TITLE:
In Silico and in Vitro Approach for the Understanding of the Xanthine Oxidase Inhibitory Activity of Uruguayan Tannat Grape Pomace and Propolis Poliphenols
AUTHORS:
Elena Alvareda, Federico Iribarne, Victoria Espinosa, Pablo Miranda, Daniela Santi, Sara Aguilera, S. Bustos, Margot Paulino Zunini
KEYWORDS:
Propolis, Tannat Grape Pomace, Xanthine Oxidase Inhibition, Polyphenols, Functional Foods
JOURNAL NAME:
Journal of Biophysical Chemistry,
Vol.10 No.1,
February
28,
2019
ABSTRACT: The use of food additives with xanthine oxidase (XO)
inhibitory activity offers an alternative approach to hyperuricemic and gout
disease treatment, and provides an example of antioxidant nutraceutics. The in vitro and in silico XO inhibitory activity of polyphenols from Uruguayan
Tannat grape pomaces and propolis extracts was evaluated as well as the
scavenging capacity of said compounds. When comparing propolis and grape pomace
samples, the in vitro studies
demonstrated that polyphenols extracted from propolis are more active as free
radical scavengers than those from Tannat grape pomace. Both natural products
effectively inhibited XO but the capacity of phenols present in GP is higher
than the one present in P. The high content of anthocyanins in GP, absent in P,
could account for this observation. In
silico assays allowed us to determine relevant ligand-receptor interactions
between polyphenols, from a database built with previously reported polyphenols
from both natural products, and the active site of XO. The in silico results showed that compound (E)-isoprenylcaffeate from
propolis was the best potential XO inhibitor displaying hydrophobic aromatic
interaction between the conjugated ring of the caffeate moiety and polar
interactions between hydroxyl groups from caffeate with the active site polar
residues. Among grape pomaces, the Cyanidin-3-O-(6-(E)-p-coumaroyl)-glucoside
was the best XO inhibitor; its moiety oxychromenyl being relevant to the
docking stabilization. All these results lead us to propose Uruguayan propolis
and Tannat grape pomace extracts as food additives as well as phytopharmaceuticals
to decrease the uric acid levels in gout disease and to act against oxidative
stress.