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

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