Lyciumines A and B: Two Pyrrole-Fused Alkaloids from the Fruits of Lycium barbarum

Two novel pyrrole-fused alkaloids, lyciumines A (1) and B (2), were isolated from the fruits of Lycium barbarum. Their structures were elucidated by analysis of NMR spectroscopic and MS spectrometric data, along with computational studies. Compound 1 represents a novel pyrroloindoline alkaloid with a rare 6/5/5/6 tetracyclic system connected with a 2-formyl-5-methylpyrrole moiety via a C-C bond. Compound 2 features an unusual pyrrole alkaloid with a 5/5/5 tricyclic skeleton. Compound 1 significantly increases glucose consumption in insulin-resistant HepG2 cells in a dose-dependent manner. Further mechanism investigations demonstrated that compound 1 regulates glucose metabolism via activating the AMPK/PI3K/Akt signaling pathway.