Dietary Flavonoids as Xanthine Oxidase Inhibitors: Structure–Affinity and Structure–Activity Relationships

Abstract

The flavonoid family has been reported to possess a high potential for inhibition of xanthine oxidase (XO). This study concerned the structural aspects of inhibitory activities and binding affinities of flavonoids as XO inhibitors. The result indicated that the hydrophobic interaction was important in the binding of flavonoids to XO, and the XO inhibitory ability increased generally with increasing affinities within the class of flavones and flavonols. The planar structure and the C2═C3 double bonds of flavonoids were advantageous for binding to XO and for XO inhibition. Both the hydroxylation on ring B and the substitution at C3 were unfavorable for XO inhibition more profoundly than their XO affinity. The methylation greatly reduced the inhibition (0.75-3.07 times) but hardly affected the affinity. The bulky sugar substitutions of flavonoids decreased the inhibition (1.69-1.99 times) and lowered the affinities (4.20-9.22 times) to different degrees depending on the conjunction site.

Antihyperuricemic effect of dietary polyphenol sinapic acid commonly present in various edible food plants

“…It has been reported that XOD inhibitors act as antioxidants to decrease ROS and prevent oxidative stress (Kumar et al, 2018;Lin et al, 2015;Nile et al, 2018). Herein, SA was shown to inhibit the XOD enzyme and to have moderate O −• 2 scavenging activity and a strong DPPH radical scavenging activity.…”

Baicalein decreases uric acid and prevents hyperuricemic nephropathy in mice

“…Natural products including flavonoids exhibit diversified bioactivities and lower toxicity compared with classical XOR inhibitors [32]. Flavonoids have a potent inhibitive effect towards XOR both in vitro and in vivo [33], such as apigenin, luteolin, hyperin etc [34]. C2 = C3 double bonds of flavonoids contributed to their planar structure and the hydroxyl groups on C-5 and C-7 were advantageous for binding to XOR [34].…”

“…Flavonoids have a potent inhibitive effect towards XOR both in vitro and in vivo [33], such as apigenin, luteolin, hyperin etc [34]. C2 = C3 double bonds of flavonoids contributed to their planar structure and the hydroxyl groups on C-5 and C-7 were advantageous for binding to XOR [34]. Baicalein is a natural flavonoid with all these structure superiorities above.…”

Quranic Verse No. 8 of Surat Al-Jumu’ah Leads us to Describe Cancer and Determine Its True Cause (Part-III)

“…A quantity of no less than 1/2 kg/day is recommended. Also black grapes and blackberries are high in the flavonoids epicatechin and catechin [53].…”