RESUMO
BACKGROUND: Deficiency of vitamin B12 (B12) and folate (FA) leads to a wide spectrum of disorders that affect all age groups. However, reports on B12 and FA status in healthy adults in India are limited. Hence, we determined the plasma levels and dietary intake of B12 and FA in the adult population. METHODS: We conducted a community-based cross-sectional study in an urban setup among 630 apparently healthy adults distributed into 3 age groups: 21-40, 41-60 and >60 years. Plasma concentrations of B12 and FA were analyzed by radio immunoassay and dietary intake by 24-hour recall method. RESULTS: The overall prevalence of FA deficiency was 12%, but there was no significant difference in plasma FA concentrations among the groups. While the overall prevalence of B12 deficiency was 35%, it was significantly higher in the 21-40 (44%) and 41-60 age groups (40%) when compared with the >60 group (30%). B12 deficiency was higher in vegetarians (54%) compared to those consuming mixed diet (31%), and the reverse was the case with FA. However, the dietary intakes of FA and B12 were not significantly different among the groups. CONCLUSIONS: These results indicate a higher prevalence of B12 deficiency in apparently healthy adults in an urban setup.
Assuntos
Ácido Fólico/metabolismo , Estado Nutricional , Vitamina B 12/metabolismo , Vitaminas/metabolismo , Adulto , Fatores Etários , Idoso , Antropometria , Estudos Transversais , Dieta , Dieta Vegetariana , Feminino , Deficiência de Ácido Fólico/epidemiologia , Humanos , Índia/epidemiologia , Masculino , Pessoa de Meia-Idade , Avaliação Nutricional , Prevalência , População Urbana , Deficiência de Vitamina B 12/epidemiologia , Adulto JovemRESUMO
BACKGROUND: Obesity is associated with various progressive age-related diseases, including neurological disorders. However, underlying molecular basis for increased risk of neurodegeneration in obesity is unknown. A suitable animal model would immensely help in understanding the obesity-linked neurological problems. METHODS: A spontaneously developed obese rat (WNIN/Ob) which is highly vulnerable for a variety of degenerative diseases was isolated from the existing WNIN stock rats. Ultrastructure of neurons in the cerebral cortex of 12-month old obese rats was evaluated by transmission electron microscopy. qRT-PCR and immunoblotting of ubiquitin C-terminal hydrolases (UCHs), ubiquitin, proteasomal sub-units, markers of ER stress and apoptosis were performed in the cerebral cortex. Proteasome activity was assayed by fluorometric method. Immunohistochemistry was performed for mediators of apoptosis, which was further confirmed by TUNEL assay. These investigations were also carried in high-fat diet-induced obese rat model. RESULTS: Neurons in the cerebral cortex of 12-month obese rats showed swollen mitochondria, disrupted ER and degenerating axons, nucleus and finally neurons. Results showed altered UPS, existence of ER stress, up-regulation of apoptotic markers and apoptosis in the cerebral cortex of obese rats. It appears that UCHL-1 mediated apoptosis through stabilizing p53 might play a role in neuronal cell death in obese rat. Similar changes were observed in the brain of diet-induced obese WNIN rats. CONCLUSION: Altered UPS could be one of the underlying mechanisms for the neuronal cell death in obese conditions. GENERAL SIGNIFICANCE: This is the first report to highlight the role of altered UPS in neurodegeneration due to obesity.
Assuntos
Apoptose , Córtex Cerebral/metabolismo , Estresse do Retículo Endoplasmático , Proteínas do Tecido Nervoso/metabolismo , Obesidade/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Ubiquitina/metabolismo , Animais , Córtex Cerebral/patologia , Gorduras na Dieta/efeitos adversos , Gorduras na Dieta/farmacologia , Modelos Animais de Doenças , Neurônios/metabolismo , Neurônios/patologia , Obesidade/induzido quimicamente , Obesidade/patologia , Ratos , Proteína Supressora de Tumor p53/metabolismo , Ubiquitina Tiolesterase/metabolismoRESUMO
Cataract, the leading cause of blindness worldwide, is associated with many risk factors including diabetes. Impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) states are associated with pre-diabetes and insulin resistance. This condition subsequently leads to the development of type-2 diabetes. Epidemiological studies indicated that not only diabetes but IGT/IFG will also lead to the development of microvascular disorders and cataract. However, there are no studies on the mechanism of insulin resistance induced changes in the eye lens. In the present study, IGT/IFG-induced changes in lens using neonatal-streptozotocin (nSTZ) rat model have been investigated. Though, nSTZ rats showed the signs of IGT and insulin resistance starting from two months old, they did not develop cataract even at the age of 8-months. However, biochemical analysis indicates a three-fold increase in sorbitol levels in nSTZ lens upon prolonged (6-months) IGT and insulin resistance. Also there was an increase in lipid peroxidation and alterations in antioxidant enzymes. Results of this study showed that activation of polyol pathway and increased oxidative stress, commonly associated with long-term complications of diabetes, have been observed in eye lens due to prolonged IGT and insulin resistance which may lead to cataract.
Assuntos
Diabetes Mellitus Experimental/metabolismo , Resistência à Insulina , Cristalino/metabolismo , Animais , Animais Recém-Nascidos , Antioxidantes/metabolismo , Glicemia/análise , Catarata/etiologia , Catarata/metabolismo , Catarata/patologia , Cristalinas/metabolismo , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Experimental/patologia , Jejum , Teste de Tolerância a Glucose , Cristalino/enzimologia , Cristalino/patologia , Masculino , Malondialdeído/metabolismo , Estresse Oxidativo , Ratos , Ratos Wistar , Estreptozocina/farmacologiaRESUMO
Accumulation of intracellular sorbitol due to increased aldose reductase (ALR2) activity has been implicated in the development of various secondary complications of diabetes. In this study we show that curcumin inhibits ALR2 with an IC(50) of 10 microM in a non-competitive manner, but is a poor inhibitor of closely-related members of the aldo-keto reductase superfamily, particularly aldehyde reductase. Results from molecular docking studies are consistent with the pattern of inhibition of ALR2 by curcumin and its specificity. Moreover, curcumin is able to suppress sorbitol accumulation in human erythrocytes under high glucose conditions, demonstrating an in vivo potential of curcumin to prevent sorbitol accumulation. These results suggest that curcumin holds promise as an agent to prevent or treat diabetic complications.
Assuntos
Aldeído Redutase/antagonistas & inibidores , Curcumina/farmacologia , Aldeído Redutase/genética , Aldeído Redutase/metabolismo , Aldo-Ceto Redutases , Animais , Antioxidantes/administração & dosagem , Antioxidantes/química , Antioxidantes/farmacologia , Bovinos , Curcumina/administração & dosagem , Curcumina/química , Suplementos Nutricionais , Relação Dose-Resposta a Droga , Eritrócitos/efeitos dos fármacos , Eritrócitos/metabolismo , Glucose/farmacologia , Humanos , Isoenzimas/antagonistas & inibidores , Isoenzimas/genética , Isoenzimas/metabolismo , Rim/enzimologia , Cinética , Estrutura Molecular , Sorbitol/metabolismoRESUMO
Activation of polyol pathway due to increased aldose reductase activity is one of the several mechanisms that have been implicated in the development of various secondary complications of diabetes. Though numerous synthetic aldose reductase inhibitors have been tested, these have not been very successful clinically. Therefore, a number of common plant/ natural products used in Indian culinary have been evaluated for their aldose reductase inhibitory potential in the present study. The aqueous extracts of 22 plant-derived materials were prepared and evaluated for the inhibitory property against rat lens and human recombinant aldose reductase. Specificity of these extracts towards aldose reductase was established by testing their ability to inhibit a closely related enzyme viz, aldehyde reductase. The ex vivo incubation of erythrocytes in high glucose containing medium was used to underscore the significance in terms of prevention of intracellular sorbitol accumulation. Among the 22 dietary sources tested, 10 showed considerable inhibitory potential against both rat lens and human recombinant aldose reductase. Prominent inhibitory property was found in spinach, cumin, fennel, lemon, basil and black pepper with an approximate IC50 of 0.2 mg/mL with an excellent selectivity towards aldose reductase. As against this, 10 to 20 times higher concentrations were required for 50% inhibition of aldehyde reductase. Reduction in the accumulation of intracellular sorbitol by the dietary extracts further substantiated their in vivo efficacy. The findings reported here indicate the scope of adapting life-style modifications in the form of inclusion of certain common sources in the diet for the management of diabetic complications.
Assuntos
Aldeído Redutase/antagonistas & inibidores , Complicações do Diabetes/prevenção & controle , Inibidores Enzimáticos/farmacologia , Fitoterapia , Extratos Vegetais/farmacologia , Aldeído Redutase/efeitos dos fármacos , Aldeído Redutase/metabolismo , Animais , Técnicas de Cultura de Células , Complicações do Diabetes/sangue , Complicações do Diabetes/enzimologia , Retinopatia Diabética/sangue , Retinopatia Diabética/enzimologia , Retinopatia Diabética/prevenção & controle , Inibidores Enzimáticos/uso terapêutico , Eritrócitos/enzimologia , Humanos , Cristalino/efeitos dos fármacos , Cristalino/enzimologia , Extratos Vegetais/uso terapêutico , Ratos , Sensibilidade e Especificidade , Sorbitol/metabolismoRESUMO
PURPOSE: Aldose reductase (AR) has been a drug target because of its involvement in the development of secondary complications of diabetes including cataract. We have previously reported that the aqueous extract of Emblica officinalis and its constituent tannoids inhibit AR in vitro and prevent hyperglycemia-induced lens opacification in organ culture. The purpose of the current study was to investigate the effect of Emblica and its enriched tannoids on streptozotocin (STZ)-induced diabetic cataract in rats. METHODS: Diabetes was induced in Wistar-NIN rats by STZ (35 mg/kg body weight, intraperitoneally) and the animals were divided into three groups (Group II, III, and IV). The control rats (Group I) received only vehicle. While Group I and Group II animals received AIN-93 diet, rats in Groups III and IV received 0.2% of standardized mixture of Emblica tannoids and 2% of Emblica pericarp, respectively, in an AIN-93 diet for a period of eight weeks. Cataract progression due to hyperglycemia was monitored by slit-lamp biomicroscope and classified into four stages. At the end of the eight weeks, the animals were sacrificed and markers of the polyol pathway, oxidative stress, and alterations in protein content and crystallin profile in the lens were measured. Blood glucose and insulin levels were also determined. RESULTS: Both Emblica and its tannoids did not prevent STZ-induced hyperglycemia as assessed by blood glucose and insulin levels. However, slit lamp microscope observations indicated that these supplements delayed cataract progression. The present studies suggest that Emblica and its tannoids supplementation inhibited AR activity as well as sorbitol formation in the lens. The results also point out that Emblica and its tannoids might counter the polyol pathway-induced oxidative stress as there was a reversal of changes with respect to lipid peroxidation, protein carbonyl content, and activities of antioxidant enzymes. Emblica also prevented aggregation and insolubilization of lens proteins caused by hyperglycemia. CONCLUSIONS: The results provide evidence that Emblica and an enriched fraction of Emblica tannoids are effective in delaying development of diabetic cataract in rats.
Assuntos
Catarata/prevenção & controle , Complicações do Diabetes/prevenção & controle , Diabetes Mellitus Experimental/prevenção & controle , Phyllanthus emblica/química , Taninos/farmacologia , Animais , Antioxidantes/metabolismo , Glicemia/análise , Peso Corporal/efeitos dos fármacos , Reagentes de Ligações Cruzadas/farmacologia , Cristalinas/metabolismo , Diabetes Mellitus Experimental/induzido quimicamente , Progressão da Doença , Comportamento Alimentar/efeitos dos fármacos , Insulina/sangue , Masculino , Estresse Oxidativo/efeitos dos fármacos , Polímeros/metabolismo , Ratos , Solubilidade/efeitos dos fármacos , EstreptozocinaRESUMO
Diabetic retinopathy is one of the most devastating microvascular complications of long standing type 1 and type 2 diabetes. Neovascularization stimulated by hyperglycemia-mediated induction of vascular endothelial growth factor (VEGF) has been implicated in the pathogenesis. Various small molecules have been investigated for their ability to inhibit angiogenesis. In this study, we evaluated whether curcumin and its dietary source turmeric can inhibit VEGF expression in strepotzotocin (STZ)-induced diabetic rat retina. Diabetes was induced in 3-month-old male WNIN rats by a single intraperitoneal injection of STZ. After induction, one group of diabetic rats were fed only the AIN-93 diet and the rest of the groups were fed with AIN-93 diet containing 0.002% or 0.01% curcumin or 0.5% turmeric for a period of 8 weeks. The control rats received sham injection and fed on the AIN-93 diet. At the end of 8 weeks animals were sacrificed and retina was dissected. The VEGF expression was analyzed by both real time PCR and immunoblotting. There was an increase in VEGF expression in diabetic retina as compared to control retina at both transcript and protein level. Notably, feeding of curcumin and turmeric to diabetic rats inhibited expression of VEGF. This study highlights the importance of biologically active compounds derived from dietary agents that could be explored further for the prevention and/or treatment of diabetic retinopathy.
Assuntos
Curcumina/farmacologia , Retinopatia Diabética/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Hiperglicemia/genética , Hiperglicemia/metabolismo , Retina/efeitos dos fármacos , Fator A de Crescimento do Endotélio Vascular/metabolismo , Animais , Retinopatia Diabética/induzido quimicamente , Hiperglicemia/patologia , Masculino , Ratos , Retina/metabolismo , Retina/patologia , EstreptozocinaRESUMO
Natural dietary ingredients are known for their antioxidant activity. Of such, curcumin, the active principle of turmeric, at 0.01% in the diet proved as pro-oxidative in galactose-induced cataract in vivo. The purpose of this study was to investigate the effect of vitamin E (VE), a well-known antioxidant, in combination with curcumin on the onset and maturation of galactose induced cataract. Periodic slit-lamp microscope examination indicated that in combination with vitamin-E, 0.01% curcumin (G-IV) delayed the onset and maturation of galactose-induced cataract. Biochemical analyses revealed that combined treatment of 0.01% curcumin and vitamin-E diet exhibited an efficient antioxidant effect, as it inhibited lipid peroxidation and contributed to a distinct rise in reduced glutathione content. The results indicate that natural dietary ingredients are effective in combination rather than the individual administration as they are complementing each other in reducing the risk of galactose induced cataract.
Assuntos
Antioxidantes/uso terapêutico , Catarata/prevenção & controle , Curcumina/uso terapêutico , Galactose , Vitamina E/uso terapêutico , Animais , Antioxidantes/administração & dosagem , Catarata/induzido quimicamente , Catarata/metabolismo , Catarata/patologia , Curcumina/administração & dosagem , Modelos Animais de Doenças , Sinergismo Farmacológico , Quimioterapia Combinada , Glutationa/metabolismo , Glutationa Redutase/metabolismo , Cristalino/efeitos dos fármacos , Cristalino/metabolismo , Cristalino/patologia , Peróxidos Lipídicos/metabolismo , Masculino , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismo , Vitamina E/administração & dosagemRESUMO
alpha-Crystallin, a predominant protein of the ocular lens, is composed of two subunits, alphaA and alphaB. Of these, alphaB-crystallin has been shown to present widely in non-lenticular tissues while alphaA-crystallin is largely lens-specific. Although, expression of alphaB-crystallin is elevated under various stress and pathological conditions, yet its physiological significance remained unknown. Some studies suggest that the expression of alphaB-crystallin gene is related to oxidative stress. Persistent hyperglycemia during uncontrolled diabetes is known to cause oxidative stress, which has been implicated in various secondary complications of diabetes. Hence, expression of alphaA- and alphaB-crystallins in various tissues of streptozotocin (STZ)-induced diabetic Wistar-NIN rats was investigated by RT-PCR and immunoblotting. While expression of alphaB-crystallin was noted in the wide range of tissues examined in the study, alphaA-crystallin expression was detected only in lens and retina. Interestingly, alphaB-crystallin expression was elevated in lens, heart, muscle, and brain, but decreased in adipose tissue of diabetic rats compared to control rats. alphaA-Crystallin expression was increased in retina of diabetic rat. Increased oxidative stress appears to be a major stimulus for the enhanced expression of alphaA- and alphaB-crystallins in the tissues of diabetic rats and elevated expression of alpha-crystallin may have a protective role against metabolic stress. Interestingly, feeding of curcumin, a dietary antioxidant, to diabetic rats attenuated the enhanced expression of alphaB-crystallin. The results indicate that elevated expression of alpha-crystallins in some tissues may have implications in pathophysiology of diabetic complications.
Assuntos
Diabetes Mellitus Experimental/metabolismo , Cristalino/metabolismo , Retina/metabolismo , Cadeia A de alfa-Cristalina/metabolismo , Cadeia B de alfa-Cristalina/metabolismo , Animais , Masculino , Especificidade de Órgãos , Ratos , Ratos Wistar , Estreptozocina , Distribuição Tecidual , Regulação para CimaRESUMO
PURPOSE: A decline in the chaperone-like activity of eye lens alpha-crystallin in diabetic conditions has been reported. In this study, we investigated whether curcumin, a dietary antioxidant, can manipulate the chaperone-like activity of alpha-crystallin in diabetic rat lens. METHODS: A group of rats received ip injection of streptozotocin (STZ; 35 mg/kg body weight in buffer) to induce hyperglycemia, while another group of rats received only buffer as vehicle and served as control. STZ-treated rats were assigned to 3 groups and fed either no curcumin or 0.002% or 0.01% curcumin, respectively. Cataract progression due to hyperglycemia was monitored with a slit lamp biomicroscope. At the end of 8 weeks animals were sacrificed and lenses were collected. alphaH- and alphaL-crystallins from a set of pooled lenses in each group were isolated by gel filtration. Chaperone activity, hydrophobicity, and secondary and tertiary structure of alphaH- and alphaL-crystallins were assessed by light scattering/spectroscopic methods. RESULTS: A decrease in chaperone-like activity of alphaH- and alphaL-crystallins was observed in STZ-treated diabetic rats. The declined chaperone-like activity due to hyperglycemia was associated with reduced hydrophobicity and altered secondary and tertiary structure of alphaH- and alphaL-crystallins. Interestingly, alphaH- and alphaL-crystallins isolated from curcumin fed diabetic rat lenses had shown improved chaperone-like activity as compared to alphaH- and alphaL-crystallins from untreated diabetic rat lens. Feeding of curcumin prevented the alterations in hydrophobicity and structural changes due to STZ-induced hyperglycemia. Modulation of functional and structural properties by curcumin was found to be greater with the alphaL-crystallin than alphaH-crystallin. Loss of chaperone activity of alpha-crystallin, particularly alphaL-crystallin, in diabetic rat lens could be attributed at least partly to increased oxidative stress. Being an antioxidant, curcumin feeding has prevented the loss of alpha-crystallin chaperone activity and delayed the progression and maturation of diabetic cataract. CONCLUSIONS: We demonstrate that curcumin, at the levels close to dietary consumption, prevented the loss of chaperone-like activity of alpha-crystallin vis-a-vis cataractogenesis due to diabetes in rat lens.
Assuntos
Catarata/metabolismo , Curcumina/administração & dosagem , Diabetes Mellitus Experimental/metabolismo , Hiperglicemia/metabolismo , Cristalino/metabolismo , Chaperonas Moleculares/metabolismo , alfa-Cristalinas/metabolismo , Animais , Antioxidantes/administração & dosagem , Glicemia/análise , Peso Corporal , Catarata/fisiopatologia , Cromatografia em Gel , Dicroísmo Circular , Dieta , Hiperglicemia/fisiopatologia , Masculino , Ratos , Espectrometria de FluorescênciaRESUMO
PURPOSE: Aldose reductase (AR) has been a drug target because of its involvement in the development of secondary complications of diabetes including cataract. Although numerous synthetic AR inhibitors (ARI) have been tested and shown to inhibit the enzyme, clinically synthetic ARIs have not been very successful. Therefore, evaluating natural sources for ARI potential may lead to the development of safer and more effective agents against diabetic complications. In the present study we have assessed the inhibition of AR by constituents of Emblica officinalis both in vitro and in lens organ culture. METHODS: E. officinalis is widely used against many chronic ailments including diabetes. Aqeous extract of E. officinalis and its major constituent tannoids were tested for inhibition against both rat lens and purified recombinant human AR. ARI potential of isolated tannoids of E. officinalis were also investigated against osmotic stress in rat lens organ culture. RESULTS: E. officinalis extract inhibited rat lens and recombinant human AR with IC50 values 0.72 and 0.88 mg/ml respectively. Since E. officinalis is a rich source of ascorbic acid, we investigated whether ascorbic acid was responsible for AR inhibition by E. officinalis extract. However, ascorbic acid did not inhibit AR even at 5 mM concentration. Further, we demonstrate that the hydrolysable tannoids of E. officinalis were responsible for AR inhibition, as enriched tannoids of E. officinalis exhibited remarkable inhibition against both rat lens and human AR with IC50 of 6 and 10 microg/ml respectively. The inhibition of AR by E. officinalis tannoids is 100 times higher than its aqueous extract and comparable to or better than quercetin. Furthermore, the isolated tannoids not only prevented the AR activation in rat lens organ culture but also sugar-induced osmotic changes. CONCLUSIONS: These results indicate that tannoids of E. officinalis are potent inhibitors of AR and suggest that exploring the therapeutic value of natural ingredients that people can incorporate into everyday life may be an effective approach in the management of diabetic complications.
Assuntos
Aldeído Redutase/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Cristalino/enzimologia , Phyllanthus emblica/química , Extratos Vegetais/farmacologia , Taninos/farmacologia , Animais , Ácido Ascórbico/farmacologia , Masculino , Ayurveda , Técnicas de Cultura de Órgãos , Fitoterapia , Ratos , Proteínas Recombinantes/antagonistas & inibidoresRESUMO
PURPOSE: To investigate the effect of food, protein, and vitamin restriction on the susceptibility of lens crystallins to aggregation and chaperone activity of alpha-crystallin. METHODS: Thirty day old Wistar/NIN rats were maintained on regular rodent diet (C), 50% food restriction (FR), 75% protein restriction (PR), and 50% vitamin restriction (VR) diet for 20 weeks. At the end, alpha-, beta-, and gamma-crystallins were isolated from the lenses of these animals and subjected to in vitro aggregation induced by oxidation, UV irradiation and heat. Aggregation and chaperone activity was assessed by light scattering methods. RESULTS: Dietary restriction has been shown to extend the mean and maximum life span and retard age-related diseases, including cataract. In this study, we demonstrate that while beta- and gamma-crystallins isolated from FR and PR groups were less susceptible to in vitro induced aggregation, beta- and gamma-crystallins from the VR group were more susceptible, compared to controls. Alpha-crystallin from any of the groups did not shown a considerable amount of aggregation. On the other hand, the chaperone activity of alpha-crystallin from FR and PR groups was not significantly different from controls. However, alpha-crystallin from the VR group demonstrated substantially higher chaperone activity than controls. CONCLUSIONS: These results indicate that while food and protein restriction appear to lower the susceptibility of beta- and gamma-crystallins towards aggregation, vitamin restriction tends to increase the aggregation. Chaperone activity of alpha-crystallin is affected (improved) by only vitamin restriction.
Assuntos
Cristalinas/metabolismo , Dieta , Chaperonas Moleculares/fisiologia , Animais , Deficiência de Vitaminas/metabolismo , Peso Corporal , Cristalinas/efeitos da radiação , Dieta com Restrição de Proteínas , Temperatura Alta , Cristalino/fisiologia , Cristalino/efeitos da radiação , Masculino , Oxirredução , Desnaturação Proteica , Distribuição Aleatória , Ratos , Ratos Wistar , Raios UltravioletaRESUMO
alpha-Crystallin, a major eye lens protein, has been shown to function like a molecular chaperone by suppressing the aggregation of other proteins induced by various stress conditions. Ultraviolet (UV) radiation is known to cause structural and functional alterations in the lens macromolecules. Earlier we observed that exposure of rat lens to in vitro UV radiation led to inactivation of many lens enzymes including glucose-6-phosphate dehydrogenase (G6PD). In the present paper, we show that alpha-crystallin (alphaA and alphaB) protects G6PD from UVB irradiation induced inactivation. While, at 25 degrees C, there was a time-dependent decrease in G6PD activity upon irradiation at 300 nm, at 40 degrees C there was a complete loss of activity within 30 min even without irradiation. The loss of activity of G6PD was prevented significantly, if alphaA- or alphaB-crystallin was present during irradiation. At 25 degrees C, alphaB-crystallin was slightly a better chaperone in protecting G6PD against UVB inactivation. Interestingly, at 40 degrees C, alphaA- and alphaB-crystallins not only prevent the loss of G6PD activity but also protect against UVB inactivation. However, alphaA- and alphaB-crystallins were equally efficient at 40 degrees C in protecting G6PD.