Effect of Original Peptide Derivatives of Galantamine on Passive Avoidance in Mice

Phytochemical Profiling, Antioxidant and Cognitive-Enhancing Effect of Helichrysum italicum ssp. italicum (Roth) G. Don (Asteraceae)

This study aimed at the evaluation of the antioxidant and cognitive-enhancing effect of methanol-aqueous extract from Helichrysum italicum ssp. italicum aerial parts. Significant radical scavenging activity (110.33 ± 3.47 and 234.70 ± 5.21 mg TE/g for DPPH and ABTS) and reducing power (354.23 ± 17.51 and 210.24 ± 8.68 mg TE/g for CUPRAC and FRAP) were observed. The extract showed average acetylcholinesterase and low butyrylcholinesterase inhibitory potential. H. italicum extract (200 mg/kg/po) administered in combination with galantamine (3 mg/kg/po) for 12 days significantly improved the memory and learning process compared with galantamine alone in the passive avoidance test. The effect was comparable to that of Ginkgo biloba extract (100 mg/kg/po). In deep secondary metabolite annotation of the extract by UHPLC-HRMS, more than 90 hydroxybenzoic and hydroxicinnamic acid-glycosides, phenylethanoid glycosides, a series of acylquinic and caffeoylhexaric acids, methoxylated derivatives of scutellarein, quercetagetin and 6-hydroxyluteolin, and prenylated phloroglucinol-α-pyrones were reported for the first time in H. italicum. Fragmentation patterns of four subclasses of heterodimer-pyrones were proposed. In-depth profiling of the pyrones revealed 23 compounds undescribed in the literature. Pyrones and acylphloroglucinols together with acylquinic acids could account for memory improvement. The presented research advanced our knowledge of H. italicum, highlighting the species as a rich source of secondary metabolites with cognitive-enhancing potential.

Kinetic and structural studies on the inhibition of acetylcholinesterase and butyrylcholinesterase by a series of multitarget-directed galantamine-peptide derivatives

Complex neurological disorders, including Alzheimer's disease, are one of the major therapeutic areas to which multitarget drug discovery strategies have been applied in the last twenty years. Due to the complex multifactorial etiopathogenesis of Alzheimer's disease, it has been proposed that to be successful the pharmaceutical agents should act on multiple targets in order to restore the complex disease network and to provide disease modifying effects. Here we report on the synthesis and the anticholinergic activity profiles of seven multitarget anti-Alzheimer compounds designed by combining galantamine, a well-known acetylcholinesterase inhibitor, with different peptide fragments endowed with inhibitory activity against BACE-1. A complementary approach based on molecular docking simulations of the galantamine-peptide derivatives in the active sites of acetylcholinesterase and of the related butyrylcholinesterase, as well as on inhibition kinetics, by global fitting of the reaction progress curves, allowed to gain insights into the enzyme-inhibitor mechanism of interaction. The resulting structure-activity relationships pave the way towards the design of more effective pharmacodynamic/pharmacokinetic multitarget inhibitors.

Effects of New Galantamine Derivatives in a Scopolamine Model of Dementia in Mice

Alzheimer's disease (AD), a progressive neurodegenerative disorder characterized by memory loss and cognitive functions decline, is a leading cause for dementia and currently ranked as the sixth foremost cause of death. As of present, treatment of AD is symptomatic without convincing therapeutic benefits and new, effective, therapeutic agents are pursued. Due to massive loss of cholinergic neurons and decreased acetylcholine levels, cholinesterase inhibitors like galantamine, remain the backbone of pharmacological treatment of the disease. In the present study, using behavioral and biochemical methods, four newly synthesized galantamine derivatives, Gal 34, Gal 43, Gal 44, and Gal 46, were evaluated for a beneficial effect in a scopolamine model of dementia in mice. They were designed to have all the advantages of galantamine and additionally to inhibit β-secretase and exert favorable effects on plasma lipids. Behavioral tests included step-through inhibitory avoidance, T-maze, and the hole-board test, whereas biochemical evaluations involved assessment of acetylcholinesterase activity, brain monoamines levels, lipid peroxidation, catalase, glutathione peroxidase, and superoxide dismutase activities along with measurement of total glutathione. Results show that Gal 43, Gal 44, and, in particular, Gal 46 are especially effective in improving both short- and long-term memory and in the case of Gal 46 having a significant effect on exploratory activity as well. Although Gal 34 did not show behavioral effects as convincing as those of the other three galantamine derivatives, it demonstrated persuasive antioxidant and restorative capacities, making all four galantamine derivatives promising AD treatment agents and prompting further research, especially that in many of our studies they performed better than galantamine.