School of Life Sciences, The Chinese University of Hong Kong, 999077, Hong Kong, China.
College of Pharmaceutical Sciences, Hebei University, Baoding, 077000, China.
J Ethnopharmacol. 2022 Jun 28;292:115175. doi: 10.1016/j.jep.2022.115175. Epub 2022 Mar 16.
Canarium album (Lour.) DC. belongs to the Burseraceae family. Its leaf, named as Ganlanye (GLY), was recorded to treat warm disease symptoms via clearing lung heat and toxicants in medical classics. Its aqueous extract had anti-influenza activity in our previous phenotypic screening. However, its active components and mechanism were not identified.
We aim to isolate the anti-influenza phytochemicals from GLY extract and explore its anti-flu mechanism.
Influenza A virus infected MDCK cells were used to test the compounds and fractions. Structural analyses of new compounds were performed via NMR calculation with the combination of DP4plus probability method and computed electronic circular dichroism (ECD). Hemagglutination inhibitory assay and neuraminidase inhibitory assay were performed to find the target protein. Molecular docking and recombinant virus were used to confirm the action site of the three new canaroleosides.
Three new phenolic glycosides, canaroleosides A-C (1-3), and three known flavonoids (4-6), were isolated from the GLY aqueous extract and their anti-influenza virus mechanism was revealed. The absolute configurations of 1-3 were determined by ECD method, with the structure of the 2,5-dihydroxybenzoic acid moiety in 1 assigned by NMR calculation. Compound 1 was found to suppress both hemagglutinin and neuraminidase activities. Compounds 2, 3 4 and 6 inhibited neuraminidase, while compound 5 inhibited hemagglutinin. 1-3 could interact with Arg152 of the viral neuraminidase based on the result of molecular docking and reverse genetics.
Six phytochemicals were isolated from GLY aqueous extract and found to inhibit influenza A strains. They were found to interact with hemagglutinin or neuraminidase and canaroleosides 1-3 could interact with Arg152 of the viral neuraminidase. This study provided more evidence on the anti-influenza effect of Ganlan and laid the foundation for further generation of potent NA inhibitors.
乌榄（Lour.）DC.属于橄榄科。其叶子名为橄榄叶（GLY），在医学经典中被记录为清热解毒治疗温病症状。其水提物在我们之前的表型筛选中具有抗流感活性。然而，其活性成分和机制尚未确定。
我们旨在从 GLY 提取物中分离抗流感植物化学物质，并探讨其抗流感机制。
使用流感 A 病毒感染的 MDCK 细胞来测试化合物和馏分。通过与 DP4plus 概率方法相结合的 NMR 计算来分析新化合物的结构，并结合计算电子圆二色性（ECD）。进行血凝抑制试验和神经氨酸酶抑制试验以找到靶蛋白。分子对接和重组病毒用于确认三种新的卡诺醇苷的作用部位。
从 GLY 水提物中分离得到三种新的酚糖苷，即卡诺醇苷 A-C（1-3）和三种已知的黄酮类化合物（4-6），并揭示了其抗流感病毒机制。通过 ECD 方法确定了 1-3 的绝对构型，通过 NMR 计算确定了 1 中 2,5-二羟基苯甲酸部分的结构。发现化合物 1 可同时抑制血凝素和神经氨酸酶活性。化合物 2、3、4 和 6 抑制神经氨酸酶，而化合物 5 抑制血凝素。基于分子对接和反向遗传学的结果，1-3 可与病毒神经氨酸酶的 Arg152 相互作用。
从 GLY 水提物中分离得到 6 种植物化学物质，发现它们抑制甲型流感病毒株。它们被发现与血凝素或神经氨酸酶相互作用，并且卡诺醇苷 1-3 可与病毒神经氨酸酶的 Arg152 相互作用。本研究为甘兰的抗流感作用提供了更多证据，并为进一步生成有效的 NA 抑制剂奠定了基础。
