Silva Bruno A, Dias Alberto C P, Ferreres Federico, Malva João O, Oliveira Catarina R
Institute of Biochemistry and Center for Neuroscience and Cell Biology of Coimbra, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal.
Neurotox Res. 2004;6(2):119-30. doi: 10.1007/BF03033214.
In the present study we assessed the neuroprotective role of a Hypericum perforatum ethanolic extract and obtained fractions in amyloid-beta peptide (Abeta)((25-35))-induced cell death in rat cultured hippocampal neurons. Lipid peroxidation was used as a marker of oxidative stress by following the formation of TBARS in rat cortical synaptosomes, after incubation with ascorbate/Fe2+, alone or in the presence of EC97 effective concentrations of H. perforatum fractions. Induced lipid peroxidation was significantly inhibited by fractions containing flavonol glycosides, flavonol and biflavone aglycones, and by a fraction containing several phenols, mainly chlorogenic acid-type phenolics (21%, 77% and 98%, respectively). Lipid peroxidation evaluated after incubation with 25 microM Abeta(25-35), was significantly inhibited by H. perforatum extract. Cell viability was assessed by use of the Syto-13/PI assay. The total ethanolic extract (TE) and fractions containing flavonol glycosides, flavonol and biflavone aglycones, reduced Abeta(25-35)-induced cell death (65%, 58% and 59%, respectively). These results were further supported by morphological analysis of cells stained with cresyl violet. Peptide beta-amyloid(25-35) induced a decrease in cell volume, chromatin condensation and nuclear fragmentation, alterations not evident in the presence of the TE and fractions containing hypericins (hypericin concentration = 11.02 microM), or fractions containing flavonoids (quercetin concentration = 21.13 microM). Dendritic lesion, an evidence of neurodegeneration, was observed by neuronal staining with cobalt following insult with Abeta(25-35), but prevented after exposure to the peptide plus the fractions referred above. The results of the present paper suggest that H. perforatum extracts may be endowed with neuroprotective compounds able to prevent Abeta(25-35)-induced toxicity.
在本研究中，我们评估了贯叶连翘乙醇提取物及其所得馏分在β-淀粉样肽（Aβ）（25-35）诱导的大鼠海马神经元细胞死亡中的神经保护作用。脂质过氧化通过在大鼠皮质突触体中与抗坏血酸/Fe2+单独孵育或在存在贯叶连翘馏分的有效浓度（EC97）的情况下孵育后，追踪硫代巴比妥酸反应物（TBARS）的形成，用作氧化应激的标志物。含有黄酮醇糖苷、黄酮醇和双黄酮苷元的馏分以及含有几种酚类（主要是绿原酸型酚类）的馏分（分别为21%、77%和98%）可显著抑制诱导的脂质过氧化。与25μM Aβ（25-35）孵育后评估的脂质过氧化被贯叶连翘提取物显著抑制。细胞活力通过Syto-13/PI检测进行评估。总乙醇提取物（TE）以及含有黄酮醇糖苷、黄酮醇和双黄酮苷元的馏分可减少Aβ（25-35）诱导的细胞死亡（分别为65%、58%和59%）。用甲酚紫染色的细胞形态分析进一步支持了这些结果。肽β-淀粉样蛋白（25-35）诱导细胞体积减小、染色质浓缩和核碎裂，在存在TE和含有金丝桃素的馏分（金丝桃素浓度 = 11.02μM）或含有黄酮类化合物的馏分（槲皮素浓度 = 21.13μM）时，这些改变不明显。在用Aβ（25-35）损伤后通过钴对神经元进行染色观察到树突损伤，这是神经退行性变的一个证据，但在暴露于该肽加上述馏分后可预防。本文结果表明，贯叶连翘提取物可能含有能够预防Aβ（25-35）诱导的毒性的神经保护化合物。
