Bio-guided isolation of acetylcholinesterase inhibitory alkaloids from the bulbs of Crinum bulbispermum

Author(s): Amina H.Abou-Donia, Eman A.Shawky, Mohamed M.Mohy El-Din, Hiromitsu Takayama, Ahmed A.Seif El Din

Inhibition of acetylcholinesterase, the key enzyme in the breakdown of acetylcholine, is considered as a promising strategy for the treatment of neurological disorders such as Alzheimer’s disease, senile dementia and myasthenia gravis. A potential source ofAChE inhibitors is certainly provided by the abundance of plants belonging to family Amaryllidaceae. In the presentwork, an In situ High Performance Thin Layer Chromatography (HPTLC) autobiographicmethod was employed for preliminary screening of extracts and fractions of the different organs of Crinum bulbispermum Milne-Redhead &Schweick. for compounds withAChE inhibitory effects. Among the tested fractions, the chloroformextract ofCrinumbulbispermum bulbs demonstrated a significant inhibition ofAChE in the assay. Complete phytochemical investigation of this biologically active extract resulted in the isolation of eight crystalline alkaloids (I-VIII) in addition to the wellknown Amaryllidaceae alkaloid, lycorine. The structures of the isolated compounds were characterized by spectral evidence and by comparing the results with the reported physical and spectral data as ismine (I), trisphaeridine (II), latifine (III), 1-O-Acetyllycorine (IV), crinamine (V), powelline (VI), crinine (VII) and 1-epideacetylbowdensine (VIII). It isworth mentioning that this is the first report for the isolation of alkaloids I-IV and VIII fromCrinum bulbispermumMilne-Redhead&Schweick.

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