Objective: Jingfang Granules have been recommended for the prevention and treatment of corona virus disease 2019 (COVID-19). Through chemical analysis and bioactivity evaluation, this study aims to elucidate the potential effective components of Jingfang Granules.
Methods: The inhibitory acti-vities of Jingfang Granules extract against 3-chymotrypsin-like protease (3CLpro), papain like protease (PLpro), spike protein receptor-binding domain (S-RBD) and human cyclooxygenase-2 (COX-2) were evaluated using enzyme assay. The antitussive effects were evaluated using the classical ammonia-induced cough model. The chemical constituents of Jingfang Granules were qualitatively and quantitatively analyzed by liquid chromatography-mass spectrometry (LC/MS). The 3CLpro and PLpro inhibitory activities of the major compounds were determined by enzyme assay, molecular docking, and site-directed mutagenesis.
Results: Jingfang Granules exhibited 3CLpro and PLpro inhibitory activities, as well as COX-2 inhibitory and antitussive activities. By investigating the MS/MS behaviors of reference standards, a total of fifty-six compounds were characterized in Jingfang Granules. Sixteen of them were unambiguously identified by comparing with reference standards. The contents of the 16 major compounds were also determined, and their total contents were 2 498.8 μg/g. Naringin, nodakenin and neohesperidin were three dominating compounds in Jingfang Granules, and their contents were 688.8, 596.4 and 578.7 μg/g, respectively. In addition, neohesperidin and naringin exhibited PLpro inhibitory activities, and the inhibition rates at 8 μmol/L were 53.5% and 46.1%, respectively. Prim-O-glucosylcimifugin showed significant inhibitory activities against 3CLpro and PLpro, and the inhibitory rates at 8 μmol/L were 76.8% and 78.2%, respectively. Molecular docking indicated that hydrogen bonds could be formed between prim-O-glucosylcimifugin and amino acid residues H163, E166, Q192, T190 of 3CLpro (binding energy, -7.7 kcal/mol) and K157, D164, R166, E167, T301 of PLpro(-7.3 kcal/mol), respectively. Site-directed mutagenesis indicated amino acid residue K157 was a key active site for the interaction between prim-O-glucosylcimifugin and PLpro.
Conclusion: Prim-O-glucosylcimifugin, neohesperidin, and naringin as the major compounds from Jingfang Granules could inhibit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus proteases 3CLpro and PLpro. The results are valuable for rational clinical use of Jingfang Granules.
目的: 荆防颗粒是新型冠状病毒肺炎预防及轻症治疗的推荐用药，本文结合化学成分分析及活性检测，阐明其潜在的活性成分。
方法: 采用酶学方法测定荆防颗粒提取物对新型冠状病毒3-chymotrypsin-like protease (3CLpro)、papain like protease (PLpro)、spike protein receptor-binding domain (S-RBD)及人cyclooxygenase-2 (COX-2)的抑制活性，利用氨水引咳小鼠模型测试其止咳作用；基于liquid chromatography-mass spectrometry(LC/MS)技术对荆防颗粒进行化学成分定性、定量分析，阐明其化学组成；采用酶学实验、分子对接、定点突变等方法测定荆防颗粒中抑制3CLpro、PLpro的主要活性成分并阐明可能的作用机制。
结果: 荆防颗粒提取物对新型冠状病毒3CLpro、PLpro蛋白酶具有一定的抑制作用，且具有COX-2抑制活性及止咳药效。进一步在荆防颗粒鉴定了56个成分，其中16个成分经与对照品比对，准确鉴定其化学结构，并测定了其含量，总量为2 498.8 μg/g。16个成分中的主要成分升麻素苷对3CLpro和PLpro均具有显著的抑制活性，8 μmol/L的抑制率分别为76.8%和78.2%；新橙皮苷、柚皮苷对PLpro有抑制活性，8 μmol/L的抑制率分别为53.5%和46.1%。分子对接结果表明，升麻素苷可与3CLpro、PLpro活性口袋的氨基酸残基形成氢键，结合能分别为-7.7和-7.3 kcal/mol。定点突变结果表明，氨基酸残基K157是升麻素苷与PLpro相互作用的重要活性位点。
结论: 荆防颗粒的主要成分升麻素苷、新橙皮苷、柚皮苷等具有抑制新型冠状病毒3CLpro及PLpro的活性，为荆防颗粒的临床合理使用提供了依据。
Keywords: 3-chymotrypsin-like protease; Effective components; Jingfang Granules; Papain like protease; Severe acute respiratory syndrome coronavirus 2.