Acetylcholinesterase inhibition and antioxidant activity of isolated compounds from Galenia africana and Combretum apiculatum

Alzheimer's disease (AD) is a neurodegenerative disorder which is characterized by loss of memory, cognitive decline, and severe behavioural abnormalities and ultimately death [1]. AD is the most common form of dementia in our aging society, which affects more than 37 million people worldwide. Inhibition of acetylcholinesterase (AChE), the key enzyme in the breaking down of acetylcholine thus serves as a promising strategy for the treatment of neurological disorders such as AD. Oxidative stress has been considered a mechanism involved in the pathogenesis of AD, and it has also played a major role in the aging process [2]. Oxidative damage by free radicals has been well investigated within the context of oxidant/antioxidant balance.

Two south African plant species Galenia africana and Combretum apiculatum were investigated for their potential to inhibit acetylcholinesterase. The DCM leaf extarct of G. africana let to the isolation of 7,8-dimethoxy-2-phenyl-4 H-chromen-4-one A, 6,7-dimethoxy-2-phenyl-4 H-chromen-4-one B, 8-phenyl-6 H-[1,3]dioxolo[4,5-h]chromen-6-one C and the MeOH leaf extract of C. apiculatum led to the isolation of quercetrin D and pinostrobin E. The isolated compounds were screened for AChE inhibition and radical scavenging activities using a TLC bioautographic method. Compound C showed acetylcholinesterase inhibitory activity and compound D and E showed radical scavenging activity.

References:

[1] Mankil J & Moonsoon P. Molecules. 2007. 12:2130 – 2139.

[2] Kumar et al. IJPSR. 2011. 2: 1188 – 1192.