“GASTROINTESTINAL AND HEPATORENAL PROTECTIVE EFFECTS OF QUERCETIN AND CURCUMIN AGAINST CADMIUM INDUCED TOXICITY IN RATS” 2827
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Date
2019-06
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JAU, JUNAGADH
Abstract
The present experiment was carried out to evaluate the gastrointestinal and
hepatorenal protective effect of quercetin and curcumin alone as well as in
combination against cadmium-induced toxicity in rats. The study was performed on
36 male rats which were randomly divided into six groups based on their body
weights at the age of 8-9 weeks. Rats of group C1 were kept as normal control. Rats
of toxic control group (C2), vehicle group (C3), quercetin treatment group (T1),
curcumin treatment group (T2) and quercetin and curcumin in combination treatment
group (T3) were administered with cadmium in drinking water (100 ppm) for 28 days.
Rats of vehicle group (C3) were administered with corn oil (vehicle). Rats of group
T1, T2 and T3 were orally administered with quercetin (50 mg/kg, P.O.), curcumin
(100 mg/kg, P.O.) and both quercetin and curcumin in combination, respectively for
28 days. Noticeable signs of toxicity were not observed in rats of any groups except
hair fall and diarrhea in toxicity control and vehicle groups, which were less in
treatment groups (T1, T2 and T3). Cadmium exposure in rats did not affect the feed
consumption. Body weight of rats of all groups were also not altered during the
experimental period. Cadmium treatment resulted in significant (P<0.05) decrease in
kidney weight and kidney body weight ratio. The weight of kidney and kidney body
weight ratio was partially improved by curcumin treatment (T2).
Cadmium exposure to rats for 28 days did not produce significant effect on
hematological parameters. However, significantly (P<0.05) higher level of ALT, AST
and ALP in the serum of cadmium exposed rats were observed suggesting of Cd related injury to the liver. Rats treated with quercetin and curcumin alone as well as in
combination of both significantly (P<0.05) lowered the levels of AST and ALP as
compared to cadmium-exposed and vehicle-treated group (C1 and C2). The total
bilirubin level was significantly (P<0.05) increased in cadmium-exposed and vehicle treated group (C2 and C3) as compared to that of control group (C1). Quercetin treated group (T1), curcumin-treated group (T2) and the group treated with quercetin
and curcumin in combination (T3) significantly (P<0.05) decreased total bilirubin
level as compared to that of animals of toxic control group (C2). The blood glucose
level was significantly (P<0.05) higher in cadmium-exposed group (C2) as compared
to that of control group (C1) and it was lowered in quercetin treated group and group
treated with combination of quercetin and curcumin.
Exposure to cadmium caused significant increase in MDA and non-significant
decrease in SOD, catalase and GSH in blood of rats. Quercetin and curcumin in combination non-significantly increased SOD activity, catalase activity and GSH
level. GSH level was well improved in quercetin treatment group (T1). All treatments
(T1, T2 and T3) significantly decreased the cadmium induced lipid peroxidation
indicating low level of MDA. In intestine, MDA level and SOD enzyme activity were
significantly (P<0.05) increased upon cadmium treatment due to lipid peroxidation.
Non-significant decrease in catalase activity and GSH level were observed upon
cadmium exposure in intestine tissue. Quercetin and curcumin alone as well as in
combination resulted in reduction of SOD activity, lipid peroxidation and
improvement in the catalase activity and GSH level in intestine. However,
significantly (P<0.05) higher level of GSH was observed in curcumin-treated group
(T2) as compared to that of animals of toxicity control group (C2). In liver, significant
increase in MDA level, non-significant increase in SOD activity and decrease in
catalase activity caused the lipid peroxidation and damage to the hepatocytes. The
quercetin treatment (T1) reduced the increased MDA level and SOD activity in liver,
simultaneously increased catalase and GSH activity. Curcumin treatment (T2)
significantly decreased the SOD activity, MDA level and significantly increased the
GSH level and partially improved the catalase activity However, quercetin when
administered along with curcumin was able to reduce the MDA level significantly by
stimulating the GSH level and higher catalase activity as compared to that of toxicity
control group (C2). In kidney, cadmium exposure resulted in increase in lipid
peroxidation as indicated by increased MDA level. Non-significant increase in SOD
activity, significant decrease in catalase activity with no significant effect on GSH
level was observed upon cadmium exposure. Quercetin and curcumin alone as well as
in combination non-significantly reduced the SOD activity and improved the catalase
activity and also stimulated the GSH level which reduced the lipid peroxidation.
Sub-acute cadmium exposure at 100 ppm level altered normal architecture of
stomach, intestine, liver and kidney in rats. Administration of quercetin and curcumin
alone as well as in combination partially protected the stomach, intestine and liver
from cadmium-induced oxidative damage. However, quercetin has more protective
effect against cadmium-induced histopathological changes in kidney as compared to
curcumin. As compared to individual treatment of quercetin and curcumin alone, the
combination of both agents significantly prevented the histopathological changes
caused by cadmium-induced oxidative stress.
Quercetin and curcumin alone as well in combination may be useful for
prevention of oxidative stress caused by continuous exposure to low level of
xenobiotics. However, further study is needed to confirm the efficacy and the
pathways of action of quercetin and curcumin against oxidative stress caused by
different environmental toxicants.