Three New Chemical Constituents of Dryopteris crassirhizoma Nakai in Lianhua Qingwen Capsule and Investigation on Their Antiviral Potential Based on 3CL Hydrolase of SARS-CoV-2

Three new chromone glycosides, named 2-methyl-5-hydroxyl-4-chromone-7-O- ss-D-glucuronide (1), 2-ethyl-5-hydroxyl- 4-chromone-7- O-ss-D-glucuronide (2) and 1-acetyl-3-C-ss-D-glucopyranosyl-5-methylphloroglucinyl-6-O-ss-D-glucopyranoside (6), together with eight known compounds were isolated from the water extract of Dryopteris crassirhizoma Nakai,and the water extract preparation process is consistent with Lianhua Qingwen capsule. All the chemical structures of new compounds were characterized by 1D and 2D NMR spectra as well as high resolution mass and IR spectra. The chemical structures of known compounds were characterized by NMR spectra along with comparison of their spectroscopic data with those reported in the literature. The binding ability of these compounds to 3CL hydrolase of SARS-COV-2 was evaluated by molecular docking. The results showed that the chromone glycosides with glucuronic acid fragment had good docking effect with 3CL hydrolase and this indicated the chromone glucuronides could be further studied as potential antiviral compounds.