Som Nath Singh

EFFECT OF AN ANTIDIABETIC EXTRACT OF CATHARANTHUS ROSEUS ON ENZYMIC ACTIVITIES IN STREPTOZOTOCIN INDUCED DIABETIC RATS

Hypoglycemic activity was detected in dichloromethane:methanol extract (1:1) of leaves and twigs of Catharanthus roseus (family Apocynaceae), a traditionally used medicinal plant, using streptozotocin (STZ) induced diabetic rat model. Extract at dose 500 mg/kg given orally for 7 and 15 days showed 48.6 and 57.6% hypoglycemic activity, respectively. Prior treatment at the same dose for 30 days provided complete protection against STZ challenge (75 mg/kg/i.p.x1). Enzymic activities of glycogen synthase, glucose 6-phosphate-dehydrogenase, succinate dehydrogenase and malate dehydrogenase were decreased in liver of diabetic animals in comparison to normal and were significantly improved after treatment with extract at dose 500 mg/kg p.o. for 7 days. Results indicate increased metabolization of glucose in treated rats. Increased levels of lipid peroxidation measured as 2-thiobarbituric acid reactive substances (TBARS) indicative of oxidative stress in diabetic rats were also normalized by treatment with the extract.

Antioxidant and hepatoprotective activities of phenolic rich fraction of Seabuckthorn (Hippophae rhamnoides L.) leaves.

Present study was aimed to investigate antioxidant and hepatoprotective activities of phenolic rich fraction (PRF) of Seabuckthorn leaves on CCl(4) induced oxidative stress in Sprague Dawley rats. Total phenolic content was found to be 319.33 mg gallic acid equivalent (GAE)/g PRF and some of its phenolic constituents, such as gallic acid, myricetin, quercetin, kaempferol and isorhamnetin were found to be in the range of 1.935-196.89 mg/g of PRF as determined by reverse-phase high-performance liquid chromatography (RP-HPLC). Oral administration of PRF at dose of 25-75 mg/kg body weight significantly protected from CCl(4) induced elevation in aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ-glutamyl transpeptidase (GGT) and bilirubin in serum, elevation in hepatic lipid peroxidation, hydroperoxides, protein carbonyls, depletion of hepatic reduced glutathione (GSH) and decrease in the activities of hepatic antioxidant enzymes; superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR) and glutathione-S-transferase (GST). The PRF also protected against histopathological changes produced by CCl(4) such as hepatocytic necrosis, fatty changes, vacuolation, etc. The data obtained in the present study suggests that PRF has potent antioxidant activity, prevent oxidative damage to major biomolecules and afford significant protection against CCl(4) induced oxidative damage in the liver.

Ghrelin and leptin levels of sojourners and acclimatized lowlanders at high altitude.

Abstract The circulatory levels of two appetite regulatory hormones i.e. leptin and ghrelin were estimated in sojourners and acclimatized subjects to investigate their possible role in high altitude (HA) induced anorexia. A group of 30 lowlanders who had never visited HA were inducted to a height of 3600m by air and after 48h they were further taken to an altitude of 4300m by road. Blood samples were collected after 48h stay at 3600m and again after 48h and 7 days of stay at 4300m during 0700–0730h. There was a decrease in energy intake (850kcal/day) of sojourners, which resulted in loss of body weight by 2.12kg at HA. At an altitude of 4300m there was a significant increase in leptin over basal levels (54.9%, p <0.001) at 48h that persisted even after 7 days of stay at this altitude. Ghrelin levels of sojourners decreased by more than 30% in comparison to basal values at 48h of ascent to HA. Leptin levels of acclimatized lowlanders were also higher in comparison with control group (acclimatized group 7.6+0.6ng/ml vs. control 5.6+0.5ng/ml, p <0.01, n =50).

Effect of high altitude (7,620 m) exposure on glutathione and related metabolism in rats

Abstract Reduced and oxidised glutathione (GSH and GSSG) contents, and glutathione reductase, and glutathione S-transferase activities were studied in the livers, muscles, and blood/erythrocytes of male Sprague-Dawley rats exposed to intermittent hypoxia (6 h · day−1) at a simulated altitude of 7,620 m for 1, 7, 14, and 21 days. Significant decreases in GSH and increases in GSSG contents were observed in the muscles and blood of hypoxia-exposed rats in comparison to unexposed rats. Significant declines in GSH content by 43% and 45% respectively in muscles and blood were observed in the group exposed for 1 day which tended to recover on subsequent exposure. Glutathione reductase and glutathione S-transferase activities were decreased in the livers and erythrocytes of hypoxia-exposed rats, but were increased significantly in muscle. Lipid peroxidation was also increased in the livers and muscles of exposed rats. The changes were indicative of an increased production of reactive oxygen species and an impairment of drug and xenobiotic metabolism during exposure to high altitude hypoxia.

Improvement of Glutathione and Total Antioxidant Status with Yoga

OBJECTIVE Several studies suggest that yoga can decrease oxidative stress. However reports are scanty regarding whether yoga training can improve the glutathione level of individual. This study is designed to appraise the role of yoga in maintaining glutathione (reduced and oxidized) levels and antioxidant status. STUDY DESIGN This study was conducted on healthy male volunteers from the Indian Navy, who were divided into two groups--a yoga (n = 30) group and a control (n = 21) group. The yoga group was trained in yoga for 6 months. The yoga schedule consisted of prayers, asana, pranayama, and meditation. The control group practiced routine physical training exercise for 6 months. Blood samples were collected when the volunteers were in fasting condition before and after completion of 6-month training period. Reduced and oxidized glutathione, glutathione reductase activity and total antioxidant status (TAS) were estimated. RESULTS Reduced glutathione level increased significantly (p < 0.05) in the yoga group after completion of training. Glutathione reductase activity increased significantly in the control group (p < 0.05). TAS increased significantly (p < 0.001) in the yoga group and decreased significantly (p < 0.001) in the control group. CONCLUSIONS Regular practice of yoga can maintain or improve antioxidant level of the body. The clinical relevance is that yoga practice can be used to maintain the antioxidant defense system under stressful conditions of training as observed in the case of soldiers and athletes.

L-carnitine supplementation attenuates intermittent hypoxia-induced oxidative stress and delays muscle fatigue in rats.

The concept of l‐carnitine (l‐CAR) supplementation to improve muscular performance is based on the role of l‐CAR in regulating aerobic metabolism. l‐CAR has also been found to attenuate free radical‐induced oxidative stress in various pathological conditions. Thus, it was hypothesized that l‐CAR may reduce intermittent hypoxia (IH)‐induced oxidative stress and thereby benefit skeletal muscle performance. Thirty‐six adult male Sprague–Dawley rats were divided into three groups: unexposed control; IH exposed (6 h day−1 for 7 consecutive days), IH exposed with l‐CAR supplementation (100 mg (kg body weight)−1 day−1). Electrical stimulation was used to induce six tetanic muscular contractions in the gastrocnemius muscle after completion of exposure. Percentage mean performed work (PW), time of decay to 50% peak force of contraction (T50), and peak force of contraction (FPeak) were measured during tetanic contractions. Mean frequency (MF) was measured using electromyography between tetanic contractions. Muscle damage was indirectly measured from plasma creatine kinase (CK) and lipid hydroperoxide (LHP) levels. The levels of thiobarbituric acid reactive substances (TBARS), protein carbonyl (PC) and LHP were estimated in the muscle tissue to investigate the efficacy of l‐CAR in attenuating oxidative stress. Significant reduction in TBARS, PC and LHP levels and CK activity in the l‐CAR‐supplemented IH group as compared to the IH placebo group suggests that l‐CAR reduces oxidative damage and thereby delays muscular fatigue, which was evident from MF, T50, PW and FPeak. From these studies, we conclude that l‐CAR delays muscle fatigue by the reducing free radical‐induced oxidative damage of IH exposure.

Total antioxidant status at high altitude in lowlanders and native highlanders: role of uric acid.

Hypobaric hypoxia causes oxidative stress and the antioxidant system of the body plays a vital role in controlling it. Urate contributes up to two-thirds of the antioxidant capacity of human blood. The urate production is catalyzed by xanthine oxidase with a concomitant release of free radicals. This study was designed to appraise the role of urate as an antioxidant at high altitude. The study was conducted on 92 male lowlanders and 66 highlanders after ascent to high altitude at 4560 m. Blood was collected at sea level and after 4 weeks of high altitude exposure. In lowlanders, a significant increase in levels of hydroperoxide (551.4 +/- 4.2 micromol/mL vs. 582.0 +/- 3.55, p < 0.001], protein carbonyl (2.4 +/- 0.11 micromol/mL/mg protein vs. 3.03 +/- 0.11, p < 0.001), TAS (1.02 +/- 0.01 mmol/L vs. 1.19 +/- 0.02, p < 0.001), and UA (298.0 +/- 6.68 micromol/L vs. 383.0 +/- 6.55, p < 0.001) was observed at high altitude. These measurements were significantly lower in highlanders than in lowlanders at high altitude. Total antioxidant status (TAS) and uric acid (UA) showed a positive correlation in lowlanders at sea level and in highlanders at high altitude. Hydroperoxide and TAS also showed a positive correlation in both groups at high altitude. This indicates increased oxidative stress at high altitude despite an increase in antioxidant capacity in lowlanders. To conclude, a hypoxia-induced increase in UA contributes an appreciable portion of plasma total antioxidant capacity, but may not be effective in preventing oxidative stress at high altitude.

Evaluation of antioxidant profile and activity of amalaki (Emblica officinalis), spirulina and wheat grass

Aqueous and alcoholic extracts of amalki (Emblica officinalis), spirulina and wheatgrass were prepared and analyzed for antioxidant vitamin content (vitamin C and E), total phenolic compounds. Antioxidant status, reducing power and effect on glutathione S-transferase (GST) activity were evaluated in vitro. Vitamin C content of crude amalaki powder was found to be 5.38 mg/g, while very less amount 0.22 mg/g was detected in wheat grass. Amalki was rich in vitamin E like activity, total phenolic content, reducing power and antioxidant activity. Total antioxidant activity of aqueous extract of amalki, spirulina and wheat grass at 1mg/ml concentration were 7.78, 1.33 and 0.278 mmol/l respectively. At similar concentrations the total antioxidant activity of alcoholic extract of amalaki, spirulina and wheat grass was 6.67, 1.73 and 0.380 mmol/l respectively. Amalki was also found to be rich source of phenolic compounds (241mg/g gallic acid equivalent). Alcoholic extract of wheat grass showed 50 % inhibition in FeCl2- ascorbic acid induced lipid peroxidation of rat liver homogenates in vitro. Both aqueous and alcoholic extracts of amalaki inhibited activity of rat liver glutathione S-transferase (GST) in vitro in dose dependant manner. Since GST acts as powerful drug metabolizing enzyme its inhibition by amalaki offers possibility of its use for lowering therapeutic dose of herbal preparations. The aqueous extracts of both amalki and spirulina also showed protection against t-BOOH induced cytotoxicity and production of ROS in cultured C6 glial cells.

High altitude induced anorexia: Effect of changes in leptin and oxidative stress levels

Abstract High altitude (HA) exposure usually leads to a significant weight loss in non-acclimatized humans. Anorexia is believed to be the main cause of this body weight loss. Appetite regulatory peptides, i.e. leptin and neuropeptide Y play a key role in food intake and energy homeostasis. Recent studies suggests increased oxidative stress during HA exposure. In present study effect of HA exposure on levels of leptin and NPY was evaluated along with N-acetyl cysteine (NAC) and vitamin E supplementation in relation to food intake and body weight changes. The study was conducted on 30 healthy male volunteers (age 19 – 29 years). Subjects were divided randomly into three groups of 10 each. Group 1 (placebo) supplemented with 400 mg of calcium gluconate, group 2 and 3 were supplemented with 400 mg of NAC and 400 mg vitamin E, respectively per day. The study was conducted at low altitude (320 m, Phase I), at HA 3600 m (Phase II) and at an altitude of 4580 m (Phase III). On HA exposure significant reduction in plasma leptin levels was observed in all the groups on day 2 (Phase II) along with decrease in food intake and reduction in body weight. Statistically significant increase in blood malondialdehyde (MDA) levels was seen in all the groups on HA exposure (Phase II, Day 2), but the maximum increase was in case of placebo group (65.1%) on day 2 (Phase II) in comparison to low altitude values. The decrease in energy intake was almost same in all the groups indicating that antioxidant supplementation did not provide any protection against HA anorexia. From the study, it may be concluded that leptin and oxidative stress possibly are not the key players for HA anorexia.

Protein nitration, lipid peroxidation and DNA damage at high altitude in acclimatized lowlanders and native highlanders: Relation with oxygen consumption

Reactive oxygen and nitrogen species have been reported to be increased due to hypobaric hypoxia. It was hypothesized that lowlanders are more susceptible to protein nitration, lipid peroxidation and DNA damage at high altitude than highlanders and formation of these biomarkers may have strong correlation with oxygen consumption. Male volunteers were randomly selected and categorized into 3 groups, i.e. lowlanders at sea level (LL-SL, n=10), lowlanders at an altitude of 4560 m (LL-HA, n=10) and highlanders (HAN, n=10). Volunteers performed maximal aerobic exercise. Resting and post-exercise blood samples were taken at sea level and high altitude. Both resting and maximum oxygen consumption showed positive correlation with stress markers. LL-HA showed increased 3-nitrotyrosine and lipid hydroperoxide than LL-SL at rest. 3-Nitrotyrosine and lipid hydroperoxide increased after exercise in 3 groups, but percentage increase was higher in HAN than LL-SL and LL-HA. LL-SL and HAN showed significant DNA damage after exercise. Results indicate that resting oxygen consumption is positively correlated with nitrosative and oxidative stress markers irrespective of environmental condition and adaptation levels. Lowlanders have shown higher susceptibility to hypoxic insult than highlanders at rest, but when subjected to exercise test, they showed better tolerance to hypoxia than highlanders.