Berberis aetnensis and B. libanotica: a comparative study on the chemical composition, inhibitory effect on key enzymes linked to Alzheimer's disease and antioxidant activity

Abstract

Abstract Objectives This study involves for the first time the evaluation of Berberis aetnensis C. Presl. and Berberis libanotica Ehrenb. ex C.K. Schneid. roots for anticholinesterase and antioxidant properties, with the aim to search compounds possibly useful for the treatment of Alzheimer's disease (AD). Methods Samples were evaluated for their ability to inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The antioxidant activity was assayed by 2,2-diphenyl-1-picrylhydrazyl radical and β-carotene bleaching tests. Berberine and palmatine were isolated by flash chromatography and identified by spectrometric methods as main constituents. Non-polar compounds were analysed by gas chromatography and gas chromatography-mass spectrometry. Key findings Extracts, fractions and isolated compounds inhibited AChE and BChE to varying degrees. The methanol fractions exhibited the strongest AChE inhibitory activity with inhibitory concentration 50% (IC50) of 7.6 and 16.9 μg/ml for B. aetnensis and B. libanotica, respectively. The alkaloid fraction of B. aetnensis inhibited AChE (IC50 of 24.5 μg/ml) and possessed the highest antioxidant activity (IC50 value of 2.2 μg/ml in β-carotene-bleaching test after 30 min of incubation). Berberine was more potent of palmatine against AChE (IC50 of 2.2 and 7.4 μg/ml, respectively). Conclusions These findings raise the possibility of developing B. aetnensis and B. libanotica as a promising candidate for the treatment of AD.