Sesquiterpenoids with New Carbon Skeletons from the Resin of Toxicodendron vernicifluum as New Types of Extracellular Matrix Inhibitors

Toxicodenanes A–C (1–3), representing sesquiterpenoids with three new carbon skeletons, were isolated from the dried resin of Toxicodendron vernicifluum. Their structures were identified by spectroscopic data and X-ray diffraction crystallography. Their plausible biosynthetic route was proposed via the isolated intermediate (4). Compounds 2 and 3 could significantly inhibit overproduction of fibronectin, collagen IV, and IL-6 in high-glucose-induced mesangial cells in a dose- and time-dependent manner, showing their potential in diabetic nephropathy.