Isolation and Biological Evaluation of Prenylated Flavonoids from Maclura pomifera

Phytochemical analysis of the ethanolic extract of Maclura pomifera fruits yielded four new compounds (I–IV) along with eleven known compounds (V–XV). The crude extract exhibited significant activity towards cannabinoid receptors (CB1: 103.4% displacement; CB2: 68.8% displacement) and possibly allosteric interaction with δ and μ opioid receptors (−49.7 and −53.8% displacement, resp.). Compound I was found to be possibly allosteric for κ and μ opioid receptors (−88.4 and −27.2% displacement, resp.) and showed moderate activity (60.5% displacement) towards CB1 receptor. Compound II exhibited moderate activity towards cannabinoid receptors CB1 and CB2 (47.9 and 42.3% displacement, resp.). The known compounds (V–VIII) exhibited prominent activity towards cannabinoid receptors: pomiferin (V) (IC(50) of 2.110 and 1.318 μM for CB1 and CB2, resp.), auriculasin (VI) (IC(50) of 8.923 μM for CB1), warangalone (VII) (IC(50) of 1.670 and 4.438 μM for CB1 and CB2, resp.), and osajin (VIII) (IC(50) of 3.859 and 7.646 μM for CB1 and CB2, resp.). The isolated compounds were also tested for inhibition of human monoamine oxidase-A and monoamine oxidase-B enzymes activities, where all the tested compounds showed fewer inhibitory effects on MAO-A compared to MAO-B activities: auriculasin (VI) (IC(50) of 1.91 and 45.98 μM for MAO-B and MAO-A, resp.).