Sideritis scardicaextracts inhibit aggregation and toxicity of amyloid-βinCaenorhabditis elegansused as a model for Alzheimer’s disease

Abstract

BackgroundBeyond its traditional uses in the Balkan area, Sideritis scardica (known as Greek mountain tea, Lamiaceae) is currently extensively investigated for its pharmacological activity in the central nervous system. Antidepressant, psychostimulating, cognition-enhancing and neuroprotective properties have been described. In this study, we tested hydroalcoholic extracts of S. scardica for their potential to counteract amyloid-β toxicity and aggregation, which plays a crucial role in the pathogenesis of Alzheimer’s disease.MethodsFor this purpose, we have chosen the nematode Caenorhabditis elegans, which is used as a model organism for neurodegenerative diseases. The concentration of different polyphenols in extracts prepared from water, 20, 40, 50, and 70% ethanol was analysed by HPLC. Additionally, polar and unpolar fractions were prepared from the 40% ethanolic extract and phytochemically analysed.ResultsEssentially, the contents of all measured constituents increased with the lipophilicity of the extraction solvents. Treatment of transgenic C. elegans strains expressing amyloid-β with the extracts resulted in a reduced number of peptide aggregates in the head region of the worms and alleviated toxicity of amyloid-β, observable through the degree of paralysed animals. The mid-polar extracts (40 and 50% ethanol) turned out be the most active, decreasing the plaque number by 21% and delaying the amyloid-β-induced paralysis by up to 3.5 h. The more lipophilic extract fractions exhibited higher activity than the hydrophilic ones.DiscussionSideritis scardica extracts demonstrated pharmacological activity against characteristics of Alzheimer’s disease also in C. elegans, supporting current efforts to assess its potential for the treatment of cognitive decline. The active principle as well as the mode of action needs to be investigated in more detail.

Jasonia glutinosa (L.) DC., a Traditional Herbal Tea, Exerts Antioxidant and Neuroprotective Properties in Different In Vitro and In Vivo Systems

“…To further investigate the in vivo neuroprotective effect of rock tea, an examination was carried out as to whether diet supplementation may affect the progression of paralysis induced by Aβ toxicity in the C. elegans transgenic strain CL4176. This strain has proven to be a good model for screening potential neuroprotective natural products [ 15 , 22 , 23 ]. Nematodes were exposed to different concentrations of RT extract (5, 10 and 25 µg/mL) from the egg stage.…”

The Acute and Chronic Cognitive and Cerebral Blood Flow Effects of a Sideritis scardica (Greek Mountain Tea) Extract: A Double Blind, Randomized, Placebo Controlled, Parallel Groups Study in Healthy Humans

“…The primary active constituents of the caffeine-free Greek mountain tea appear to be phenolic acids, principally ferulic acid and chlorogenic acid and the flavone compound apigenin [ 3 ], and it is likely the latter which underpins the small number of published psychophysiological effects of Greek mountain tea in humans. Sideritis scardica is a triple monoamine (serotonin, noradrenaline and dopamine) reuptake inhibitor in vitro [ 4 ] with apigenin individually demonstrating a capacity to interact with monoamine transporters [ 5 ] as well as being a ligand for the benzodiazepine receptor.…”

Catechins as Tools to Understand the Molecular Basis of Neurodegeneration

“…Among the low MW ligands, polyphenolic compounds naturally found in green tea, also termed catechins, have attracted considerable interest for their ability to remodel neurotoxic oligomers into non-neurotoxic assemblies [ 23 , 24 , 25 , 26 , 27 ]. Catechins have also shown inhibitory effects on Aβ aggregation in model organisms such as Caenorhabditis elegans [ 28 , 29 ]. In addition, catechins exhibit other neuroprotective effects, including antioxidant and anti-inflammatory properties [ 30 , 31 , 32 ].…”