Four new diarylheptanoids and two new terpenoids from the fruits of Alpinia oxyphylla and their anti-inflammatory activities

Four previously unreported diarylheptanoids ( 1a / 1b ~ 2a / 2b ), one undescribed sesquiterpenoid ( 8 ), one new diterpenoid ( 12 ) and twelve known analogues were isolated and identified from the fruits of Alpinia oxyphylla. The structures of these compounds were elucidated by comprehensive spectroscopic data analysis, X-ray single crystal diffraction, ECD and modified Mosher’s method. Separation of the enantiomeric mixtures ( 1a / 1b , 2a / 2b , 3a / 3b , 4a / 4b , and 5a / 5b ) were achieved on a chiral column using acetonitrile-water mixtures as eluents. Among them, compounds 3a / 3b , 4a / 4b were optically pure obtained by the first chiral splitting. Furthermore, most of the isolates were evaluated for their inhibitory effects on the production of NO and IL-6 in lipopolysaccharide (LPS)-induced RAW264.7 macrophage. Interestingly, 2 and 4 showed significant inhibitory activities on NO production with IC₅₀ values of 33.65 μM and 9.88 μM (hydrocortisone: IC₅₀ = 34.26 μM), respectively. Additionally, they also partially decreased the secretion of IL-6.