Abd El-Aziz Nourhan Mohammad, Shehata Mohamed Gamal, Alsulami Tawfiq, Badr Ahmed Noah, Elbakatoshy Marwa Ramadan, Ali Hatem Salama, El-Sohaimy Sobhy Ahmed
Department of Food Technology, Arid Lands Cultivation Research Institute (ALCRI), City of Scientific Research and Technological Applications (SRTA-City), Alexandria 21934, Egypt.
Food Research Section, R&D Division, Abu Dhabi Agriculture and Food Safety Authority (ADAFSA), Abu Dhabi P.O. Box 52150, United Arab Emirates.
Pharmaceuticals (Basel). 2022 Dec 22;16(1):12. doi: 10.3390/ph16010012.
Alzheimer's disease (AD) is a devastating neurodegenerative disorder without a cure. Hence, developing an effective treatment or protective agent is crucial for public health. The present study aims to characterize orange peel extract (OPE) through in vitro and in silico studies. Furthermore, it examines the protective effect of OPE against experimentally-induced Alzheimer's disease in rats. The total phenolic and flavonoid content of OPE was 255.86 ± 1.77 and 52.06 ± 1.74 (mg/100 g), respectively. Gallic acid, the common polyphenol in OPE detected by HPLC was 3388.60 μg/100 g. OPE antioxidant IC was 67.90 ± 1.05, 60.48 ± 0.91, and 63.70 ± 0.30 by DPPH, ABTS and Hydroxyl radical scavenging activity methods, respectively. In vitro anti-acetylcholinesterase (AChE) IC was 0.87 ± 0.025 mg/mL for OPE and 2.45 ± 0.001 mg/mL for gallic acid. Molecular docking analysis for human AChE (4EY7) with donepezil, gallic acid, and acetylcholine showed binding energy ΔG values of -9.47, -3.72, and -5.69 Kcal/mol, respectively. Aluminum chloride injection (70 mg/Kg/day for 6 weeks) induced Alzheimer's-like disease in male rats. OPE (100 and 200 mg/kg/d) and gallic acid (50 mg/kg/d) were administered orally to experimental animals for 6 weeks in addition to aluminum chloride injection (as protective). OPE was found to protect against aluminum chloride-induced neuronal damage by decreasing both gene expression and activity of acetylcholinesterase (AChE) and a decrease in amyloid beta (Aβ42) protein level, thiobarbituric acid-reactive substances (TBARS), and nitric oxide (NO), and increased reduced glutathione (GSH) level and activity of the antioxidant enzymes in the brain tissues. Additionally, gene expressions for amyloid precursor protein (APP) and beta secretase enzyme (BACE1) were downregulated, whereas those for presinilin-2 (PSEN2) and beta cell lymphoma-2 (BCL2) were upregulated. Furthermore, the reverse of mitochondrial alternation and restored brain ultrastructure might underlie neuronal dysfunction in AD. In conclusion, our exploration of the neuroprotective effect of OPE in vivo reveals that OPE may be helpful in ameliorating brain oxidative stress, hence protecting from Alzheimer's disease progression.
阿尔茨海默病（AD）是一种毁灭性的神经退行性疾病，尚无治愈方法。因此，开发有效的治疗方法或保护剂对公众健康至关重要。本研究旨在通过体外和计算机模拟研究对橙皮提取物（OPE）进行特性分析。此外，还研究了OPE对实验性诱导的大鼠阿尔茨海默病的保护作用。OPE的总酚含量和黄酮含量分别为255.86±1.77和52.06±1.74（mg/100 g）。通过高效液相色谱法检测到的OPE中常见的多酚没食子酸为3388.60μg/100 g。通过DPPH、ABTS和羟自由基清除活性方法测定，OPE的抗氧化IC50分别为67.90±1.05、60.48±0.91和63.70±0.30。体外抗乙酰胆碱酯酶（AChE）的IC50，OPE为0.87±0.025 mg/mL，没食子酸为2.45±0.001 mg/mL。人AChE（4EY7）与多奈哌齐、没食子酸和乙酰胆碱的分子对接分析显示结合能ΔG值分别为-9.47、-3.72和-5.69 Kcal/mol。注射氯化铝（70 mg/Kg/天，持续6周）可诱导雄性大鼠出现类似阿尔茨海默病的疾病。除注射氯化铝外（作为保护措施），给实验动物口服OPE（100和200 mg/kg/d）和没食子酸（50 mg/kg/d），持续6周。结果发现，OPE可通过降低乙酰胆碱酯酶（AChE）的基因表达和活性、降低淀粉样β蛋白（Aβ42）水平、硫代巴比妥酸反应性物质（TBARS）和一氧化氮（NO），以及提高脑组织中还原型谷胱甘肽（GSH）水平和抗氧化酶活性，来保护大鼠免受氯化铝诱导的神经元损伤。此外，淀粉样前体蛋白（APP）和β分泌酶（BACE1）的基因表达下调，而早老素2（PSEN2）和β细胞淋巴瘤-2（BCL2）的基因表达上调。此外，线粒体改变的逆转和脑超微结构的恢复可能是AD神经元功能障碍的基础。总之，我们对OPE体内神经保护作用的探索表明，OPE可能有助于改善脑氧化应激，从而防止阿尔茨海默病的进展。
