Indazole-Type Alkaloids from Nigella sativa Seeds Exhibit Antihyperglycemic Effects via AMPK Activation in Vitro

Six rare naturally occurring indazole-type alkaloids including two new compounds, 17-O-(beta-d-glucopyranosyl)-4-O-methylnigellidine (1) and nigelanoid (2), and four known compounds (3-6) were isolated from a defatted extract of Nigella sativa (black cumin) seeds. 17-O-(beta-d-Glucopyranosyl)-4-O-methylnigellidine (1) increased glucose consumption by liver hepatocytes (HepG2 cells) through activation of AMP-activated protein kinase (AMPK). Also, this is the first report of compounds 4 and 6 from a natural source.