Lepule Keagile, Sandasi Maxleene, Chen Weiyang, Viljoen Alvaro
Department of Pharmaceutical Sciences, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa; SAMRC Herbal Drugs Research Unit, Faculty of Science, Tshwane University of Technology, Pretoria, 0001, South Africa.
Department of Pharmaceutical Sciences, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa.
J Ethnopharmacol. 2025 Jul 19;353(Pt A):120314. doi: 10.1016/j.jep.2025.120314.
Parkinson's disease (PD) is characterised by the loss of dopaminergic neurons, resulting in reduced dopamine levels in the brain. The exact cause of dopaminergic neuron loss remains unknown but factors such as increased oxidative stress (OS), neuroinflammation and mitochondrial dysfunction have been implicated in the progression of the disease. The behavioural and molecular repertoire of PD can be modelled in zebrafish larvae using a neurotoxin, 6-hydroxydopamine (6-OHDA). Currently, there is no cure for PD, however, medicinal plants such as Mesembryanthemum tortuosum may provide neuroprotective or neurorestorative benefits resulting from their psychoactive nature, which has been widely reported.
This study aimed to evaluate the neuroprotective and neurorestorative effects of M. tortuosum extracts on 6-OHDA-induced deficits in zebrafish larvae.
The mesembrine alkaloid profiles of a methanol and acid-base extract of M. tortuosum and Zembrin® were obtained using ultra-performance liquid chromatography coupled to mass spectrometry. In the neuroprotection assay, zebrafish larvae at 2 days post-fertilisation (dpf) were treated concurrently with 6-OHDA (250.0 μM) and M. tortuosum extracts or Zembrin® (standardised commercial M. tortuosum), and incubated for 72 h. At the end of the incubation period, locomotion was monitored using high-throughput EthoVision XT tracking software, and the reactive oxygen species (ROS) and total glutathione content (tGSH) in the larvae were also assessed. In the neurorestoration assay, the 2 dpf larvae were initially pre-treated with 6-OHDA (250.0 μM) for 24 h, and the extracts or Zembrin® were added after 24 h and incubation proceeded for a further 48 h. Locomotion, ROS and tGSH were determined at the end of the 48 h incubation. Both assays utilised L-dopa and selegiline as the positive controls.
The acid-base extract contained higher levels of Δ-mesembrenone and mesembrine compared to mesembranol and mesembrenone. Δ-Mesembrenone was identified as the major compound in the methanol extract, while Zembrin® contained mesembrenol, mesembranol, mesembrenone and mesembrine as major compounds. Zembrin® displayed the best neuroprotective activity by significantly attenuating locomotor deficits and increasing tGSH content at all the three tested concentrations. The methanol extract displayed the best neurorestorative activity significantly restoring tGSH content, locomotor activity and ROS at varying concentrations.
The M. tortuosum extracts and Zembrin® containing various levels of mesembrine alkaloids improved both locomotion and oxidative stress associated with PD in a zebrafish larvae model. Furthermore, the effects of L-dopa and selegiline as core treatments in the management of PD were further confirmed in this PD zebrafish larvae model.
帕金森病（PD）的特征是多巴胺能神经元丧失，导致大脑中多巴胺水平降低。多巴胺能神经元丧失的确切原因尚不清楚，但氧化应激增加（OS）、神经炎症和线粒体功能障碍等因素与该疾病的进展有关。PD的行为和分子特征可以在斑马鱼幼体中使用神经毒素6-羟基多巴胺（6-OHDA）进行模拟。目前，PD尚无治愈方法，然而，像扭刺仙人掌这样的药用植物可能因其具有广泛报道的精神活性而提供神经保护或神经恢复益处。
本研究旨在评估扭刺仙人掌提取物对6-OHDA诱导的斑马鱼幼体缺陷的神经保护和神经恢复作用。
使用超高效液相色谱-质谱联用技术获得扭刺仙人掌甲醇提取物、酸碱提取物和Zembrin®的美登木碱谱。在神经保护试验中，受精后2天（dpf）的斑马鱼幼体同时用6-OHDA（250.0 μM）和扭刺仙人掌提取物或Zembrin®（标准化商业扭刺仙人掌）处理，并孵育72小时。在孵育期结束时，使用高通量EthoVision XT跟踪软件监测运动，并评估幼体中的活性氧（ROS）和总谷胱甘肽含量（tGSH）。在神经恢复试验中，2 dpf幼体最初用6-OHDA（250.0 μM）预处理24小时，24小时后加入提取物或Zembrin®，并继续孵育48小时。在孵育48小时结束时测定运动、ROS和tGSH。两项试验均使用左旋多巴和司来吉兰作为阳性对照。
与美登木醇和美登木酮相比，酸碱提取物中Δ-美登木酮和美登木碱的含量更高。Δ-美登木酮被鉴定为甲醇提取物中的主要化合物，而Zembrin®包含美登木醇、美登木醇、美登木酮和美登木碱作为主要化合物。Zembrin®在所有三个测试浓度下均通过显著减轻运动缺陷和增加tGSH含量表现出最佳的神经保护活性。甲醇提取物在不同浓度下显著恢复tGSH含量、运动活性和ROS，表现出最佳的神经恢复活性。
含有不同水平美登木碱的扭刺仙人掌提取物和Zembrin®改善了斑马鱼幼体模型中与PD相关的运动和氧化应激。此外，在这个PD斑马鱼幼体模型中进一步证实了左旋多巴和司来吉兰作为PD管理核心治疗方法的效果。
