Long-term effect of Trigonella foenum graecum and its combination with sodium orthovanadate in preventing histopathological and biochemical abnormalities in diabetic rat ocular tissues

Trigonella foenum graecum seed powder (TSP) and Sodium Orthovanadate (SOV) have been shown to demonstrate antidiabetic effects by stabilizing glucose homeostasis and carbohydrate metabolism in experimental type-1 diabetes. However their efficacy in controlling histopathological and biochemical abnormalities in ocular tissues associated with diabetic retinopathy is not known. The purpose of this study was to investigate the comparative efficacy of individual as well as combination therapy of TSP and SOV in 8 weeks diabetic rat lens and retina. Retinas and lenses were taken from control, alloxan-induced diabetic rats and diabetic rats treated separately with insulin, 5%TSP, SOV (0.6 mg/ml) and a combined dose of SOV (0.2 mg/ml) and 5%TSP for 60 days. Control and each experimental group had six rats. Alterations in the activities of enzymes HK (hexokinase), AR (aldose reductase), SDH (sorbitol dehydrogenase), G-6-PD (glucose-6-phosphate dehydrogenase), GPx (glutathione peroxidase), GR (glutathione reductase) and levels of metabolites like sorbitol, fructose, glucose, MDA (malondialdehyde) and GSH (reduced glutathione) were measured in the cytosolic fraction of lenses besides measuring blood glucose levels and glycosylated haemoglobin. Histopathological abnormalities were studied in the lens using photomicrography and retina using transmission electron microscopy. Blood glucose, glycosylated haemoglobin levels and polyol pathway enzymes AR and SDH increased significantly causing accumulation of sorbitol and fructose in the diabetic lens and treatment with SOV and TSP significantly (p < 0.05) decreased these to control levels. Similarly, SOV and TSP treatments modulated the activities of HK, G-6-PD, GPx and GR in the rat lens to control values. Ultrastructure of the diabetic retina revealed disintegration of the inner nuclear layer cells with reduction in rough endoplasmic reticulum and swelling of mitochondria in the bipolar cells; and these histopathological events were effectively restored to control state by SOV and TSP treatments. In this study SOV and TSP effectively controlled ocular histopathological and biochemical abnormalities associated with experimental type-1 diabetes, and a combination regimen of low dose of SOV with TSP demonstrated the most significant effect. In conclusion, the potential of SOV and TSP alone or in low dose combination may be considered as promising approaches for the prevention of diabetic retinopathy and other ocular disorders.     

Amelioration of altered antioxidant status and membrane linked functions by vanadium andTrigonella in alloxan diabetic rat brains

Trigonella foenum graecum seed powder (TSP) and sodium orthovanadate (SOV) have been reported to have antidiabetic effects. However, SOV exerts hypoglycemic effects at relatively high doses with several toxic effects. We used low doses of vanadate in combination with TSP and evaluated their antidiabetic effects on antioxidant enzymes and membrane-linked functions in diabetic rat brains. In rats, diabetes was induced by alloxan monohydrate (15 mg/100 g body wt.) and they were treated with 2 IU insulin, 0.6 mg/ml SOV, 5% TSP and a combination of 0.2 mg/ml SOV with 5% TSP for 21 days. Blood glucose levels, activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), Na⁺/K⁺ ATPase, membrane lipid peroxidation and fluidity were determined in different fractions of whole brain after 21 days of treatment. Diabetic rats showed high blood glucose (P < 0.001), decreased activities of SOD, catalase and Na⁺/K⁺ ATPase (P < 0.01,P < 0.001 andP < 0.01), increased levels of GPx and MDA (P < 0.01 andP < 0.001) and decreased membrane fluidity (P < 0.01). Treatment with different antidiabetic compounds restored the above-altered parameters. Combined dose ofTrigonella and vanadate was found to be the most effective treatment in normalizing these alterations. Lower doses of vanadate could be used in combination with TSP to effectively counter diabetic alterations without any toxic effects.     

Trigonella foenum graecum (fenugreek) seed powder improves glucose homeostasis in alloxan diabetic rat tissues by reversing the altered glycolytic,gluconeogenic and lipogenic enzymes

Trigonella foenum graecum (fenugreek) seed powder has been suggested to have potential antidiabetic effects. The effect of oral administration of Trigonella whole seed powder (5% in the diet) for 21 days on glycolytic, gluconeogenic and NADPlinked lipogenic enzymes were studied in liver and kidney tissues of alloxan-induced diabetic Wistar rats. Diabetic rats were characterised by a 4fold higher blood glucose level and a 0.7fold lower body weight compared to normal controls. The activities of the glycolytic enzymes were significantly lower in the diabetic liver and higher in the diabetic kidney. The activities of gluconeogenic enzymes were higher in both liver and kidney during diabetes, however the activities of the lipogenic enzymes were decreased in both tissues during diabetes. Trigonella seed powder treatment to diabetic rats for 21 days brought down the elevated fasting blood glucose levels to control levels. The altered enzyme activities were significantly restored to control values in both the liver and kidney after Trigonella seed powder treatment. The therapeutic role of Trigonella seed powder in type1 diabetes as exemplified in this study can be attributed to the change of glucose and lipid metabolising enzyme activities to normal values, thus stabilizing glucose homeostasis in the liver and kidney. These biochemical effects exerted by Trigonella seeds make it a possible new therapeutic in type1 diabetes.     

Oral administration of orthovanadate and Trigonella foenum graecum seed powder restore the activities of mitochondrial enzymes in tissues of alloxan-induced diabetic rats

The effect of oral administration of sodium orthovanadate (SOV) and Trigonella foenum graecum seed powder (TSP), a medicinal plant used extensively in Asia, on the mitochondrial metabolism in the alloxan diabetic rats has been investigated. Rats were injected with alloxan monohydrate (20 mg/100 g body wt) or vehicle (Na-acetate buffer), the former were treated with either 2 IU insulin i.p., 0.6 mg/ml SOV ad libitum, 5% TSP ad libitum, and a combination of 0.2% SOV and 5% TSP ad libitum for 21 days. Selected rate-limiting enzymes of the tricarboxylic acid cycle, hydrogen shuttle system, ketone body metabolism, amino acid metabolism and urea cycle were measured in the mitochondrial and cytosolic fractions of liver, kidney and brain tissues of the experimental rats. Majority of the mitochondrial enzymes in the tissues of the diabetic rats had significantly higher activities compared to the control rats. Similarly, the activities of mitochondrial and cytosolic aminotransferases and arginase were significantly higher in liver and kidney tissues of the diabetic rats. The separate administrations of SOV and TSP to diabetic rats were able to restore the activities of these enzymes to control values. The lower dose of SOV (0.2%) administered in combination with TSP to diabetic rats lowered the enzyme activities more significantly than when given in a higher dose (0.6%) separately. This is the first report of the effective combined action of oral SOV and TSP in ameliorating the altered mitochondrial enzyme activities during experimental type-1 diabetes. Our novel combined oral administration of SOV and TSP to diabetic rats thus conclusively proves as a possible method to minimize potential vanadate toxicity without compromising its positive effects in the therapy of experimental type-1 diabetes.     

Relation between electrokinetic potentials and growth in callus cultures ofTrigonella foenum-graecum

Callus cultures ofTrigonella foenum-graecum were initiated from radicle or cotyledon portions of seedlings and young leaves and maintained on modified 1-B5 medium. The callus mass was disaggregated by mechanical agitation and the discrete cells thus obtained were used to measure their electrokinetic potential. Studies pertaining to the effects of ageing on electrokinetic potential and growth index revealed a relationship between these two parameters. Thus, the rate of change of electrokinotie potential with age could be employed as a parameter to study the growth kinetics of cells in callus cultures.     

Restoration of ultrastructural and biochemical changes in alloxan-induced diabetic rat sciatic nerve on treatment with Na3VO4 and Trigonella—a promising antidiabetic agent

Vanadium has been reported to have broad pharmacological activity both in vitro and in vivo. Vanadium compound, sodium orthovanadate, Na₃VO₄, is well known for its hypoglycaemic effects. However, Na₃VO₄ exerts these effects at relatively high doses (0.6 mg/ml) and exhibit several toxic effects. In the present study lower doses of Na₃VO₄ (0.2 mg/ml) are combined with Trigonella foenum graecum seed powder (TSP), another hypoglycaemic agent, to reduce its toxicity without compromising its antidiabetic potential. The efficacy of the lower doses of Na₃VO₄ has been investigated in restoring the altered glucose metabolism and histological structure in the sciatic nerves in 21 and 60 days alloxan diabetic rats. A portion of the glucose was found to be channelled from the normal glycolytic route to polyol pathway, evident by the reduced hexokinase activity and increased polyol pathway enzymes aldose reductase and sorbitol dehydrogenase activity causing accumulation of sorbitol and fructose in diabetic conditions. Ultrastructural observation of the sciatic nerve showed extensive demylination and axonal loss after eight weeks of diabetes induction. Blood glucose levels increased in diabetic rats were normalized with the lower dose of vanadium and Trigonella treatment. The treatment of the diabetic rats with vanadium and Trigonella prevented the activation of the polyol pathway and sugar accumulations. The sciatic nerves were also protected against the structural abnormalities found in diabetes with Trigonella foenum graecum as well as Na₃VO₄. Results suggest that lower doses of Na₃VO₄ may be used in combination with TSP as an efficient antidiabetic agent to effectively control the long-term complications of diabetes in tissues like peripheral nerve.     

Low doses of vanadate and Trigonella synergistically regulate Na+/K+-ATPase activity and GLUT4 translocation in alloxan-diabetic rats

Oral administration of vanadate to diabetic animals have been shown to stabilize the glucose homeostasis and restore altered metabolic pathways. However, vanadate exerts these effects at relatively high doses with several toxic effects. Low doses of vanadate are relatively safe but unable to elicit any antidiabetic effects. The present study explored the prospect of using low doses of vanadate with Trigonella foenum graecum, seed powder (TSP), another antidiabetic agent, and to evaluate their antidiabetic effect in diabetic rats. Alloxan diabetic rats were treated with insulin, vanadate, TSP and low doses of vanadate with TSP for three weeks. The effect of these antidiabetic compounds was examined on general physiological parameters, Na⁺/K⁺ ATPase activity, membrane lipid peroxidation and membrane fluidity in liver, kidney and heart tissues. Expression of glucose transporter (GLUT4) protein was also examined by immunoblotting method in experimental rat heart after three weeks of diabetes induction. Diabetic rats showed high blood glucose levels. Activity of Na⁺/K⁺ ATPase decreased in diabetic liver and heart. However, kidney showed a significant increase in Na⁺/K⁺ ATPase activity. Diabetic rats exhibited an increased level of lipid peroxidation and decreased membrane fluidity. GLUT4 distribution was also significantly lowered in heart of alloxan diabetic rats. Treatment of diabetic rats with insulin, TSP, vanadate and a combined therapy of lower dose of vanadate with TSP revived normoglycemia and restored the altered level of Na⁺/K⁺ ATPase, lipid peroxidation and membrane fluidity and also induced the redistribution of GLUT4 transporter. TSP treatment alone is partially effective in restoring the above diabetes-induced alterations. Combined therapy of vanadate and TSP was the most effective in normalization of altered membrane linked functions and GLUT4 distribution without any harmful side effect.     

Alterations in antioxidant enzymes and oxidative damage in experimental diabetic rat tissues: Effect of vanadate and fenugreek (Trigonella foenum graecum)

With the premise that oxygen free radicals may be responsible for the severity and complications of diabetes, the level of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) as well as the oxidative damage were examined in the tissues of control, diabetic and treated rats. After three weeks of diabetes, the activity of CAT was significantly increased in heart in diabetes (about 6-fold) but decreased in liver. The SOD activity decreased significantly in liver but increased in brain. The activity of GPx decreased significantly in liver and increased in kidney. A significant increase was observed in oxidative damage in heart and kidney and a small increase in brain with decrease in liver and muscle. Vanadate and fenugreek (Trigonella foenum graecum) administration to diabetic animals showed a reversal of the disturbed antioxidant levels and peroxidative damage. Results suggest that oxidative stress play a key role in the complications of diabetes. Vanadate and fenugreek seeds showed an encouraging antioxidant property and can be valuable candidates in the treatment of the reversal of the complications of diabetes.     

Tinospora cordifolia induces enzymes of carcinogen/drug metabolism and antioxidant system, and inhibits lipid peroxidation in mice

The present study is an effort to identify a potent chemopreventive agent against various diseases (including cancer) in which oxidative stress plays an important causative role. Here, we investigated the effect of a hydroalcoholic (80% ethanol: 20% distilled water) extract of aerial roots of Tinospora cordifolia (50 and 100mg/kg body wt./day for 2 weeks) on carcinogen/drug metabolizing phase-I and phase-II enzymes, antioxidant enzymes, glutathione (GSH) content, lactate dehydrogenase and lipid peroxidation in liver of 8-week-old Swiss albino mice. The modulatory effect of the extract was also examined on extrahepatic organs, i.e., lung, kidney and forestomach, for the activities of GSH S-transferase (GST), DT-diaphorase (DTD), superoxide dismutase (SOD) and catalase. Significant increases in the levels of acid-soluble sulfhydryl (-SH) and cytochrome P(450) contents, and enzyme activities of cytochrome P(450) reductase, cytochrome b(5) reductase, GST, DTD, SOD, catalase, GSH peroxidase (GPX) and GSH reductase (GR) were observed in the liver. Both treated groups showed decreased malondialdehyde (MDA) formation. In lung SOD, catalase and GST; in kidney SOD and catalase; and in forestomach SOD, DTD and GST showed significant increase at both dose levels of treatment. BHA (0.75%, w/w in diet), a pure antioxidant compound, was used as a positive control. This group showed increase in hepatic levels of GSH content, cytochrome b(5), DTD, GST, GR and catalase, whereas MDA formation was inhibited significantly. In the BHA-treated group, the lung and kidney showed increased levels of catalase, DTD and GST, whereas SOD was significantly increased in the kidney and forestomach; the latter also showed an increase in the activities of DTD and GST. The enhanced GSH level and enzyme activities involved in xenobiotic metabolism and maintaining antioxidant status of cells are suggestive of a chemopreventive efficacy of T. cordifolia against chemotoxicity, including carcinogenicity, which warrants further investigation of active principle (s) present in the extract responsible for the observed effects employing various carcinogenesis models.     

Quantitative aspects of glucose metabolism by Escherichia coli B/r,grown in the presence of pyrroloquinoline quinone

Escherichia coli B/r was grown in chemostat cultures under various limitations with glucose as carbon source. Since E. coli only synthesized the glucose dehydrogenase (GDH) apo-enzyme and not the appropriate cofactor, pyrroloquinoline quinone (PQQ), no gluconate production could be observed. However, when cell-saturating amounts of PQQ (nmol to mol range) were pulsed into steady state glucose-excess cultures of E. coli, the organisms responded with an instantaneous formation of gluconate and an increased oxygen consumption rate. This showed that reconstitution of GDH in situ was possible.Hence, in order to examine the influence on glucose metabolism of an active GDH, E. coli was grown aerobically in chemostat cultures under various limitations in the presence of PQQ. It was found that the presence of PQQ indeed had a sizable effect: at pH 5.5 under phosphate- or sulphate- limited conditions more than 60% of the glucose consumed was converted to gluconate, which resulted in steady state gluconate concentrations up to 80 mmol/l. The specific rate of gluconate production (0.3–7.6 mmol·h^-1·(g dry wt cells)^-1) was dependent on the growth rate and the nature of the limitation. The production rate of other overflow metabolites such as acetate, pyruvate, and 2-oxoglutarate, was only slightly altered in the presence of PQQ. The fact that the cells were now able to use an active GDH apparently did not affect apo-enzyme synthesis.Abbreviations HEPES N-2-hydroxy-ethylpiperazine-N-2-ethane sulphonic acid - MES 2-morpholinoethane sulphonic acid - PQQ pyrroloquinoline quinone (systematic name: 2,7,9-tricarboxy-1H-pyrrolo-(2,3-f)-quinoline-4,5-dione) - WB Wurster's Blue (systematic name: 1,4-bis-(dimethylamino)-benzene perchlorate     

The effects of peroxovanadate and peroxovanadyl on glucose metabolism in vivo and identification of signal transduction proteins involved in the mechanism of action in isolated soleus muscle

The insulin-like effects of peroxovanate (POV) and peroxovanadyl (PSV) on rates of lactate formation and glycogen synthesis were measured in isolated incubated soleus muscle preparations. In another experiment rats were made insulin deficient by streptozotocin injection and treated with POV and PSV (0.25 mM) administered in the drinking water and in the course of 7 days glycemia were determined. Also, signal transduction proteins ERK 1 and ERK 2 involved in the insulin signaling were measured in soleus muscle of diabetic rats treated with POV and PSV. Peroxides of vanadate and vanadyl significantly stimulated glucose utilization in soleus muscle preparations in vitro. The stimulation of glycogen synthesis and lactate formation by POV and PSV was similar to insulin stimuli. Rats treated with POV or PSV presented reduction of glycemia, food and fluid intake with amelioration of the diabetic state during the short period of treatment (7 days). POV and PSV modulated ERK1/2 phosphorilation and the insulin administration in these rats caused an addictive effect on phosphorilation state of these proteins.     

Modulatory influence of Adhatoda vesica (Justicia adhatoda) leaf extract on the enzymes of xenobiotic metabolism,antioxidant status and lipid peroxidation in mice

The effect of two different doses (50 and 100 mg/kg body wt/day for 14 days) of 80% ethanolic extract of the leaves of Adhatoda vesica were examined on drug metabolizing phase I and phase II enzymes, antioxidant enzymes, glutathione content, lactate dehydrogenase and lipid peroxidation in the liver of 8 weeks old Swiss albino mice. The modulatory effect of the extract was also examined on extra-hepatic organs viz. lung, kidney and forestomach for the activities of glutathione S-transferase, DT-diaphorase, superoxide dismutase and catalase. Significant increase in the activities of acid soluble sulfhydryl (-SH) content, cytochrome P450, NADPH-cytochrome P450 reductase, cytochrome b₅, NADH-cytochrome b₅ reductase, glutathione S-transferase (GST), DT-diaphorase (DTD), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) were observed in the liver at both dose levels of treatments. Adhatoda vesica acted as bifunctional inducer since it induced both phase I and phase II enzyme systems. Both the treated groups showed significant decrease in malondialdehyde (MDA) formation in liver, suggesting its role in protection against prooxidant induced membrane damage. The cytosolic protein was significantly inhibited at both the dose levels of treatment indicating the possibility of its involvement in the inhibition of protein synthesis. BHA has significantly induced the activities of GR and GSH in the present study. The extract was effective in inducing GST and DTD in lung and forestomach, and SOD and CAT in kidney. Thus, besides liver, other organs viz., lung, kidney and forestomach were also stimulated by Adhatoda, to increase the potential of the machinery associated with the detoxification of xenobiotic compounds. But, liver and lung showed a more consistent induction. Since the study of induction of the phase I and phase II enzymes is considered to be a reliable marker for evaluating the chemopreventive efficacy of a particular compound, these findings are suggestive of the possible chemopreventive role played by Adhatoda leaf extract.     

Effects of water extract of Usnea longissima on antioxidant enzyme activity and mucosal damage caused by indomethacin in rats

In this study, the antiulcerogenic effect of a water extract obtained from the lichen species Usnea longissima was investigated using indomethacin-induced ulcer models in rats. Experimental groups consisted of six rats. Antiulcerogenic activities of 50, 100 and 200mg/kg body wt. doses of the water extract were determined by comparing the negative (treated only with indomethacin) and positive (ranitidine) control groups. Although all doses of the water extract of U. longissima showed significant antiulcerogenic activity as compared to negative control groups, the highest activity was observed with 100 mg/kg body wt. doses (79.8%). The water extract of U. longissima showed moderate antioxidant activity when compared with trolox and ascorbic acids used as positive antioxidants. In addition, the activities of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST)] were determined in the stomach tissues of rats and compared with those of the negative and positive control groups to expose the effects of antioxidant enzymes on antiulcerogenic activity. SOD and GST enzymes activities in indomethacin-administrated tissues were reduced significantly by indomethacin in comparison to control groups. These enzymes were activated, however, by the water extracts of U. longissima. In contrast to SOD and GST activities, CAT activity was increased by indomethacin and reduced by all doses of U. longissima and ranitidine. The present results indicate that the water extract of U. longissima has a protective effect in indomethacin-induced ulcers, which can be attributed to its antioxidant potential.     

Dapsone induces oxidative stress and impairs antioxidant defenses in rat liver

Dapsone (DDS) is currently used in the treatment of leprosy, malaria and in infections with Pneumocystis jirovecii and Toxoplasma gondii in AIDS patients. Adverse effects of DDS involve methemoglobinemia and hemolysis and, to a lower extent, liver damage, though the mechanism is poorly characterized. We evaluated the effect of DDS administration to male and female rats (30 mg/kg body wt, twice a day, for 4 days) on liver oxidative stress through assessment of biliary output and liver content of reduced (GSH) and oxidized (GSSG) glutathione, lipid peroxidation, and expression/activities of the main antioxidant enzymes glutathione peroxidase, superoxide dismutase, catalase and glutathione S-transferase. The influence of DDS treatment on expression/activity of the main DDS phase-II-metabolizing system, UDP-glucuronosyltransferase (UGT), was additionally evaluated. The involvement of dapsone hydroxylamine (DDS-NHOH) generation in these processes was estimated by comparing the data in male and female rats since N-hydroxylation of DDS mainly occurs in males. Our studies revealed an increase in the GSSG/GSH biliary output ratio, a sensitive indicator of oxidative stress, and in lipid peroxidation, in male but not in female rats treated with DDS. The activity of all antioxidant enzymes was significantly impaired by DDS treatment also in male rats, whereas UGT activity was not affected in any sex. Taken together, the evidence indicates that DDS induces oxidative stress in rat liver and that N-hydroxylation of DDS was the likely mediator. Impairment in the activity of enzymatic antioxidant systems, also associated with DDS-NHOH formation, constituted a key aggravating factor.     

The effect of swimming exercise and powdered-Salicornia herbacea L. ingestion on glucose metabolism in STZ-induced diabetic rats

Purpose

The purpose of this study is to observe the effects of Salicornia herbacea L. powder ingestion on carbohydrate metabolism in STZ-induced diabetic rats.

Methods

To achieve this objective, 35 Sprague-Dawley male rats were raised with feed mixed with Salicornia herbacia L. powder and given specific periods to swim for 5 weeks. There was no significant difference in the insulin increase rate while ingesting Salicornia herbacea L. powder and simultaneously exercising.

Results

Compared to the diabetes mellitus group, HOMA-IR was significantly decreased in the diabetes mellitus + exercise group, diabetes mellitus + Salicornia herbacea group, and the diabetes mellitus + Salicornia herbacea + exercise group. However, changes in blood glucose were significant in each group. Thus, for the result of GLUT-4 and GLUT-2, which are the glycose transporters of the liver and muscle, diabetes mellitus + exercise group, diabetes mellitus + Salicornia herbacea group, and diabetes mellitus + Salicornia herbacea + exercise group showed significantly higher expressions. The glycogen concentration of the liver and muscle was significantly increased in the diabetes mellitus + exercise group, diabetes mellitus + Salicornia herbacea group, and diabetes mellitus + Salicornia herbacea + exercise group.

Conclusion

With the results above, it seems that taking Salicornia herbacea L. powder and exercise will help prevent various diabetic complications. Therefore, the findings of this study could justify Salicornia herbacea L. powder with its basal data of physiological activities and pharmacological components as a type of health functional food.     

Changes in the antioxidant status in leaves of Solanum species in response to elicitor from Phytophthora infestans

Three Solanum genotypes with various polygenic resistance levels to the oomycete pathogen Phytophthora infestans (Mont.) De Bary were studied for their antioxidant response to the pathogen culture filtrate (CF). Detached plant leaves were treated with CF for 6, 18 and 30 h, and assayed for changes in hydrogen peroxide content, total ascorbate and glutathione pools and redox ratios (reduced form to total pool), as well as for changes in activities of ascorbate peroxidase, glutathione reductase and glutathione-S-transferase. In CF treated leaves of non-host resistant S. nigrum var. gigantea and field resistant S. tuberosum cv Bzura, the H(2)O(2) content did not change in comparison to water treated control leaves, whereas in the susceptible S. tuberosum clone H-8105 it decreased below the control level. In CF treated leaves of all genotypes, the total ascorbate pools were relatively unaltered and their redox ratio changed only transiently. In Bzura leaves the total glutathione content increased earlier than in the two other genotypes. The glutathione redox ratio remained rather stable, except for the susceptible clone H-8105, where it decreased transiently by about 42%. The relative increases in activity of all the studied enzymes were the highest in the susceptible clone H-8105. The results are discussed in the light of oxidative processes occurring in CF treated leaves. We conclude that stringent control of pro- and anti-oxidant reactions bringing the H(2)O(2) and/or cellular redox state to the threshold level is decisive for deployment of an effective defense strategy.     

Localization of antioxidant enzymes in the cellular compartments of sorghum leaves

The localization of antioxidant enzymes between the mesophyll and bundle sheath cells were determined in sorghum (Sorghum vulgare L.) leaves. The activity of antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (POD), ascorbate peroxidase (APX) and glutathione reductase (GR) were assayed in whole leaf, mesophyll and bundle sheath fractions of sorghum leaves subjected to water-limited conditions. Drought was imposed by withholding water and the plants were maintained at different water potentials ranging from 0.5–2.0 MPa. The purity of the isolates was tested using the marker enzymes like RuBPcase and PEPcase. GR was mostly localized in mesophyll fraction, while SOD, APX and peroxidase were located in bundle sheath cells. Catalase was found to be equally distributed between the two cell types. Under water stress conditions, most of the SOD activity was found in the bundle sheath tissues. Little or no activity of the enzymes CAT, APX or POD was found in the mesophyll extracts when exposed to water stress. GR activity increased when exposed to low water regimes. From this study, it is clear that antioxidants are differentially distributed between the mesophyll and bundle sheath cells in sorghum leaves. Under water stress conditions, the mesophyll cells showed less damage from oxidative stress when compared to the bundle sheath cells. This is critical for determining the sensitivity of sorghum to extreme climatic conditions.     

1型糖尿病小鼠肝脏的口服葡萄糖代谢及差异表达基因

目的：观察口服葡萄糖在1型糖尿病小鼠肝脏的代谢,比较1型糖尿病小鼠与正常小鼠口服葡萄糖后肝组织基因表达的差异。方法：链脲霉素（STZ）诱导C57雄性小鼠1型糖尿病模型为实验组（n=8）,正常C57雄性小鼠为对照组（n=8）。每组随机取2只,按50ml／kg给予4％葡萄糖生理盐水溶液灌胃,2h取肝组织检测基因表达谱（Mouse Genome 430 2．0Array）。每组另6只．同样剂量给予含14C标记葡萄糖。结果：糖尿病小鼠口服14C标记葡萄糖2h后,肝组织同位素水平是正常对照组的4倍。以正常对照组为参比,共有舛条基因的表达变化差异在2倍以上,其中上调基因61个,下调基因33个。根据功能基因组分析,11条差异表达基因与脂代谢、胆固醇代谢相关,其中7条上调基因与脂、胆固醇合成相关,1条下调基因与脂肪酸分解相关。结论：SIZ诱导的1型糖尿病小鼠口服葡糖后2h,肝脏脂、胆固醇合成相关基因表达增高。     

Electron paramagnetic resonance studies and effects of vanadium in Saccharomyces cerevisiae

Vanadium uptake by whole cells and isolated cell walls of the yeast Saccharomyces cerevisiae was studied. When orthovanadate was added to wild-type S. cerevisiae cells growing in rich medium, growth was inhibited as a function of the VO₄ ^3- concentration and the growth was completely arrested at a concentration of 20 mM of VO₄ ^3- in YEPD. Electron paramagnetic resonance (EPR) spectroscopy was used to obtain structural and dynamic information about the cell-associated paramagnetic vanadyl ion. The presence of EPR signals indicated that vanadate was reduced by whole cells to the vanadyl ion. On the contrary, no EPR signals were detected after interaction of vanadate with isolated cell walls. A mobile and an immobile species associated in cells with small chelates and with macromolecular sites, respectively, were identified. The value of rotational correlation time _r indicated the relative motional freedom at the macromolecular site. A strongly immobilized vanadyl species bound to polar sites mainly through coulombic attractions was detected after interaction of VO²⁺ ions with isolated cell walls.     

The effect of Smallanthus sonchifolius leaf extracts on rat hepatic metabolism

Smallanthus sonchifolius (yacon), originating from South America, has become popular in Japan and in New Zealand for its tubers which contain beta-1,2-oligofructans as the main saccharides. The plant is also successfully cultivated in Central Europe in the Czech Republic in particular. Its aerial part is used in Japan and in Brazil as a component in medicinal teas; while aqueous leaf extracts have been studied for their hypoglycemic activity in normal and diabetic rats. We have already demonstrated the high content of phenolic compounds in yacon leaf extracts and their in vitro antioxidant activity. In this paper, we present the effects of two organic fractions and two aqueous extracts from the leaves of S. sonchifolius on rat hepatocyte viability, on oxidative damage induced by tert-butyl hydroperoxide (t-BH) and allyl alcohol (AA), and on glucose metabolism and their insulin-like effect on the expression of cytochrome P450 (CYP) mRNA. All the extracts tested exhibited strong protective effect against oxidative damage to rat hepatocyte primary cultures in concentrations ranging from 1 to 1000 microg/ml, reduced hepatic glucose production via gluconeogenesis and glycogenolysis at 1000 microg/ml. Moreover, the effects of the organic fractions (200 and 250 microg/ml) and to a lesser extent, the tea infusion (500 microg/ml) on rat CYP2B and CYP2E mRNA expression, were comparable to those observed with insulin. The combination of radical scavenging, cytoprotective and anti-hyperglycemic activity predetermine S. sonchifolius leaves for use in prevention and treatment of chronic diseases involving oxidative stress, particularly diabetes.