In-vitro evaluation of acetylcholinesterase inhibition and antioxidant activity of selected Palestinian medicinal plants: Implications for Alzheimer’s disease therapy
Background:
Cholinesterase inhibitory therapy serves as a strategy for the
treatment of Alzheimer’s disease (AD), several acetylcholineesterase
inhibitors are used for the symptomatic treatment of patients with mild
to moderate AD. These compounds have been reported to have adverse
effects including gastrointestinal disturbances. Numerous medicinal
plants have been used in Traditional Arabic Palestinian Herbal Medicine
(TAPHM) for the treatment of several diseases, including improvement of
memory, Alzheimer’s disease (AD) and old age related disease.
Ethnopharmacological approach and bioassay guided isolation have
provided a lead in identifying potential AChE inhibitors from plant
sources. This study was therefore aimed at investigating in vitro
possible acetylcholinesterase inhibitors (AChEIs) in herbal medicines
traditionally used in Palestine for the treatment of memory loss, and to
point out the role of these plants as potential sources for development
of newly potent and safe natural therapeutic agents of AD. Methods:
The effect on AChE activity of 92 extracts of 47 medicinal plants
including ten medicinal plants reported in TAPHM for treatment of age
related diseases were evaluated for its anticholinestrase and
antioxidant activity. Results:
Thirty eight percent of extracts inhibited AChE by > 50%, only 8
extracts showed irreversible inhibition, Antioxidant activity was
demonstrated by 73 extracts of which Majorana syriaca and Rosmarinus
officinalis (IC50 0.21 and 0.38 mg/ml) were the most active.
Interestingly, differential results have been obtained which indicate
the variability of the mode of actions for the selected plants; 27
extracts inhibited the enzyme reversibly while eight extracts showed
irreversible inhibition. Additionally, the reversible interaction of
Majorana syriaca, Juglans regia, Rosmarinus officinalis, Menthe spicata,
and Feoniculum vulgare against AChE make them effective, new and
promising agents for treatment of AD in the future, either as total
extracts or their single bioactive constituents. Conclusions:
Palestinian flora have shown to be a rich source for, new and promising
agents (AChEIs) for the treatment of AD Further studies are needed to
isolate and identify the active compounds responsible for AChEI
activities.