Two new triterpenoids, teuviscins A (1) and B (2), were isolated from the whole plants of Teucrium viscidum. Compound 1 possessed a rare 7(8→9)abeo-9R-D:C-friedo-B′:A′-neo-gammacerane skeleton, and compound 2 is a taraxerane triterpene acid. Their structures were characterized by extensive spectroscopic methods (HR-ESI-MS, 1D and 2D NMR), and the absolute configurations of 1 and 2 were secured by single-crystal X-ray diffraction analyses using Cu Kα radiation. Compound 2 showed anti-AD bioactivity which delayed animals paralysis of transgenic AD Caenorhabditis elegans.

Three new iridoids, valejatanins A–C (1–3), and one new natrual iridoid (4), together with four known sesquiterpenoids (5–8), were isolated from the roots of Valeriana jatamansi Jones. Compounds 3 and 4 are C(4)-epimers. Their structures were elucidated by extensive spectroscopic analysis (IR, HRESIMS, 1D and 2D NMR) and by comparison of their NMR data with those of related compounds. The absolute configuration of 5 was determined for the first time by single-crystal X-ray diffraction analysis with Cu-Kα irradiation. The cytotoxic activities of all compounds were evaluated against HT29, K562 and B16 cancer cell lines in vitro by MTT assay. Valejatanin A (1) showed noteworthy cytotoxic activities with IC50 values of 22.17, 15.26, 3.53 μg/mL against three cancer cell lines. The antibacterial activities of all compounds against bacteria were tested in vitro. Compound 6 exhibited antibacterial activities against Staphylococcus aureus and Pseudomonas aeruginosa.Download high-res image (105KB)Download full-size image

Euphorikanin A (1), an unprecedented diterpenoid lactone which possesses a novel 5/6/7/3-fused tetracyclic ring skeleton, was isolated from the roots of Euphorbia kansui. The chemical structure and absolute stereochemistry were elucidated on the basis of extensive spectroscopic methods and single-crystal X-ray diffraction analysis. Compound 1 exhibited moderate cytotoxicity against two human tumor cell lines HeLa and NCI-446. A proposed biosynthetic pathway of compound 1 is also described.

Crocrassins A (1) and B (2), two novel sesquiterpenoids with a unique skeleton, were isolated from a Chinese medicinal plant Croton crassifolius. Their structures were assigned on the basis of detailed spectroscopic analyses (especially HRESIMS and 2D NMR), and their absolute configuration was established via single-crystal X-ray diffraction studies as well as chemical transformation.