Securinega Alkaloids from the Twigs of Securinega suffruticosa and Their Biological Activities

Seven new Securinega alkaloids, securingines A–G ( 1 – 7 ), together with seven known analogues ( 8 – 14 ), were isolated from the twigs of Securinega suffruticosa . Their chemical structures were elucidated by a combined approach of spectroscopic analysis, chemical methods, ECD calculations, and DP4+ probability analysis. The full NMR assignments and the absolute configuration of compound 8 are also reported. In addition, all the isolated phytochemicals ( 1 – 14 ) were assessed for their cytotoxic, anti-inflammatory, and potential neuroprotective activities. Compound 4 showed cytotoxic activity (IC 50 values of 1.5–6.8 μM) against four human cell lines (A549, SK-OV-3, SK-MEL-2, and HCT15). Compounds 3, 10, 12, and 13 showed potent inhibitory effects on nitric oxide production (IC 50 values of 12.6, 12.1, 1.1, and 7.7 μM, respectively) in lipopolysaccharide-stimulated murine microglia BV-2 cells. Compound 5 exhibited a nerve growth factor production effect (172.6 ± 1.2%) in C6 glioma cells at 20 μg/mL.