Sesquiterpenoids from Carpesium abrotanoides and their anti-inflammatory activity both in vitro and in vivo

Twenty-nine sesquiterpenoids, including pseudoguaiane-type (1-11), eudesmane-type (12-23), and carabrane-type (24-29), have been identified from the plant Carpesium abrotanoides. Of them, compounds 1-4, 12-15, and 24-27, namely carpabrotins A-L, are twelve previously undescribed ones. Compound 3 possessed a pseudoguaiane backbone with a rearrangement modification at C-11, C-12 and C-13, while compound 4 suffered a carbon bond break between the C-4 and C-5 to form a rare 4,5-seco-pseudoguaiane lactone. Compounds 1-3, 5, 13-16 and 25-27 exhibited anti-inflammatory activity by inhibiting NO production in LPS-induced RAW264.7 macrophages with IC₅₀ values less than 40 μM, while compounds 1, 2, 5, 13, 14, 16, and 25-27 showed significant inhibitory activity comparable to that of dexamethasone. The anti-atopic dermatitis (AD) effects of compounds 5 and 16 were tested according to 2,4-dinitrochlorobenzene (DNCB)-induced AD-like skin lesions in KM mice, and the results revealed that the major products 5 and 16 improved the histological features of AD-like skin lesions and mast cell infiltration in mice. This study suggested that sesquiterpenoids in C. abrotanoides should play a key role in its anti-inflammatory use.