Department of Veterinary Tropical Diseases, University of Pretoria, Pretoria, South Africa.
Influenza and Other Respiratory Viruses Department, Pasteur Institute of IRAN, Tehran, Iran.
BMC Complement Altern Med. 2018 Jun 15;18(1):184. doi: 10.1186/s12906-018-2246-1.
Influenza infection is a major public health threat. The role of influenza A virus-induced inflammatory response in severe cases of this disease is widely recognized. Drug resistance and side effects of chemical treatments have been observed, resulting in increased interest in alternative use of herbal medications for prophylaxis against this infection. The South African medicinal plant, Rapanea melanophloeos (RM) (L.) Mez of the family Myrsinaceae was selected owing to its traditional use for the treatment of several diseases such as respiratory ailments and also previous preliminary studies of anti-influenza activity of its methanolic extract. The aim of this study was to investigate the immunomodulatory properties of a glycoside flavone isolated from RM against influenza A virus.
The non-cytotoxic concentration of the quercetin-3-O-α-L-rhamnopyranoside (Q3R) was determined by MTT assay and tested for activity against influenza A virus (IAV) in simultaneous, pre-penetration and post-penetration combination treatments over 1 h incubation on MDCK cells. The virus titer and viral load targeting NP and M2 viral genes were determined using HA and qPCR, respectively. TNF-α and IL-27 as pro- and anti-inflammatory cytokines were measured at RNA and protein levels by qPCR and ELISA, respectively.
Quercetin-3-O-α-L-rhamnopyranoside at 150 μg/ml decreased the viral titer by 6 logs (p < 0.01) in the simultaneous procedure. The NP and M2 genes copy numbers as viral target genes, calculated based on the Ct values and standard formula, significantly decreased in simultaneous treatment (p < 0.01). The expression of cytokines was also considerably affected by the compound treatment.
This is the first report of quercetin-3-O-α-L-rhamnopyranoside from RM and its immunomodulatory properties against influenza A virus. Further research will focus on detecting the specific mechanism of virus-host interactions.
流感感染是一个主要的公共卫生威胁。甲型流感病毒诱导的炎症反应在该病的严重病例中的作用已得到广泛认可。已观察到化学治疗药物的耐药性和副作用，这导致人们对替代草药药物预防这种感染的兴趣增加。南非药用植物 Rapanea melanophloeos（RM）（L.）Mez 属于紫金牛科，因其传统上用于治疗多种疾病（如呼吸道疾病），以及先前对其甲醇提取物的抗流感活性的初步研究，而被选中。本研究旨在研究从 RM 中分离出的糖苷黄酮对甲型流感病毒的免疫调节特性。
通过 MTT 测定法确定槲皮素-3-O-α-L-鼠李糖苷（Q3R）的非细胞毒性浓度，并在 MDCK 细胞上孵育 1 小时，通过同时、预渗透和渗透后联合处理，测试其对甲型流感病毒（IAV）的活性。通过 HA 和 qPCR 分别测定病毒滴度和针对 NP 和 M2 病毒基因的病毒载量。通过 qPCR 和 ELISA 分别在 RNA 和蛋白质水平上测量 TNF-α 和 IL-27 作为前炎症和抗炎细胞因子。
在同时处理过程中，150μg/ml 的槲皮素-3-O-α-L-鼠李糖苷可将病毒滴度降低 6 个对数级（p<0.01）。基于 Ct 值和标准公式计算的 NP 和 M2 基因拷贝数作为病毒靶基因，在同时处理中显著降低（p<0.01）。细胞因子的表达也受到化合物处理的显著影响。
这是首次从 RM 中分离出槲皮素-3-O-α-L-鼠李糖苷及其对甲型流感病毒的免疫调节特性的报道。进一步的研究将集中于检测病毒-宿主相互作用的特定机制。
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