Anti-inflammatory Constituents Isolated From Launaea sarmentosa Against Infection by LPS-stimulated Macrophages

Inflammation is one of the basic pathological processes due to the adaption of immune system against infection or irritation. Since non-steroidal anti-inflammatory drugs (NSAIDs) cause many side effects, investigation of anti-inflammatory natural products promising to provide novel therapeutic agents. Here, Launaea sarmentosa (Willd.) Kuntze, a medicinal herb applied to treat inflammation diseases, was investigated for its anti-inflammatory components to find new therapies for inflammatory syndromes. This study indicated that ethyl acetate fractional extract reduced the expression of pro-inflammatory cytokines, representing the highest activity for both NO radical-scavenging and NO secretion inhibition during LPS-stimulated RAW264.7 macrophages. Besides, five anti-inflammatory compounds, including succinic acid, quercetin, 2(4-hydroxyphenyl)acetic acid, luteolin-7-O-β-D-glucopyranoside, and quercetin-3-O-rutinoside, were isolated and elucidated the structure according to 1D and 2D- NMR. Among these compounds, succinic acid and 2(4-hydroxyphenyl)acetic acid were first reported in this species. Moreover, this study indicated that the presence of these compounds, typically quercetin and luteolin-7-O-β-D-glucopyranoside, enhanced anti-inflammatory ability via deactivation of NF-кB/MAPK pathway to mitigate the expression of IL-6. Hence, this study contributed the initial evidence of anti-inflammatory constituents from Launaea sarmentose and highlighted an approach to discovering natural items or phytotherapeutic agents.