Protective effect of Azadirachta indica A. Juss against doxorubicin-induced cardiac toxicity in tumour bearing mice.

Doxorubicin (DOX) treatment (12 µg/g body weight, once a week for 2 weeks) resulted in a significant decrease in the heart rate along with an increase in QRS, ST, and QT intervals. Histopathological studies showed cardiomyocyte degeneration, cytoplasmic vacuolation and macrophage infiltration in cardiac tissue. A marked increase in the rate of apoptosis was also observed. An increased oxidative stress was evidenced by significantly higher levels of lipid peroxidation (LPO) and depletion of reduced glutathione. A decrease in the activity of cellular antioxidant defence enzymes was also observed. The decrease in the heart rate and ECG alterations were prevented significantly by AAILE (100 µg/g body weight, po) co-treatment, started two weeks prior to DOX treatment and continued till the termination of the experiment. The cardioprotection was also evident from histopathology and decrease in the rate of apoptosis in cardiomyocytes. AAILE co-treatment also prevented DOX-induced increase in LPO and decrease in antioxidant defence enzymes. The results suggest that AAILE administration prevents DOX-induced cardiotoxicity.

Azadirachta indica mitigates DMBA-induced hepatotoxicity: A biochemical and radiometric study.

The hepatoprotective potential of aqueous Azadirachta indica leaf extract (AAILE) was assessed against DMBA-induced hepatotoxicity. DMBA  (7,12-dimethylbenz[a] anthracene) treatment (40 mg/kg body weight, ip) to male Balb/c mice resulted in the derailment of liver function as revealed by extremely slow clearance of 99mTc-mebrofenin from liver, elevated levels of alkaline phosphatase (ALP) and alanine transaminase (ALT), compared to control group. In addition, elevated micronuclei score and high apoptotic index indicated hepatogenotoxicity in DMBA-treated mice. DMBA treatment also upregulated cytochrome P450 (CYP), cytochrome b5 (Cyt b5) and decreased glutathione-S-transferase activity in hepatic tissue, compared to control group. Enhanced lipid peroxidation (LPO) levels along with decreased reduced glutathione (GSH) level were also observed in DMBA group, compared to control group. AAILE co-treatment (200 mg/kg body weight, po, thrice a week) for 8 weeks followed by DMBA injection showed significant improvement in hepatic status, as revealed by normalization of 99mTc-mebrofenin clearance rate, decreased ALP and ALT levels, reduced genotoxicity in terms of micronuclei score and apoptotic index. Levels of LPO were significantly decreased along with increased hepatic GST and GSH levels in AAILE + DMBA group, compared to DMBA group. However, no significant change was observed in hepatic CYP and Cyt b5 levels, compared to DMBA group. The results indicated that AAILE effectively ameliorated DMBA-induced hepatotoxicity.

Effect of (+)-catechin hydrate on oxidative stress induced by high sucrose and high fat diet in male Wistar rats.

Increased lipid peroxidation and reduced glutathione levels in liver of rats fed high sucrose high fat (HSHF) diet were normalized by concomitant administration of (+)-catechin hydrate. Plasma non-enzymatic antioxidants viz. α-tocopherol, ascorbic acid and total thiols decrease were also significantly less in rats administered with (+)-catechin hydrate concomitantly with HSHF diet. Thus the present results indicate that (+)-catechin hydrate has antioxidant activity and is effective in reducing oxidative stress. The study is of clinical importance as oxidative stress is known to be the cause of many clinical manifestations viz. cancer, Parkinson’s disease, atherosclerosis, heart failure, myocardial infarction and many other diseases.

Phytomodulatory potential of lycopene from Lycopersicum esculentum against doxorubicin induced nephrotoxicity.

An elevated level of serum urea and creatinine was observed in doxorubicin (DOX) treated animals indicating DOX-induced nephrotoxicity. Enhanced lipid peroxidation (LPO) in the renal tissue was accompanied by a significant decrease in the levels of reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione reductase (GR) and catalase (CAT) activities. Administration of lycopene (LycT) extracted from tomato to DOX treated mice showed a significant reduction in serum creatinine and urea levels which were associated with significantly low levels of LPO and significantly enhanced level of GSH and related antioxidant enzymes activity (GPx, GR and CAT) when compared to DOX group. Histopathological analysis revealed severe damage in the renal tissue of DOX treated animals. However, animals pretreated with LycT were observed to have reduced damage. Thus, from present results it may be inferred that lycopene may be beneficial in mitigating DOX induced nephrotoxicity in mice.

Celecoxib mitigates cigarette smoke induced oxidative stress in mice.

Cigarette smoke (CS) is a rich source of radicals, predisposing the cell to oxidative stress resulting in inflammation. Chronic inflammation is a recognized risk factor for carcinogenesis. Cyclooxygenase-2 (COX-2) is a mediator of inflammatory pathway and may, therefore, contribute to carcinogenesis. There are several reports that suggest the association between CS and COX-2 associated risk to cancer. In the present study, we examined the role of celecoxib (a selective COX-2 inhibitor) in modulating the oxidative stress caused by CS inhalation in mice. CS exposure for a period of 10 weeks caused oxidative stress in the pulmonary and hepatic tissues, as evident from the increase in lipid peroxidation levels (LPO) and decrease in reduced glutathione (GSH) levels. Celecoxib (125 mg/kg body weight for 8 weeks) administration to CS inhaling mice reduced the oxidative stress by decreasing the LPO levels and enhancing the GSH levels in comparison to the CS-exposed group. CS exposure repressed the enzymatic antioxidant defense system, as evident from the decrease in catalase (CAT) and superoxide dismutase (SOD) activities. Co-adminstration of celecoxib considerably reversed the changes in the enzymatic antioxidant defense system. Histopathological studies of lungs showed that CS exposure induced alveolar wall destruction and air space enlargement. In co-treated group, the alveolar septa were thicker than normal with apparent infiltration of inflammatory cells. In CS-exposed group, hepatic tissue exhibited vacuolization and macrophage infiltration. Co-treatment with celecoxib restored the normal histoarchitechture in hepatic tissues of CS inhaling mice. Thus, the present study demonstrated that celecoxib adminstration reduced the oxidative stress-mediated risk to carcinogenesis, due to its ability to boost the antioxidant defense system.

Celecoxib administration exhibits tissue specific effect on 3H-benzo(a)pyrene-DNA adduct formation in cigarette smoke inhaling mice.

In the present study, cigarette smoke (CS) exposure significantly enhanced 3H-B(a)P-DNA adduct formation in both the pulmonary and hepatic tissues. Mice co-treated with CS and celecoxib (a specific COX-2 inhibitor) exhibited a significant decrease in hepatic carcinogen-DNA adduct formation in comparison to the smoke exposed group, however the lungs of the co-treated animals exhibited a significant increase in carcinogen-DNA adduct formation when compared to the control group and smoke exposed group. CS exposure enhanced the activity of carcinogen activation enzymes in both the tissues and decreased the activity of carcinogen detoxification enzymes in the hepatic tissue only, when compared to the control group. Celecoxib administration to CS inhaling mice modulated the carcinogen biotransformation considerably when compared to the CS exposed group. Celecoxib administration to CS inhaling mice produced a low index of carcinogenesis in the hepatic tissue but increased the index of carcinogenesis in the pulmonary tissue. These observations seem to be critical and tissue specific when related to carcinogenesis.

Azadirachta indica leaf extract modulates initiation phase of murine forestomach tumorigenesis.

The effects of aqueous Azadirachta indica leaf extract (AAILE) on benzo(a)pyrene [B(a)P]-induced forestomach tumorigenesis, B(a)P-DNA adduct formation and certain parameters of carcinogen biotransformation system in mice have been reported earlier from our laboratory. In this study, the effects of AAILE on the enzymes of B(a)P biotransformation, which play crucial role in initiation of chemical carcinogenesis - aryl hydrocarbon hydroxylase (AHH) and uridinediphosphoglucuronosyltransferase (UDP-glucuronosyltransferase) have been evaluated in murine forestomach and liver. In addition, lipid peroxidation (LPO) levels in forestomach as well as liver and the activities of tissue injury marker enzymes - lactate dehydrogenase, aspartate aminotransferase and alkaline phosphatase in the serum have also been evaluated. Oral administration of AAILE (100 mg/kg body wt for 2 weeks) reduces the AHH activity and enhances the UDP-glucuronosyltransferase activity in both the tissues, suggesting its potential in decreasing the activation and increasing the detoxification of carcinogens. The LPO levels decrease upon AAILE treatment in the hepatic tissue, suggesting its antioxidative and hence anti-carcinogenic effects. Non-significant alterations have been observed in tissue injury marker enzymes upon AAILE treatment, suggesting its safety at the given dose. In conclusion, AAILE appears to modulate initiation phase of carcinogenesis and may be suggested as safe and an effective agent for chemoprevention.

Impediment of diethylnitrosamine induced hepatotoxicity in male Balb/c mice by pretreatment with aqueous Azadirachta indica leaf extract.

Considering the hepatoprotective properties of Azadirachta indica, the present study was designed to evaluate its preventive effects against diethylnitrosamine (NDEA) induced hepatotoxicity in male Balb/c mice. Exposure of NDEA caused a significant increase in micronucleated cell score, lipid peroxidation levels (LPO) and activity of lactate dehydrogenase (LDH). A significant decrease in reduced glutathione (GSH) contents and activity of glutathione-S-transferase (GST) was also observed upon NDEA treatment, whereas their activities of cytochrome P450 and cytochrome b5 showed non-significant alterations. Aqueous A. indica leaf extract (AAILE) pretreatment showed protective effects against NDEA induced toxicity by decreasing the frequency of micronucleated cell, levels of LPO and LDH activity. Also, a decreased activity of GST, cytochrome P450 and an increased activity of cytochrome b5, GSH contents was observed when AAILE pretreated mice were injected with NDEA. Only AAILE treatment caused a noticeable decrease in the frequency of micronuclei, activity of cytochrome P450 and cytochrome b5, but a significant increase in the activity of GST and GSH contents, whereas, non significant alterations were observed in the activity of LDH and levels of LPO. Significance of these observations with respect to hepatoprotective efficacy of A. indica has been discussed in the present manuscript.

Modulatory effects of different doses of alpha-tocopherol on benzo(a)pyrene-DNA adduct formation in the pulmonary tissue of cigarette smoke inhaling mice.

Cigarette smoke (CS) has been established as one of the major risk factors for many pathologies including lung cancer in humans and experimental animals. In view of the discrepancy about the role of alpha-tocopherol (AT) in carcinogenesis, the present study was designed to investigate the effects of different doses of AT on benzo(a)pyrene-DNA [B(a)P-DNA] adduct formation in lungs of CS inhaling mice. Extent of carcinogen-DNA adduct formation has been considered as an index for carcinogenesis. Feeding of 35 IU AT/kg body weight increased B(a)P-DNA adducts formation significantly whereas feeding of 5 IU AT/kg body weight did not altered much the B(a)P-DNA adduct levels when both were compared to the control counterparts. With CS inhalation, the B(a)P-DNA adducts formation increased in all the groups when compared to their respective sham counterparts. Interestingly, in CS exposed groups, there was least increase in B(a)P-DNA adducts formation in 5 IU AT/kg fed animals followed by the control and 35 IU AT/kg body weight fed groups respectively. The results suggest that higher doses of AT accentuate DNA adduct formation in CS inhaling mice.