Mitigation of lens opacification by a functional food in a diabetic rodent model.

The current study was designed to test a functional food (FF) mixture containing aldose reductase inhibitors and antiglycation bioactive compounds for suppressing the onset and progression of cataracts in a diabetic rat model. Two-month-old Sprague Dawley rats were grouped as control (C), diabetes untreated (D), and diabetic rats treated with FF at two doses (FF1 = 1.35 g and FF2 = 6.25 g/100g of diet). Diabetes was induced by a single injection of streptozotocin. The FF is a mixture of amla, turmeric, black pepper, cinnamon, ginger, and fenugreek added to the rodent diet. The status of cataracts was monitored weekly by a slit lamp examination for 20 weeks, after which animals were sacrificed to collect eye lenses. Feeding FF1 and FF2 to diabetic rats yielded a significant anti-hyperglycaemic effect and marginally prevented body weight loss. FF delayed cataract progression, and FF2 showed better efficacy than FF1. FF prevented the loss of lens crystallins and their insolubilization in diabetic rats. The antioxidant potential of FF was evident with the lowered protein carbonyls, lipid peroxidation, and prevention of altered antioxidant enzyme activities induced by diabetes. These studies demonstrate the efficacy of plant-derived dietary supplements against the onset and progression of cataracts in a well-established rat model of diabetic eye disease.

Neuroprotective role of vitamin B12 in streptozotocin-induced type 1 diabetic rats.

Chronic hyperglycemia-induced neuropathological changes include neuronal apoptosis, astrogliosis, decrease in neurotrophic support, impaired synaptic plasticity, and impaired protein quality control (PQC) system. Vitamin B12 is indispensable for neuronal development and brain function. Several studies reported the neuroprotective effect of B12 supplementation in diabetic patients. However, the underlying molecular basis for the neuroprotective effect of B12 supplementation in diabetes needs to be thoroughly investigated. Two-month-old Sprague-Dawley rats were randomly assigned into three groups: Control (CN), diabetes (D; induced with streptozotocin; STZ), and diabetic rats supplemented with vitamin B12 (DBS; vitamin B12; 50 µg/kg) for four months. At the end of 4 months of experimentation, the brain was dissected to collect the cerebral cortex (CC). The morphology of CC was investigated with H&E and Nissl body staining. Neuronal apoptosis was determined with TUNEL assay. The components of neurotrophic support, astrogliosis, synaptic plasticity, and PQC processes were investigated by immunoblotting and immunostaining methods. H& E, Nissl body, and TUNEL staining revealed that diabetes-induced neuronal apoptosis and degeneration. However, B12 supplementation ameliorated the diabetes-induced neuronal apoptosis. Further, B12 supplementation restored the markers of neurotrophic support (BDNF, NGF, and GDNF), and synaptic plasticity (SYP, and PSD-95) in diabetic rats. Interestingly, B12 supplementation also attenuated astrogliosis, ER stress, and ameliorated autophagy-related proteins in diabetic rats. Overall, these findings suggest that B12 acts as a neuroprotective agent by inhibiting the neuropathological changes in STZ-induced type 1 diabetes. Thus, B12 supplementation could produce beneficial outcomes including neuroprotective effects in diabetic patients.

Dietary zinc inadequacy affects neurotrophic factors and proteostasis in the rat brain.

Zinc (Zn) deficiency has many adverse effects, including growth retardation, loss of appetite, vascular diseases, cognitive and memory impairment, and neurodegenerative diseases. In the current study, we investigated the hypothesis that dietary Zn inadequacy affects neurotrophic factors and proteostasis in the brain. Three-week-old Wistar/Kyoto male rats were fed either a Zn-deficient diet (D; < 1 mg Zn/kg diet; n = 18) or pair-fed with the control diet (C; 48 mg Zn/kg diet; n = 9) for 4 weeks. Subsequently, the rats in the D group were subdivided into two groups (n = 9), in which one group continued to receive a Zn-deficient diet, whereas the other received a Zn-supplemented diet (R; 48 mg Zn/kg diet) for 3 more weeks, after which the rats were sacrificed to collect their brain tissue. Markers of endoplasmic reticulum stress, ubiquitin-proteasome system, autophagy, and apoptosis, along with neurotrophic factors, were investigated by immunoblotting. Proteasomal activity was analyzed by the spectrofluorometric method. The results showed an altered ubiquitin-proteasome system and autophagy components and increased gliosis, endoplasmic reticulum stress, and apoptosis markers in Zn-deficient rats compared with the control group. Zinc repletion for 3 weeks could partially restore these alterations, indicating a necessity for an extended duration of Zn supplementation. In conclusion, a decline in Zn concentrations below a critical threshold may trigger multiple pathways, leading to brain-cell apoptosis.

Perspective: When the cure might become the malady: the layering of multiple interventions with mandatory micronutrient fortification of foods in India.

When public health programs with single nutrients are perceived to have a poor impact on the target health outcome, the policy response can be to supply more, by layering additional mandatory programs upon the extant programs. However, we argue for extreme caution, because nutrients (like medicines) are beneficial in the right dose, but potentially harmful when ingested in excess. Unnecessary motivations for the reactionary layering of multiple intervention programs emerge from incorrect measurements of the risk of nutrient inadequacy in the population, or incorrect biomarker cutoffs to evaluate the extent of nutrient deficiencies. The financial and social costs of additional layered programs are not trivial when traded off with other vital programs in a resource-poor economy, and when public health ethical dilemmas of autonomy, equity, and stigma are not addressed. An example of this conundrum in India is the perception of stagnancy in the response of the prevalence of anemia to the ongoing pharmacological iron supplementation program. The reaction has been a policy proposal to further increase iron intake through mandatory iron fortification of the rice provided in supplementary feeding programs like the Integrated Child Development Services and the School Mid-Day Meal. This is in addition to the ongoing pharmacological iron supplementation as well as other voluntary iron fortifications, such as those of salt and manufactured food products. However, before supplying more, it is vital to consider why the existing program is apparently not working, along with consideration of the potential for excess intake and related harms. This is relevant globally, particularly for countries contemplating multiple interventions to address micronutrient deficiencies. Supplying more by layering multiple nutrient interventions, instead of doing it right, without thoughtful considerations of social, biological, and ethics frameworks could be counterproductive. The cure, then, might well become the malady.

Prevalence of Iron Deficiency and its Sociodemographic Patterning in Indian Children and Adolescents: Findings from the Comprehensive National Nutrition Survey 2016-18.

BACKGROUND: Anemia control programs in India focus mainly on the measurement of hemoglobin in response to iron-folic acid supplementation. However, representative national estimates of iron deficiency (ID) are not available. OBJECTIVES: The objective of the present study was to evaluate ID prevalence among children and adolescents (1-19 y) using nationally representative data and to examine the sociodemographic patterning of ID. METHODS: Cross-sectional data from the Comprehensive National Nutrition Survey in children (1-4 y: n = 9635; 5-9 y: n = 11,938) and adolescents (10-19 y; n = 11,507) on serum ferritin (SF) and other biomarkers were analyzed to determine inflammation-adjusted ID prevalence [SF (µg/L): <12 in 1-4 y and <15 in 5-19 y] and its relation to sociodemographic indicators. Multiple-regression analyses were conducted to identify the exposure associations of iron status. In addition, the relation between SF and hemoglobin was assessed as an indicator of iron utilization in different wealth quintiles. RESULTS: ID prevalence was higher in 1- to 4-y-old children (31.9%; 95% CI: 31.0%, 32.8%) and adolescent girls (30.4%; 95% CI: 29.3%, 31.5%) but lower in adolescent boys and 5- to 9-y-old children (11%-15%). In all age groups, ID prevalence was higher in urban than in rural participants (1-4 y: 41% compared with 29%) and in those from richer quintiles (1-4 y: 44% in richest compared with 22% in poorest), despite adjustment for relevant confounders. SF significantly interacted with the wealth index, with declining trends in the strength of association between hemoglobin and SF from the richest to the poorest groups suggesting impaired iron utilization for hemoglobin synthesis in poorer wealth quintiles. CONCLUSIONS: ID prevalence was indicative of moderate (in preschool children and adolescent girls) or mild (in 5- to 9-y-old children and adolescent boys) public health problem with significant variation by state and age. Focusing on increasing iron intake alone, without addressing the multiple environmental constraints related to poverty, may not result in intended benefits.

Vitamin A deficiency among children younger than 5 y in India: an analysis of national data sets to reflect on the need for vitamin A supplementation.

BACKGROUND: Biochemical vitamin A deficiency (VAD) is believed to be a serious public health problem (low serum retinol prevalence >20%) in Indian children, justifying universal high-dose vitamin A supplementation (VAS). OBJECTIVE: To evaluate in Indian children younger than 5 y the risk of biochemical VAD from the Comprehensive National Nutrition Survey, as well as dietary vitamin A inadequacy and excess over the tolerable upper limit of intake (TUL) from national and subnational surveys, factoring in fortification and VAS. METHODS: Child serum retinol data, corrected for inflammation, were examined to evaluate national- and state-level prevalence of VAD. Simultaneously, dietary intakes from the National Sample Survey Office and the National Nutrition Monitoring Bureau were examined for risk of dietary vitamin A deficiency against its average requirement (AR) derived for Indian children. Theoretical estimates of risk reduction with oil and milk vitamin A fortification were evaluated along with the risk of exceeding the TUL, as well as when combined with intake from VAS. RESULTS: The national prevalence of biochemical VAD measured in 9563 children was 15.7% (95% CI: 15.2%, 16.3%), and only 3 states had prevalence significantly >20%. The AR of vitamin A was 198 and 191 µg/d for boys and girls; the risk of dietary inadequacy was ∼70%, which reduced to 25% with oil and milk fortification. Then, the risk of exceeding the TUL was 2% and 1% in 1- to 3-y-old and 4- to 5-y-old children, respectively, but when the VAS dose was added to this intake in a cumulative 6-mo framework, the risk of exceeding the TUL rose to 30% and 8%, respectively. CONCLUSION: The national prevalence of VAD risk is below 20% in Indian children. Because there is risk of excess intake with food fortification and VAS, serious consideration should be given to a targeted approach in place of the universal VAS program in India.

Effect of vitamin B12 supplementation on retinal lesions in diabetic rats.

Purpose: Diabetic retinopathy (DR) is the most common complication of diabetes involving microvasculature and neuronal alterations in the retina. Previously, we reported that vitamin B12 deficiency could be an independent risk factor for DR in humans. However, the effect of vitamin B12 supplementation in experimental DR is unknown. Thus, in this study, we investigated the impact of dietary supplementation of vitamin B12 on retinal changes in diabetic rats. Methods: Diabetes was induced in 2-month-old Sprague-Dawley rats and maintained for 4 months. One group of diabetic rats were fed normal levels of vitamin B12, and one group double the quantity of vitamin B12 (50 µg/kg diet). Vitamin B12 and homocysteine levels in the plasma were analyzed with radioimmunoassay (RIA) and high-performance liquid chromatography (HPLC), respectively. At the end of 4 months of experimentation, the eyeballs were collected. Retinal changes were analyzed with hematoxylin and eosin (H&E) staining, immunoblotting, and immunofluorescence methods. Results: Dietary supplementation of vitamin B12 had no effect on food intake, bodyweight, fasting blood glucose, and plasma homocysteine levels in the diabetic rats. However, vitamin B12 supplementation prevented loss of rhodopsin, and overexpression of VEGF, and completely prevented overexpression of HIF1α, GFAP, and endoplasmic reticulum (ER) stress markers (GRP78, ATF6α, XBP1, CHOP, and caspase 12) in the diabetic rat retina. Further, vitamin B12 ameliorated apoptosis in the retina as shown with terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) and prevented retinal thinning. Conclusions: Vitamin B12 supplementation of diabetic rats appeared to be beneficial by circumventing retinal hypoxia, VEGF overexpression, and ER stress-mediated cell death in the retina. The present study adds another potential therapeutic strategy of vitamin B12 in diabetes.

Procyanidin-B2 enriched fraction of cinnamon acts as a proteasome inhibitor and anti-proliferative agent in human prostate cancer cells.

Altered activity of the proteolytic machine-the 26S proteasome is observed in many disease conditions. Hence, either inhibition or activation of the 26S proteasome is thought to be a novel therapy for treatment of certain diseases such as cancer and neurodegenerative disorders. In this study, we tested the potential of cinnamon and one of its active ingredients, procyanidin-B2 (PCB2), in inhibiting the catalytic activities of the proteasome and suppressing prostate cancer cell growth. Proteasome activities were measured using fluorogenic substrates specific for the different enzymatic activities of the 26S proteasome by flourometry. Cell viability was assessed using the 3-[4, 5-dimethylthiazol-2-yl]-2.5-diphenyl-tetrazolium bromide assay, while apoptosis was examined by Hoechst and propidium iodide staining and caspase-3 activity. Both, the cinnamon extract and its PCB2-enriched F2 fraction inhibited the catalytic activities of the purified proteasome and the proteasome in cancer cells but not in normal cells. Furthermore, cinnamon and its active component decreased cell proliferation of human prostate cancer cells but not normal lung cells, decreased expression of anti-apoptotic and angiogenic markers in prostate cancer cell lysates. These results demonstrate that cinnamon extract and its PCB2-enriched fraction act as proteasome inhibitors and have prospects as anti-cancer agents. © 2018 IUBMB Life, 70(5):445-457, 2018.

Folate, vitamin B12, ferritin and haemoglobin levels among women of childbearing age from a rural district in South India.

BACKGROUND: Low folate and vitamin B12 levels have negative effect on pregnancy outcomes but there is paucity of data on their levels among Indian women. Ferritin and haemoglobin are associated with maternal mortality and low birth-weight. Our aim was to estimate the prevalence of deficiency of serum folate and vitamin B12, and low levels of serum ferritin and blood haemoglobin among women of childbearing age from a rural population of South India. METHODS: We conducted a community-based cross-sectional study among 15-35 year women in a rural district. We used multistage stratified random sampling. Trained staff interviewed women to collect socio-demographic information and draw blood samples. We analysed samples for serum folate, vitamin B12, ferritin and blood haemoglobin levels and computed means and medians. We computed the proportion of deficiency based on cut-offs recommended by WHO. We examined the association of levels with age, parity and current pregnancy or breastfeeding by multi-variable regression using Stata 13.0. RESULTS: We recruited 979 women. One-fifth (185, 19%) were pregnant and one-fifth (196, 20%)were breastfeeding. Median serum folate levels were 2.5 ng/ml (IQR, 1.2-4.8), median vitamin B12 levels were 228.0 pg/ml (IQR, 121 - 390), median ferritin levels were 13.0 µg/l (IQR, 6.0 - 20.0) and median blood haemoglobin levels were 12.1 mg/dl (IQR, 10.7 - 13.6). Low levels of serum folate, vitamin B12, ferritin and haemoglobin were found in 57% (95% CI, 54-60%), 44% (95% CI, 41-48%), 46% (95% CI, 43-49%) and 28% (95% CI, 25-31%) respectively. Women with folic acid deficiency had two times higher prevalence of having vitamin B12 deficiency. In adjusted regression analysis folate levels were lower in older and breastfeeding women, but not associated with parity and were higher among pregnant women. Similar associations were not found with Vitamin B12 deficiency. Ferritin levels were higher in older women; but not associated with parity, pregnancy or breastfeeding. Haemoglobin levels were lower in pregnant and breastfeeding women. CONCLUSION: Our findings suggest that folic acid, vitamin B12 and iron deficiency are important public health problems in India. We observed that half of the women of childbearing age were deficient in these nutrients. Folic acid and vitamin B12 deficiencies co-exist and should be supplemented together.

In Vivo Inhibition of Proteasome Activity and Tumour Growth by Murraya koenigii Leaf Extract in Breast Cancer Xenografts and by Its Active Flavonoids in Breast Cancer Cells.

Inhibition of the 26S proteasome is an attractive approach for anticancer therapy. Proteasome inhibitors are known to selectively target cancer cells and make them more sensitive to chemotherapeutic agents. Murraya koenigii is a medicinally important herb of Asian origin and a rich source of bioactive compounds such as flavonoids and alkaloids. In the present study, we investigated the proteasome inhibitory and apoptotic effect of M. koenigii leaf extract in vivo in a xenograft tumor mouse model, and also assessed the toxicity if any in normal mice. M. koenigii extract did not lead to any toxicity in mice. Analysis of extract revealed the presence of flavonoid compounds which act as proteasome inhibitors. Quercetin treatment led to the decrease in the cell viability and arrest of cells in G2/M phase. Quercetin, Apigenin, Kaempferol and Rutin; flavonoids present in the leaf extract, dose-dependently inhibited the endogenous 26S proteasome activity in MDA-MB-231 cells. Reduction in tumor growth was associated with a decrease in proteasomal enzyme activities in the treated groups. Increased caspase-3 activity and TUNEL-positive cells indicated enhanced apoptosis with Murraya leaf extract treatment. Decreased expression of angiogenic and anti-apoptotic gene markers is indicative of inhibition of angiogenesis and promotion of apoptosis in the leaf extract treated tumors.

Gentiana lutea exerts anti-atherosclerotic effects by preventing endothelial inflammation and smooth muscle cell migration.

BACKGROUND AND AIMS: Studies suggest that Gentiana lutea (GL), and its component isovitexin, may exhibit anti-atherosclerotic properties. In this study we sought to investigate the protective mechanism of GL aqueous root extract and isovitexin on endothelial inflammation, smooth muscle cell migation, and on the onset and progression of atherosclerosis in streptozotocin (STZ)-induced diabetic rats. METHODS AND RESULTS: Our results show that both GL extract and isovitexin, block leukocyte adhesion and generation of reactive oxygen species in human umbilical vein endothelial cells (HUVECs) and rat aortic smooth muscle cells (RASMCs), following TNF-alpha and platelet derived growth factor-BB (PDGF-BB) challenges respectively. Both the extract and isovitexin blocked TNF-α induced expression of ICAM-1 and VCAM-1 in HUVECs. PDGF-BB induced migration of RASMCs and phospholipase C-γ activation, were also abrogated by GL extract and isovitexin. Fura-2 based ratiometric measurements demonstrated that, both the extact, and isovitexin, inhibit PDGF-BB mediated intracellular calcium rise in RASMCs. Supplementation of regular diet with 2% GL root powder for STZ rats, reduced total cholesterol in blood. Oil Red O staining demonstrated decreased lipid accumulation in aortic wall of diabetic animals upon treatment with GL. Medial thickness and deposition of collagen in the aortic segment of diabetic rats were also reduced upon supplementation. Immunohistochemistry demonstrated reduced expression of vascular cell adhesion molecule-1 (VCAM-1), inducible nitric oxide synthase (iNOS), and vascular endothelial cadherin (VE-cadherin) in aortic segments of diabetic rats following GL treatment. CONCLUSIONS: Thus, our results support that GL root extract/powder and isovitexin exhibit anti-atherosclerotic activities.

Ellagic acid, a new antiglycating agent: its inhibition of Nϵ-(carboxymethyl)lysine.

Non-enzymatic glycation is a complex series of reactions between reducing sugars and amino groups of proteins. Accumulation of AGEs (advanced glycation end-products) due to non-enzymatic glycation has been related to several diseases associated with aging and diabetes. The formation of AGEs is accelerated in hyperglycaemic conditions, which alters the structure and function of long-lived proteins, thereby contributing to long-term diabetic complications. The present study describes AGE inhibition and the mechanism of action of a new antiglycating agent, EA (ellagic acid), a flavonoid present in many dietary sources. Inhibition of AGE formation by EA was demonstrated with different proteins, namely eye lens TSP (total soluble protein), Hb (haemoglobin), lysozyme and BSA, using different glycating agents such as fructose, ribose and methylglyoxal by a set of complementary methods. These results suggest that the antiglycating action of EA seems to involve, apart from inhibition of a few fluorescent AGEs, predominantly inhibition of CEL [Nϵ-(carboxyethyl)lysine] through scavenging of the dicarbonyl compounds. Furthermore, MALDI-TOF-MS (matrix-assisted laser-desorption ionisation-time-of-flight MS) analysis confirms inhibition of the formation of CEL on lysozyme on in vitro glycation by EA. Prevention of glycation-mediated ß-sheet formation in Hb and lysozyme by EA confirm its antiglycating ability. Inhibition of glycosylated Hb formation in human blood under ex vivo high-glucose conditions signifies the physiological antiglycating potential of EA. We have also determined the effectiveness of EA against loss of eye lens transparency through inhibition of AGEs in the lens organ culture system. These findings establish the antiglycating potential of EA and its in vivo utility in controlling AGE-mediated diabetic pathologies.

Inhibition of aldose reductase by dietary antioxidant curcumin: mechanism of inhibition, specificity and significance.

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.

Prevention of non-enzymic glycation of proteins by dietary agents: prospects for alleviating diabetic complications.

The accumulation of advanced glycation endproducts (AGE) due to non-enzymic glycation of proteins has been implicated in several pathophysiologies associated with ageing and diabetes. The formation of AGE is accelerated in hyperglycaemic conditions, which alter the structure and function of long-lived proteins. Thus inhibition of the formation of AGE is believed to play a role in the prevention of diabetic complications. In the present study we evaluated the antiglycating effect of aqueous extracts of various plant-based foods. The effect of aqueous extracts of these agents in terms of their ability to prevent the accumulation of AGE due to fructose-mediated in vitro glycation of eye lens soluble proteins was investigated. The degree of protein glycation in the absence and presence of dietary extracts was assessed by different complementary methods, i.e. non-tryptophan AGE fluorescence, AGE-induced cross-linking by SDS-PAGE and glyco-oxidative damage by carbonyl assay. Five out of the seventeen agents tested showed significant inhibitory potential against in vitro protein glycation in a dose-dependent manner. Prominent among them were ginger, cumin, cinnamon, black pepper and green tea, which inhibited in vitro AGE formation to lens proteins 40-90 % at 1.0 mg/ml concentration. Assessing their potential to reduce the amount of glycated protein using boronate affinity chromatography and also their ability to prevent the formation of specific antigenic-AGE structures by immunodetection further substantiated the importance of ginger, cumin and cinnamon in reducing AGE burden. These findings indicate the potential of some dietary components to prevent and/or inhibit protein glycation. Thus these dietary agents may be able to be exploited for controlling AGE-mediated diabetic pathological conditions in vivo.

Dietary sources of aldose reductase inhibitors: prospects for alleviating diabetic complications.

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.

Cumulative antioxidant defense against oxidative challenge in galactose-induced cataractogenesis in Wistar rats.

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.

Curcumin and turmeric delay streptozotocin-induced diabetic cataract in rats.

PURPOSE: The purpose of this study was to investigate the effect of curcumin and its source, turmeric, on streptozotocin-induced diabetic cataract in rats. METHODS: Wistar-NIN rats were selected and diabetes was induced by streptozotocin (35 mg/kg body weight, intraperitoneally) and divided into four groups (group II-V). The control (group I) rats received only vehicle. Group I and II animals received an unsupplemented AIN-93 diet, and those in groups III, IV, and V received 0.002% and 0.01% curcumin and 0.5% turmeric, respectively, in an AIN-93 diet for a period of 8 weeks. Cataract progression due to hyperglycemia was monitored by slit lamp biomicroscope and classified into four stages. At the end of 8 weeks, the animals were killed and the biochemical pathways involved in the pathogenesis of cataract such as oxidative stress, polyol pathway, alterations in protein content and crystallin profile in the lens were investigated, to understand the possible mechanism of action of curcumin and turmeric. Blood glucose and insulin levels were also determined. RESULTS: Although, both curcumin and turmeric did not prevent streptozotocin-induced hyperglycemia, as assessed by blood glucose and insulin levels, slit lamp microscope observations indicated that these supplements delayed the progression and maturation of cataract. The present studies suggest that curcumin and turmeric treatment appear to have countered the hyperglycemia-induced oxidative stress, because there was a reversal of changes with respect to lipid peroxidation, reduced glutathione, protein carbonyl content and activities of antioxidant enzymes in a significant manner. Also, treatment with turmeric or curcumin appears to have minimized osmotic stress, as assessed by polyol pathway enzymes. Most important, aggregation and insolubilization of lens proteins due to hyperglycemia was prevented by turmeric and curcumin. Turmeric was more effective than its corresponding levels of curcumin. CONCLUSIONS: The results indicate that turmeric and curcumin are effective against the development of diabetic cataract in rats. Further, these results imply that ingredients in the study's dietary sources, such as turmeric, may be explored for anticataractogenic agents that prevent or delay the development of cataract.

Effect of Diabecon on sugar-induced lens opacity in organ culture: mechanism of action.

Cataract is the leading cause of blindness worldwide. Apart from ageing, diabetes has been considered to be one of the major risk factors of cataract. The high sugar levels in diabetes may cause tissue disruption and intumescences by osmotic changes induced via aldose reductase (AR) mediated polyol pathway. Therefore, agents that can inhibit AR and prevent sorbitol accumulation may be helpful to combat sugar-induced cataract. In the present study, AR inhibitory activity of Diabecon (an herbal drug used for diabetes) was studied together with its effect against sugar-induced lens opacity in organ culture. Diabecon aqueous extract (DAE) showed potential inhibitory activity with an IC50 value of 10 microg/ml against rat lens AR. Incubation of goat lens with supraphysiological concentrations of glucose (100 mM) led to the loss of lens transparency associated with increased AR activity, decreased soluble protein and increased protein carbonyls and glycation. Addition of DAE (0.3 mg/ml) to the medium preserved transparency and ameliorated the decrease in lens soluble protein due to hyperglycemia and also prevented the formation of glycated protein. Interestingly DAE inhibited aldose reductase activity in lens incubated with 100 mM glucose. DAE decreased protein carbonyls, prevented the loss of beta(L)-crystallin against 100 mM of glucose. We have also demonstrated here that most of these effects are mainly due to Gymnema sylvestre, one of the constituent herbs of Diabecon. These results suggest that Diabecon protect the lens against sugar-induced cataract by multiple mechanisms.

Inhibition of aldose reductase by tannoid principles of Emblica officinalis: implications for the prevention of sugar cataract.

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.