Lycibarbarines A–C, Three Tetrahydroquinoline Alkaloids Possessing a Spiro-Heterocycle Moiety from the Fruits of Lycium barbarum

Three tetrahydroquinoline alkaloids, lycibarbarines A–C (1–3), possessing a unique tetracyclic tetrahydroquinoline–oxazine–ketohexoside fused motif, were isolated from the fruits of Lycium barbarum. Their structures were determined by spectroscopic analysis and quantum-chemical calculations. Compounds 1 and 3 exhibited neuroprotective activity when evaluated for corticosterone-induced injury by reducing the apoptosis of PC12 cells through the inhibition of caspase-3 and caspase-9.