Derksen Andrea, Hensel Andreas, Hafezi Wali, Herrmann Fabian, Schmidt Thomas J, Ehrhardt Christina, Ludwig Stephan, Kühn Joachim
Institute of Pharmaceutical Biology and Phytochemistry, University of Münster, Münster, Germany.
Institute of Medical Microbiology - Clinical Virology, University Hospital Münster, Münster, Germany.
PLoS One. 2014 Oct 10;9(10):e110089. doi: 10.1371/journal.pone.0110089. eCollection 2014.
Infections by influenza A viruses (IAV) are a major health burden to mankind. The current antiviral arsenal against IAV is limited and novel drugs are urgently required. Medicinal plants are known as an abundant source for bioactive compounds, including antiviral agents. The aim of the present study was to characterize the anti-IAV potential of a proanthocyanidin-enriched extract derived from the aerial parts of Rumex acetosa (RA), and to identify active compounds of RA, their mode of action, and structural features conferring anti-IAV activity. In a modified MTT (MTTIAV) assay, RA was shown to inhibit growth of the IAV strain PR8 (H1N1) and a clinical isolate of IAV(H1N1)pdm09 with a half-maximal inhibitory concentration (IC50) of 2.5 µg/mL and 2.2 µg/mL, and a selectivity index (SI) (half-maximal cytotoxic concentration (CC50)/IC50)) of 32 and 36, respectively. At RA concentrations>1 µg/mL plaque formation of IAV(H1N1)pdm09 was abrogated. RA was also active against an oseltamivir-resistant isolate of IAV(H1N1)pdm09. TNF-α and EGF-induced signal transduction in A549 cells was not affected by RA. The dimeric proanthocyanidin epicatechin-3-O-gallate-(4β→8)-epicatechin-3'-O-gallate (procyanidin B2-di-gallate) was identified as the main active principle of RA (IC50 approx. 15 µM, SI≥13). RA and procyanidin B2-di-gallate blocked attachment of IAV and interfered with viral penetration at higher concentrations. Galloylation of the procyanidin core structure was shown to be a prerequisite for anti-IAV activity; o-trihydroxylation in the B-ring increased the anti-IAV activity. In silico docking studies indicated that procyanidin B2-di-gallate is able to interact with the receptor binding site of IAV(H1N1)pdm09 hemagglutinin (HA). In conclusion, the proanthocyanidin-enriched extract RA and its main active constituent procyanidin B2-di-gallate protect cells from IAV infection by inhibiting viral entry into the host cell. RA and procyanidin B2-di-gallate appear to be a promising expansion of the currently available anti-influenza agents.
甲型流感病毒（IAV）感染是人类面临的重大健康负担。目前针对IAV的抗病毒药物储备有限，迫切需要新型药物。药用植物是生物活性化合物的丰富来源，其中包括抗病毒剂。本研究的目的是表征从酸模（RA）地上部分提取的富含原花青素的提取物的抗IAV潜力，并鉴定RA的活性成分、其作用方式以及赋予抗IAV活性的结构特征。在改良的MTT（MTTIAV）试验中，RA被证明可抑制IAV毒株PR8（H1N1）和IAV（H1N1）pdm09临床分离株的生长，半数最大抑制浓度（IC50）分别为2.5μg/mL和2.2μg/mL，选择性指数（SI）（半数最大细胞毒性浓度（CC50）/IC50））分别为32和36。当RA浓度>1μg/mL时，IAV（H1N1）pdm09的蚀斑形成被消除。RA对IAV（H1N1）pdm09的耐奥司他韦分离株也有活性。RA不影响A549细胞中TNF-α和EGF诱导的信号转导。二聚体原花青素表儿茶素-3-O-没食子酸酯-（4β→8）-表儿茶素-3'-O-没食子酸酯（原花青素B2-二没食子酸酯）被鉴定为RA的主要活性成分（IC50约为15μM，SI≥13）。RA和原花青素B2-二没食子酸酯可阻止IAV的附着，并在较高浓度下干扰病毒的穿透。原花青素核心结构的没食子酰化被证明是抗IAV活性的先决条件；B环中的邻三羟基化增加了抗IAV活性。计算机对接研究表明，原花青素B2-二没食子酸酯能够与IAV（H1N1）pdm09血凝素（HA）的受体结合位点相互作用。总之，富含原花青素的提取物RA及其主要活性成分原花青素B2-二没食子酸酯通过抑制病毒进入宿主细胞来保护细胞免受IAV感染。RA和原花青素B2-二没食子酸酯似乎是现有抗流感药物的一个有前途的补充。
