Discovery of a Novel Pharmacological and Structural Class of Gamma Secretase Modulators Derived from the Extract of Actaea racemosa

Citations Over TimeTop 10% of 2012 papers

Abstract

A screen of a library of synthetic drugs and natural product extracts identified a botanical extract that modulates the processing of amyloid precursor protein (APP) in cultured cells to produce a lowered ratio of amyloid-beta peptide (1-42) (Aβ42) relative to Aβ40. This profile is of interest as a potential treatment for Alzheimer's disease. The extract, from the black cohosh plant (Actaea racemosa), was subjected to bioassay guided fractionation to isolate active components. Using a combination of normal-phase and reverse-phase chromatography, a novel triterpene monoglycoside, 1, was isolated. This compound was found to have an IC(50) of 100 nM for selectively reducing the production of amyloidogenic Aβ42 while having a much smaller effect on the production of Aβ40 (IC(50) 6.3 μM) in cultured cells overexpressing APP. Using IP-MS methods, this compound was found to modulate the pool of total Aβ produced by reducing the proportion of Aβ42 while increasing the relative amounts of shorter and less amyloidogenic Aβ37 and Aβ39. Concentrations of 1 sufficient to lower levels of Aβ42 substantially (up to 10 μM) did not significantly affect the processing of Notch or other aspects of APP processing. When 1 (10 μg) was administered to CD-1 normal mice intracerebroventricularly, the level of Aβ42 in brain was reduced. Assays for off-target pharmacology and the absence of overt signs of toxicity in mice dosed with compound 1 suggest a comparatively selective pharmacology for this triterpenoid. Compound 1 represents a new lead for the development of potential treatments for Alzheimer's disease via modulation of gamma-secretase.

Related Papers

• → Chlorination Diversifies Cimicifuga racemosa Triterpene Glycosides(2007)14 cited
• → Direct Analysis and Identification of Triterpene Glycosides by LC/MS in Black Cohosh,Cimicifuga racemosa, and in Several Commercially Available Black Cohosh Products(2000)55 cited
• → Stability Evaluation of Selected Polyphenols and Triterpene Glycosides in Black Cohosh(2008)18 cited
• → Profiles of Phenolic Acids and Triterpene Glycosides in Commercial and Cultivated Black Cohosh(2019)2 cited
• Progress of APP secretase and targeted intervention on Alzheimer's disease(2011)