In vitro antimalarial and xanthine oxidase inhibition of 2-Aminoanthraquinone

In the present research study 2-Aminoanthraquinone were scrutinized for their antimalarial and Xanthine oxidase inhibitor potential. It demonstrated marked concentration dependent antimalarial activity with maximum effect of 89.06% and with IC[50] of 34.17 micro M. Regarding Xanthine oxidase inhibitor activity, it evoked significant effect with 57.45% activity with IC[50] value of 81.57.19 micro M. In conclusion, 2-Aminoanthraquinone showed potent antimalarial and xanthine oxidase inhibitory activity

Effect of Trimetaphosphate and Fluoride Association on Hydroxyapatite Dissolution and Precipitation In Vitro

The present study analyzed the action of sodium trimetaphosphate (TMP) and/or fluoride on hydroxyapatite. Hydroxyapatite powder was suspended in different solutions: deionized water, 500 µg F/mL, 1,100 µg F/mL, 1%TMP, 3%TMP, 500 µg F/mL plus 1%TMP and 500 µg F/mL plus 3%TMP. The pH value of the solutions was reduced to 4.0 and after 30 min, raised to 7.0 (three times). After pH-cycling, the samples were analyzed by X-ray diffraction and infrared spectroscopy. The concentrations of calcium fluoride, fluoride, calcium and phosphorus were also determined. Adding 1% or 3% TMP to the solution containing 500 µg F/mL produced a higher quantity of calcium fluoride compared to samples prepared in a 1,100 µg F/mL solution. Regarding the calcium concentration, samples prepared in solutions of 1,100 µg F/mL and 500 µg F/mL plus TMP were statistically similar and showed higher values. Using solutions of 1,100 µg F/mL and 500 µg F/mL plus TMP resulted in a calcium/phosphorus ratio close to that of hydroxyapatite. It is concluded that the association of TMP and fluoride favored the precipitation of a more stable hydroxyapatite.

O presente estudo avaliou a ação do trimetafosfato de sódio (TMP) e/ou fluoreto sobre a hidroxiapatita. Pó de hidroxiapatita foi suspenso em diferentes soluções: água deionizada, 500 µg F/mL, 1100 µg F/mL, 1%TMP, 3%TMP, 500 µg F/mL adicionado a 1%TMP e 500 µg F/mL associado a 3%TMP. O pH das soluções foi reduzido para 4,0 e depois de 30 min, elevado para 7,0 (três vezes). Depois do processo de ciclagem de pH, as amostras foram analisadas por difração de raios-X e espectroscopia por infravermelho. As concentrações de fluoreto de cálcio, fluoreto, cálcio e fósforo também foram determinadas. A adição de 1% ou 3% TMP na solução contendo 500 µg F/mL produziu uma maior quantidade de fluoreto de cálcio comparado às amostras tratadas com uma solução de 1100 µg F/mL. A respeito da concentração de cálcio, amostras tratadas com soluções de 1100 µg F/mL e 500 µg F/mL adicionado ao TMP foram estatisticamente similares e mostraram maiores valores. Soluções de 1100 µg F/mL e 500 µg F/mL adicionado ao TMP resultaram em uma proporção molar Ca/P mais próxima à da hidroxiapatita. Conclui-se que a associação de TMP e F favoreceu a precipitação de uma hidroxiapatita mais estável.

Detección temprana de cáncer de mama y cervicouterino en localidades con concentración de población indígena en Morelos / Early detection of breast and cervical cancer among indigenous communities in Morelos, Mexico

Objetivo. Analizar la percepción de mujeres y proveedores de salud sobre cuándo y cómo realizar acciones para la detección temprana del cáncer de mama y cervicouterino en localidades de Morelos con presencia de población indígena. Material y métodos. Se entrevistó a 10 proveedores de salud y 58 usuarias en unidades médicas del primer nivel de atención de cinco localidades; luego se analizó la información con base en el paradigma de la teoría fundamentada. Resultados. El personal de salud está deficientemente familiarizado con los lineamientos oficiales para la detección de cáncer cervicouterino y de mama. Pocos practican sus labores bajo una perspectiva de sensibilización intercultural. Las usuarias tienen nociones imprecisas o equivocadas de las acciones de detección. Conclusiones. La necesidad de capacitación con apego a las normas es evidente. Urge asumir un abordaje con pertinencia cultural que permita la comunicación eficiente y alfabetización en salud para la detección oportuna de estos dos cánceres.

Objective. To analyze the perception in relation to when and how to perform actions for the early detection of breast and cervical cancer among women and health care providers in communities with a high percentage of indigenous population in Morelos, Mexico. Materials and methods. Ten health providers and 58 women users of health services were interviewed which have a first level of attention in five communities. The analysis was developed under the approach of the Grounded Theory. Results. Providers are poorly informed about current regulations and specific clinical indications for the detection of cervical and breast cancer. Few propitiate health literacy under intercultural sensitization. The users have imprecise or wrong notions of the early detection. Conclusions. The need for training in adherence to norms is evident. It is urgent to assume a culturally relevant approach to enable efficient communication and promote health literacy for early detection of these two cancers.

Allopurinol as a preventive contrivance after acute ischemic stroke in patients with a high level of serum uric acid: a randomized, controlled trial

To assess the clinical relevance [functional outcome] of a 3-month allopurinol regimen in patients with high serum uric acid [SUA] levels and acute ischemic stroke without considering the changes in SUA levels. In a randomized, double-blind, controlled study, 70 patients [45 females, 25 males] with acute ischemic stroke who had elevated levels of SUA were included. They were divided in two 35-patient groups to investigate the effect of 3 months of an allopurinol [200 mg/day] regimen versus placebo on their functional outcome, which was evaluated using a modified Rankin scale. The overall mean age was 68.9 +/- 11.33 years [range 27-89]. The final favorable functional status [mRS = 0-2] was 23 [65.7%] and 14 [40.0%] in the treated and placebo groups, respectively, which was strongly associated with allopurinol consumption [OR = 4.646, p = 0.014] and age

In vitro xanthine oxidase inhibitory and in vivo hypouricemic activity of herbal coded formulation [Gouticin]

Currently, natural products have been used in treating gouty arthritis and are recognized as xanthine oxidase inhibitors. Current study was designed to evaluate in vitro xanthine oxidase inhibitory potential of Gouticin and its ingredients extracts and in vivo hypouricemic activity of gouticin tablet 500 mg twice daily. Ethanol extracts of Gouticin and its ingredients were evaluated in vitro, at 200, 100, 50, 25 microg/ml concentrations for xanthine oxidase inhibitory activity. IC[50] values of Gouticin and its ingredients were estimated. Further, in vivo therapeutic effect of Gouticin was investigated in comparison with allopathic medicine [Allopurinol] to treat gout. Total patients were 200 that were divided into test and control group. Herbal coded medicine [Gouticin] was given to test group and allopathic medicine allopurinol was administered to control group. In vitro, Gouticin has the highest percent inhibition at 96% followed by Allopurinol with 93% inhibition. In vivo study, mean serum uric acid level of patients was 4.62 mg/dl and 5.21mg/dl by use of Gouticin and Allopurinol at end of therapy. The study showed that herbal coded formulation gouticin and its ingredients are potential sources of natural xanthine oxidase inhibitors. Gouticin 500 mg twice daily is more effective than the allopurinol 300mg once daily in the management of gout.

El tratamiento con atorvastatina reduce la actividad de xantina-oxidasa unida al endotelio en pacientes con insuficiencia cardíaca crónica: ¿un posible nuevo efecto pleiotrópico? / Treatment with atorvastatin reduces the activity of xanthine oxydase bound to endothelium in patients with chronic heart failure

El aumento en la actividad de la xantina-oxidasa unida al endotelio (XOec) puedeparticipar como un importante mediador de la disfunción endotelial en la insuficiencia cardíaca crónica (IC). Las estatinas son capaces de reducir el estrés oxidativo y restaurar la disfunción endotelial a través de mecanismos independientes de la reducción del colesterol. Sin embargo, el efecto de estos fármacos en la actividad de XOec es completamente desconocido. Nosotros estudiamos la hipótesis que atorvastatina durante 8 semanas reduce la actividad de XOec de manera independiente de los cambios en el colesterol. Metodología: Un total de 25 pacientes con IC (Fracción de eyección < 40 por ciento y Clase funcional NYHA II-III) recibieron placebo por 4 semanas, seguido por 8 semanas de atorvastatina 20 mg por día. Muestras desangre fueron recolectadas basalmente, 4 semanas y 12 semanas. La actividad de XOec y los niveles de ácido úrico fueron medidos por espectrofotometría.Resultados: El tratamiento con atorvastatina, pero no el placebo, redujo la actividad de ecXO (p<0.01), los niveles de ácido úrico (p<0.05), colesterol total (p<0.01), LDL-colesterol (p<0.01) y triglicéridos (p<0.05) sin cambios en los niveles de HDL-colesterol y creatinina. Además, no se encontraron correlaciones estadísticas entre la fracción de cambio de XOec y las fracciones de cambio de parámetros lipídicos. Conclusión: El efecto beneficioso a corto plazo de la atorvastatina en relación a la mejoría de la función endotelial demostrado en estudios previos, estaría asociado a una disminución en la actividad de XOec de una manera independiente a los cambios en el colesterol, lo que sugiere la presencia de un nuevo efecto pleiotrópico de las estatinas.

An increased activity of endothelium bound xanthine oxydase (XOeb) may play an important role as a mediator of endothelial dysfunction in chronic heart failure (CHF). Statins reduce oxydative stress and improve endothelial dysfunction through mechanisms unrelated to cholesterol lowering. However, the effect of statins on XOeb activity is unknown. We hypothesized that atorvastatin administered for 6 weeks would reduce XOeb independently of changes in serum cholesterol levels. Methods: 25 patients with CHF (NYHA class II or III with ejection fraction <40 percent received placebo for 4 weeks followed by atorvastatin, 20mg per day, for 8 weeks. Blood samples were obtained before statin administration and 4 and 12 weeks later. Spectrophotometry was used to determine XOeb and uric aced levels. Results: Atorvastatin, but not placebo, reduced XOeb activity (p<0.01), and uric acid (p<0.05), total cholesterol (p<0.01), LDL-cholesterol (p<0.01) and triglyceride levels (p<0.05). No changes were observed inHDL and creatinine levels. There was no correlation between XOeb changes and changes in the other lipid parameters. Conclusion: The known improvement in endothelial dysfuncion related to statin use previously reported is associated to a decrease in XOec activity independently of changes in cholesterol levels, suggesting a new pleiotropic effect of statins.

[In vitro evaluation of xanthine oxidase inhibitory activity of aqueous extracts of six medicinal plants]

Overproduction of uric acid by xanthine oxidase [XO] causes gout. XO inhibitors such as allopurinol, are the most important available anti-gout drugs. Medicinal plants are available natural sources that may be useful for the treatment of gout. In this study, the XO inhibitory activity of aqueous extracts of Phaseolus vulgaris, Cinnamomum zeylanicum, Mentha longifolia, Cichorium intybus, Capparis spinosa and Trigonella foenum-graecum that their anti-gout effects have been reported in the literature, were measured. In these experiments, under controlled conditions xanthine turns into uric acid by XO. Uric acid absorbance was measured at 295 nm using a UV spectrophotometer. Adding allopurinol [as positive control] or aqueous extracts to the solution containing XO, can decrease uric acid production by inhibition of this enzyme. At first, XO inhibitory activity of allopurinol and reproducibility of the method were evaluated by conducting three experiments. After that, the XO inhibitory activity of aqueous extracts at 0.1, 0.5, 1, 1.5, 2 and 3 mg/ml were measured. The results showed an EC50= 0.38micro gram/ml for allopurinol. The obtained data showed that Mentha longifolia in compare with its control could inhibit enzyme up to 72% [p< 0.001] at 3 mg/ml. Maximum XO inhibitory activity of Phaseolus vulgaris at 3 mg/ml in compare with its control was 27% [p< 0.001]. Other extracts did not have any significant effect on XO. The results showed that part of the anti-gout effects of Mentha longifolia and Phaseolus vulgaris is due to XO inhibition

Effects of allopurinol on the left ventricular ejection fraction in patients with left ventricular failure

Efficacy of xanthine oxidase inhibitors on the improvement of cardiac performance is not clearly defined. This study was designed to study the efficacy of allopurinol on the improvement of left ventricular ejection fraction [LVEF] in patients with chronic heart failure. A randomized, double blind, placebo controlled clinical trial was performed on two groups of patients suffered from class II to III heart failure of New York Heart Association classification. 16 cases were in intervention group who intake allopurinol [100 mg/day in the first three days, 200 mg/day in the second three days and 300 mg/day for one month]; 15 cases were in control group and intaked placebo like case group. Left ventricular ejection fraction was measured by echocardiography with Simpson's method and compared before and after the intervention. The mean of LVEF before and after intervention, in case group were 38.8 +/- 9.9 and 41.9 +/- 9.7 respectively [p0.05]. In intervention group EF was increased 3.1% from base level. Allopurinol can be effective in improvement of cardiac performance. However its clinical use for heart failure patients needs to be approved by more trials, in various situations and longer periods

The role of allopurinol in experimental acute necrotizing pancreatitis.

BACKGROUND & OBJECTIVES: Acute pancreatitis (AP) in its severe form can lead to severe complications and death. Translocation of bacteria from the gut is one of the most important factors in the development of septic complications and mortality in acute pancreatitis. Oxygen-derived free radicals have been suggested to play a major role in the pathogenesis of AP. Xanthine oxidase enzyme is an important source of reactive oxygen metabolites. We undertook this study to evaluate the effect of allopurinol on bacterial translocation, oxidative stress and the course of AP in a rat model. METHODS: Male Sprague-Dawley rats (n=48) were randomly allocated into three equal groups. Acute pancreatitis (AP) was induced in group II (AP+Saline), and group III (AP+allopurinol) by retrograde infusion of taurocholate into the common biliopancreatic duct. Group I rats (Sham) received normal saline infusion into the common biliopancreatic duct for mimicking pressure effect. Group III rats were treated with allopurinol intraperitoneally for 48 h after induction of pancreatitis. Blood samples were drawn from all animals for biochemical analyses and pancreatic tissues were examined for bacterial translocation. RESULTS: Acute pancreatitis was developed in all groups, but not in group I (Sham), as indicated by microscopic parenchymal necrosis, fat necrosis and abundant turbid peritoneal fluid. Pathologic score of the pancreatitis in the allopurinol group (14.0 +/- 0.5) was lower when compared with group II (19.2 +/- 0.6) (P<0.001). Bacterial translocation to pancreas in group treated with allopurinol was significantly lower when compared with control group (p<0.02). Plasma glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) levels were higher and malondialdehyde (MDA) levels were lower in allopurinol group when compared with those in control groups. INTERPRETATION & CONCLUSION: Our findings suggested that addition of allopurinol to the treatment protocol in the acute pancreatitis might improve the pathologic score, bacterial translocation and oxidative stress parameters. However, more studies need to be done to confirm these findings.

Bioassay screening of Amazonian plants

OBJECTIVE: The purpose of this study was to evaluate several biological activities of thirty plant extracts collected in the North West Amazon (Ecuador). Some of these plants are being used for their reputed medicinal properties by the natives of this region. METHODS: Five in vitro bioassays were used to screen the plant material. 1. The brine shrimp lethality examination (BSLT) in microplate is a general test that seems capable of detecting a broad spectrum of bioactivity present in crude plant extracts. 2. Free radical scavenging properties were studied in a colorimetric assay using 2,2-diphenyl-1-picrylhydrazyl (DPPH). 3. The beta-glucosidase inhibition test is thought to be a method for the evaluation of anti-AIDS, anti-diabetic or anti-obesity compounds. 4. The xanthine oxidase inhibition assay is used to identify potential anti-gout agents. 5. The antibacterial activity that is being used to isolate and identify antibiotic drugs. RESULTS: In the BSLT, we found that Piscidia carthagenensis demonstrated very good activity with a LC50: 21.81 micrograms/mL. It is considered that plant extracts with low LC50 values may contain metabolites with cytotoxic, antifungal, insecticidal or pesticide activities. In the antioxidant activity bioassay, several plant extracts were confirmed to have excellent free radical scavenging properties. Rhus juglandifolia and Clusia venusta leaves exhibited an ED50: 3.12 micrograms/mL and 3.61 micrograms/mL, respectively. Piper reticulatum (84 per cent), Inga heteroptera (77 per cent), Clusia venusta (70.9 per cent), and Rhus juglandifolia (70.5 per cent) showed fairly good inhibition activity for beta-glucosidase. On the other hand, none of the plant extracts was capable of inhibiting xanthine oxidase. Finally, the Gram-positive microorganisms Staphylococcus aureus and Corynebacterium diphteriae were found to be sensitive to the majority of the plant extracts, whereas the Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, and Salmonella typhi were proved to be resistant toward the plant extracts. CONCLUSIONS: It is important to continue investigating our plant kingdom, especially the world tropical reserves as an alternative for finding new or better drugs. It should be essential to follow-up this type of investigation to isolate and elucidate the active principles of the bio-positive plants.

Post-irradiation free radical generation: evidence from the conversion of xanthine dehydrogenase into xanthine oxidase.

The xanthine oxidoreductase (XOR) system which consists of xanthine dehydrogenase (XDH) and xathine oxidase (XO), is one of the major sources of free radicals in biological systems. The XOR system is pre-dominantly present as XDH in normal tissues and converts into the free radical generating XO-form in the damaged tissue. Therefore, the XO-form of the XOR system is expected to be mainly found in radiolytically damaged tissues. In such an event, XO may catalyze the generation of free radicals and potentiate radiation effects in the post-irradiation period. Recent findings on the effect of ionizing radiation on the XOR system in the liver of mice, peroxidative damage and lactate dehydrogenase support this possibility. From these results it has been hypothesized that free radical generating systems could be activated in the radiolytically damaged cell and in turn contribute to the cause and complications of late effects and their persistence in post-irradiation period. This aspect may have great significance in the understanding of radiation-induced damages. It may also have serious implication in various fields like radiation therapy, health physics, carcinogenesis, space travelling radiation exposures and post nuclear accident care. Further, it is suggested that efforts need to be made to search more system(s) which could be activated particularly at lower doses of radiation to generate free radicals in the post-exposure period.

Taxa de mortalidade em ratos submetidos à isquemia e reperfusão hepática, tratados ou não com alopurinol / Mortality rates in rats submitted to hepatic ischemia-reperfusion, treated or not with allopurinol

A isquemia transitória hepática tem sido cada vez mais amplamente utilizada. Contudo, essa atitude, embora muitas vezes benéfica, é contrabalançada pelos efeitos adversos advindos da isquemia hepática e da congestão esplênica, assim como, das conseqüências da reperfusão. O objetivo dos autores é determinar os efeitos da isquemia seletiva em animais pré-tratados ou não com alopurinol, inibidor da xantina oxidase sobre a mortalidade dos animais. Foram utilizados 30 ratos assim divididos: Grupo I (n=10): pré-tratados com alopurinol e submetidos à laparotomia e exposição do pedículo hepático por 45 minutos. Grupo II (n=10): tratados com alopurinol e submetidos à isquemia hepática seletiva por 45 minutos. Grupo III (n=10): submetidos apenas à isquemia por 45 minutos. A mortalidade pós-operatória foi avaliada a cada 24 horas, por um período de 10 dias. Entre os animais do grupo I, não foram observados óbitos, entretanto, naqueles dos grupos II e III, as mortalidades globais foram respectivamente 20 e 46,7 por cento. Diferença estatisticamente significativa, apenas, entre a mortalidade observada no grupo III em relação ao controle (p<0,05). A mortalidade pós-operatória no grupo de animais submetidos à isquemia sem pré-tratamento com alopurinol ascende as cifras de 46,67 por cento dos animais, enquanto naqueles pré-tratados com alopurinol houve um importante decréscimo para 20 por cento. Embora sem uma distinção estatisticamente significativa, reflete uma tendência de um efeito protetor do alopurinol na isquemia e reperfusão hepática

The role of xanthine oxidase and the effects of antioxidants in ischemia reperfusion cell injury

During last years considerable interest has been devoted to understand the role of oxugen radicals in the inschemia induced cell injury associated with reperfusion. In the brain and in others tissues, free radicals play a role as modulators of vascular tone as well as a cytotoxic role as part of the ischemia associated pathology. This review discusses methods for free radical detection in brain and in other tissues, mechanisms of radical production in the course of the ischemia reperfusion process, and the efficacy of potential antioxidant agents in post ischemia therapy, especially with respect to allopurinol, an inhibitor of xanthine oxidase, and the role of taurine and its derivatives as antioxidants in different organs including the brain.

Inhibition of xanthine oxidase by Puerto Rican plant extracts

OBJECTIVES: This study was conducted to search for xanthine oxidase inhibitors in natural products obtained from plants collected in Puerto Rico and to assess the influence of these extracts in the prevention of cataractogenesis. BACKGROUND: Allopurinol is currently a xanthine oxidase inhibitor used in the treatment of gout. New alternatives with increased therapeutic activity and less side effects should be investigated. Preclusion of cataractogenesis in diabetic rats is also the focus of this investigation. Natural products in the form of plant extracts from Puerto Rico offer a rich and relatively untapped source for the discovery of new drugs that may address these kind of problems. METHODS: Nineteen collections of Myrtaceae plant extracts were screened for xanthine oxidase inhibition. A spectrophotometrical method was used employing allopurinol as positive control and a blank as negative control. A protocol of the assay with slight modifications was followed from the literature. Two extracts with the highest percentages of xanthine oxidase inhibition were evaluated for possible prevention of cataractogenesis in streptozotocin diabetic rats. The animals were given to drink these plant extracts ad libitum for three months while controls received water. The appearance of cataracts was assessed physically. RESULTS: Two of the nineteen plant extracts showed high inhibition percentages of xanthine oxidase. Eucalyptus deglupta and Syzygium malaccense displayed 51 per cent and 64 per cent inhibitions (IC50 44.5 micrograms/ml and IC50 51 micrograms/ml), respectively. As for the cataractogenesis inhibition, laboratory animals that drank E. deglupta for three months did not develop cataracts. CONCLUSIONS: Two plant extracts provided positive results with varying degrees of inhibition of xanthine oxidase. S. malaccense demonstrated the greatest xanthine oxidase inhibitory activity whereas E. deglupta presented the best finding for cataractogenesis prevention. The procedures used in this investigation are useful for the in vitro screening of xanthine oxidase inhibition and the in vivo evaluation of cataractogenesis prevention.

El efecto de un inhibidor de la xantinoxidasa asociado a la inhibición reversible de la monoaminoxidasa en el daño renal por isquemia reperfusión / The effect of a xanthine oxidase inhibitor associated to the reversible inhibition of monoamine oxidase in renal failure by ischemic-reperfusion

Diversas sustancias han mostrado efectividad en la protección del daño renal por isquemia-reperfusión. La inhibición de la xantínoxidasa (XO) por alopurinol (ALO) ha sido una de las más estudiadas. Previamente, mostramos el efecto protector de la Moclobemida (MOC), un inhibidor reversible de la monoaminoxidasa (MAO). El propósito del presente trabajo fue evaluar la asociación MOC + ALO sobre la función renal en un modelo de isquemia-reperfusión. Cincuenta ratas Sprague Dowley fueron sometidas a 60 minutos de clampeo de la arteria renal derecha y nefrectomía izquierda.El grupo I recibió MOC (100 mg/Kg) en cuatro dosis perioperatorias; el grupo II recibió ALO (50 mg/Kg) en una dosis previa al clampeo arterial y el grupo III recibió los dos esquemas (MOC + ALO). Los tres grupos tratados presentaron un descenso significativo de la creatinina plasmática en relación al control durante todo el período de insuficiencia renal (p < 0.001 para todos los días). Los grupos I y III presentaron una creatinina plasmática inferior al grupo II el primer día (grupo I: 1.64; grupo III: 1,51 v/s grupo II: 3,12; p < 0.001). Los grupos tratados con MOC presentaron una curva de insuficiencia renal más plana y una recuperación funcional más rápida. El grupo III mostró un leve efecto adivitivo. Se concluye que MOC es muy efectiva y superior a ALO en proteger la función renal. El efecto aditivo de la asociación MOC + ALO no es significativo en este modelo

Xantina oxidasa hepática: experiencias con inhibidores / Liver xanthine oxidase: experiences with inhibitors

Los grupos amino de la XOD (Xantina oxidasa) del hígado de rata son inhibidos por reactivos como el benzaldehído y el 2,4-dinitrofluorbenceno. Esta inhibición ocurre más rápidamente a elevados pH y es progresiva e irreveersible. Estos reactivos atacan grupos amino de la XOD, pero no se excluye que haya otros grupos que puedan ser bloqueados. Si se representa la inhibición en función de la unión con el benaldehído o 2,4-dinitrofluorbenceno, se observa que una fracción relativamente pequeña del total de grupos amino de la XOD es más reactiva a esta inhibició y que estos grupos amino se modifican por estos inhibidores. Los estudios de unión del benzaldehído sugieren dos clases de actividad enzimática, presentes en igual proporción, pero difieren en su sensibilidad frente al benzaldehído. Los parámetros cinéticos de la actividad residual de la XOD tratada con benzaldehído se asemejan a los de la enzima nativa, excepto el comprotamiento inhibitorio frente a altas concentraciones de sustrato

Amino acids: modifiers of xanthine oxidase activity.

L-Glutamic acid has been found to be a positive and L-lysine a negative modifier of the xanthine oxidase activity at the optimum pH (7.4) of the enzyme. Increase in pH was observed to be associated with a progressive decrease in the inhibition produced by L-lysine.