Cao Zeyu, Ding Yue, Ke Zhipeng, Cao Liang, Li Na, Ding Gang, Wang Zhenzhong, Xiao Wei
State Key Laboratory of New-tech for Chinese Medicine Pharmaceutical Process, Jiangsu Kanion Pharmaceutical Co., Ltd., Lianyungang, Jiangsu, China.
PLoS One. 2016 Feb 12;11(2):e0148693. doi: 10.1371/journal.pone.0148693. eCollection 2016.
Luteoloside is a member of the flavonoids family that exhibits several bioactivities including anti-microbial and anti-cancer activities. However, the antiviral activity of luteoloside against enterovirus 71 (EV71) and the potential mechanism(s) responsible for this effect remain unknown. In this study, the antiviral potency of luteoloside against EV71 and its inhibitory effects on 3C protease activity were evaluated. First, we investigated the cytotoxicity of luteoloside against rhabdomyosarcoma (RD) cells, which was the cell line selected for an in vitro infection model. In a subsequent antiviral assay, the cytopathic effect of EV71 was significantly and dose-dependently relieved by the administration of luteoloside (EC50 = 0.43 mM, selection index = 5.3). Using a plaque reduction assay, we administered luteoloside at various time points and found that the compound reduced EV71 viability in RD cells rather than increasing defensive mobilization or viral absorption. Moreover, biochemical studies focused on VP1 (a key structural protein of EV71) mRNA transcript and protein levels also revealed the inhibitory effects of luteoloside on the EV71 viral yield. Finally, we performed inhibition assays using luteoloside to evaluate its effect on recombinant 3C protease activity. Our results demonstrated that luteoloside blocked 3C protease enzymatic activity in a dose-dependent manner (IC50 = 0.36 mM) that was similar to the effect of rutin, which is a well-known C3 protease inhibitor. Collectively, the results from this study indicate that luteoloside can block 3C protease activity and subsequently inhibit EV71 production in vitro.
木犀草苷是黄酮类化合物家族的一员，具有多种生物活性，包括抗菌和抗癌活性。然而，木犀草苷对肠道病毒71型（EV71）的抗病毒活性及其潜在作用机制尚不清楚。在本研究中，评估了木犀草苷对EV71的抗病毒效力及其对3C蛋白酶活性的抑制作用。首先，我们研究了木犀草苷对横纹肌肉瘤（RD）细胞的细胞毒性，RD细胞是用于体外感染模型的细胞系。在随后的抗病毒试验中，给予木犀草苷可显著且剂量依赖性地减轻EV71的细胞病变效应（半数有效浓度=0.43 mM，选择指数=5.3）。通过蚀斑减少试验，我们在不同时间点给予木犀草苷，发现该化合物降低了RD细胞中EV71的活力，而不是增加防御动员或病毒吸附。此外，针对VP1（EV71的关键结构蛋白）mRNA转录本和蛋白水平的生化研究也揭示了木犀草苷对EV71病毒产量的抑制作用。最后，我们使用木犀草苷进行抑制试验，以评估其对重组3C蛋白酶活性的影响。我们的结果表明，木犀草苷以剂量依赖性方式阻断3C蛋白酶的酶活性（半数抑制浓度=0.36 mM），这与已知的C3蛋白酶抑制剂芦丁的作用效果相似。总体而言，本研究结果表明，木犀草苷可阻断3C蛋白酶活性，进而在体外抑制EV71的产生。
