1. The aim of this investigation was to see whether 7-OH-flavone, 5-OH-flavone and 3-OH-flavone, which are present in edible vegetables, fruit and wine, are substrates or inhibitors of human liver and duodenum sulfotransferase. 2. An assay was set up to study the sulfation of 7-OH-flavone, and using this assay, it was observed that 7-OH-flavone was sulfated and the rate of sulfation (mean +/- SD) was 324 +/- 87 pmol min(-1) mg(-1) (liver) and 584 +/- 164 pmol min(-1) mg(-1) (duodenum; P < 0.0001). 3. 7-OH-flavone sulfotransferase followed Michaelis-Menten kinetics and the K-m (mean +/- SD) was 0.2 +/- 0.04 μM (liver) and 1.1 +/- 0.3 μM (duodenum; p = 0.008). V-max (mean +/- SD) was 392 +/- 134 pmol min(-1) mg(-1) (liver) and 815 +/- 233 pmol min(-1) mg(-1), (duodenum; p = 0.016). 4. 5-OH-flavone and 3-OH-flavone were not sulfated and were inhibitors of human liver and duodenum SULT1A1 activity and 7-OH-flavone sulfation rate. 5. The IC50 of 5-OH-flavone for SULT1A1 was 0.3 +/- 0.06 μM (liver) and 0.3 +/- 0.1 μM (duodenum; n.s.) and those of 3-OH-flavone were 1.0 +/- 0.1 μM (liver) and 1.6 +/- 0.03 μM (duodenum; p = 0.0006). 6. There was inhibition of 7-OH-flavone sulfation rate by 5-OH-flavone and 3-OH-flavone. The IC50 of 5-OH-flavone for the sulfation rate of 7-OH-flavone was 3.5 +/- 0.5 μM (liver) and 69 +/- 18 μM (duodenum; p < 0.0001) and for 3-OH-flavone it was 18 +/- 3.4 muM (liver) and 213 +/- 47 muM (duodenum; p < 0.0001). 7. The position of the hydroxy group confers to the molecules of OH-flavones the quality of substrate or inhibitor of sulfotransferase.
7-OH-flavone is sulfated in the human liver and duodenum, whereas 5-OH-flavone and 3-OH-flavone are potent inhibitors of SULT1A1 activity and 7-OH-flavone sulfation rate
SPISNI, ROBERTO;MOSCA, FRANCO;PACIFICI, GIAN MARIA
2002-01-01
Abstract
1. The aim of this investigation was to see whether 7-OH-flavone, 5-OH-flavone and 3-OH-flavone, which are present in edible vegetables, fruit and wine, are substrates or inhibitors of human liver and duodenum sulfotransferase. 2. An assay was set up to study the sulfation of 7-OH-flavone, and using this assay, it was observed that 7-OH-flavone was sulfated and the rate of sulfation (mean +/- SD) was 324 +/- 87 pmol min(-1) mg(-1) (liver) and 584 +/- 164 pmol min(-1) mg(-1) (duodenum; P < 0.0001). 3. 7-OH-flavone sulfotransferase followed Michaelis-Menten kinetics and the K-m (mean +/- SD) was 0.2 +/- 0.04 μM (liver) and 1.1 +/- 0.3 μM (duodenum; p = 0.008). V-max (mean +/- SD) was 392 +/- 134 pmol min(-1) mg(-1) (liver) and 815 +/- 233 pmol min(-1) mg(-1), (duodenum; p = 0.016). 4. 5-OH-flavone and 3-OH-flavone were not sulfated and were inhibitors of human liver and duodenum SULT1A1 activity and 7-OH-flavone sulfation rate. 5. The IC50 of 5-OH-flavone for SULT1A1 was 0.3 +/- 0.06 μM (liver) and 0.3 +/- 0.1 μM (duodenum; n.s.) and those of 3-OH-flavone were 1.0 +/- 0.1 μM (liver) and 1.6 +/- 0.03 μM (duodenum; p = 0.0006). 6. There was inhibition of 7-OH-flavone sulfation rate by 5-OH-flavone and 3-OH-flavone. The IC50 of 5-OH-flavone for the sulfation rate of 7-OH-flavone was 3.5 +/- 0.5 μM (liver) and 69 +/- 18 μM (duodenum; p < 0.0001) and for 3-OH-flavone it was 18 +/- 3.4 muM (liver) and 213 +/- 47 muM (duodenum; p < 0.0001). 7. The position of the hydroxy group confers to the molecules of OH-flavones the quality of substrate or inhibitor of sulfotransferase.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
