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 analogs were isolated from the fruits of Alpinia oxyphylla. The structural elucidation of these compounds was achieved through a comprehensive analysis of spectroscopic data, single-crystal X-ray diffraction, electronic circular dichroism（ECD）,and modified Mosher's method. Enantiomeric mixtures（1a/1b, 2a/2b, 3a/3b, 4a/4b, and 5a/5b） were separated on a chiral column using acetonitrile-water mixtures as eluents. Among them, compounds 3a/3b and 4a/4b were isolated as optically pure enantiomers in the initial chiral separation. Furthermore, most of the isolates were evaluated for their inhibitory effects against the production of nitric oxide（NO） and interleukin-6（IL-6） in lipopolysaccharide（LPS）-induced RAW264.7 macrophages. Interestingly, 2 and 4 showed significant inhibitory activities against NO production with IC50 values of 33.65 and 9.88 μmol·L-1(hydrocortisone: IC50 34.26 μmol·L-1),respectively. Additionally, they also partially reduced the secretion of IL-6.