Anuradha Thakur
Alzheimer’s disease is a slow and progressive neurodegenerative
disease that destroys memory and other important
mental functions. APP (Amyloid precursor protein) is an
integral membrane protein expressed in higher levels in
brain and its abnormal cleavage produces beta amyloid
(Aβ42). Accumulation of Aβ42 in the brain produces amyloid
plaques, the hallmark of the Alzheimer’s disease.
A literature survey was done for the selection of plants
by using the keywords central nervous disorders and African
medicinal plants. The plants were prioritized by a
scoring system following the key criteria- plant part use,
strength of the traditional use in relative to memory loss,
plant toxicity, plant availability, published information
against acetylcholinesterase inhibition. Different plant
parts were collected from the University of Pretoria gardens
and extracted with DCM:MeOH (1:1) after drying
and grinding. The 33 plant extracts were screened to determine
their inhibitory properties for Aβ42 production
in HeLa cells stably transfected with APPsw. We found
that of 33 extracts, 11 extracts were found to significantly
reduce the Aβ42 level. Amongst them, three extracts of
leaves of Xysmalobiumundulatum, Cussoniapaniculata
and Schotiabrachypetala potently reduced the secreted
level of Aβ42 by 77.3 ± 0.5%, 57.5 ± 1.3% and 44.8 ±
0.1% respectively. Thus, we selected these extracts for
further study. Through bioassay guided fractionation,
five pure compounds from the plant X. undulatum were
isolated. Of these, four compounds were found to significantly
inhibit formation of Aβ42. For the other two plant
extracts, UPLC-QTOF-MS analysis was done to identify
the active ingredient