Potential Anti-Acetylcholinesterase Activity of Cassia timorensis DC.

Nurul Amira Nurul Azman,Toshihiko Nogawa,Mira Syahfriena Amir Rawa,Maram B Alhawarri,Roza Dianita,Amirah Mohd Gazzali,Habibah A Wahab

doi:10.3390/molecules25194545

Abstract

Seventeen methanol extracts from different plant parts of five different Cassia species, including C. timorensis, C. grandis, C. fistula, C. spectabilis, and C. alata were screened against acetylcholinesterase (AChE). C. timorensis extracts were found to exhibit the highest inhibition towards AChE whereby the leaf, stem, and flower methanol extracts showed 94–97% inhibition. As far as we are aware, C. timorensis is one of the least explored Cassia spp. for bioactivity. Further fractionation led to the identification of six compounds, isolated for the first time from C. timorensis: 3-methoxyquercetin (1), benzenepropanoic acid (2), 9,12,15-octadecatrienoic acid (3), β-sitosterol (4), stigmasterol (5), and 1-octadecanol (6). Compound 1 showed moderate inhibition towards AChE (IC50: 83.71 μM), while the other compounds exhibited poor to slightly moderate AChE inhibitory activity. Molecular docking revealed that the methoxy substitution of 1 formed a hydrogen bond with TYR121 at the peripheral anionic site (PAS) and the hydroxyl group at C5 formed a covalent hydrogen bond with ASP72. Additionally, the OH group at the C3′ position formed an interaction with the protein at the acyl pocket (PHE288). This possibly explains the activity of 1 in blocking the entry of acetylcholine (ACh, the neurotransmitter), thus impeding the hydrolysis of ACh.

Highlights

Cassia is a huge genus of flowering plants belongs to the Fabaceae family which comprised of more than 500 species that are diverse in herbs, shrubs, and trees [1]
We present the results of AChE inhibition of selected Cassia spp., which led us towards the phytochemical investigation of C. timorensis
Acetylcholinesterase (AChE) from Electrophorus electricus type VI-S (510 units/mg), Acetylcholinesterase (AChE) from Electrophorus electricus type VI-S (510 substrate acetylthiocholine iodide (ATCI), phosphate buffer, sodium phosphate monobasic and sodium units/mg), substrate acetylthiocholine iodide (ATCI), phosphate buffer, sodium phosphate phosphate dibasic, quercetin, and galantamine were purchased from Sigma-Aldrich

Summary

Introduction

Cassia is a huge genus of flowering plants belongs to the Fabaceae family which comprised of more than 500 species that are diverse in herbs, shrubs, and trees [1]. This genus is widely distributed in tropical countries such as the South-East Asia, tropical America and African regions. Many species of Cassia have medicinal values and they might differ from one to another depending on their phytochemical constituents [2]. For most known Cassia species, the leaves, stems, pods, and seeds have been shown to possess different pharmacological values [3,4].

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