Synthesis and biological evaluation of benzothiazin-4-ones: a possible new class of acetylcholinesterase inhibitors.

A series of nineteen benzothiazin-4-ones from N-(3-aminopropyl) piperidine, 4-(2-aminoethyl)morpholine or 1-(2-aminoethyl)piperidine, aliphatic or aromatic aldehyde and thiosalicylic acid, were synthesized in good yields by multicomponent one-pot reactions. The solvent was toluene and this efficient procedure afforded the desired heterocycles in 5 h. Identification and characterization were achieved by NMR and GC-MS techniques. In vitro AChE activities of all compounds were evaluated in cerebral cortex and hippocampus of rats and in general, the results in cortex were more promising than hippocampus. The benzothiazinone 5Bd showed the best AChE inhibition activity IC50 8.48 µM (cortex) and IC50 39.80 µM (hippocampus). The cytotoxicity of seven compounds in MCR-5 human fibroblast cell by SRB test in 24 h were evaluated and 5Bd suggest preliminary safety, showing no cytotoxicity at 100 µM. Finally, these important findings could be a starting point for the development of new AChE inhibitors agents and will provide the basis for new studies.

Efficient synthesis and antioxidant evaluation of 2-aryl-3-(pyrimidin-2-yl)-thiazolidinones.

In the present study, we reported the efficient synthesis of 11 3-(pyrimidin-2-yl)-thiazolidinones in good yields using molecular sieve as the desiccant agent. In addition, we have evaluated the antioxidant capacity of the synthesized compounds by the 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH•) and the 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS(+•) ) radicals scavenging assay. Six compounds showed antioxidant activity towards DPPH• (EC50 between 16.13 and 49.94 µg/mL) and also demonstrated excellent activity regarding ABTS(+•) (TEAC: 10.32-53.52). These results showed that compounds 3-(pyrimidin-2-yl)-thiazolidinones may be easily synthesized by a less expensive procedure and could be a good starting point to the development of new antioxidant compounds.

7-chloroquinolin-4-yl arylhydrazone derivatives: synthesis and antifungal activity.

Fifteen 7-chloro-4-arylhydrazonequinolines have been evaluated for their in vitro antifungal activity against eight oral fungi: Candida albicans, C. parapsilosis, C. lipolytica, C. tropicalis, C. famata, C. glabrata, Rhodutorula mucilaginosa, and R. glutinis. Several compounds exhibited minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) activities comparable with the first-line drug fluconazole. These results could be considered as an important starting point for the rational design of new antifungal agents.

Sonochemistry: a good, fast and clean method to promote the synthesis of 5-arylidene-2,4-thiazolidinediones.

The efficient synthesis of sixteen 5-arylidene-2,4-thiazolidinediones by aldol condensation reaction of 2,4-thiazolidinedione, mono- and di-substituted arenealdehydes and KOH using ultrasound irradiation is reported. The desired compounds were obtained in a few min (10-30 min) with moderate to good yields (25-81%).

Antifungal activity of 3-(heteroaryl-2-ylmethyl)thiazolidinone derivatives.

Thiazolidinones, synthesized from multicomponent reactions of 2-heteroarylmethylamine, arenealdehydes and mercaptoacetic acid, have been tested against six yeasts, namely Candida albicans, C. parapsilosis, C. guilliermondii, Cryptococcus laurentii, Trichosporon asahii and Rhodotorula spp. The activities were expressed as minimum inhibitory concentrations (MIC) and the minimum fungicidal concentrations (MFC). The most affected yeasts were Rhodotorula spp and T. asahii. The cytotoxicities of the thiazolidinones against the fibroblast 3T3/NIH cell line are also described. The antifungal results and the low cytotoxicity of the compounds in this work provide good guides for the further development of active compounds.

Ultrasonics promoted synthesis of thiazolidinones from 2-aminopyridine and 2-picolilamine.

The efficient multicomponent synthesis of thiazolidinones from the reaction of arenealdehydes, mercaptoacetic acid and 2-picolilamine or 2-aminopyridine under ultrasound irradiation are reported. The reaction with 2-aminopyridine needs a Lewis acid catalysis to afford the corresponding 2-aryl-3-(pyridin-2-yl)-1,3-thiazolidin-4-ones. All novel compounds were identified and characterized by (1)H and (13)C NMR spectra. Applying the sonochemical methodology, two series of heterocyclic thiazolidinones were synthesized in good yields after short reaction times.

Ultrasound-promoted synthesis of 3-trichloromethyl-5-alkyl(aryl)-1,2,4-oxadiazoles.

The alternative synthesis of 12 1,2,4-oxadiazoles using ultrasound irradiation from trichloroacetoamidoxime and acyl chlorides is reported. Seven of them are novel compounds. The 3-trichloromethyl-5alkyl(aryl)-1,2,4-oxadiazoles have been synthesised in better yields and shorter reaction times compared to the conventional method. This protocol can be applicable for preparation of 1,2,4-oxadiazoles containing aryl or alkyl groups attached at their C-5 side-chain.

Ultrasound promoted synthesis of thioesters from 2-mercaptobenzoxa(thia)zoles.

An ultrasound-enhanced method has been developed for the synthesis of a variety of thioesters from benzoyl chlorides and 2-mercaptobenzoxa(thia)zoles. Applying this methodology, 14 compounds were synthesized in excellent yields.