Department of Pharmaceutical Sciences, Faculty of Science, Tshwane University of Technology, Pretoria, South Africa.
Department of Pharmacognosy, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran.
Fitoterapia. 2020 Oct;146:104650. doi: 10.1016/j.fitote.2020.104650. Epub 2020 May 30.
Inhibition of acetylcholinesterase (AChE) is considered a promising strategy for the treatment of Alzheimer's disease (AD) and dementia. Members of the Amaryllidaceae family are well known for their pharmacologically active alkaloids, including galanthamine, which is used to treat AD. The aim of this study was to evaluate the potential of South African Amaryllidaceae species to inhibit AChE, to isolate the active compounds, and probe their ability to bind the enzyme using molecular docking. The AChE inhibitory activity of extracts of 41 samples, representing 14 genera and 28 species, as well as isolated compounds, were evaluated in vitro using a qualitative thin layer chromatography (TLC) bio-autography assay and Ellman's method in a quantitative 96-well microplate assay. Targeted isolation of compounds was achieved with the aid of preparative-high perfomance liquid chromatography-mass spectrometry. The structures of the isolates were elucidated using nuclear magnetic resonance spectrocopy, and were docked into the active site of AChE to rationalise their biological activities. The most active species were found to be Amaryllis belladonna L (IC 14.3 ± 2.6 μg/mL), Nerine huttoniae Schönland (IC 45.3 ± 0.4 μg/mL) and Nerine undulata (L.) Herb. (IC 52.8 ± 0.5 μg/mL), while TLC bio-autography indicated the presence of several active compounds in the methanol extracts. Four compounds, isolated from A. belladonna, were identified as belladine, undulatine, buphanidrine and acetylcaranine. Acetylcaranine and undulatine were previously isolated from A. belladonna, while belladine and buphanidrine were reported from other South African Amaryllidaceae species. Using Ellman's method, acetylcaranine was found to be the most active of the isolates towards AChE, with an IC of 11.7 ± 0.7 μM, comparable to that of galanthamine (IC = 6.19 ± 2.60 μM). Molecular docking successfully predicted the binding modes of ligands within receptor binding sites. Acetylcaranine was predicted by the docking workflow to have the highest activity, which corresponds to the in vitro results. Both qualitative and quantitative assays indicate that several South African Amaryllidaceae species are notable AChE inhibitors.
乙酰胆碱酯酶（AChE）的抑制被认为是治疗阿尔茨海默病（AD）和痴呆的有前途的策略。石蒜科植物以其具有药理活性的生物碱而闻名，其中加兰他敏被用于治疗 AD。本研究的目的是评估南非石蒜科物种抑制 AChE 的潜力，分离活性化合物，并通过分子对接探测它们与酶结合的能力。使用定性薄层色谱（TLC）生物自显影测定法和定量 96 孔微量板测定法，在体外评估了 41 个样本的提取物（代表 14 个属和 28 个种）以及分离化合物的 AChE 抑制活性。在制备高效液相色谱-质谱联用的辅助下，实现了化合物的靶向分离。使用核磁共振光谱解析了分离物的结构，并将其对接入 AChE 的活性部位，以合理化它们的生物学活性。最活跃的物种是阿玛丽利斯·贝拉多纳 L（IC 14.3 ± 2.6μg/mL）、尼林·赫顿尼亚·斯科兰兰（IC 45.3 ± 0.4μg/mL）和尼林·昂杜拉塔（L.）赫布（IC 52.8 ± 0.5μg/mL），而 TLC 生物自显影表明甲醇提取物中存在几种活性化合物。从阿玛丽利斯·贝拉多纳中分离出的 4 种化合物被鉴定为贝拉丁、昂杜拉丁、布法林和乙酰卡兰宁。乙酰卡兰宁和昂杜拉丁以前从阿玛丽利斯·贝拉多纳中分离出来，而贝拉丁和布法林从其他南非石蒜科物种中报道。使用埃勒曼法，发现乙酰卡兰宁是对 AChE 最活跃的分离物之一，IC 为 11.7 ± 0.7μM，与加兰他敏（IC = 6.19 ± 2.60μM）相当。分子对接成功预测了配体在受体结合位点中的结合模式。通过对接工作流程预测乙酰卡兰宁具有最高的活性，这与体外结果相对应。定性和定量测定均表明，几种南非石蒜科物种是显著的 AChE 抑制剂。
