Sesquiterpenoids from the rhizomes of Homalomena pendula and their anti-inflammatory activities.

Sixteen sesquiterpenoids including two new ones, homalolides A - B (1 ‒ 2) , were firstly isolated from the methanolic extract of the rhizomes of Homalomena pendula collected in Vietnam. The structures and relative stereochemistry of new compounds were elucidated by 1D-/2D-NMR, IR, UV and HRESIMS analyses. The GCMS experiment demonstrated that homalolide A ( 1 ) is an artifact due to the methylation during methanolic extraction process. All isolates ( 1 ‒ 16 ) were tested for their inhibitory activities against lipopolysaccharide-induced nitric oxide production in the RAW 264.7 macrophage cell line. Compounds 1 , 3 , 6 ‒ 8 , 10 ‒ 12 displayed moderate inhibitory effect on NO production with IC 50 values ranging from 35.41 to 64.06 μM.