Pyrrolo-isoquinoline and glycosylated pyrrolidine alkaloids from Nigella glandulifera and their anti-PTP1B activity

Abstract Two new alkaloids, nigellisoquinomine ( 1 ) with a novel pyrrolo-isoquinoline skeleton, and nigellapyrrolidine ( 2 ) possessing a rare glycosylated pyrrolidine moiety, together with two known alkaloids, agrocybenine ( 3 ) and 4,6,6-trimethyl-3,4-epoxypiperidin-2-one ( 4 ), were isolated from the seeds of Nigella glandulifera Freyn. Their structures were identified by extensive NMR and HR-ESIMS analysis. Compound 1 exhibited potent protein tyrosine phosphatase 1B (PTP1B) inhibitory activity with an IC 50 value of 3.65 ± 0.08 μM.