| ABSTRACT: |
|
Four dietary, naturally occurring anticarcinogens (flavone, coumarin,
alpha-angelicalactone and ellagic acid) were studied with respect to their
effects on oesophageal, gastric and pancreatic (i) glutathione
S-transferase (GST) enzyme activity, (ii) GST isozyme levels and (iii)
glutathione (GSH) content in male Wistar rats. GST enzyme activity was
significantly increased in the oesophagus by flavone, coumarin and
alpha-angelicalactone (125, 240 and 155% respectively) and in the stomach
by coumarin and alpha-angelicalactone (140 and 230%). No change in
pancreatic GST activity was observed. In addition, class- and
tissue-specific changes in GST isozyme levels occurred. Class alpha GSTs
were induced in the oesophagus by flavone, coumarin and
alpha-angelicalactone (570, 1580 and 570%), but did not change in the
stomach. GST-alpha was undetectable in the pancreas. GST-mu was expressed
at high levels in all three tissues investigated, but only pancreatic
GST-mu levels of ellagic acid-fed rats were increased (160%). GST-pi was
induced in the stomach by coumarin and alpha-angelicalactone (470 and
1120%) and in the pancreas by flavone (200%). GST-pi was detectable at low
levels in rat oesophageal epithelium of coumarin-fed animals only. GSH
concentrations were uninfluenced by the dietary anticarcinogens in all
tissues. These results suggest that dietary ellagic acid and, more
especially, flavone, coumarin and alpha-angelicalactone may exert strong
chemoprotective effects by selective enhancement of members of the GST
detoxification system in the oesophagus or stomach and, to a lesser
extent, in the pancreas. |