No abstract

Some novel derivatives of thiosemicarbazide and 1,2,4-triazole-3-thiol were synthesized and evaluated for their biological activities. The title compounds were prepared starting from readily available pyridine-2,5-dicarboxylic acid. The reaction carboxylic acid with absolute ethanol afforded the corresponding dimethyl pyridine-2,5-dicarboxylate (1). The reaction of dimethyl-2,5-pyridinedicarboxylate (1) with hydrazine hydrate good yielded pyridine-2,5-dicarbohydrazide (2). Refluxing compound 2 with alkyl/aryl isothiocyanate derivatives for 3-8 h afforded 1,4-disubstituted thiosemicarbazides (3a-e). Base-catalyzed intra-molecular dehydrative cyclization of these intermediates furnished the 4,5-disubstituted bis-mercaptotriazoles (4a-e) in good yield (85%-95%). Among the target compounds, 2,2 ′ -(pyridine-2,5-diyldicarbonyl)bis[N-(pmethoxyphenyl)hydrazinecarbothioamide] (3c) showed very high activity with value of 72.93% against 1,1-diphenyl-2-picrylhydrazyl free radical at the concentration of 25 g/mL. The inhibitory effects of the target compounds against acetylcholinesterase (AChE), hCA I, and II were studied. AChE, cytosolic hCA I and II isoforms were potently inhibited by synthesized these derivatives with K i s in the range of 3.07 ± 0.76-87.26 ± 29.25 nM against AChE, in the range of 1.47 ± 0.37-10.06 ± 2.96 nM against hCA I, and in the range of 3.55 ± 0.57-7.66 ± 2.06 nM against hCA II, respectively.

5-Furan-2-yl[1,3,4]oxadiazole-2-thiol (Ia) and 5-furan-2-yl-4H-[1,2,4]- triazole-3-thiol (Ib) were synthesized from furan-2-carboxylic acid hydrazide. Mannich bases and methyl derivatives were then prepared. The structures of the synthesized compounds were confirmed by elemental analyses, IR and 1H-NMR spectra. Their thiol-thione tautomeric equilibrium is described.

The first-trimester scan is important in routine antenatal care for early detection of fetal defects, and determination of the fetuses at risk of cardiac anomalies and genetic syndromes.

No abstract