Cotinine (COT) and 6-hydroxy-L-nicotine (6HLN) are two nicotinic derivatives that possess cognitive-improving abilities and antioxidant properties in different rodent models of Alzheimer’s disease (AD), eluding the side-effects of nicotine (NIC), the parent molecule. In the current study, we evaluated the impact of COT and 6HLN on memory deterioration, anxiety, and oxidative stress in the scopolamine (SCOP)-induced zebrafish model of AD. For this, COT and 6HLN were acutely administered by immersion to zebrafish that were treated with SCOP before testing. The memory performances were assessed in Y-maze and object discrimination (NOR) tasks, while the anxiety-like behavior was evaluated in the novel tank diving test (NTT). The acetylcholinesterase (AChE) activity and oxidative stress were measured from brain samples. The RT-qPCR analysis was used to evaluate the npy, egr1, bdnf, and nrf2a gene expression. Our data indicated that both COT and 6HLN attenuated the SCOP-induced anxiety-like behavior and memory impairment and reduced the oxidative stress and AChE activity in the brain of zebrafish. Finally, RT-qPCR analysis indicated that COT and 6HLN increased the npy, egr1, bdnf, and nrf2a gene expression. Therefore, COT and 6HLN could be used as tools for improving AD conditions.

The nicotinic derivatives, cotinine (COT), and 6-hydroxy-L-nicotine (6HLN), showed promising cognitive-improving effects without exhibiting the nicotine’s side-effects. Here, we investigated the impact of COT and 6HLN on memory impairment and the oxidative stress in the Aβ_25-35-induced rat model of Alzheimer’s disease (AD). COT and 6HLN were chronically administered to Aβ_25-35-treated rats, and their memory performances were assessed using in vivo tasks (Y-maze, novel object recognition, and radial arm maze). By using in silico tools, we attempted to associate the behavioral outcomes with the calculated binding potential of these nicotinic compounds in the allosteric sites of α7 and α4β2 subtypes of the nicotinic acetylcholine receptors (nAChRs). The oxidative status and acetylcholinesterase (AChE) activity were determined from the hippocampal tissues. RT-qPCR assessed bdnf, arc, and il-1β mRNA levels. Our data revealed that COT and 6HLN could bind to α7 and α4β2 nAChRs with similar or even higher affinity than nicotine. Consequently, the treatment exhibited a pro-cognitive, antioxidant, and anti-AChE profile in the Aβ_25-35-induced rat model of AD. Finally, RT-qPCR analysis revealed that COT and 6HLN positively modulated the bdnf, arc, and il-1β genes expression. Therefore, these nicotinic derivatives that act on the cholinergic system might represent a promising choice to ameliorate AD conditions.

Over the past decade, cold atmospheric plasma (CAP) has undergone extensive research as a promising therapeutic approach in oncology, with different treatment methods and exposure configurations being investigated and resulting in various biological effects, most of them after long exposure or treatment durations. This study aimed to evaluate the potential of a custom-made CAP generation source to produce plasma-activated medium (PAM) with cytotoxic effects and subsequently to establish the optimal exposure and treatment parameters. The exposure’s electrical parameters, as well as pH and ${\mathrm{NO}}_2^{-}$ content of PAM were analyzed. The cytotoxic potential and optimal parameters of the treatment were established by evaluating the viability of human osteosarcoma cells (HOS cell line) and human osteoblasts (HOB cell line) treated with PAM under different conditions. Our results showed that indirect treatment with CAP presents selective dose-dependent cytotoxic effects, while the cell viability decrease was not found to be correlated with the PAM acidification due to CAP exposure. The Griess assay revealed very high and long-term stable concentrations of ${\mathrm{NO}}_2^{-}$ in PAM. Overall, this study presents a simple and faster method of producing PAM treatment with cytotoxic effects on HOS cells, by using a custom-built CAP source.