Modulation of hepatic phase II phenol sulfotransferase and antioxidant status by phenolic acids in rats

Phenolic acids have significant biological and pharmacological properties and some have demonstrated remarkable ability to alter sulfate conjugation. However, the modulatory effects of phenolic acids on phenol sulfotransferases (PSTs) in vivo have not been described. The present investigation evaluates the role of phenolic acid on the expression of PSTs in male Sprague-Dawley rat liver. According to the results, gentisic acid, gallic acid and p-coumaric acid in a dosage of 100 mg/kg of body weight for 14 consecutive days significantly increased P-form PST (PST-P) activity as compared with that of the control rats (P<.05), whereas the activity of M-form PST (PST-M) in rats that received gallic acid and p-coumaric acid were also significantly (P<.05) higher than in the control rats. Reverse transcriptase-polymerase chain reaction results indicated that the changes in both PST-P and PST-M mRNA levels by phenolic acids were similar to those noted in the enzyme activity levels. The plasma obtained from phenolic acid-administered rats had significantly (P<.05) increased oxygen radical absorbance capacity (ORAC _ROO ^{{radical dot}}) values than that from control rats. In a bioavailability study, following oral administration of gallic acid and p-coumaric acid, the phenolic acids were detected in the plasma, and the C _max values after 2.0-h administration were 665±23 and 550±33 nmol/L, respectively. There was a significant correlation between the activity of both forms of PSTs and the antioxidant capacity of ORAC _ROO ^{{radical dot}} value by phenolic acids (r=.74, P<.05 and r=.77, P<.05). These data suggest that phenolic acids might alter sulfate conjugation and antioxidant capacity in living systems.