Our previous study demonstrated neuroprotective and therapeutic effects of a standardized flavonoid extract from leaves of Diospyros kaki L.f. (DK) on middle cerebral artery occlusion-and-reperfusion (MCAO/R)-induced brain injury and its underlying mechanisms. This study aimed to clarify flavonoid components responsible for the effects of DK using in vitro and in vivo transient brain ischemic models. Organotypic hippocampal slice cultures (OHSCs) subjected to oxygen- and glucose-deprivation (OGD) were performed to evaluate in vitro neuroprotective activity of DK extract and nine isolated flavonoid components. MCAO/R mice were employed to elucidate in vivo neuroprotective effects of the flavonoid component that exhibited the most potent neuroprotective effect in OHSCs. DK extract and seven flavonoids [quercetin, isoquercetin, hyperoside, quercetin-3-O-(2″-O-galloyl-β-d-galactopyranoside), kaempferol, astragalin, and kaempferol-3-O-(2″-O-galloyl-β-d-glucopyranoside) compound (9)] attenuated OGD-induced neuronal cell damage and compound (9) possessed the most potent neuroprotective activity in OHSCs. The MCAO/R mice showed cerebral infarction, massive weight loss, characteristic neurological symptoms, and deterioration of neuronal cells in the brain. Compound (9) and a reference drugs, edaravone, significantly attenuated these physical and neurological impairments. Compound (9) mitigated the blood–brain barrier dysfunction and the change of glutathione and malondialdehyde content in the MCAO mouse brain. Edaravone suppressed the oxidative stress but did not significantly affect the blood–brain barrier permeability. The present results indicated that compound (9) is a flavonoid constituent of DK with a potent neuroprotective activity against transient ischemia-induced brain damage and this action, at least in part, via preservation of blood–brain barrier integrity and suppression of oxidative stress caused by ischemic insult.

Graphical abstract

中文翻译：

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Kaempferol-3-O-(2″-O-galloyl-β-d-glucopyranoside)：一种来自柿树的新型神经保护剂，可对抗脑缺血引起的脑损伤

我们之前的研究证明了柿叶标准化黄酮提取物(DK) 对大脑中动脉闭塞再灌注 (MCAO/R) 诱导的脑损伤及其潜在机制的神经保护和治疗作用。本研究旨在利用体外和体内短暂脑缺血模型来阐明与 DK 作用相关的类黄酮成分。进行缺氧和缺糖 (OGD) 的器官型海马切片培养物 (OHSC)，以评估 DK 提取物和九种分离的黄酮类成分的体外神经保护活性。使用 MCAO/R 小鼠来阐明类黄酮成分的体内神经保护作用，该成分在 OHSC 中表现出最有效的神经保护作用。DK提取物和七种黄酮类化合物[槲皮素、异槲皮素、金丝桃苷、槲皮素-3-O-(2″-O-没食子酰-β-d-吡喃半乳糖苷)、山奈酚、黄芪甲苷和山奈酚-3-O-(2″-O-没食子酰-β- d-吡喃葡萄糖苷）化合物（9） ]减轻了OGD诱导的神经元细胞损伤，并且化合物（9）在OHSC中具有最有效的神经保护活性。MCAO/R 小鼠表现出脑梗塞、体重大幅减轻、特征性神经系统症状以及大脑神经元细胞退化。化合物(9)和参考药物依达拉奉显着减轻了这些身体和神经损伤。化合物(9)减轻了MCAO小鼠脑中的血脑屏障功能障碍以及谷胱甘肽和丙二醛含量的变化。依达拉奉抑制氧化应激，但没有显着影响血脑屏障的通透性。目前的结果表明，化合物（9）是 DK 的类黄酮成分，对短暂性缺血引起的脑损伤具有有效的神经保护活性，并且这种作用至少部分是通过保护血脑屏障完整性和抑制氧化应激引起的。通过缺血性损伤。

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