Reactive oxygen species (ROS) and reactive metabolic intermediates generate
d from various chemical carcinogens are known to play an important role in
cell damage and in the initiation and progression of carcinogenesis. Many r
adical scavengers, interestingly naturally occuring antioxidants have been
found to be effective in inhibiting the induction of carcinogenesis by a wi
de variety of chemical carcinogens. Studies have also indicated that variou
s spice principles form an important group as antioxidants. In the present
study our goal was to investigate whether piperine an pungent principle of
black and long peppers was able to inhibit or reduce the oxidative changes
induced by chemical carcinogens in rat intestinal model. Carcinogenesis was
initiated in intestinal lumen of male rats with 7,12, dimethyl benzanthrac
ene, dimethyl amino-methyl azobenzene and 3-methyl cholenthrene. Oxidative
alterations were assessed by determining thiobarbituric reactive substances
, mainly malonaldehyde las st measure of lipid peroxidation), thiol status
and expression of gamma-GT and Na+-K+-ATPase activity in intestinal mucosa.
Data indicated that carcinogens treatment induced GSH depletion with substa
ntial increase in thiobarbituric reactive substances and enzyme activities.
Piperine treatment with carcinogens resulted in inhibition of thiobarbitur
ic reactive substances. It mediated a significant increase in the GSH level
s and restoration in gamma-GT and Na+-K+-ATPase activity. The studies thus
indicate a protective role of piperine against the oxidative alterations by
carcinogens. It may be suggested that piperine modulates the oxidative cha
nges by inhibiting lipid peroxidation and mediating enhanced synthesis or t
ransport of GSH thereby replenishing thiol redox.