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Binding of an Oxindole Alkaloid from Uncaria tomentosa to Amyloid Protein (Aβ1-40)

Teresa Frąckowiak, Tomasz Bączek, Roman Kaliszan, Beata Żbikowska, Michał Gleńsk, Izabela Fecka, Wojciech Cisowski
Zeitschrift für Naturforschung 2014 v.61 no.11-12 pp. 821-826
Alzheimer disease, Uncaria tomentosa, alkaloids, amyloid, capillary electrophoresis, electrospray ionization mass spectrometry, high performance liquid chromatography, therapeutics, thin layer chromatography
The primary aim of this work was to determine the interactions of an oxindole alkaloid (mitraphylline) isolated from Uncaria tomentosa with β-amyloid 1-40 (Aβ1-40 protein) apply­ing the capillary electrophoresis (CE) method. Specifically the Hummel-Dreyer method and Scatchard analysis were performed to study the binding of oxindole alkaloids with Aβ1-40 protein. Prior to these studies extraction of the alkaloid of interest was carried out. Identifica­tion of the isolated alkaloid was performed by the use of thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) combined with electrospray ionization mass spectrometry (ESI-MS). The proposed approach was proved to be an efficient and accurate method for specific compound isolation and identification purposes. Moreover, ana­lytical information from the CE approach can be considered as the valuable tool for binding constant determination. The binding constant of mitraphylline with Aβ1-40 protein deter­mined by the Hummel-Dreyer method and Scatchard analysis equals K = 9.95 x 10⁵ m⁻¹. The results obtained showed the significant binding of the tested compound with Aβ1-40 protein. These results are discussed and interpreted in the view of developing a strategy for identifica­tion of novel compounds of great importance in Alzheimer disease therapy.