In the present study, a procyanidins-enriched fraction (PCE) from the rhizome of Fagopyrum dibotrys was obtained by anticomplement activity-guided fractionation. PCE could alleviate H1N1-induced ALI in mice by reducing weight loss, decreasing lung index, and regulating cytokine levels in lung tissue. PCE contained 76.5 ± 1.1% procyanidins with a mean degree of polymerization (mDP) of 5.24 ± 0.16. Meanwhile, thirty-three chemical constituents, including 27 procyanidins and 6 other compounds, were recognized by UPLC-Triple-TOF-MS/MS. Among them, twenty recognized procyanidins were composed of (epi)catechin with B-type link, while the rest consisted of (epi)catechin gallate. Furthermore, six compounds were obtained by preparative HPLC on a C18 column (250 × 10.0 mm, 5 µm), and their structures were confirmed by mass spectrum (MS), nuclear magnetic resonance (NMR), and specific rotation. The structure-activity relationship analysis indicated that DP and galloylation were closely related to the anticomplement activity of procyanidins. The obtained results revealed that anticomplement procyanidins were one kind of the potentially effective materials of F. dibotrys against H1N1 influenza virus infection, and the in vivo efficacy of these compounds was worthy of further investigation.
Keywords: Complement system; Fagopyrum dibotrys (D. Don); Procyanidins; Recognition; Structure-activity relationship.
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