Suresh K. Abraham

Protective effects of chlorogenic acid, curcumin and β-carotene against γ-radiation-induced in vivo chromosomal damage

Abstract The mouse bone marrow micronucleus test was carried out to evaluate the possible role of the dietary constituents chlorogenic acid (CGA), curcumin (CR) and β-carotene (BC) in modulating the in vivo chromosomal damage induced by γ-radiation. The results obtained suggest that oral administration of CGA (50, 100 and 200 mg/kg b.w.), CR (5, 10 and 20 mg/kg b.w.) and BC (0.5 and 2.5 mg/kg b.w.) to mice can significantly reduce the frequencies of micronucleated polychromatic erythrocytes (Mn PCEs) induced by whole body exposure to γ-radiation (1.15) Gy; 0.05 Gy/s). With CGA and CR, this effect was observed after a single administration either 2 h before or immediately after irradiation. However, with BC a 7-day feeding before irradiation was necessary to obtain a significant reduction in the incidence of Mn PCEs. The protective effects of CGA, CR and BC were observed in bone marrow cells sampled 24, 30 and 48 h after exposure to radiation.

INHIBITION OF GENOTOXICITY BY SAFFRON (CROCUS SATIVUS L.) IN MICE

Experiments were carried out to ascertain whether or not saffron (dried stigmas of Crocus sativus L.), a commonly used agent for flavoring and coloring food can exert modulatory effects on the in vivo genotoxicity of cisplatin (CIS), cyclophosphamide (CPH), mitomycin C(MMC) and urethane (URE). For this purpose, Swiss albino mice were pretreated for five consecutive days with three doses (20, 40 and 80 mg/kg body weight) of the aqueous extract of saffron. Genotoxic effects were assessed in the mouse bone marrow micronucleus test. The results obtained suggest that pretreatment with saffron can significantly inhibit the genotoxicity of CIS, CPH, MMC and URE. This inhibitory effect was not always dose-dependent. In addition, the hepatic glutathione S-transferase (GST) activity was assessed in the control and treated animals. No significant change in GST activity was observed after pretreatment with saffron alone. Treatment with the genotoxins alone significantly inhibited GST activity. Saffron pretreatment attenuated the inhibitory effects of the genotoxins on GST activity.

Effect of Spirulina fusiformis on cyclophosphamide and mitomycin-C induced genotoxicity and oxidative stress in mice

Spirulina fusiformis was tested for its possible in vivo protective effects against cyclophosphamide (CP) and mitomycin-C (MMC) induced genotoxicity and oxidative stress in mice. Pre-treatment with S. fusiformis (250, 500 and 1000 mg kg(-1), p.o., daily for 5 days) significantly reduced the chromosomal damage and lipid peroxidation with concomitant changes in antioxidants and detoxification systems. All the three tested doses were effective in exerting a protective effect against CP and MMC.

Protective effect of saffron (Crocus sativus L.) aqueous extract against genetic damage induced by anti-tumor agents in mice

The genotoxic potential of anti-tumor drugs limits their efficacy in the treatment of cancers. Since ancient times, saffron (dried stigmas of Crocus sativus L.) has been used as a spice and medicinal herb. Saffron is a rich source of carotenoids and is known for its anti-cancer and antitumor properties. The present study was designed to ascertain the chemoprotective potential of saffron against the genotoxicity of three well-known anti-tumor drugs-cisplatin (CIS), cyclophosphamide (CPH) and mitomycin C (MMC)-using comet assay. Three doses of saffron (20, 40 and 80 mg/kg b.w.) were orally administered to mice for five consecutive days prior to the administration of anti-tumor drugs under investigation. Pre-treatment with saffron significantly inhibited anti-tumor drugs induced cellular DNA damage (strand breaks) as revealed by decreased comet tail length, tail moment and percent DNA in the tail. These findings, together with our previous results, suggest a potential role for saffron as an anti-genotoxic, anti-oxidant and chemopreventive agent and could be used as an adjuvant in chemotherapeutic applications.

Protective Effects of Ethanolic Neem Leaf Extract on N‐Methyl‐N′‐nitro‐N‐nitrosoguanidine‐Induced Genotoxicity and Oxidative Stress in Mice

We evaluated the effects of pretreatment with ethanolic neem leaf extract on N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG)‐induced genotoxicity and oxidative stress in male Swiss albino mice. The frequency of micronuclei (MN), concentrations of lipid peroxides and the status of the antioxidants, reduced glutathione (GSH), glutathione peroxidase (GPx) and glutathione‐S‐transferase (GST) were used as intermediate biomarkers of chemoprotection. Animals were divided into four groups of five animals each. Animals in group 1 were given MNNG (40 mg/kg body weight) by intragastric intubation. Animals in group 2 received intragastric administration of ethanolic neem leaf extract at a concentration of 200 mg/kg body weight for 5 days followed by MNNG 1.5 h after the final feeding. Group 3 animals received ethanolic neem leaf extract alone for five days. Group 4 received the same volume of normal saline and served as control. The animals were sacrificed by cervical dislocation 27 h after the carcinogen exposure. In MNNG‐treated mice, enhanced lipid peroxidation with compromised antioxidant defences in the stomach, liver and erythrocytes was accompanied by increase in bone marrow micronuclei. Pretreatment with ethanolic neem leaf extract significantly reduced MNNG‐induced micronuclei and lipid peroxides and enhanced GSH‐dependent antioxidant activities. The results of the present study demonstrate that ethanolic neem leaf extract exerts protective effects against MNNG‐induced genotoxicity and oxidative stress by augmenting host antioxidant defence mechanisms.

Inhibitory effects of coffee on the genotoxicity of carcinogens in mice.

The mouse bone marrow micronucleus test was carried out to evaluate the possible inhibitory effects of 3 doses (125, 250 and 500 mg/kg) of standard instant coffee on the in vivo genotoxicity of 7,12-dimethylbenz[a]anthracene (DMBA), benzo[a]pyrene (BP), aflatoxin B1 (AFB1) and urethane (UR). Coffee was orally administered twice, 2 and 20 h before the carcinogens were injected intraperitoneally. From the results obtained, it was evident that the administration of 250 and 500 mg coffee/kg body weight could significantly inhibit the in vivo genotoxicity of these carcinogens. A linear dose response was observed for the inhibitory effect of coffee. Furthermore, inhibition of genotoxicity by coffee was observed in bone marrow cells which were sampled at 6-h intervals (48, 54, 60, 66 and 72 h) from the time of peak induction of micronuclei by DMBA.

In vivo radioprotection with garlic extract.

Garlic extract was evaluated in the mouse bone marrow micronucleus test for its possible protective effects against gamma-radiation-induced chromosomal damage. Together with this, biochemical assays were carried out to determine the changes in sulfhydryl content and glutathione S-transferase activities. Three doses of freshly prepared garlic extract (125, 250 and 500 mg/kg b.w.) were orally administered for 5 consecutive days, and the animals were irradiated 2 h after the final feeding. The results of the micronucleus test demonstrated that pre-treatment with garlic extract can lead to significant dose-related reductions in the frequencies of gamma-radiation-induced (2 Gy) micronucleated polychromatic erythrocytes. The anticlastogenic effect of garlic extract was observed against lower radiation doses of 0.5 and 1 Gy, but not 0.25 Gy. Significant increases in the sulfhydryl content and glutathione S-transferase activity were observed after either pre-treatment with garlic extract or irradiation. However, the irradiated garlic-extract pre-treated animals showed a significant reduction in sulfhydryl content and glutathione S-transferase activities.

Role of chlorophyllin as an in vivo anticlastogen: protection against gamma-radiation and chemical clastogens

Chlorophyllin was evaluated in the mouse bone marrow micronucleus test for its possible protective effects against chromosomal damage induced by gamma-radiation, cyclophosphamide, N-nitroso-N-ethylurea and urethane. Three doses of chlorophyllin (50, 100 and 200 mg/kg, b.w.) were orally administered to mice 2 h before exposure to the clastogens under investigation. The results obtained demonstrated that chlorophyllin can significantly reduce the incidence of micronucleated polychromatic erythrocytes induced by gamma-radiation (1.15 Gy) and all the three chemical clastogens. However with the exception of cyclophosphamide there was no indication of a dose response for the in vivo anticlastogenic effects of chlorophyllin.

Role of Syzygium cumini seed extract in the chemoprevention of in vivo genomic damage and oxidative stress

ETHNOPHARMACOLOGICAL RELEVANCE [corrected] The seeds of Syzygium cumini, Skeels (Jamun) are extensively used in India for treatment of diabetes and other ailments. AIM OF THE STUDY The aim of this work was to assess the role of Jamun seed extract (JSE) as a chemoprotective agent against in vivo oxidative stress and genomic damage. MATERIALS AND METHODS Experiments were carried out to evaluate in vitro protective effects of JSE against hydroxyl radical induced damage in pBR322 DNA, and in vivo genomic damage and oxidative stress in mice which received JSE orally for 5 days before exposure to genotoxic carcinogens urethane (URE) and 7,12-dimethyl benz(a)anthracene (DMBA). RESULTS Aqueous and ethanolic extracts of JSE showed significant protective effects against hydroxyl radical induced strand breaks in pBR322 DNA. The in vivo experiments with aqueous JSE showed significant protective effects against chromosomal damage induced by the genotoxic carcinogens URE and DMBA. Biochemical assays registered significant inhibition of hepatic lipid peroxidation and increase in GSH level and activity of GST, SOD and CAT. CONCLUSION Our findings suggest that JSE can possibly play an important role as a chemopreventive agent against oxidative stress and genomic damage.

Tomato and garlic by gavage modulate 7,12-dimethylbenz[a]anthracene-induced genotoxicity and oxidative stress in mice

Chemoprotection by dietary agents is a promising strategy for cancer prevention. The aim of the present study was to evaluate the combined effect of tomato and garlic against 7,12-dimethylbenz-[a]anthracene (DMBA)-induced genetic damage and oxidative stress in 12-14-week-old male Swiss albino mice. The animals were randomized into experimental and control groups and divided into eight groups of five animals each. Group 1 animals were injected intraperitoneally with 35 mg/kg body weight DMBA suspended in peanut oil as a single dose. Groups 2-4 animals received tomato (500 mg/kg body weight), garlic (125 mg/kg body weight) and a combination of tomato and garlic for 5 days by gavage, respectively, followed by DMBA 1.5 h after the final feeding. The doses of tomato and garlic correspond to the average human daily consumption. Animals in groups 5, 6 and 7 received tomato alone, garlic alone and tomato + garlic combination, respectively, for 5 days. Group 8 animals received the same volume of water and served as control. The incidence of bone marrow micronuclei and the extent of lipid peroxidation and the concentrations of antioxidants glutathione, glutathione peroxidase and glutathione-S-transferase were measured in the liver, 48 h after DMBA exposure. Increased frequency of micronuclei and enhanced lipid peroxidation accompanied by compromised antioxidant defenses were observed in DMBA-treated animals. Although pretreatment with tomato or garlic significantly reduced the frequency of DMBA-induced bone marrow micronuclei, the combination of tomato and garlic exhibited more profound effect in inhibiting DMBA-induced genotoxicity and oxidative stress. We suggest that a broad spectrum of antimutagenic and anticlastogenic effects can be achieved through an effective combination of functional foods such as tomato and garlic.