Rotenoids and Other Specialized Metabolites from the Roots of Mirabilis multiflora: Opioid and Cannabinoid Receptor Radioligand Binding Affinities.

ABSTRACT

Mirabilis multiflora is an acclaimed hallucinogen consumed traditionally by the Hopi Indians to induce diagnostic visions. Its root extract afforded a new (3) and four known (2, 5, 6, and 7) 12a-hydroxyrotenoids, a known rotenoid (4), and two known secondary metabolites (1 and 8). The structures of the compounds were elucidated based on spectroscopic and spectrometric data analysis. Electronic circular dichroism data were used to define the (6aS,12aR) absolute configuration of the 12a-hydroxyrotenoids. Compounds 2-7 were screened for their radioligand binding affinities toward the opioid (δ, κ, and µ) and cannabinoid (CB1 and CB2) receptor subtypes. The 6-methoxy-substituted rotenoids 3, 4, and 7 showed the highest receptor binding affinity with moderate selectivity toward the δ-opioid receptor subtype, with negligible binding affinities for CB1 and CB2. Their binding affinities toward the δ-opioid receptor were 64.5% (4), 58.7% (7), and 55.3% (3) at 10 µM, respectively.