Skeleton-diversity-oriented chemical conversion from pure natural products is a valuable method to obtain natural product-like compounds, especially those with novel architecture. The application of phytochemical methods to iridoids yielded three novel secoiridoid dimers: sweritranslactones A-C (1-3). These molecules possess a 6/6/6/6/6/6-fused hexacyclic skeleton and were obtained from swertiamarin, one of the major constituents of the genus Swertia, via a [4 + 2] cycloaddition and intramolecular nucleophilic addition under aqueous conditions. The structures were established based on extensive spectroscopic characterization and X-ray crystallographic diffraction analysis.

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A new ellagic acid derivative, 3,3'-dimethylellagic acid-4'-O-(6″-galloyl)-β-D-glucoside, named runcinatside (5), together with four known compounds 3,3'-dimethylellagic acid (1), 3,3',4'-trimethylellagic acid (2), 3,3'-dimethylellagic acid-4'-O-β-D-glucoside (3) and 3-methylellagic acid-4'-O-α-L-rhamno-pyranoside (4), was isolated from the roots of Polygonum runcinatum Buch.-Ham. ex D.Don Var. sinense Hemsl and the structures of these compounds were established by spectroscopic methods and comparison with previously reported data. All compounds showed antioxidant activities in vitro and compound 5 possessed the highest activity.

Taxadiene (3), a new taxane diterpenoid with an unusual hydroxy substituting at C-17, and six known compounds including two taxane diterpenoids (1 and 2) and four flavonoids (4-7) were isolated from the whole seedling of the Taxus chinensis var. mairei. Among them, compound 7 was isolated from T. chinensis var. mairei for the first time. Structures of these compounds were elucidated on the basis of spectroscopic data and by comparison with reported literature data.