Studies of methyl 2-nitroimidazole-1-acetohydroxamate (KIN-804) 2: effect on certain antioxidant enzyme systems in mice bearing Ehrlich ascites carcinoma

In order to decrease toxicity and/or increase radiosensitizing activity, a new 2-nitroimidazole derivative, methyl 2-nitroimidazole-1-acetohydroxamate (KIN-804), was synthesized to solve the problem of tumor hypoxia. Evaluation of the efficiency of KIN-804 was carried out through studying the antioxidant enzyme system: The superoxide dismutase (SOD), catalase and lipid peroxide levels provide a rough index of the balance between free radical generation and scavenging. Female albino mice were inoculated with Ehrlich ascites carcinoma (EAC) in the thigh. The administration of KIN-804 (i.p. 80 mg/kg body weight) was carried out 20 min before localized irradiation of 10 Gy. In general, the data revealed that KIN-804 administration, followed or not by gamma irradiation, exerted significant inhibition of SOD and catalase activities accompanied by a significant increase in lipid peroxide level in tumor-bearing mice.     

Studies of methyl 2-nitroimidazole-1-acetohydroxamate (KIN-804) 1: effect on free radical scavenging system in mice bearing Ehrlich ascites carcinoma

Methyl 2-nitroimidazole-1-acetohydroxamate (KIN-804) is a 2-nitroimidazole derivative containing a hydroxamate side chain designed to enhance the radiosensitization response of hypoxic cells. The possible sensitization of tumor tissue by KIN-804 can be evaluated through investigation of the levels of the free radical scavengers; namely, glutathione (GSH) and its complex enzyme system including glutathione reductase (GR) and glutathione peroxidase (GSH-Px), as well as glucose-6-phosphate dehydrogenase (G-6-PD). Female albino mice were inoculated with Ehrlich carcinoma in the thigh. Administration of KIN-804 (i.p. 80 mg/kg body weight) was carried out 20 min before localized irradiation of 10 Gy. The data revealed that KIN-804 administration, followed or not by gamma irradiation, resulted in a significant decrease in GSH content in tumor tissues associated with inhibition in GR and G-6-PD activities. Blood GSH-Px was enhanced in tumor inoculated mice and the administration of KIN-804 returned it to the normal value. These changes were more noticeable in tumor bearing mice exposed to both KIN-804 and irradiation.     

Anticlastogenic activity of morin against whole body gamma irradiation in Swiss albino mice

Anticlastogenic activity of morin was explored against whole body gamma radiation, at a dose rate of 1.66 Gy/min in Swiss albino mice pretreated intraperitoneal or orally. Pretreatment with morin 10, 25, 50, 75, 100, 125, and 150 mg/kg, i.p. delayed and reduced percentage mortality and increased mean survival times in mice irradiated with 10 Gy gamma radiation. Intraperitoneal route was found superior to oral route. An i.p. dose of 100 mg/kg was found to be the most effective dose in preventing radiation-induced weight loss, increasing the mean survival times and reducing percentage mortality. Morin (100 mg/kg) pretreatment effectively maintained spleen index (spleen weight/body weight x 100) and stimulated endogenous spleen colony forming units. Pretreatment with morin (100 mg/kg) significantly reduced dead, inflammatory, and mitotic cells in irradiated mice jejunum along with a significant increase in goblet cells and rapidly multiplying crypt cells. Morin (100 mg/kg) also maintained the villus height close to normal, prevented mucosal erosion and basement membrane damage in irradiated jejunum. Nuclear enlargement in epithelial cells of jejunum was lower in morin treated mice compared to radiation control. Morin (100 mg/kg) also significantly elevated the endogenous antioxidant enzymes viz. glutathione S transferase (GST), superoxide dismutase (SOD) and reduced glutathione (GSH), in normal mice at 2, 4 and 8 h post treatment. Drastic decrease in endogenous enzymes (GSH, GST, catalase and SOD) and total thiols was observed in irradiated mice at 2, 4 and 8 h post irradiation, while pretreatment with morin (100 mg/kg) prevented this decrease. Morin (100 mg/kg) also elevated radiation LD(50) from 9.2 to 10.1 Gy, indicating a dose modifying factor (DMF) of 1.11.     

Evaluation of the radioprotective effect of Ageratum conyzoides Linn. extract in mice exposed to different doses of gamma radiation

The effect of various doses (0, 25, 50, 75, 100, 125, 150, 300, 600 and 900 mg kg(-1)) of the alcoholic extract of the plant Ageratum conyzoides Linn. (ACE), on the alteration of radiation-induced mortality in mice exposed to 10 Gy of gamma radiation was studied. The acute toxicity studies showed that the drug was non-toxic up to a dose of 3000 mg kg(-1), the highest dose that could be tested for acute toxicity. Administration of ACE resulted in a dose-dependent decline in radiation-induced mortality up to a dose of 75 mg kg(-1), the dose at which the highest number of survivors (70.83%) was observed. Thereafter, the number of survivors declined with increasing doses of ACE and a nadir was reached at 900 mg kg(-1) ACE. Since the number of survivors was highest for 75 mg kg(-1) ACE, this was considered the optimum dose for radioprotection and used in further studies in which mice were treated with 75 mg kg(-1) ACE before exposure to 6, 7, 8, 9, 10 and 11 Gy of gamma radiation. The treatment of mice with 75 mg kg(-1) ACE reduced the severity of symptoms of radiation sickness and mortality at all exposure doses, and a significant increase in survival was observed compared with the non-treated irradiated group. The ACE treatment effectively protected mice against the gastrointestinal as well as bone marrow related death, as revealed by the increased number of survivors at all irradiation doses. The dose reduction factor was found to be 1.3. To understand the mechanism of action, various doses of ACE were evaluated for their in-vitro scavenging action on 1,1-diphenyl-2-picrylhydrazyl (DPPH), a chemically stable free radical. ACE was found to scavenge DPPH radicals in a concentration-dependent manner, indicating that the radioprotection afforded by ACE may be in part due to the scavenging of reactive oxygen species induced by ionizing radiation.     

Protective Effect of Nardostachys jatamansi Against Radiation-induced Damage at Biochemical and Chromosomal Levels in Swiss Albino Mice

The effect of 100 mg of ethanol extract of Nardostachys jatamansi was studied on the mice exposed to 6 Gy electron beam radiation. Treatment of mice with 100 mg of Nardostachys jatamansi extract for 15 days before irradiation reduced the symptoms of radiation sickness when compared with the nondrug treated irradiated groups. The irradiation of animals resulted in an elevation in lipid peroxidation and reduction in glutathione, total antioxidants and antioxidant enzymes such as glutathione peroxidase and catalase activities. Irradiated group had shown micronucleus in the bone marrow cells. Treatment of mice with Nardostachys jatamansi extract before irradiation caused a significant depletion in lipid peroxidation followed by significant elevation in reduced glutathione, total antioxidants, glutathione peroxidase and catalase activity. It also showed a reduction in the micronucleus formation in the bone marrow cells. Our results indicate that the radioprotective activity of Nardostachys jatamansi extract may be due to free radical scavenging and increased antioxidant level in mice.     

Extract of Xylopia aethiopica (Annonaceae) protects against gamma-radiation induced testicular damage in Wistar rats

Ionizing radiation is an important environmental risk factor and, a major therapeutic agent for cancer treatment. This study was designed to evaluate the protective effect of extract of Xylopia aethiopica (XA) on gamma-radiation-induced testicular damage in rats. Vitamin C (VC) served as the reference antioxidant during the study. The study consists of 4 groups of 11 rats each. Group I received corn oil (vehicle), groups II and IV were pretreated with XA (250 mg/kg) and VC (250mg/kg) for 6 weeks before and 8 weeks after exposure to gamma-radiation; group III was exposed to a single dose of gamma-radiation (5 Gy). Biochemical analysis revealed that gamma-irradiation caused a significant increase (p < .05) in serum and testicular lipid peroxidation (LPO) levels by 217% and 221%, respectively. Irradiated rats had markedly decreased testicular catalase (CAT), superoxide dismutase (SOD), glutathione-S-transferase (GST), and reduced glutathione (GSH) levels. Irradiation resulted in 59% and 40% decreases in spermatozoa motility and live/dead sperm count, respectively, and a 161% increase in total sperm abnormalities. Histologically, testes of the irradiated rats showed extensive degenerative changes in the seminiferous tubules and defoliation of spermatocytes. Supplementation of XA and VC reversed the adverse effects of gamma-radiation on biochemical and histological indices of the rats. These findings demonstrated that Xylopia aethiopica has a protective effect by inhibiting oxidative damage in testes of irradiated rats.     

Evaluation of the antineoplastic activity of guduchi (Tinospora cordifolia) in Ehrlich ascites carcinoma bearing mice

The anticancer activity of dichloromethane extract of guduchi [Tinospora cordifolia (Willd.) Miers ex Hook. F. & Thoms. Family: Menispermaceae (TCE)] in the mice transplanted with Ehrlich ascites carcinoma (EAC) was investigated. The EAC mice receiving 25, 30, 40, 50 and 100 mg/kg, TCE showed a dose dependent elevation in tumor-free survival and a highest number of survivors were observed at 50 mg/kg TCE, which was considered as an optimum dose for its neoplastic action. The average survival time (AST) and median survival time (MST) for this dose were approximately 56 and 55 d, respectively when compared with 19 d of non-drug treated controls. Administration of 50 mg/kg TCE resulted in 100% long-term survivors (up to 90 d). An attempt was also made to evaluate the effectiveness of TCE in the various stages of tumor development, where 50 mg/kg TCE was administered intraperitoneally after 1, 3, 6, 9, 12 or 15 d of tumor inoculation and these days have been arbitrarily designated as stage I, II, III, IV or V, respectively for reasons of clarity. The greatest anticancer activity was recorded for stage I, II and III where number of long term survivors (LTS) was approximately 33, 25 and 17%, respectively. However, treatment of mice at stage IV and V did not increase LTS, despite an increase in AST and MST. The EAC mice receiving 50 mg/kg TCE showed a time dependent depletion in the glutathione (GSH) activity up to 12 h post-treatment and marginal elevation thereafter. This depletion in GSH was accompanied by a drastic elevation in lipid peroxidation (LPx) and a maximum elevation in LPx was observed at 6 h that declined gradually thereafter. TCE exerted cytotoxic effect on tumor cells by reducing the GSH concentration and increase in LPx simultaneously.     

Radioprotective effect of sesamol on gamma-radiation induced DNA damage, lipid peroxidation and antioxidants levels in cultured human lymphocytes

Sesamol pretreated (1, 5 and 10 microg/ml) lymphocytes were exposed to different doses of gamma-radiation, i.e., 1, 2 and 4 Gray (Gy) and the cellular changes were estimated by using cytokinesis blocked micronucleus assay (MN), dicentric aberration (DC), thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) and the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Radiation significantly increased MN, DC frequencies, TBARS levels and decreased GSH and antioxidant enzyme levels in a dose dependent manner. The highest damage to lymphocytes was observed at 4 Gy irradiation. On the other hand, sesamol pretreatment significantly decreased MN, DC frequencies, TBARS levels and increased GSH levels and SOD, CAT and GPx activities in a concentration dependent manner. At 1 Gy irradiation all concentrations of sesamol (1, 5 and 10 microg/ml) significantly protects the lymphocytes from radiation damage. At 2 Gy irradiation 5 and 10 microg/ml of sesamol shows significant radioprotection. Since the highest damage was observed at 4 Gy irradiation both 1 and 5 microg/ml of sesamol pretreatment were not sufficient to protect the lymphocytes from radiation damage but 10 microg/ml of sesamol significantly (p<0.05) protects the lymphocytes from radiation effect. Thus, sesamol pretreatment gives significant protection to cultured human lymphocytes against gamma-radiation induced cellular damage. The possible mechanism involved in the radioprotective influence of sesamol is discussed.     

Aegle marmelos (L.) Correa inhibits the proliferation of transplanted Ehrlich ascites carcinoma in mice

The anticancer effect of hydroalcoholic extract of Aegle marmelos (AME) was studied in the Ehrlich ascites carcinoma bearing Swiss albino mice. The spatial effect of various AME administration schedules showed that six-day administration increased the survival of tumor bearing mice. The best antineoplastic action of AME was obtained when AME administered through intraperitoneal route than the oral route at equimolar dose. Administration of AME once daily for six consecutive days to the tumor bearing mice caused a dose dependent remission of the tumor at 400 mg/kg body weight, where the greatest antitumor effect was observed and the higher doses showed toxic manifestations. A 24-d lengthening in life span was observed in EAC animals treated with 400 mg/kg AME. This dose of 400 mg/kg was considered as the best dose, where the animals survived up to 43 d post-tumor-cell inoculation as against no survivors in the saline treated control group. The antitumor activity when tested for different schedules for triple administrations, the best effect was observed for 1-2-3, followed by 1-3-5 and 1-5-9 days, respectively. Stage specific evaluation of AME inhibited the increase in body weight gain in animals due to tumor development during early stages only. The AME treatment resulted in a dose dependent elevation in the median survival time (MST) and average survival time (AST) up to 400 mg/kg AME and decline thereafter. The effective dose of 400 mg of AME is 1/6th of the LD50 dose, which increased the MST and AST up to 29 and 27 d, respectively. The acute toxicity study of AME showed that the drug was non-toxic up to a dose of 1750 mg/kg b. wt. The LD10 and LD50 was found to be 2000 and 2250 mg/kg.     

Genistein treatment protects mice from ionizing radiation injury

The radioprotective and behavioral effects of an acute administration of the isoflavone genistein (4',5,7-trihydroxyflavone) were investigated in adult CD2F1 male mice. Mice were administered a single subcutaneous (s.c.) dose of genistein either 24 h or 1 h before a lethal dose of gamma radiation (9.5-Gy of cobalt-60 at 0.6 Gy min(-1)). Mice received saline, PEG-400 vehicle or genistein at 3.125, 6.25, 12.5, 25, 50, 100, 200, or 400 mg kg(-1) body weight. For mice treated 24 h before irradiation there was a significant increase in 30-day survival for animals receiving genistein doses of 25 to 400 mg kg(-1) (p<0.001). In contrast, the 30-day survival rates of mice treated with genistein 1 h before irradiation were not significantly different from those of the vehicle control group. Additionally, the acute toxicity of genistein was evaluated in non-irradiated male mice administered a single s.c. injection of saline, vehicle, or genistein at 100, 200 or 400 mg kg(-1). At these genistein doses there were no adverse effects, compared with controls, on locomotor activity, grip strength, motor coordination, body weight, testes weight, or histopathology. These results demonstrate that a single s.c. administration of the flavonoid genistein at non-toxic doses provides protection against acute radiation injury.     

Influence of teniposide (VM-26) on radiation-induced damage to mouse spermatogenesis: a flow cytometric evaluation

The effect of teniposide (VM-26) 0.05 mg/kg body weight treatment on spermatogenesis of mice exposed to 0, 0.5, 1, 2, and 3 Gy gamma-radiation was evaluated flow cytometrically. Whole body irradiation with 1 to 3 Gy resulted in a significant decline in testis weight from Day 14 to 35 post-irradiation depending on the exposure dose. Treatment of mice with teniposide before irradiation advanced the decline in testicular weight by several days, especially at 3 Gy, where a significant decline in testicular weight was observed at Day 7 post-irradiation when compared with the double distilled water (DDW)+irradiation group. The relative percentage of the 2C population declined significantly in the VM-26+irradiation group in comparison with the DDW+irradiation group at various post-irradiation time periods depending on the exposure dose. A significant depletion in the relative percentage of S-phase cells was observed as early as Day 1 post-irradiation in the VM-26+irradiation group when compared with the DDW+irradiation group after exposure to 1 to 3 Gy. This decline continued up to Day 21 post-irradiation after exposure to 2 Gy. The relative percentage of primary spermatocytes showed a consistent decline after exposure to various doses of gamma-radiation in the VM-26+irradiation group when compared with the DDW+irradiation group at different time periods, with a few exceptions, especially at higher doses. The pattern of decline in the relative percentage of round spermatids was similar to that of primary spermatocytes, where a significant decline was observed at various post-irradiation time periods in the VM-26+irradiation group in comparison with the DDW+irradiation group. These changes in the relative germ cell percentages are manifested as alterations in the ratios of various germ cell populations. The 4C:2C ratio declined consistently from Day 1 to Day 70 post-irradiation in the VM-26+irradiation group at all exposure doses. Similarly, the 4C:S-phase ratio in the VM-26+irradiation group also showed a significant decline at different post-irradiation time periods when compared with the DDW+irradiation group depending on the exposure dose. The reduction observed in the relative percentages of various cell populations was higher in the combination group when compared with the DDW+irradiation controls, indicating potentiation of damage to male germ cells by teniposide treatment before irradiation.     

Influence of alpha-lipoic acid on intracellular glutathione in vitro and in vivo.

The influence of alpha-lipoic acid (CAS 62-46-4) on the amount of intracellular glutathione (GSH) was investigated in vitro and in vivo. Using murine neuroblastoma as well as melanoma cell lines in vitro, a dose-dependent increase of GSH content was observed. Dependent on the source of tumor cells the increase was 30-70% compared to untreated controls. Normal lung tissue of mice also revealed about 50% increase in glutathione upon treatment with lipoic acid. This corresponds with protection from irradiation damage in these in vitro studies. Survival rate of irradiated murine neuroblastoma was increased at doses of 100 micrograms lipoic acid/d from 2% to about 10%. In agreement with the in vitro studies, in vivo experiments with whole body irradiation (5 and 8 Gy) in mice revealed that the number of surviving animals was doubled at a dose of 16 mg lipoic acid/kg. Improvement of cell viability and irradiation protection by the physiological compound lipoic acid runs parallel with an increase of intracellular GSH/GSSG ratio.     

Protective effect of N-acetylcysteine against radiation induced DNA damage and hepatic toxicity in rats

The present study was designed to evaluate the radioprotective effect of N- acetylcysteine (NAC) on gamma-radiation induced toxicity in hepatic tissue in rat. The cellular changes were estimated using malondialdehyde (MDA, an index of lipid peroxidation), superoxide dismutase (SOD), glutathione peroxidase (GSHPx), reduced glutathione (GSH), and total nitrate/nitrite (NO(x)) as markers of hepatic oxidative stress in rats following gamma-irradiation. The DNA damage was determined by agarose gel electrophoresis. To achieve the ultimate goal of this study, 40 adult rats were randomly divided into 4 groups of 10 animals each. Group I was injected intraperitoneally with saline solution for 7 consecutive days and served as control group. Group II was irradiated with a single dose of 6Gy gamma-radiation. Group III was daily injected with NAC (1g/kg, i.p.) for 7 consecutive days. Group IV received a daily i.p. injection of NAC (1g/kg, i.p.) for 7 consecutive days and 1h after the last dose, rats were irradiated with a single dose (6Gy) gamma-radiation. The animals were sacrificed after 24h. DNA damage was observed in tissue after total body irradiation with a single dose of 6Gy. Malondialdehyde and total nitrate/nitrite were increased significantly whereas the levels of GSH and antioxidant enzymes were significantly decreased in gamma-irradiated group. Pretreatment with NAC showed a significant decrease in the levels of MDA, NO(x) and DNA damage. The antioxidant enzymes increased significantly along with the levels of GSH. Moreover, histopathological examination of liver tissues confirmed the biochemical data. Thus, our results show that pretreatment with N-acetylcysteine offers protection against gamma-radiation induced cellular damage.     

Polysaccharides isolated from Ganoderma lucidum occurring in Southern parts of India, protects radiation induced damages both in vitro and in vivo

The in vivo and in vitro radioprotective property of the polysaccharides isolated from Ganoderma lucidum were determined by survival studies, induction of micronucleus in reticulocytes of mice, strand breaks in plasmid pBR322 DNA and inhibition of lipid peroxidation (TBARS assay). Polysaccharides were administered as a single dose after whole body exposure to 10 Gy ⁶⁰Co γ-radiation to Swiss albino mice. At a dose of 500 μg/kg body wt, the polysaccharides were most effective in protecting animals from radiation induced loss of lethality. Administration of 500 μg/kg body wt to animal exposed to 10 Gy gamma radiation resulted in more than 60% survival on the 30th day compared to the dose of 300 mg/kg/body wt administration of amifostine, a clinically used radioprotective drug. The induction of micronuclei was reduced by the administration of polysaccharides. The decrease in micronuclei induction was dose dependent. Thus following 4 Gy exposure the micronuclei in polychromatic erythrocytes (MNCE) was reduced from 28.16 ± 3.049 to 16.0243 ± 2.074 and 6.30 ± 2.422 by polysaccharides at doses of 250 μg/kg body wt and 500 μg/kg body wt, respectively, and to 10.4 ± 2.581 by amifostine at a dose of 300 mg/kg body wt. The results indicate the significant protective effect of Ganoderma polysaccharides against radiation induced damages. The findings thus suggest the potential use of Ganoderma polysaccharides as novel radioprotective agent.     

Radioprotective effect of silymarin against radiation induced hepatotoxicity

The radioprotective effect of silymarin using different modes of treatment against radiation (3 or 6 Gy) induced hepatotoxicity 1, 3 and 7 days post-irradiation was studied. Whole-body gamma-irradiation revealed an increase in serum alkaline phosphatase (AP) activity as well as liver glutathione reductase (GR) and glutathione peroxidase (GSH-PX) activities on the first post-exposure day with respect to the control value. However, 3 days after radiation exposure, these parameters showed a significant decrease below the control level which persisted till the end of the experimental time except for serum AP activity that showed another increase on the seventh post-exposure day at 3 Gy dose of radiation. A gradual increase in serum alanine and aspartate aminotransferase (ALT&AST) as well as gamma glutamyl transpeptidase activities were observed due to irradiation throughout the experimental time. Administration of silymarin as single (70 mg kg (-1)), fractionated (490 mg kg (-1)) oral doses or as intravenous (i.v.) injection (50 mg kg (-1)), caused significant protection. Intravenous treatment showed the most pronounced protection. The protective effect of silymarin was attributed to its antioxidant and free radicals scavenging properties.     

Study on pre-treatment of melatonin against radiation-induced oxidative stress in mice

Antioxidants are part of the primary cellular defense against radiation-generated free radicals. Reports on low-level chronic administration of melatonin with its antiradiation influence are scanty. Although compelling logic suggests that melatonin may be effective for a variety of disorders, the mode and optimal dose of melatonin are still not clear. Most studies have used doses of supraphysiological blood levels. Present investigation reported that pre-treatment with the lower concentration of melatonin (0.1mg/kg b.w./day) for 15 consecutive days affords potential protective effect against radiation-induced oxidative stress and mortality in mice. Radiation-induced augmentation in the levels of lipid peroxidation, glutathione disulphide (GSSG) and acid phosphatase was significantly ameliorated by melatonin pre-treatment. Radiation-induced depletion in the level of reduced glutathione (GSH), as well as glutathione peroxidase (GSH-Px) and alkaline phosphatase activities, was inhibited significantly by melatonin administration. Regression analysis of survival data yielded LD(50/30) as 7.16 and 11Gy for control (irradiation alone) and experimental (melatonin-treated irradiated) mice, respectively, and produced a dose reduction factor (DRF), 1.53. Radiation-induced deficit in the body and organ weight also got inhibited significantly in the melatonin pre-treated mice. The findings support property of melatonin as a free radical scavenger and singlet oxygen quencher and indicate the antioxidative properties of melatonin against the gamma radiation.     

喜树碱前体多相脂体的药理学研究

本文报道了对喜树碱前体(A-CPT)及喜树碱前体多相脂质体(A-CPT-pl)的药理学研究结果。结果表明,A-CPT腹腔注射给药(ip)及经口腔给药(PO),寇氏法求得小鼠的LD50分别为159.3mg/kg及33.7mg/kg,较喜树碱钠盐(CTP-Na)的毒性降低,按最大允许给药容量(0.5ml/10g)ip或PO A-CPT-pl 50mg/kg,在观察期间未见死亡。抑瘤试验结果表明,A-CPT-pl对S180及HepS的抑制率可达74%及82%,可使荷EAC小鼠的生命延长126%;A-CPT对S180及HepS的抑制率可达52%及53%,可使荷EAc小鼠的生命延长54%。肿瘤相伴免疫试验结果表明,每日ip,A-CPT-pl 0.5mg/kg,连续9天,对小鼠肿瘤相伴免疫没有明显影响。     

Plumbagin,A Plant Naphthoquinone with Antitumor and Radiomodifying Properties

The tumor inhibitory and radiomodifying effects of plumbagin (Pl), a naphthoquinone isolated from Plumbago rosea, on mouse Ehrlich ascites carcinoma was studied. Tumor response was assessed by increase in life span (% ILS) and animal survival at 120 days. The acute LD 50 of plumbagin in normal mice was 9.4 mg/kg body weight. Single doses from 2 to 6 mg/kg Pl, given intraperitoneally (i.p.), produced inhibition of exponentially growing tumors. However, increases in dose above 3 mg/kg did not increase 120 day survival significantly over that produced by 3 mg/kg. Multiple dose treatment, starting from 24 h after tumor cell inoculation, showed that a total dose of 9 mg/kg, administered in three fractions of 3 mg/kg, once daily, gave the maximum %ILS and tumor free survival. Combination of radiation (RT, 7.5 Gy to the abdomen) after the first Pl dose (1-3mg/kg/fraction) synergistically increased mouse survival at 120 days. The tumor inhibitory effect was less pronounced when treatment was started at more advanced tumor stages, but combination of low dose fractions (2.5 or 3 mg/kg/fraction) with RT enhanced the %ILS and animal survival. Higher dose fractions in combination with radiation were not tolerated by the mice. DNA appears to be the likely target of Pl cytotoxicity; the mechanism of interaction of Pl + RT in enhancing tumor response is not clear.     

Induction of glutathione and activation of immune functions by low-dose, whole-body irradiation with gamma-rays

We first examined the relation between the induction of glutathione and immune functions in mice after low-dose gamma-ray irradiation. Thereafter, inhibition of tumor growth by radiation was confirmed in Ehrlich solid tumor (EST)-bearing mice. The total glutathione level of the splenocytes transiently increased soon after irradiation and reached a maximum at around 4 h postirradiation. Thereafter, the level reverted to the 0 h value by 24 h postirradiation. A significantly high splenocyte proliferative response was also recognized 4 h postirradiation. Natural killer (NK) activity was also increased significantly in a similar manner. The time at which the response reached the maximum coincided well with that of maximum total glutathione levels of the splenocytes in the gamma-ray-irradiated mice. Reduced glutathione exogenously added to splenocytes obtained from normal mice enhanced the proliferative response and NK activity in a dose-dependent manner. The inhibitory effects of radiation on tumor growth was then examined in EST-bearing mice. Repeated low-dose irradiation (0.5 Gy, four times, before and within an early time after inoculation) significantly delayed the tumor growth. Finally, the effect of single low-dose (0.5 Gy), whole-body gamma-ray irradiation on immune balance was examined to elucidate the mechanism underlying the antitumor immunity. The percentage of B cells in blood lymphocytes was selectively decreased after radiation, concomitant with an increase in that of the helper T cell population. The IFN-gamma level in splenocyte culture prepared from EST-bearing mice was significantly increased 48 h after radiation, although the level of IL-4 was unchanged. IL-12 secretion from macrophages was also enhanced by radiation. These results suggest that low-dose gamma-rays induce Th1 polarization and enhance the activities of tumoricidal effector cells, leading to an inhibition of tumor growth.     

Radioprotective effect of Panax ginseng on the phosphatases and lipid peroxidation level in testes of Swiss albino mice

The Panax ginseng has been used as traditional medicine for past several years among oriental people. The present investigation has been made to assess the radioprotective efficacy of ginseng root extract in the testicular enzymes of Swiss albino mice. The Swiss albino mice were divided into different groups. (i) Ginseng treated group: The animals were administered 10 mg/kg body weight ginseng root extract i.p. (ii) Radiation treated group: The animals were exposed to 8 Gy gamma radiation at the dose rate of 1.69 Gy/min at the distance of 80 cm. (iii) Combination group: Animals were administered ginseng extract continuously for 4 d and on 4th day they were irradiated to 8 Gy gamma radiation after 30 min of extract administration. The animals from above groups were autopsied on day 1, 3, 7, 14 and 30. Biochemical estimations of acid and alkaline phosphatases and Lipid peroxidation (LPO) in testes were done. In ginseng treated group acid and alkaline phosphatases activity and LPO level did not show any significant alteration. In irradiated animals there was a significant increase in acid phosphatase activity and LPO level. However, significant decline in alkaline phosphatase activity was observed. The treatment of ginseng before irradiation causes significant decrease in acid phosphatase and LPO level and significant increase in alkaline phosphatase activity. One of the cause of radiation damage is lipid peroxidation. Due to lipid peroxidation, lysosomal membrane permeability alters and thus results in release of hydrolytic enzymes. So, an increase in acid phosphatase was noticed after radiation treatment. The alkaline phosphatase activity is associated with membrane permeability and different stages of spermatogenesis. Due to membrane damage and depletion of germ cells of testes after irradiation the enzyme activity was decreased. Ginseng markedly inhibits lipid peroxidation. It acts in indirect fashion to protect radical processes by inhibition of initiation of free radical processes and thus reduces the radiation damages in testes of Swiss albino mice.