Investigation of the effects of Hypericum uniglandulosum Hausskn. ex Bornm. Achillea pseudoaleppica Hub.-Mor. and Nepeta nuda subsp. nuda L. essential oils on the central nervous system with in vivo and in silico models

In this study, the effects of Hypericum uniglandulosum Hausskn. ex Bornm. (Hypericaceae), Achillea pseudoaleppica Hub.-Mor. (Asteraceae) and Nepeta nuda subsp. nuda L. (Lamiaceae), essential oils on the central nervous system were examined with in vivo and in silico models. In this regard, the effects and mechanism of action of essential oils from these plants, naturally distributed in Turkey, on memory impairment, anxiety and depression-like behavior were investigated in scopolamine-induced Alzheimer's type dementia animal model. Primarily, essential oils of these plant species were extracted and characterized by Gas Chromatography-Mass Spectrometry (GC-MS) system. The animals were subjected to the essential oils (1% and 3%) for 21 days prior to the behavioral tests. In the essential oil-treated groups, positive effects on spatial memory performances in Y-maze task and radial arm maze tests as well as significant improvements in anxiety and depression-like behaviors in the elevated plus maze and forced swimming tests were observed compared to scopolamine-alone treated rats. Subsequent to the behavioral tests, decreases in the acetylcholinesterase enzyme activity and malondialdehyde level while increases in the total reduced glutathione amount and superoxide dismutase activity were observed in the hippocampus and amygdala brain homogenates of the euthanized animals in the essential oil-treated groups. In addition, interactions between the essential oil components and acetylcholinesterase enzyme were evaluated with molecular modelling method. Molecular modelling studies had provided clues about the strong interactions between some of the essential oil components and acetylcholinesterase. The results demonstrate that the essential oils of the plants decrease scopolamine-induced central nervous sytem damage by reducing oxidative stress damage and inhibiting the enzyme acetylcholinesterase. In conclusion, our findings suggest that N. nuda subsp. nuda, H. uniglandulosum and A. pseudoaleppica essential oils could be protective against neurodegenerative diseases such as Alzheimer's disease by reducing memory impairment and exhibiting anxiolytic and antidepressant activity and are useful to discover new agents targeting these diseases.