of 2-methylthiopyrido[2,3-d]pyrimidines

The synthesis of a series of 12 compounds referring to 4-anilino-2-methylthiopyrido [2,3-d]pyrimidines (1-12), and the results of a study of their diuretic, saliuretic and antihypertensive activities are reported. Most of this compounds showed significant diuretic activity at the dosage of 3-24 mg/kg. The 4-Anilino-2-methylthiopirido[2,3-d]pyrimidine 1 remained active to a dosage of 1 mg/kg. The diuretic activity of these compounds implied an increase in the Na+ excretion. Some of the most active diuretics have been studied for antihypertensive effect.