Experimental and theoretical conformational studies of hydrazine derivatives bearing a chromene scaffold

Neuroprotective evaluation of novel substituted 1,3,4-oxadiazole and aroylhydrazone derivatives

The paper reports on the facile and convenient synthesis of a series of novel 2,5-substituted 1,3,4-oxadiazoles 3a-f and that of aroylhydrazone-based molecular hybrids 5a-g from readily available starting materials. The structure of the compounds was confirmed by IR, ¹H-NMR, ¹³C-NMR and HRESI-MS spectral data. The toxicological potential of the compounds was evaluated by monitoring the synaptosomal viability and the levels of reduced glutathione in rat brain synaptosomes, isolated by Percoll gradient. The neuroprotective effects were assessed in vitro in a model of 6-hydroxydopamine-induced neurotoxicity. Administered alone, at a concentration of 40 µM, most of the 1,3,4-oxadiazole derivatives and all of the hydrazone derivatives exhibited weak statistically significant neurotoxic effects, compared to the control. Two of the compounds from the novel oxadiazoles 3a and 3d did not have any toxicity. In a model of 6-OHDA-induced oxidative stress, again 3a and 3d and all aroylhydrazone derivatives 5a-g revealed statistically significant neuroprotective effect by preserving the synaptosomal viability and the level of reduced glutathione, against the toxic agent. Some of the compounds may have neuroprotective effects due to possible stabilization of the synaptosomal membrane and/or because of the preserved reduced glutathione. Additionally, all the compounds display a good predicted ADME profile.

Investigation of 4-Hydrazinobenzoic Acid Derivatives for Their Antioxidant Activity: In Vitro Screening and DFT Study

Hydrazinobenzoic acid derivatives with isothiocyanate, benzylidene, and acid anhydride core units (1-13) were previously synthesized and fully characterized. Targets 1-13 were investigated for their antioxidant activities using different in vitro assays such as 1,1-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS), ferric reducing antioxidant power (FRAP), and reducing power capability. All derivatives showed antioxidant properties in relation to the standard butylated hydroxylanisole (BHA). Superior antioxidant activities was observed for compounds 3 and 5-9 at a concentration of 20 μg/mL (70-72%) when tested by the DPPH method in comparison to BHA (92%), and compounds 1-10 showed the highest free radical quenching activity (80-85%) when examined by ABTS at 20 μg/mL in relation to BHA (85%). Density function theory (DFT) studies were carried out using the B3LYP/6-311G(d,p) level of theory. Several antioxidant descriptors were calculated for targets 1-13 compared with BHA. Targets 1-13 were proposed to exhibit their antioxidant activities via the following three proposed antioxidant mechanisms: single electron transfer (SET), hydrogen atom transfer (HAT), and sequential proton loss electron transfer (SPLET). The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies and electron levels for 1-13 were also determined.