Structurally Diverse Sesquiterpenoid Glycoside Esters from Pittosporum qinlingense with Anti-neuroinflammatory Activity.

Thirteen new sesquiterpenoid glycoside esters, including 11 aromadendrane-type compounds, pitqinlingosides A-K ( 1 - 11 ), one cadinane-type compound, pitqinlingoside L ( 12 ), and one eudesmane-type compound, pitqinlingoside M ( 13 ), together with seven known analogues ( 14 - 20 ) were isolated from the twigs, fruits, and leaves of Pittosporum qinlingense. Structures were elucidated by analysis of spectroscopic data, gas chromatography mass spectrometry (GC-MS), and chemical methods. The absolute configuration was confirmed by single-crystal X-ray crystallography analysis or electronic circular dichroism spectra. Unusual glycoside esters are characterized by the presence of polyacylated β-d-fucopyranosyl, β-d-glucopyranosyl, and β-d-xylopyranosyl units. Pitqinlingosides A ( 1 ), B ( 2 ), D ( 4 ), and F ( 6 ), pittosporanoside A 1 acetate ( 14 ), and pittosporanoside A 1 ( 16 ) showed significant nitric oxide production inhibition in lipopolysaccharide (LPS)-induced BV-2 microglial cells with IC 50 values ranging from 0.95 to 24.12 μM. Structure-activity relationships of the isolated compounds are discussed.