Synthesis, Spectroscopic Analysis, and in Vitro/in Silico Biological Studies of Novel Piperidine Derivatives Heterocyclic Schiff-Mannich Base Compounds.

In the present study, 3-substitued-4-(4-hydroxybenzylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (S1-8) were synthesized by treating 4-hydroxybenzaldehyde (B) with eight different 3-substitued-4-amino-4,5-dihydro-1H-1,2,4-triazole-5-ones (T1-8) in acetic acid medium, separately. The synthesized Schiff bases (S) were reacted with formaldehyde and secondary amine such as 4-piperidinecarboxyamide to afford novel heterocyclic bases. 3-Substitued-4-(4-hydroxybenzylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (T) were treated with 4-piperidinecarboxyamide in the presence of formaldehyde to synthesize eight new 1-(4-piperidinecarboxyamide-1-yl-methyl)-3-substitued-4-(4-hydroxybenzylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (M1-8). The structure characterization of compounds was carried out using 1 H-NMR, IR, HR-MS, and 13 C-NMR spectroscopic methods. The inhibitory properties of the newly synthesized compounds were calculated against the acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and glutathione S-transferase (GST) enzymes. Ki values were calculated in the range of 20.06±3.11-36.86±6.17 µM for GST, 17.87±2.91-30.53±4.25 µM for AChE, 9.08±0.69-20.02±2.88 µM for BChE, respectively, Besides, IC50 values were also calculated. Best binding scores of -inhibitors against used enzymes were calculated as -12.095 kcal/mol, -12.775 kcal/mol, and -9.336 kcal/mol, respectively. While 5-oxo-triazole piperidine-4-carboxamide moieties have a critical role in the inhibition of AChE and GST enzymes, hydroxy benzyl moiety is important for BChE enzyme inhibition.

Cholinesterases, α-glycosidase, and carbonic anhydrase inhibition properties of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives: Synthetic analogues for the treatment of Alzheimer's disease and diabetes mellitus.

In this study, using the Cu(OTf)2 catalyst, 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivative molecules were carried out in one step and with high yield (86-91%). The previously synthesized 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives, carbonic anhydrase I and II isozymes (hCA I and II), acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and α-glycosidase (α-Gly) enzymes with Ki values in the range of 4.88-15.94 nM for hCA I, 7.04-20.83 nM for hCA II, 68.25-158.27 for AChE, 60.17-91.27 for BChE and 0.36-2.36 nM for α-Gly, respectively. In silico studies were performed on the molecules inhibiting hCA I, hCA II, AChE, BChE and α-Gly receptors. When we evaluated the data obtained in this work, we determined the inhibition type of the 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives at the receptors. Reference inhibitors were used for all enzymes.