Biological activity of carotenoids: its implications in cancer risk and prevention.

Recently nontoxic natural compounds are getting immense importance for the prevention of diseases of different etiology. Natural product provitamin A "carotenoids", largely α-carotene, ß-carotene, and ß-cryptoxanthin, are typical constituents of orange/red/yellow colored fruits and green vegetables. Different in vitro and in vivo studies have shown that carotenoids possess the capacity to scavenge DNA damaging free radicals, suppress angiogenesis, inhibit cell proliferation and induce apoptosis. Epidemiological reports of case-control studies, nested case-control studies, and cohort studies support significant association between dietary intake and circulating levels of carotenoids and reduction in cancer risk/carcinoma of various organs. However, randomized trials regarding ß-carotene supplementation, alone or in combination with other supplements, have not always well corroborated with this. Of seven trials, one observed a significant benefit on cancer mortality, four reported no significant benefit or harm, while the remaining two trials found an unexpected, but significant increase in lung cancer incidence. This review discusses implications and significance of carotenoids in the field of cancer risk and prevention.

Combined supplementation of vanadium and fish oil suppresses tumor growth, cell proliferation and induces apoptosis in DMBA-induced rat mammary carcinogenesis.

The anti-cancer activity of vanadium and fish oil has been shown in a large number of studies. This study was undertaken to analyze the combined effect of vanadium and fish oil on 7,12-dimethylbenz(α)anthracene (DMBA)-induced mammary carcinogenesis in female Sprague-Dawley rats. The whole experiment was divided into three parts: (1) DNA strand breaks study, (2) morphological analysis, and (3) histological and immunohistochemical study. Rats were treated with DMBA (0.5 mg/0.2 ml corn oil/100 g body weight) by a tail vein injection. Rats received vanadium (w/v) as ammonium monovanadate at a concentration of 0.5 ppm (4.27 µmol/L) in the drinking water and given ad libitum and/or fish oil (0.5 ml/day/rat) by oral gavage. Histology, morphology, DNA strand breaks, cell proliferation, and apoptosis of the mammary tissue were assessed in this study. Treatment with vanadium or fish oil alone significantly reduced the DNA strand breaks, palpable mammary tumors, tumor multiplicity, and cell proliferation but the maximum protection effect was found in the group that received both vanadium and fish oil and the combination treatment offered an additive effect (P < 0.05). Furthermore, vanadium and fish oil significantly increased the TUNEL-positive apoptotic cells (P < 0.05) but the increase was maximal with combination treatment and had an additive effect. These results affirm the benefits of administration of vanadium and fish oil in the prevention of rat mammary carcinogenesis which was associated with reduced DNA strand breaks, palpable mammary tumors and cell proliferation and increased TUNEL-positive apoptotic cells.

Combinatorial effect of fish oil (Maxepa) and 1alpha,25-dihydroxyvitamin D(3) in the chemoprevention of DMBA-induced mammary carcinogenesis in rats.

The present study demonstrates the anti-tumor effects of combined supplementations of dietary fish oil (Maxepa) and 1alpha,25-dihydroxyvitamin D(3) (vitamin D(3)) on 7,12-dimethylbenz(alpha)anthracene (DMBA)-induced rat mammary carcinogenesis. Female Sprague-Dawley rats at 50 days of age were treated with 7,12-dimethylbenz(alpha)anthracene (DMBA; 0.5mg/100g body weight) by a single tail vein injection in an oil emulsion. Both fish oil (rich in EPA and DHA) and vitamin D(3) were administered orally at a dose of 0.5 ml/day/rat and 0.3 microg/100 microL propylene glycol twice a week respectively and continued to 35 weeks after DMBA administration. Fish oil in combination with vitamin D(3) resulted in a significant reduction in incidence, multiplicity and volume of mammary tumors. These supplementation also inhibited DMBA-induced mammary 7-methylguanine DNA adducts formation, which was measured by HPLC-fluorescence assay (at four sequential time points; ANOVA, F=42.56, P<0.0001). Immunohistochemical analysis revealed that the effect of fish oil and vitamin D(3) occurred through suppression of cell proliferation (BrdU-LI: P<0.0001). Fish oil and vitamin D(3) together also reduced the mRNA expression of iNOS (84%, P<0.05). In view of their natural availability, non-toxicity and acceptability; combined supplementation of fish oil and vitamin D(3) might be effective for chemoprevention of mammary carcinogenesis.

Dietary fish oil associated with increased apoptosis and modulated expression of Bax and Bcl-2 during 7,12-dimethylbenz(alpha)anthracene-induced mammary carcinogenesis in rats.

The present study investigated the chemopreventive effect of dietary fish oil (Maxepa), rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on induction of apoptosis in mammary carcinogenesis model. Mammary carcinogenesis was initiated by a single, tail vein injection of 7,12-dimethylbenz(alpha)anthracene (DMBA) (0.5mg/0.2ml corn oil/100g body weight) at 7 weeks of animal age. Ninety female Sprague-Dawley rats were divided into two parts: part one was used for histology and immunohistochemical study and part two for morphological analysis. Each part consists of three experimental groups having 15 animals, i.e., Group A (DMBA control), Group B (DMBA+fish oil) and Group C (DMBA+corn oil). Rats were fed either fish oil or corn oil (0.5ml/day/rat) by oral gavage, 2 weeks prior to DMBA injection. Treatment was continued 25 weeks, studying histopathology, expression of Bax and Bcl-2 proteins by immunohistochemistry and apoptosis by TUNEL assay and morphological study at 36 weeks. Results showed that the fish oil-treated group exhibited a substantial increase in Bax (p<0.05) immunolabelling and a reduction of Bcl-2 immunopositivity (p<0.05), and increased TUNEL-positive apoptotic cells (p<0.05); however, corn oil treatment did not show these beneficial effects toward mammary preneoplasia. We conclude that fish oil has the potential to play a significant role in limiting mammary tumourigenesis in vivo.

Vanadium and 1, 25 (OH)2 vitamin D3 combination in inhibitions of 1,2, dimethylhydrazine-induced rat colon carcinogenesis.

The current investigation demonstrates the antitumor effects of combined supplementations of vanadium (V) (4.27 micromol/L drinking water ad libitum) and 1alpha, 25-dihydroxy vitamin D(3) (Vitamin D(3)) (0.3 mug/100 muL propylene glycol per os twice a week) on 1, 2 dimethylhydrazine (DMH) (20 mg/kg body weight) induced rat colon carcinogenesis. There was a significant reduction in incidence (70%), multiplicity (P<0.0001) and volume (P<0.01) of colon tumors. HPLC-fluorescence assay detected the combinatorial actions of V and Vitamin D(3) against DMH-induced colonic O(6)-methylguanine DNA adducts formation (at four sequential time points; ANOVA, F=13.56, P<0.01). Simultaneous inhibition of DNA single strand breaks (P<0.001) indicates the potency of the combination regimen in limiting the initiation event of colon carcinogenesis. Immunohistochemical analysis revealed that the effect of V and vitamin D(3) occurred through suppression of cell proliferation (BrdU-LI: P<0.001) along with an induction of apoptosis (TUNEL-LI: P<0.01). The immunoexpression of tumor suppressor p53 and downregulation of antiapoptotic protein BCl-2 in subsequent immunofluorescence assay further provide strong evidence for the combinatorial inhibitory actions of vanadium and vitamin D(3) against DMH-induced rat colon carcinogenesis.

Acanthus ilicifolius plant extract prevents DNA alterations in a transplantable Ehrlich ascites carcinoma-bearing murine model.

AIM: To investigate the chemopreventive efficacy of the Indian medicinal plant Acanthus ilicifolius L Acanthaceae in a transplantable Ehrlich ascites carcinoma (EAC)-bearing murine model. METHODS: Male Swiss albino mice were divided into four groups: Group A was the untreated normal control; Group B was the EAC control mice group that received serial, intraperitoneal (ip) inoculations of rapidly proliferating 2 x 10(5) viable EAC cells in 0.2 mL of sterile phosphate buffered saline; Group C was the plant extract-treated group that received the aqueous leaf extract (ALE) of the plant at a dose of 2.5 mg/kg body weight by single ip injections, once daily for 10, 20 and 30 consecutive days following tumour inoculation (ALE control); and Group D was the EAC + ALE-treatment group. The chemopreventive potential of the ALE was evaluated in a murine model by studying various biological parameters and genotoxic markers, such as tumour cell count, mean survival of the animals, haematological indices, hepatocellular histology, immunohistochemical expression of liver metallothionein (MT) protein, sister-chromatid exchanges (SCEs), and DNA alterations. RESULTS: Treatment of the EAC-bearing mice with the ALE significantly (P < 0.001) reduced viable tumour cell count by 68.34% (228.7 x 10(6) +/- 0.53) when compared to EAC control mice (72.4 x 10(6) +/- 0.49), and restored body and organ weights almost to the normal values. ALE administration also increased (P < 0.001) mean survival of the hosts from 35 +/- 3.46 d in EAC control mice to 83 +/- 2.69 d in EAC + ALE-treated mice. Haematological indices also showed marked improvement with administration of ALE in EAC-bearing animals. There was a significant increase in RBC count (P < 0.001), hemoglobin percent (P < 0.001), and haematocrit value (P < 0.001) from 4.3 +/- 0.12, 6.4 +/- 0.93, and 17.63 +/- 0.72 respectively in EAC control mice to 7.1 +/- 0.13, 12.1 +/- 0.77, and 30.23 +/- 0.57 respectively in EAC + ALE-treated group, along with concurrent decrement (P < 0.001) in WBC count from 18.8 +/- 0.54 in EAC control to 8.4 +/- 0.71 in EAC + ALE. Furthermore, treatment with ALE substantially improved hepatocellular architecture and no noticeable neoplastic lesions or foci of cellular alteration were observed. Daily administration of the ALE was found to limit liver MT expression, an important marker of cell proliferation with concomitant reduction in MT immunoreactivity (62.25 +/- 2.58 vs 86.24 +/- 5.69, P < 0.01). ALE was also potentially effective in reducing (P < 0.001) the frequency of SCEs from 14.94 +/- 2.14 in EAC control to 5.12 +/- 1.16 in EAC + ALE-treated group. Finally, in comparison to the EAC control, ALE was able to suppress in vivo DNA damage by abating the generations of 'tailed' DNA by 53.59% (98.65 +/- 2.31 vs 45.06 +/- 1.14, P < 0.001), and DNA single-strand breaks (SSBs) by 38.53% (3.14 +/- 0.31 vs 1.93 +/- 0.23, P < 0.01) in EAC-bearing murine liver. CONCLUSION: Our data indicate that, ALE is beneficial in restoring haematological and hepatic histological profiles and in lengthening the survival of the animals against the proliferation of ascites tumour in vivo. Finally, the chemopreventive efficacy of the ALE is manifested in limiting MT expression and in preventing DNA alterations in murine liver. The promising results of this study suggest further investigation into the chemopreventive mechanisms of the medicinal plant A. ilicifolius in vivo and in vitro.

Hepatoprotective effect of aqueous extract of Phyllanthus niruri on nimesulide-induced oxidative stress in vivo.

Nimesulide (NIM), an atypical non-steroidal anti-inflammatory drug (NSAID) is also used as analgesic. In the present study, we evaluated its effect on the prooxidant-antioxidant system of liver and the hepatoprotective potential of aqueous extract of the herb Phyllanthus niruri (PN) on NIM-induced oxidative stress in vivo using a murine model, by determining the activities of hepatic anti-oxidant enzymes superoxide dismutase (SOD) and catalase (CAT), levels of reduced glutathione (GSH) and lipid peroxidation (expressed as malonaldialdehyde, MDA). Aqueous extract of PN at a dose of 50 or 100 mg/kg body wt was administered either intraperitoneally or orally for 7 days, before NIM administration at a dose of 8 mg/kg body wt twice daily for 7 days in mice. Animals were sacrificed 24 h after administration of final dose of NIM. In another set of experiments, both aqueous extract of PN (at a dose of 50 or 100 mg/kg body wt) and NIM (8 mg/kg body wt) were administered simultaneously for 7 days. Animals were sacrificed 24 h after administration of final dose of the extract and NIM, liver tissues were collected, and the activities of SOD and CAT and levels of GSH and lipid peroxidation end-product (as MDA), were determined from the livers of all the experimental animals. Appropriate NIM control was maintained for all sets of experiments. NIM administration (8 mg/kg body wt) for 7 days caused significant depletion of the levels of SOD, CAT and reduced GSH, along with the increased levels of lipid peroxidation. Intraperitoneal administration of the extract at a dose of 50 mg/kg body wt for 7 days,. prior to NIM treatment, significantly restored most of the NIM-induced changes and the effect was comparable to that obtained by administering 100 mg/kg body wt of the extract orally. Thus, results suggested that intraperitoneal administration of the extract could protect liver from NIM-induced hepatic damage more effectively than oral administration. Antioxidant property of the aqueous extract of PN was also compared with that of a known potent antioxidant, vitamin E. The PN extract at a dose of 100 mg/kg body wt along with NIM was more effective in suppressing the oxidative damage than the PN extract at a dose of 50 mg/kg body wt. Results suggested that beneficial effect of the aqueous extract of PN, probably through its antioxidant property, might control the NIM-induced oxidative stress in the liver.

Herbal (Phyllanthus niruri) protein isolate protects liver from nimesulide induced oxidative stress.

Present study was conducted to evaluate the role of a protein fraction (PI, protein isolate) of the herb, Phyllanthus niruri (P. niruri) against nimesulide-induced oxidative stress in vivo using a murine model. Mice were intraperitoneally treated with that at a dose of 5mg/kg body weight for 7 days before and separately 1-5 days after nimesulide (at a dose of 10mg/kg body weight for 7 days) administration to evaluate its preventive and curative role. Levels of reduced glutathione (GSH), antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), as well as thiobarbituric acid reactive substances (TBARS) were measured in the liver homogenates of all study groups. Pretreatment with isolated P. niruri protein fraction significantly enhanced nimesulide-induced reduced levels of antioxidant enzymes and GSH as well as reduced the enhanced level of lipid peroxidation. Post-treatment studies showed that the recovery after nimesulide induced oxidative stress was more rapid if PI was administered compared to the spontaneous recovery of liver. Histological studies also suggest that this protein fraction could prevent as well as cure liver from nimesulide induced oxidative stress. DPPH radical scavenging assay showed that it could scavenge free radicals. Its antioxidant property was compared with that of a known potent antioxidant, Vitamin E. Besides, the effect of a non-relevant protein, BSA, was also included in the study. Heat treatment and trypsin digestion destroyed the biological activity of this protein fraction. In conclusion, data obtained suggest that the P. niruri protein fraction may protect liver from nimesulide-induced oxidative stress probably via promotion of antioxidant defense.