Prenylated flavonoids from Dalea genus as xanthine oxidase inhibitors: In vitro bioactivity evaluation and molecular docking studies

Prenylated flavanones are a family of compounds with an important biological potential. Previously, anti-tyrosinase activity, acetylcholinesterase inhibitory activity, and neuroprotective effects of several prenyl flavanones isolated from different American Dalea genus species were reported. The biological potency of these kinds of compounds, together with the particularity of their chemical structures, encouraged us to investigate them for in vitro and in silico anti-xanthine oxidase activity. So, five prenyl-flavanones obtained from different Dalea sp (Dalea elegans, Dalea boliviana, and Dalea pazensis) were studied and the relationships between the structure of these prenyl-flavanones and their inhibitory activity were evaluated. Molecular docking studies were performed in order to propose the binding mode of the most active natural compound. 2′,4′-dihydroxy-5′-(1‴,1‴-dimethylallyl)-8-prenylpinocembrin (1) was the most active in this series showing an IC50 of 0.26 ± 0.07 µM comparable with the reference inhibitor, allopurinol. The presence of 5,7,2′,4′-tetrahydroxy substitution, accompanied by a prenyl group at 8-position in the A-ring, and a 5′ (1‴,1‴-dimethylallyl) were important to present a xanthine oxidase inhibitory activity. This fact was confirmed with molecular docking studies showing relevant interactions of 1 with the residues of the catalytic site of xanthine oxidase, and a binding energy of −7.3297 kcal mol−1. These results contributed not only to understanding the binding mode but also to validating the in vitro results. The obtained findings lead us to propose these prenyl-flavanones as lead compounds for the design and development of novel xanthine oxidase inhibitors for the treatment of diseases in which this enzyme is involved.