Xanthine oxidase inhibitors from Archidendron clypearia(Jack.) I.C. Nielsen: Results from systematic screening of Vietnamese medicinal plants

Objective: To screen Vietnamese medicinal plants for xanthine oxidase(XO) inhibitory activity and to isolate XO inhibitor(s) from the most active plant. Methods: The plants materials were extracted by methanol. The active plant materials were fractionated using different organic solvents, including n-hexane, ethyl acetate, and n-butanol. Bioassay-guided fractionation and column chromatography were used to isolate compounds. The compounds structures were elucidated by analysis of spectroscopic data, including IR, MS, and NMR. Results: Three hundreds and eleven methanol extracts(CME) belonging to 301 Vietnamese herbs were screened for XO inhibitory activity. Among these plants, 57 extracts displayed XO inhibitory activity at 100 μg/m L with inhibition rates of over 50%. The extracts of Archidendron clypearia, Smilax poilanei, Linociera ramiflora and Passiflora foetida exhibited the greatest potency with IC_(50) values below 30 μg/m L. Chemical study performed on the extract of Archidendron clypearia resulted in the isolation of six compounds, including 1-octacosanol, docosenoic acid, daucosterol, methyl gallate, quercitrin and(-)-7-O-galloyltricetiflavan. The compound(-)-7-O-galloyltricetiflavan showed the most potent XO inhibitory activity with an IC_(50) value of 25.5 μmol/L. Conclusions: From this investigation, four Vietnamese medicinal plants were identified to have XO inhibitory effects with IC_(50) values of the methanol extracts below 30 μg/m L. Compound(-)-7-O-galloyltricetiflavan was identified as an XO inhibitor from Archidendron clypearia with IC_(50) value of 25.5 μmol/L.

Identifi cation of egg protein-derived peptides as xanthine oxidase inhibitors:virtual hydrolysis,molecular docking,and in vitro activity evaluation

The purpose of this study was to screen the xanthine oxidase(XO)inhibitory peptides from egg white proteins through virtual hydrolysis,in vitro activity validation,and molecular docking.The results demonstrated that tripeptide EEK from ovalbumin exhibited potent XO inhibitory activity with an IC50 value of 141μmol/L.The molecular docking results showed that tripeptide EEK bound with the active center of XO via 3 carbon hydrogen bond interactions,2 salt bridges,5 conventional hydrogen bond interactions,and 4 attractive charge interactions.The residues Glu802,Phe1009,and Arg880 may play key roles in the XO catalytic reaction.Especially,the key intermolecular forces of inhibiting XO activity may be special type of hydrogen bonds including carbon hydrogen bond interactions and attraction charge interactions.The novel tripeptide EEK is potential candidates for controlling hyperuricemia.

Determination of inhibitory activity of Salvia miltiorrhiza extracts on xanthine oxidase with a paper-based analytical device

A novel paper-based analytical device(PAD)was prepared and applied to determine the xanthine oxidase(XOD)inhibitory activity of Salvia miltiorrhiza extracts(SME).First,polycaprolactone was 3D printed on filter paper and heated to form hydrophobic barriers.Then the modified paper was cut according to the specific design.Necessary reagents including XOD for the colorimetric assay were immobilized on two separate pieces of paper.By simply adding phosphate buffer,the reaction was performed on the double-layer PAD.Quantitative results were obtained by analyzing the color intensity with the specialized device system(consisting of a smartphone,a detection box and sandwich plates).The 3Dprinted detection box was small,with a size of 9.0 cm×7.0 cm×11.5 cm.Color component G performed well in terms of linearity and detection limits and thus was identified as the index.The reaction conditions were optimized using a definitive screening design.Moreover,a 10%glycerol solution was found to be a suitable stabilizer.When the stabilizer was added,the activity of XOD could be maintained for at least 15 days under 4℃ or-20℃ storage conditions.The inhibitory activity of SME was investigated and compared to that of allopurinol.The results obtained with the PAD showed agreement with those obtained with the microplate method.In conclusion,the proposed PAD method is simple,accurate and has a potential for point-of-care testing.It also holds promise for use in rapid quality testing of medicinal herbs,intermediate products,and preparations of traditional Chinese medicines.

Effect of TongFengNing Decoction on Uric Acid Levels and Xanthine Oxidase Activity in Hyperuricemia Rats

Objective To observe the effect of TongFengNing Decoction （TD） on uric acid levels, xanthine oxidase （XOD） activity, and XOD mRNA expression of hyperuricemia （HUA） model rats. Methods： 90 rats were randomly divided into 6 groups （n=15）, and the HUA model in all groups except the blank group was established by administering hypoxanthine （HX） by gavage and injecting potassium oxonate （OAPS） intraperitoneally. Rats in all TD groups and allopurinol group were administered multiple doses of TD and a single dose of allopurinol by gavage twice daily for 21 days, while the blank group and the model group were administered normal saline. On the 7th, 14th, and 21st days of drug intervention, serum uric acid （SUA）, urine uric acid （UUA）, intestinal uric acid （IUA）, as well as XOD activity and mRNA expression in the liver and small intestine were measured in randomly selected 5 rats of each group. Results： On the 14th and 21st days of intervention, all TD dose groups and the allopurinol group showed decreased SUA and IUA levels, increased UUA levels, as well as decreased XOD activity and mRNA expression in the liver and small intestine, compared with the model group （P 〈 0.05）. The low- and high-dose TD group and the allopurinol group showed increased SUA and IUA levels, as well as XOD activity and mRNA expression in the liver and small intestine, and decreased UUA levels, compared with the moderate-dose TD group （P〈0.05）. Upon extending the drug intervention time of each TD dose group, SUA and IUA levels, XOD activity, and XOD mRNA expression in the liver and small intestine decreased and UUA levels increased （P 〈 0.05）. Conclusion： TD reduces SUA levels in HUA model rats, which promotes uric acid excretion and inhibits XOD activity and XOD mRNA expression to reduce uric acid production. The reduction in uric acid level by the intermediate dose of TD was better than that by allopurinol and the low and high doses of TD.

Inhibition of xanthine oxidase alleviated pancreatic necrosis via HIF-1α-regulated LDHA and NLRP3 signaling pathway in acute pancreatitis

Acute pancreatitis(AP)is a potentially fatal condition with no targeted treatment options.Although inhibiting xanthine oxidase(XO)in the treatment of AP has been studied in several experimental models and clinical trials,whether XO is a target of AP and what its the main mechanism of action is remains unclear.Here,we aimed to re-evaluate whether XO is a target aggravating AP other than merely generating reactive oxygen species that trigger AP.We first revealed that XO expression and enzyme activity were significantly elevated in the serum and pancreas of necrotizing AP models.We also found that allopurinol and febuxostat,as purine-like and non-purine XO inhibitors,respectively,exhibited protective effects against pancreatic acinar cell death in vitro and pancreatic damage in vivo at different doses and treatment time points.Moreover,we observed that conditional Xdh overexpression aggravated pancreatic necrosis and severity.Further mechanism analysis showed that XO inhibition restored the hypoxia-inducible factor 1-alpha(HIF-1α)-regulated lactate dehydrogenase A(LDHA)and NOD-like receptor family pyrin domain containing 3(NLRP3)signaling pathways and reduced the enrichment of^(13)C_(6)-glucose to^(13)C_(3)-lactate.Lastly,we observed that clinical circulatory XO activity was significantly elevated in severe cases and correlated with C-reactive protein levels,while pancreatic XO and urate were also increased in severe AP patients.These results together indicated that proper inhibition of XO might be a promising therapeutic strategy for alleviating pancreatic necrosis and preventing progression of severe AP by downregulating HIF-1α-mediated LDHA and NLRP3 signaling pathways.

Pueraria isoflavones inhibit XOD and GLUT9 to decrease uric acid production and promote uric acid excretion, respectively

Objective: To analyze the possible mechanism of Pueraria isoflavones inhibiting XOD and GLUT9 to reduce uric acid production and promote uric acid excretion. Methods: August 2021-April 2022, a total of forty SPF male Kunming mice were divided into the healthy group (carboxymethylcellulose sodium at a dose of 250 mg/kg), the model group (HUA mice were given carboxymethylcellulose sodium at a dose of 250 mg/kg), the low group (HUA mice were given pueraria isoflavone at a dose of 125 mg/kg), HUA mice were given pueraria isoflavones at a dose of 250 mg/kg once d frequency)and the high group (HUA mice were given pueraria isoflavones at a dose of 500 mg/kg once d frequency) dosage groups, with 8 mice in each group. The contents of uric acid (SUA), urea nitrogen (BUN) and creatinine (SCr) in serum and urine of each group were compared before and after intervention (30 d). Statistical differences of xanthine oxidase (XOD) and human glucose transporter 9(GLUT9), cy- clooxygenase- 2(COX-2), tumor necrosis factor (TNF-α) and interleukin-1 (IL-1β) contents in renal tissues of each group after intervention (30 d) were compared. Results: After intervention, kidney inflammatory factors (COX-2, TNF-α and IL-1β) in the model group were compared. Blood and urine indexes (SUA, BUN, SCr);The contents of XOD and GLUT9 were higher than those of healthy group(P<0.05). Renal inflammatory cytokines (COX-2, TNF-α and IL-1β) in low, medium and high dose groups;Blood and urine indexes (SUA, BUN, SCr);The contents of XOD and GLUT9 were lower than those of model group, and there were low > medium > high dose groups, the comparison between the two groups had statistical significance(P< 0.05). After intervention, the contents of 3 indicators in blood or urine(COX-2, TNF-α and IL-1β) all decreased compared with before intervention, and the differences in intra-group comparison were statistically significant (P<0.05). Conclusion: Pueraria isoflavones can treat HUA mice by inhibiting the expression of XOD and GLUT9, and then play a role in reducing uric acid pro- duction and promoting uric acid excretion, as well as alleviating the degree of disease inflammation.

Linking uric acid metabolism to diabetic complications

Hyperuricemia have been thought to be caused by the ingestion of large amounts of purines, and prevention or treatment of hyperuricemia has intended to prevent gout. Xanthine dehydrogenase/xanthine oxidase(XDH/XO) is rate-limiting enzyme of uric acid generation, and allopurinol was developed as a uric acid(UA) generation inhibitor in the 1950 s and has been routinely used for gout prevention since then. Serum UA levels are an important risk factor of disease progression for various diseases, including those related to lifestyle. Recently, other UA generation inhibitors such as febuxostat and topiroxostat were launched. The emergence of these novel medications has promoted new research in the field. Lifestyle-related diseases, such as metabolic syndrome or type 2 diabetes mellitus, often have a common pathological foundation. As such, hyperuricemia is often present among these patients. Many in vitro and animal studies have implicated inflammation and oxidative stress in UA metabolism and vascular injury because XDH/XO act as one of the major source of reactive oxygen species Many studies on UA levels and associated diseases implicate involvement of UA generation in disease onset and/or progression. Interventional studies for UA generation, not UA excretion revealed XDH/XO can be the therapeutic target forvascular injury and renal dysfunction. In this review, the relationship between UA metabolism and diabetic complications is highlighted.

Protection of PC12 Cells against Superoxide-induced Damage by Isoflavonoids from Astragalus mongholicus

Objective To further investigate the neuroprotective effects of five isoflavonoids from Astragalus mongholicus on xanthine （XA）/xanthine oxidase （XO）-induced injury to PC12 cells. Methods PC12 cells were damaged by XA/XO. The activities of antioxidant enzymes, MTT, LDH, and GSH assays were used to evaluate the protection of these five isofavonoids. Contents of Bcl-2 family proteins were determined with flow cytometry. Results Among the five isoflavonoids including formononetin, ononin, 9, 10-dimethoxypterocarpan-3-O-β-D-glucoside, calycosin and calycosin-7-O-glucoside, calycosin and calycosin-7-O-glucoside were found to inhibit XA/XO-induced injury to PC12 cells. Their ECs0values of formononetin and calycosin were 0.05 μg/mL. Moreover, treatment with these three isoflavonoids prevented a decrease in the activities of antioxidant enzymes, superoxide dismutase （SOD） and glutathione peroxidase （GSH-Px）, while formononetin and calycosin could prevent a significant deletion of GSH. In addition, only calycosin and calycosin-7-O-glucoside were shown to inhibit XO activity in cell-free system, with an approximate IC50 value of 10 μg/mL and 50 μg/mL. Formononetin and calycosin had no significant infuence on Bcl-2 or Bax protein contents. Conclusion Neuroprotection of formononetin, calycosin and calycosin-7-O-glucoside may be mediated by increasing endogenous antioxidants, rather by inhibiting XO activities or by scavenging free radicals.

Antihyperuricemic effect of mangiferin aglycon derivative J99745 by inhibiting xanthine oxidase activity and urate transporter 1 expression in mice

A mangiferin aglycon derivative J99745 has been identified as a potent xanthine oxidase(XOD) inhibitor by previous in vitro study. This study aimed to evaluate the hypouricemic effects of J99745 in experimental hyperuricemia mice, and explore the underlying mechanisms. Mice were orally administered 600 mg/kg xanthine once daily for 7 days and intraperitoneally injected 250 mg/kg oxonic acid on the 7 th day to induce hyperuricemia. Meanwhile, J99745(3, 10, and 30 mg/kg), allopurinol(20 mg/kg) or benzbromarone(20 mg/kg) were orally administered to mice for 7 days. On the 7 th day,uric acid and creatinine in serum and urine, blood urea nitrogen(BUN), malondialdehyde(MDA) content and XOD activities in serum and liver were determined. Morphological changes in kidney were observed using hematoxylin and eosin(H&E) staining. Hepatic XOD, renal urate transporter 1(URAT1), glucose transporter type 9(GLUT9), organic anion transporter 1(OAT1) and ATP-binding cassette transporter G2(ABCG2) were detected by Western blot and real time polymerase chain reaction(PCR). The results showed that J99745 at doses of 10 and 30 mg/kg significantly reduced serum urate, and enhanced fractional excretion of uric acid(FEUA). H&E staining confirmed that J99745 provided greater nephroprotective effects than allopurinol and benzbromarone. Moreover, serum and hepatic XOD activities and renal URAT1 expression declined in J99745-treated hyperuricemia mice. In consistence with the ability to inhibit XOD, J99745 lowered serum MDA content in hyperuricemia mice. Our resultssuggest that J99745 exerts urate-lowering effect by inhibiting XOD activity and URAT1 expression, thus representing a promising candidate as an anti-hyperuricemia agent.

Protective effects of apocynin and allopurinol on ischemia/reperfusion-induced liver injury in mice

AIM: To determine the effects of allopurinol, an inhibitor of xanthine oxidase, and apocynin, an inhibitor of NADPH oxidase, on oxidant stress and liver injury caused by hepatic ischemia/reperfusion (I/R) procedure in mice. METHODS: Mice were pretreated with a xanthine oxidase inhibitor, allopurinol, or NADPH oxidase (NOX) inhibitor, apocynin before the hepatic I/R procedure. Then treated or untreated mice underwent the hepatic I/R procedure. The effects on hepatic injury and superoxide anions were determined after starting reperfusion. RESULTS: A standard warm hepatic I/R procedure led to a marked increase in superoxide anion production as indicated by a superoxide anion tracer, MCLA. At the same time, the procedure caused profound acute liver injury, as indicated by elevated serum alanine aminotransferase and tumor necrosis factor-α levels, reduced liver glutathione levels and elevated malondialdehyde contents, as well as a high apoptotic cell count. All these changes were reversed by the use of apocynin or allopurinol prior to the hepatic I/R procedure. CONCLUSION: Allopurinol and apocynin exerted protective effects on hepatic ischemia/reperfusion injury. The protection is associated with blocking the generationof superoxide anions during the hepatic I/R procedure by inhibiting xanthine oxidase and NADPH oxidase activity.

Effects of acupuncture at Shu,Yuan,and Mu acupoints on blood se-rum uric acid and xanthine oxidase levels in a rat model of gout and hyperuricemia

OBJECTIVE: To investigate the effects of needling the Shu, Yuan, and Mu acupoints on serum uric acid(SUA), xanthine oxidase(XOD), and alkaline phosphatase(ALP) levels and the kidney index in a rat model of gout and hyperuricemia.METHODS: Fifty rats were randomly divided into five groups: blank, model, Shu-acupoint, Yuan-acupoint, and Mu-acupoint groups. A rat model of hyperuricemia was developed by intragastric administration of adenine and ethambutol. This experiment last for 90 d in total. Treatment groups underwent 3 courses of acupuncture. Each course involved a total of 10 interventions(one intervention every second day) with each intervention lasting15 min. There was a break for 10 d between courses. SUA and ALP were analyzed using an automatic biochemical analyzer and XOD was analyzed using immunofluorescence.RESULTS: Compared with the blank group, SUA and XOD levels in the model group were significantly higher and the renal index significantly improved. Compared with the model group, SUA and XOD levels in the three treatment groups decreased and the renal index significantly improved.When the three treatment groups were compared,the Mu-acupoint group showed the greatest decreases in SUA and XOD levels, followed by the Yuan-acupoint group. There was no significant difference in kidney index among the three treatment groups. There was no significant difference in ALP levels among the groups.CONCLUSION: The three treatments showed significantly reduced SUA and XOD levels compared with the control groups, possibly suggesting reduced renal damage.

Effect of methylmercury on LPO levels, SH groups and activities of GSH-Px, SOD, XOD in liver of rats

In recent years, lipid peroxidation has been considered as the initial step for foreign toxic substances to damage cells. In this paper, the effects of methylmercury (MeHg) on LPO (lipid peroxide) levels, SH (sulfhydryl) groups and activities of GSH\|Px (glutathione peroxidase), SOD (superoxide dismutase), XOD (xanthine oxidase) in liver of rats treated with doses of MeHg at different intervals were studied by TBA, Ellman Reagent, NBT colorimetric methods and chemilluminescence. Meanwhile, the contents of FR (free radical)and MeHg in the liver of female rats were measured by ESR and GC. Results showed that the LPO levels in the experimental group increased significantly over those of the control group ( p<0.05— p<0.001) , reaching maximum point on the first poisoning day. Both male and female rats showed marked positive dose\|effect relations (Male: Y=261.4±49.4X, r=0.94, p<0.02; Female : Y=255.0±73.0X, r=0.99, p<0.001 ). N-SH (nonprotein sulfhydryl), P\|SH (protein sulfhydryl), T-SH (total sulfhydryl) contents and GSH\|Px activities decreased significantly (p<0.05-p<0.001). For GSH\|Px, both groups reached minimum value on the first poisoning day. In female rats, activities of SOD and XOD increased markedly ( p<0.02-p<0.01 ) although the contents of FR showed no significant changes. The contents of MeHg was determined by GC, and it ranged from 0.0081—0.0191 ppm.

In vitro xanthine oxidase inhibitory properties of Flos Sophorae Immaturus and potential mechanisms

Flos Sophorae Immaturus (FSI) possessed potential xanthine oxidase (XO) inhibitory activity as a uric acid-lowing natural product.The present work identified and quantified the free and bound polyphenols of FSI by UPLC-QTOF-MS.Then determined the primary polyphenols with XO inhibitory effect and clarified their potential mechanisms by omission experiment,interaction assay,inhibition type,and fluorescence measurements.The results revealed that nine polyphenols were detected in the free polyphenol extract and ten polyphenols were detected in the bound polyphenol extract.Meanwhile,seven polyphenols were identified as XO inhibitors,including quercetin,kaempferol,isorhamnetin,rutin,hyperoside,protocatechuic acid,and quercitrin with the IC50 values of 0.03,0.11,0.07,5.62,11.48,22.13,and 367.82 mg/mL,but their inhibition stability was lower than 24 h.Although the content of quercetin (18.87 mg/g) was not the highest,it played a crucial role to the XO inhibitory effect of FSI.Furthermore,kaempferol and isorhamnetin alone revealed the sub-additive effect with quercetin,while the combination of other polyphenols with quercetin generated the interference or antagonism effects.Quercetin,isorhamnetin,and kaempferol were mixed-type and competitive inhibitors,which significantly quenched the fluorescence intensity of XO.Moreover,the binding processes of quercetin-XO,kaempferol-XO,and isorhamnetin-XO were spontaneous and endothermic,and the hydrophobic interaction was the key driving force.In general,quercetin,kaempferol,and isorhamnetin in FSI can be used as potential XO inhibitors.

Febuxostat, a nonpurine selective inhibitor of xanthine oxidase： a promising medical therapy for chronic heart failure？

Heart failure is currently one of the most common and most cost-intensive of the chronic diseases The main cause of chronic heart failure （CHF） is the abnormalities of both cardiac contractile performance and myocardial energy metabolism. Elevated levels of reactive oxygen species （ROS） have been proposed to contribute to both of them. Xanthine oxidoreductase （XO） is a major source of ROS in the cardiovascular system. XO inhibitors （XOIs） have been the cornerstone of the clinical management of gout and conditions associated with hyperuricemia for several decades.

Preparation of a Xanthine Sensor Based on the Immobilization of Xanthine Oxidase on a Chitosan Modified Electrode by Cross-linking

Here in this paper, xanthine oxidase （XOD） was immobilized onto the chitosan （CHT） modified electrode by a simple way of cross-linking with glutaraldehyde （GTD） and 3-aminopropyltriethoxysilane （KH）. The electrode displayed a sharp peak to the oxidation of xanthine at a potential about 0.67 V and the optimum of pH for determination was investigated. Under the optimum conditions, the biosensor fabricated on the KH/GTD/XOD/CHT modified electrode showed excellent response to the oxidation of xanthine within the range of 0.5 to 18 μmol/L with a low detection limit of 0.0215 μmol/L, a good stability and a high selectivity. The sensor can also be used for the determination of hypoxantbine. The electrochemical results indicated that the immobilized enzyme still retained its biological activity and this provided a new way for the construction of biosensors and determination of xanthine.

The inhibitory effect of lotus leaf extract on hyperuricemia and its potential mechanism

Objective:Lotus leaf is a traditional Chinese herb that has been used successfully for centuries for relieving edema by inducing diuresis.Based on its good clinical evidence and anti-hypertensive effectiveness,this study aimed to investigate the potential mechanism of the hyperuricemic inhibitory effects of lotus leaf crude extract(LL)and lotus leaf total alkaloids fraction(LA).Methods:The xanthine oxidase(XOD)inhibitory effect of LL and LA was analyzed in vitro by determining mRNA expression and protein expression levels of hepatic XOD.The hyperuricemic inhibitory effect of the lotus leaf was analyzed in vivo in a potassium oxonate(PO)-induced rat model by determining mRNA expression for renal urate transporters.Results:At a concentration of 40mg/mL,LL and LA suppressed XOD enzymatic activity by 37.35%±9.50%and 47.73%±8.32%,respectively.Both LL and LA administration significantly reduced the concentration of uric acid in the serum and liver of PO-induced hyperuricemic rats.Both LL and LA administration could inhibit XOD mRNA and protein expression,activate renal organic anion transporter 1/3 mRNA expression,and inhibit renal urate reabsorption by decreasing renal GLUT9 and renal urate transporter 1.Conclusions:Insight was gained into the mechanism behind the hyperuricemic inhibitory effects of LL and LA.Our results suggest that they act on two targets:decreasing the production of uric acid by inhibiting mRNA and protein expression of XOD in the liver,and regulating the mRNA expression of renal urate transporters in the kidneys.

Delphinidin-3-O-sambubioside: a novel xanthine oxidase inhibitor identified from natural anthocyanins

Objectives:This study was conducted to investigate the xanthine oxidase(XO)inhibitory activities of 18 monomeric anthocyanins from berry fruits and roselle,and to illustrate the underlying mechanism of the most active anthocyanin delphinidin-3-O-sambubioside.Materials and Methods:Eighteen monomeric anthocyanins were prepared and purified in our laboratory.The inhibitory properties of anthocyanins were investigated by in vitro inhibitory activity studies and fluorescence quenching studies;the inhibitory mechanism was explored through kinetic studies,fluorescence quenching studies,circular dichroism analysis and computational docking simulations.Results:XO inhibitory activities of anthocyanins were related to the structures of B rings and glycosides.Among all the tested anthocyanins,delphinidin-3-O-sambubioside showed the most potent inhibitory activity with an IC_(50) of 17.1μmol/L,which was comparable to the positive control allopurinol.Spectroscopic results revealed that delphinidin-3-O-sambubioside could spontaneously interact with XO and induce conformational changes.Computational docking study indicated that delphinidin-3-O-sambubioside could bind to XO with a proper orientation,stably formed π-π interactions and hydrogen bonds with key residues,thus preventing the substrate from entering the active pocket.Conclusions:In brief,our study identified delphinidin-3-O-sambubioside as a potent XO inhibitor from natural anthocyanins,which is potentially applicable for prevention and treatment of hyperuricemia.

Anti-epileptic effect of morin against experimental pentylenetetrazol-induced seizures via modulating brain monoamines and oxidative stress

Objective: To evaluate the protective effect of morin against pentylenetetrazol(PTZ)-induced tonic-clonic convulsions in mice. Methods: Swiss albino mice(18-22 g) was used to induce convulsions by intraperitoneal(i.p.) administration of PTZ(90 mg/kg). Mice were either pretreated with morin(10, 20 and 40 mg/kg) or vehicle(distilled water, 10 mg/kg) 45 min before PTZ administration. Various behavioral and biochemical parameters were assessed. Results: PTZ administration resulted in significant production(P<0.001) of tonic-clonic conclusion and mortality in mice. PTZ-induced increase in the duration of convulsion, onset of convulsion and mortality was inhibited significantly by morin(20 and 40 mg/kg) administration. The PTZinduced decrease in brain GABA, dopamine and Na+K+ATPase levels and increase in xanthine oxidase activity were inhibited significantly by morin(20 and 40 mg/kg) treatment. The increased levels of malondialdehyde and nitric oxide level were significantly decreased by morin(20 and 40 mg/kg) treatment. Also, reduced levels of superoxide dismutase and glutathione were increased significantly by morin treatment. Conclusions: Results of the present study indicate that morin showed its anti-convulsant effect via modulating the levels of brain GABA, Na^+K^+ATPase, and oxido-nitrosative stress. Thus, morin can be a potential candidate for further clinical evaluations as an anti-epileptic agent.

A sensitive xanthine oxidase electrode with silk net for estimating fish freshness

An enzyme biosensor was constructed using a plate platinum electrode and immobilized xanthine oxidase (XOD). Only a very small quantity of enzyme was chemically immobilized on a special silk net. Hydrogen peroxide released during the enzymatic reaction was detected by the electrode at +0.65 V (vs. Ag/AgCl). The electrode was very sensitive to hypoxanthine and its detection limit was 1X10(-7) mol/L. When it was applied to the determination of fish freshness, the results agreed well with those obtained by traditional methods-determination of total volatile basic nitrogen (TVB-N) and microbial count. A range for estimating the freshness of river fish was suggested.

The Effect of Traditional Chinese Medicine on Serum AMS,LPS and XOD of Piglets with Spleen Deficiency

[Objective] The experiment aimed to determine the effect of Guchangcuzhangsan on serum amylase, lipase and xanthine oxidase of piglets with spleen deficiency. [ Method] The model of piglets with spleen deficiency was produced by the methods of injecting reserpine into piglets, and alternating between no feed and good feed. The determinations of serum amylase, lipase and xanthine oxidase of piglets with spleen deficiency were done before injecting reserpine, on the day when reserpine was injected last time, the next day of finishing giving powder, the eighth day after finishing giving powder. [ Result] After the experiment was finished, all 3 enzymes activities of Guchangcuzhangsan group had no significant differ- ence from that of normal contrast group, enzyme activities of spleen deficiency group and smecta group had significant difference compared with that of normal contrast group. [ Conclusion] Guchangcuzhangsan can promote the recovery of serum amylase, lipase and xanthine oxidase of piglets with spleen deficiency which was caused by reserpine.