Secoiridoid Glucosides from the Twigs of Syringa oblata var. dilatata and Their Neuroprotective and Cytotoxic Activities

Phytochemical investigation of the twigs of Syringa oblata var. diatata led to the isolation of two new secoiridoid glucosides, dilatioside A-B (1-2), along with thirteen known ones (3-15). The structures were determined by spectroscopic methods including one and two dimensional (1-and 2D-) NMR techniques, high resolution (HR)-FAB-MS, and chemical methods. The isolated compounds (1-15) were tested for the induction of nerve growth factor (NGF) secretion in a C6 rat glioma cell line and their cytotoxicity against four human cancer cell lines (A549, SK-OV-3, SK-MEL-2, HCT15) in vitro using a sulforhodamine B bioassay. Compounds 5, 7, 8, 10, and 14 were found to induce upregulation of NGF secretion without causing significant cell toxicity.