Triterpenes isolated from acorns of Quercus serrata var. brevipetiolata exert anti-inflammatory activity

⿢Ten pentacyclic triterpenes, including three novels, were isolated from acorns.⿢Most of the triterpenes showed potent anti-inflammatory activities.⿢The triterpenes may be responsible for the anti-inflammatory activity of acorn.

Acorns serve as an important role as an important cash crop in human history and are a source of food for many countries. In this study, ten pentacyclic triterpenes, three of which were novel, were isolated from acorns (Quercus serrata var. brevipetiolata). The structures of novel triterpenoids were established based on the interpretation of chemical and spectroscopic analyses, including IR, HR-ESI⿿MS, and NMR experiments (1D and 2D NMR), which were elucidated to be 3,23-O-methyl butyrate-2α,3β,19α,23-tetrahydroxy-urs-12-en-28-oic acid β-d-glucopyranosyl ester (1), 3,23-O-methyl butyrate-2α,3β,19α,23-tetrahydroxy-olean-12-en-28-oic acid β-d-glucopyranosyl ester (2), and 23-acetoxy-2α,3β,19α-trihydroxyurs-12-en-28-oic acid (3), respectively. All isolated compounds were tested for their inhibitory effects on LPS-induced nitric oxide (NO) production in RAW 264.7 macrophages. Most of the triterpenes from acorns showed pronounced anti-inflammatory activities compared to positive control indomethacin. Furthermore, based on the results of the nitric oxide assay, production of pro-inflammatory markers including interleukin-6 (IL-6) and interleukin-8 (IL-8) of compound 1⿿3 in TNF-α stimulated RAW 264.7 were investigated by ELISA, which showed these pentacyclic triterpenes may be responsible with the two pro-inflammatory cytokines for the anti-inflammatory activity of acorn.

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