Background

Polyphenolic compounds isolated from pomegranate fruit possess several pharmacological activities including anti-inflammatory, hepatoprotective, antigenotoxic and anticoagulant activities. The present work focuses the attention on PDIA3 interaction with punicalagin and ellagic acid, the most predominant components of pomegranate extracts. PDIA3, a member of the protein disulfide isomerase family involved in several cellular functions, is associated with different human diseases and it has the potential to be a pharmacological target.

Methods

The interaction of polyphenols with PDIA3 purified protein was explored by fluorescence quenching and calorimetric techniques and their effect on PDIA3 activity was investigated.

Results

A higher affinity was observed for punicalagin which also strongly affects PDIA3 reductase activity in vitro as a non-competitive inhibitor. Isothermal titration calorimetry confirmed the high affinity of punicalagin for PDIA3. Considering the PDIA3 involvement in oxidative cellular stress response observed in neuroblastoma cells after treatment with hydrogen peroxide, a comparative study was conducted to evaluate the effect of punicalagin on wild type and PDIA3-silenced cells. Punicalagin increases the cell sensitivity to hydrogen peroxide in neuroblastoma cells, but this effect is drastically reduced in PDIA3-silenced cells treated in the same experimental conditions.

Conclusions

Punicalagin binds PDIA3 and inhibits its redox activity. Comparative experiments conducted on unsilenced and PDIA3-silenced neuroblastoma cells suggest the potential of punicalagin to modulate PDIA3 reductase activity also in a biological model.

General significance

Punicalagin can be used as a new PDIA3 inhibitor and this can provide information on the molecular mechanisms underlying the biological activities of PDIA3 and punicalagin.

中文翻译：

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石榴素是石榴的活性成分，是PDIA3还原酶活性的新抑制剂

背景

从石榴果实中分离出的多酚类化合物具有多种药理活性，包括抗炎，保肝，抗毒素和抗凝活性。目前的工作集中在与石榴提取物最主要成分punicalagin和鞣花酸的PDIA3相互作用上。PDIA3是参与多种细胞功能的蛋白质二硫键异构酶家族的成员，与不同的人类疾病相关，并且有可能成为药理学靶标。

方法

通过荧光猝灭和量热技术研究了多酚与PDIA3纯化蛋白的相互作用，并研究了它们对PDIA3活性的影响。

结果

观察到对punicalagin的亲和力更高，而punicalagin作为一种非竞争性抑制剂，在体外也会强烈影响PDIA3还原酶的活性。等温滴定热法证实了punicalagin对PDIA3的高度亲和力。考虑到PDIA3参与过氧化氢处理后在神经母细胞瘤细胞中观察到的氧化细胞应激反应，进行了一项比较研究，以评估punicalagin对野生型和PDIA3沉默的细胞的作用。葛根素增加了神经母细胞瘤细胞对过氧化氢的细胞敏感性，但在相同实验条件下处理的PDIA3沉默细胞中，这种作用被大大降低。

结论

Punicalagin结合PDIA3并抑制其氧化还原活性。在无沉默和PDIA3沉默的神经母细胞瘤细胞上进行的比较实验表明，在生物学模型中，punicalagin可能具有调节PDIA3还原酶活性的潜力。

一般意义

Punicalagin可用作新的PDIA3抑制剂，这可以提供有关PDIA3和punicalagin生物学活性的分子机制的信息。