Structurally Diverse Sesquiterpenoids with NO Production and α-Glucosidase Inhibitory Activities from the Fruits of Schisandra chinensis

Chemical fractionation of the AcOEt partition, generated from the EtOH extract of the fruits of Schisandra chinensis, afforded a series of sesquiterpenyl constituents including two new cadinanes, a new eudesmane, two new widdranes (a handling artefact and a new natural product), a new bisabolane and two new natural cuparane enantiomers, along with 15 known structurally related analogs. Structures of the new compounds were unambiguously characterized by interpretation of detailed spectroscopic data including ESI-MS and 1D/2D NMR, with their absolute configurations being established by electronic circular dichroism (ECD) calculation and induced ECD experiment. The inhibitory effects of all the isolates against α-glucosidase and lipopolysaccharide (LPS) induced nitric oxide (NO) production in murine RAW264.7 macrophages, as well as their antibacterial and cytotoxic potential, were evaluated, with selective compounds showing moderate α-glucosidase and NO inhibitory activity. Notably, canangaterpene III exhibited the most significant NO inhibitory effect with an IC₅₀ value of 31.50±1.49 μM.