Dendrocandin U from Dendrobium officinale Kimura et Migo Inhibits M1 Polarization in Alveolar Macrophage by Suppressing NF‐κB Signaling Pathway

Abstract Dendrobium officinale Kimura et Migo is a valuable and homologous medicine and food traditional Chinese medicine. Currently there are few studies on the anti‐inflammatory activity of lipophilic components. The aim of this study was to explore the anti‐inflammatory effect and mechanism of the lipophilic compounds in Dendrobium officinale . Six compounds were isolated and identified, including three bibenzyl compounds, dendrocandin U, dendronbibisline B, erianin, and three lignans, (−)‐syringaresinol, (+)‐syringaresinol‐O‐ β ‐D‐glucopyranoside, 5‐methoxy‐(+)‐isolariciresinol. Among them, dendronbibisline B and 5‐methoxy‐(+)‐isolariciresinol were isolated from Dendrobium officinale for the first time. Besides, we found dendrocandin U, dendronbibisline B and (−)‐syringaresinol exhibited the anti‐inflammation to inhibit nitric oxide secretion induced by lipopolysaccharide (LPS)/interferon (IFN‐γ) in MH−S cells. Furthermore, dendrocandin U could inhibit the expression of tumor necrosis factor‐α (TNF‐α), Cluster of Differentiation 86 (CD86), and reduce inflammatory morphological changes of macrophages. Meanwhile, we confirmed that the anti‐inflammation mechanism of dendrocandin U was to inhibit M1 polarization by suppressing toll‐like receptor 4 (TLR4)/recombinant myeloid differentiation factor 88 (MyD88)/nuclear factor kappa B (NF‐κB) signaling pathway. In this paper, dendrocandin U with significant anti‐inflammatory activity was found from Dendrobium officinale , which could provide a basis for the study of its anti‐inflammatory drugs.