In vitro Antioxidant and Anticholinesterase Activities of Extracts from the Leaves of Cassia moschata Kunth

Abstract

Alzheimer’s disease (AD) is a neurodegenerative disorder, which is the most common cause of dementia. This disease commonly occurs in elderly people. The increase in life expectancy means that that the number of people suffering from AD is expected to rise each year if there is no effective treatment found. The relation of cholinesterase and oxidative stress to Alzheimer’s disease has been reported. In our previous study, we have investigated the potency of the ethanolic extract of Cassia moschata leaves as an anticholinesterase. The current study aimed to investigate the antioxidant and anticholinesterase properties of the ethanolic and aqueous extracts of C. moschata as well as to determine the total phenolic content (TPC). Two different methods were used to evaluate the antioxidant activity by 2,2-diphenyl-1-picryl hydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. The anticholinesterase assay was carried out against acetylcholinesterase (AChE) according to the modified Ellman’s method. The TPC was determined by a colorimetric method using Folin-Ciocalteu’s phenol reagent, and employing gallic acid as a reference. The ethanolic and aqueous extracts of C. moschata demonstrated antioxidant activity in both DPPH and ABTS assays. There were statistically significant differences in the IC50 values of the ethanolic and aqueous extracts in both DPPH and ABTS assays. The aqueous extract exhibited a lower IC50 value compared to the ethanolic extract. The IC50 value for the aqueous extract was 36.46 µg/mL in the DPPH assay, and 10.61 µg/mL in the ABTS method compared to IC50 38.74 µg/mL and 17.17 µg/mL for the ethanolic extract, respectively. Meanwhile, the ethanolic extract showed higher potency as anticholinesterase with the IC50 value of 44.43 µg/mL compared to the aqueous extract with an IC50 value of 114.60 µg/mL. The TPC measurement revealed that the aqueous extract has a higher amount of phenolic than the ethanolic extract. These data suggest that the aqueous extract from the leaves of C. moschata has a higher ability to scavenge free radicals compared to the ethanolic extract, which also contains a higher amount of phenolic compounds. However, the high content of phenolic compounds in the aqueous extract did not correspond to the anticholinesterase activity. The presence of non-phenolic compounds may also contribute to the anticholinesterase activity in the ethanolic extract.