Abstract

Papain-like protease (PLpro) enzyme plays a vital role in viral replication as it breaks down polyproteins and disrupts the host's immune response. There are few reports on Kampo formulas that focus on PLpro activity. In this study, we evaluated the inhibitory effects of senkyuchachosan, a traditional Japanese medicine, on PLpro of SARS-CoV-2, the virus responsible for causing COVID-19. We purified the PLpro enzyme and conducted in vitro enzymatic assays using specific substrates. Among the nine crude drugs present in senkyuchachosan, four (Cyperi Rhizoma, Schizonepetae Spica, Menthae Herba, and Camelliae sinensis Folium [CsF]) strongly inhibited PLpro activity. CsF, derived from Camellia sinensis (green tea), contains polyphenols, including catechins and tannins. To confirm that the PLpro inhibitory effects of senkyuchachosan predominantly stem from tannins, the tannins were removed from the decoction using polyvinylpolypyrrolidone (PVPP). The inhibitory effect of senkyuchachosan on PLpro activity was reduced by the removal of PVPP. In addition, the tannin fraction obtained from the CsF extracts showed significant PLpro inhibitory effects. These findings lay the groundwork for the potential development of therapeutic agents that target SARS-CoV-2 infection by intervening in proteolytic cleavage of the virus.

Graphical Abstract

摘要

木瓜蛋白酶 (PLpro) 在病毒复制中发挥着至关重要的作用，因为它会分解多蛋白并破坏宿主的免疫反应。关于汉方制剂中关注 PLpro 活性的报道很少。在这项研究中，我们评估了日本传统药物 senkyuchachochsan 对 SARS-CoV-2（引起 COVID-19 的病毒）PLpro 的抑制作用。我们纯化了 PLpro 酶并使用特定底物进行了体外酶测定。在千九茶秋散中存在的九种生药中，四种（香附、荆芥、薄荷和茶叶 [CsF]）强烈抑制 PLpro 活性。 CsF 源自茶树（绿茶），含有多酚，包括儿茶素和单宁。为了确认千九茶长散的 PLpro 抑制作用主要来自单宁，使用聚乙烯聚吡咯烷酮 (PVPP) 从汤剂中去除单宁。去除 PVPP 后，senkyuchach Chosan 对 PLpro 活性的抑制作用降低。此外，从 CsF 提取物中获得的单宁部分显示出显着的 PL​​pro 抑制作用。这些发现为通过干预病毒的蛋白水解裂解来靶向 SARS-CoV-2 感染的治疗药物的潜在开发奠定了基础。

图形概要