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.

Chemical Profiles and In Vitro Cholinesterase Inhibitory Activities of the Flower Extracts of Cassia spectabilis

“…Amongst the plants tested, extracts from the leaves, stems, and flowers of C. timorensis showed significant inhibition against AChE [ 28 ]. We have investigated the cholinesterase inhibitory activities of various extracts from the leaves and stems of C. spectabilis that showed the potency of the leaves and stems extracts against both AChE and BChE enzymes [ 22 ]. Franca et al reported the AChE inhibitory potency of the methanolic extract of C. spectabilis flower using a TLC bioautography method, which however, cannot determine the activity quantitatively [ 23 ].…”

“…Silva et al synthesized 12 analogous from (−)-cassine and (−)-spectaline, and four of the semisynthetic compounds significantly inhibited BChE in the in vitro assay [ 38 ]. Our previous study showed that the ethanolic extract of C. spectabilis leaves contains piperidine alkaloids and displays significant cholinesterase inhibitory activities [ 21 , 22 ]. Based on the various reports on the potency of piperidine alkaloids as cholinesterase inhibitors [ 34 – 38 ], it can be suggested that the cholinesterase inhibitory activities of the ethanolic and water extracts of C. spectabilis flowers in this study possibly due to the presence of the piperidine alkaloids detected in the samples.…”

“…The assay was carried out according to the modified Ellman's method, as described in the previous publications [ 22 , 24 ]. The extracts were dissolved in methanol to make 10 mg/mL and diluted with water to obtain 1 mg/mL.…”

“…In the previous study, we investigated the potency of the ethanolic and water extracts of C. spectabilis leaves and stems as antioxidant and cholinesterase inhibitors. The leaves and stems extract of C. spectabilis exhibited significant cholinesterase inhibitory activities against AChE and BChE as well as moderate antioxidant activities [ 21 , 22 ]. In the development of herbal medicinal product for the treatment of Alzheimer's disease from C. spectabilis , information on the extraction solvent that gives the optimum potency as a cholinesterase inhibitor is needed.…”

Prominent Medicinal Plants for the Treatment of Neurodegenerative Disorders

“…It protects against dopaminergic neuronal degeneration in the substantia nigra and striatum in MPTP-induced PD in rat models. The supplementation of C. obtusifolia attenuates cellular damage, depolarization of the mitochondrial membrane, and diminished ROS generation (Rizqiyah et al, 2022).…”