Modulation of CYP1A1, CYP1B1 and DNA adducts level by green and white tea in Balb/c mice.

In the current investigation the ameliorative effect of 2% extract of green tea (GT) and white tea (WT) against benzo(a)pyrene (BaP) induced toxicity and DNA damage has been studied in liver and lung of Balb/c mice (8 animals per group). The activities of phase I enzymes such as 7-ethoxyresorufin O-deethylase (EROD) and pentoxyresorufin O-depentylase (PROD) were found to be increased (p<0.05) both in liver and lung of BaP treated (125 mg/kg b.w. orally) group. The enhanced activities of EROD and PROD were inhibited in group that received pretreatment with GT and WT for 35 days. Pretreatment with GT and WT also elevated (p<0.05) the level of detoxifying enzymes such as glutathione S-transferase (GST) and quinone reductase (QR) in both the tissues. The BaPDE-DNA adducts level reflected the decreasing pattern from BaP treated group to the groups that received pretreatment with GT and WT. BaP exposure induced drastic alterations in the morphology of erythrocytes, pretreatment of GT and WT to BaP administered groups showed reduced alteration in topography of erythrocytes. WT elucidate greater efficacy in ameliorating BaP toxicity, but further long term studies are required to validate white tea as a cancer chemopreventive agent.

Excessive zinc in diet induces leptin resistance in Wistar rat through increased uptake of nutrients at intestinal level.

PROJECT: The ob gene has either been found to be mutant defective resulting in a deficiency of its product leptin or leptin has been found to be resistant to its receptors in obese human and rodents. The factors inducing leptin resistance have not been identified. Since excessive bioavailability of Zn has been implicated in obesity, we investigated if its excess in diet induces leptin resistance. PROCEDURE: For the investigations, three groups of Wistar rats were included in this study and they were fed on equicalories semi synthetic basal diet containing 20 mg, 40 mg or 80 mg Zn/kg diet for 120 days. There after they were sacrificed for hormonal status and intestinal investigations. RESULTS: The data of this study revealed that the food intake, gain in body weight, serum leptin, glucose, insulin, cortisol increased with increased Zn concentration in diet. TEM study showed a positive correlation between Zn concentration in diet and number of microvilli/unit surface area of the mucosal epithelial cells of the intestine. CONCLUSION: The results of this study suggest that excessive bioavailability of Zn induces leptin resistance through increased uptake of nutrients at intestinal level, leading to the growth of the fat cells which aggravated the leptin synthesis and its release in the blood stream. In spite of its higher circulating level, it was unable to reduce the food intake and gain in body weight in Zn treated rats equivalent to the control group.

Protective effects of green and white tea against benzo(a)pyrene induced oxidative stress and DNA damage in murine model.

In the current investigation, the ameliorative effect of green tea (GT) and white tea (WT) against benzo(a)pyrene (BaP) induced oxidative stress and DNA damage has been studied in the livers and lungs of Balb/c mice. A single dose of BaP (125 mg/kg, b.w. orally) increased the levels of lipid peroxidation (LPO) and decreased endogenous antioxidants such as superoxide dismutase (SOD), glutahione reductase (GR), catalase (CAT), and glutathione (GSH) significantly. Pretreatment with GT and WT for 35 days before a single dose of BaP elevated the decreased activity of GR, SOD, and CAT in liver tissue and also tended to normalize the levels of GSH and LPO in both hepatic and pulmonary tissues. The percentage of DNA in comet tail and 8-hydroxy-2'-deoxyguanosine levels reflected the decreasing pattern of DNA damage from the BaP-treated group to the groups that received pretreatment with GT and WT. Our study concludes that both GT and WT are effective in combating BaP induced oxidative insult and DNA damage. However, WT was found to be more protective than GT with respect to CAT (only in the liver), percentage of DNA in comet tail (only in the lungs), GST activity, and GSH content in both the tissues.

Synergistic effects of piperine and curcumin in modulating benzo(a)pyrene induced redox imbalance in mice lungs.

The objective of the present study was to evaluate the effects of curcumin alone and with adjuvant piperine against benzo(a)pyrene (BaP) induced oxidative stress in lungs of male Swiss albino mice. Mice were pretreated either with curcumin (100 mg/kg body weight), or piperine (20 mg/kg body weight), and in combination of both for one week, followed by single dose of benzo(a)pyrene (125 mg/kg body weight) treatment. Treatment with benzo(a)pyrene resulted in increased levels of lipid peroxides (LPO), protein carbonyl content (PCC) and with consequent decrease in the levels of tissue antioxidants like superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx) and reduced glutathione (GSH), which however, were increased significantly following curcumin treatment, but the increase was more pronounced when piperine was used as an adjuvant. BaP treatment alone did not alter significantly the GST activity. Pretreatment with curcumin increased the GST activity in BaP treated group, which was enhanced further upon synergistic treatment with piperine and curcumin. Therefore, combined administration of curcumin and piperine shall prove to be more effective in attenuating BaP induced toxicity.