Taurine Prevents Oxidative Damage of High Glucose-Induced Cataractogenesis in Isolated Rat Lenses

Oxymatrine impedes the progression of endotoxin-induced glaucoma via redox system modulations

This study aimed to provide irrefutable evidence of the preventive effects of oxymatine (OMT) on a model of endotoxin induced glaucoma in Wistar rats which can be attributed to its anti-inflammatory, antioxidant, and TNF-α antagonistic properties. To assess the impact of OMT on uveitic glaucoma, the normal group received 100 μL distilled water topically for 15 days, while the glaucoma control group was induced with uveitic glaucoma by applying 10 μL of 10 μg/mL lipopolysaccharide (LPS) topically for 3 consecutive days. The treatment groups were then given OMT solution at a volume of 50 μL with varying doses of 0.25%, 0.5%, and 1% once a day via topical administration for 15 days. In addition, as a standard, the animals were also given 100 μL of 1% dorzolamide topically for 15 days. All ophthalmic dosing was carried out by pulling the lower eye-lid of the experimental animals and administration of the respective solutions. The study uses cutting-edge real-time imaging of the retinal vasculature in anesthetized animals, postsacrifice lenticular picturization and biochemical evidence to support the changes in the retinal layers. LPS induced animals demonstrated increased IOP, disrupted antioxidant systems, massive lipid damage, enhanced TNF-α activity and changes in intracellular ATPase and ionic activities. The damaged retinal vasculature and lenticular opacification further supported the biochemical evidence. However, using OMT at a 1% dosage effectively enhanced the antioxidant levels, regulated intracellular ion concentration and ATPases, decreased TNF-α activity, and counteracted mechanobiological changes in the visual front and retina. Moreover, OMT can successfully normalize intraocular pressure, making it a highly beneficial treatment option for glaucoma.

Ornipural® Mitigates Malathion-Induced Hepato-Renal Damage in Rats via Amelioration of Oxidative Stress Biomarkers, Restoration of Antioxidant Activity, and Attenuation of Inflammatory Response

The current study was instigated by investigating the ameliorative potential of Ornipural^® solution against the hepato-renal toxicity of malathion. A total number of 35 male Wistar albino rats were divided equally into five groups. Group 1 served as control and received normal saline intraperitoneally. Group 2, the sham group, were administered only corn oil (vehicle of malathion) orally. Group 3 was orally intoxicated by malathion in corn oil at a dose of 135 mg/kg BW via intra-gastric gavage. Group 4 received malathion orally concomitantly with Ornipural^® intraperitoneally. Group 5 was given Ornipural^® solution in saline via intraperitoneal injection at a dose of (1 mL/kg BW). Animals received the treatment regime for 30 days. Histopathological examination revealed the harmful effect of malathion on hepatic and renal tissue. The results showed that malathion induced a significant decrease in body weight and marked elevation in the activity of liver enzymes, LDH, and ACP. In contrast, the activity of AchE and Paraoxonase was markedly decreased. Moreover, there was a significant increase in the serum content of bilirubin, cholesterol, and kidney injury markers. A significant elevation in malondialdehyde, nitric oxide (nitrite), and 8-hydroxy-2-deoxyguanosine was observed, along with a substantial reduction in antioxidant activity. Furthermore, malathion increased tumor necrosis factor-alpha, the upregulation of IL-1B, BAX, and IFN-β genes, and the downregulation of Nrf2, Bcl2, and HO-1 genes. Concurrent administration of Ornipural^® with malathion attenuated the detrimental impact of malathion through ameliorating metabolic biomarkers, restoring antioxidant activity, reducing the inflammatory response, and improving pathologic microscopic alterations. It could be concluded that Ornipural^® solution demonstrates hepatorenal defensive impacts against malathion toxicity at biochemical, antioxidants, molecular, and cellular levels.

Oxymatrine Protects TGFβ1-Induced Retinal Fibrosis in an Animal Model of Glaucoma

Glaucoma has engulfed a huge population of the world into its claws of blindness as it remains asymptomatic until nearly 40% of the neurons are lost and the only option left is for patients to be subjected to symptomatic treatments or surgical methods, neither of which is completely effective in curing the disease as they do not restore the physiological dimensions at the neuronal level. Among the several factors that drive the pathophysiology of glaucoma, one is the involvement of fibrogenic factors, such as transforming growth factor β (TGFβ) which remodels the extracellular matrix (ECM) and, thus, the deposition of fibrotic material in the retina, resulting in the progression of primary open-angle glaucoma (POAG). The primary objectives of this study were to evaluate the protective effects of oxymatrine (OMT) in the steroid-induced glaucoma model in experimental rats and to determine the role of transforming growth factor β1 (TGFβ1) in the pathogenesis of glaucoma and its consequent inhibition due to the antioxidant and the antiinflammatory, and also the TGFβ1 antagonistic, behavior of OMT. To that end, we experimentally elucidated the role of OMT, a TGFβ1 antagonist, that is known to play antiinflammatory and antioxidant roles in the steroid-induced glaucoma model in experimental rats, and using the enzyme-linked immunosorbent assay (ELISA), we observed a direct inhibitory effect of OMT on the pathogenesis of glaucoma. The antioxidant and the antiinflammatory potentials of OMT were determined using several biochemical methods to determine the major antioxidants in the retinal layers, such as superoxide dismutase (SOD), glutathione peroxidase (GP_X), catalase (CAT), and glutathione (GSH), along with the nitrite and the malondialdehyde (MDA) concentration levels. As a result, OMT was found to reduce the total protein content in the retinal layers, a correlation that has not been previously reported. Moreover, the impacts of OMT on the major governing ATPases, namely Na⁺/K⁺ ATPase and Ca²⁺ATPase, along with its impacts on the intracellular ionic concentrations of Na⁺, K⁺, and Ca²⁺, were determined and were found to point toward OMT, restoring homeostasis in glaucomatous animals. A clearer picture of the changes during the treatment was obtained using retinal images of the live animals and of the lenticular changes in the sacrificed animal; these images provided data on the pathological pathways leading to glaucoma inception and its consequent inhibition by OMT. The data reported in this study clearly indicate that OMT has a possible role in inhibiting the pathogenesis of glaucoma, and the data also permit the quantification of several biochemical parameters of concern.

Hallmarks of lens aging and cataractogenesis

Lens homeostasis and transparency are dependent on the function and intercellular communication of its epithelia. While the lens epithelium is uniquely equipped with functional repair systems to withstand reactive oxygen species (ROS)-mediated oxidative insult, ROS are not necessarily detrimental to lens cells. Lens aging, and the onset of pathogenesis leading to cataract share an underlying theme; a progressive breakdown of oxidative stress repair systems driving a pro-oxidant shift in the intracellular environment, with cumulative ROS-induced damage to lens cell biomolecules leading to cellular dysfunction and pathology. Here we provide an overview of our current understanding of the sources and essential functions of lens ROS, antioxidative defenses, and changes in the major regulatory systems that serve to maintain the finely tuned balance of oxidative signaling vs. oxidative stress in lens cells. Age-related breakdown of these redox homeostasis systems in the lens leads to the onset of cataractogenesis. We propose eight candidate hallmarks that represent common denominators of aging and cataractogenesis in the mammalian lens: oxidative stress, altered cell signaling, loss of proteostasis, mitochondrial dysfunction, dysregulated ion homeostasis, cell senescence, genomic instability and intrinsic apoptotic cell death.

Fundamentals of Diabetic Cataractogenesis and Promising Ways of its Pharmacological Correction

Cataracts in diabetes mellitus lead to decreased visual function and blindness. Cataract surgery for diabetes mellitus has limitations and complications. The search for effective means of conservative cataract therapy continues. The review presents the analysis of data from scientific sources, mainly for 2015–2020 using Internet resources (PubMed, Web of Science, Medline, eLibrary.Ru, Cyberleninka). In the work, diabetic cataractogenesis is presented as a sum of interrelated pathobiochemical processes. The main ones are the polyol pathway of glucose conversion, non-enzymatic glycation and oxidative modification of lens proteins, which are enhanced in diabetes mellitus. The lens has a high protein content. The formation of high molecular weight protein aggregates is of particular importance for the appearance of light scattering zones and a decrease in lens transparency. This review presents data on anti-cataract compounds that affect post-translational crystallin modification, prevent osmotic and oxidative stress in the lens, and exhibit antiglycation properties. This information shows that the search for means of pharmacological correction of cataractogenesis should be carried out among compounds with antioxidant and antiglycation activity. 

Taurine Attenuates the Hypotaurine-Induced Progression of CRC via ERK/RSK Signaling

Colorectal cancer (CRC) is one of the most common malignant tumors, and previous metabolomics work has demonstrated great promise in identifying specific small molecules of tumor phenotype. In the present study, we analyzed the metabolites of resected tissues through gas chromatography-mass spectrometry (GC-MS), and found that the concentration of taurine in CRC tissues diminished whereas the concentration of hypotaurine increased. The results in vitro demonstrated that taurine significantly suppressed cellular proliferation, metastasis, and colony formation whereas it induced apoptosis in CRC cells. Furthermore, taurine regulated the expression levels of epithelial mesenchymal transition (EMT)-associated genes in a dose-dependent manner. Taurine also alleviated hypotaurine-induced CRC progression, which was linked to the inhibition of the ERK/RSK-signaling pathway and diminution in intracellular hypotaurine. Taurine additionally attenuated hypotaurine-induced tumor growth and metastasis in vivo. Patients with CRC exhibited lower levels of serum taurine, suggesting that taurine might be a promising biomarker reflecting a poor prognosis in CRC. Collectively, our results demonstrated that taurine-attenuated, hypotaurine-induced CRC progression provides a potential target for CRC therapy.

Most abundant metabolites in tissues of freshwater fish pike-perch (Sander lucioperca)

Quantitative metabolomic analysis was performed for eleven tissues of freshwater fish pike-perch (Sander lucioperca), including gill, heart, liver, kidney, spleen, muscle, brain, milt, lens, aqueous (AH) and vitreous (VH) humors with the use of NMR spectroscopy. The absolute values of concentrations were determined for more than 65 most abundant metabolites in every tissue. It was found that from the metabolomic viewpoint, kidney and gill are the most similar tissues, while the metabolomic compositions of ocular tissues—lens, AH, and VH significantly differ from that of other tissues. The combinations of intracellular osmolytes and antioxidants are specific for every tissue. In particular, the concentration of antioxidant ovothiol A in the lens is much higher than in any other tissue, while the brain enjoys the elevated level of ascorbate. The most abundant osmolyte in the fish spleen, muscle, and heart is taurine, and in the brain, gill, and lens—myo-inositol. Other important osmolytes specific for particular tissues are N-acetyl-histidine, N-acetyl-aspartate, betaine, threonine-phosphoethanolamine, and serine-phosphoethanolamine. The quantitative data obtained in the present work can be used as the baseline metabolite concentrations in the fish tissues to evaluate the influence of seasonal, ecological and other factors on the fish metabolism.

Significance of taurine transporter (TauT) in homeostasis and its layers of regulation (Review)

Taurine (2‑aminoethanesulfonic acid) contributes to homeostasis, mainly through its antioxidant and osmoregulatory properties. Taurine's influx and efflux are mainly mediated through the ubiquitous expression of the sodium/chloride‑dependent taurine transporter, located on the plasma membrane. The significance of the taurine transporter has been shown in various organ malfunctions in taurine‑transporter‑null mice. The taurine transporter differentially responds to various cellular stimuli including ionic environment, electrochemical charge, and pH changes. The renal system has been used as a model to evaluate the factors that significantly determine the regulation of taurine transporter regulation.

Cytoprotective Effect of Taurine against Hydrogen Peroxide-Induced Oxidative Stress in UMR-106 Cells through the Wnt/β-Catenin Signaling Pathway

Osteoporosis development is closely associated with oxidative stress and reactive oxygen species (ROS). Taurine has potential antioxidant effects, but its role in osteoblasts is not clearly understood. The aim of this study was to determine the protective effects and mechanisms of actions of taurine on hydrogen peroxide (H₂O₂)-induced oxidative stress in osteoblast cells. UMR-106 cells were treated with taurine prior to H₂O₂ exposure. After treatment, cell viability, apoptosis, intracellular ROS production, malondialdehyde content, and alkaline phosphate (ALP) activity were measured. We also investigated the protein levels of β-catenin, ERK, CHOP and NF-E2-related factor 2 (Nrf2) along with the mRNA levels of Nrf2 downstream antioxidants. The results showed that pretreatment of taurine could reverse the inhibition of cell viability and suppress the induced apoptosis in a dose-dependent manner: taurine significantly reduced H₂O₂-induced oxidative damage and expression of CHOP, while it induced protein expression of Nrf2 and β-catenin and activated ERK phosphorylation. DKK1, a Wnt/β-catenin signaling inhibitor, significantly suppressed the taurine-induced Nrf2 signaling pathway and increased CHOP. Activation of ERK signaling mediated by taurine in the presence of H₂O₂ was significantly inhibited by DKK1. These data demonstrated that taurine protects osteoblast cells against oxidative damage via Wnt/β-catenin-mediated activation of the ERK signaling pathway.

Ursodeoxycholic acid suppresses the formation of fructose/streptozotocin-induced diabetic cataract in rats

The main objective of this study was to investigate the potential protective effect of ursodeoxycholic acid (UDCA) on fructose/streptozotocin-induced diabetic cataract in rats. The diabetic model (DM) was induced through the administration of 10% fructose in drinking water for 2 weeks followed by streptozotocin injection (intraperitoneal). One week later, hyperglycemia was assisted and diabetic animals were treated with UDCA either as local eye drops (0.5% solution, four times/day) or orally (100 mg/kg b.w.). Cataract formation was monitored biweekly and scored into four stages. After 12 weeks of treatment, rats were subjected to ophthalmological examination, and then, their blood and lenses were prepared for biochemical analysis of glucose, insulin, reduced glutathione, total antioxidant capacity, malondialdehyde, hydrogen peroxide, caspase-12, and lenticular total proteins. In addition, tertiary structure and conformational changes of lenticular soluble proteins were analyzed using SDS-PAGE and UV absorption while changes in lenticular α-crystallin structure were investigated using intrinsic tryptophan fluorescence. Results demonstrated that both local and oral UDCA restored the normal levels of lens T-AOC, MDA, H₂ O₂ , and caspase-12 and improved noticeably the levels of the lens GSH and total proteins. In addition, conformational and tertiary structure changes of soluble lens proteins were significantly reduced in UDCA-treated groups. Morphological examination of lenses revealed decreased score of cataract progression in UDCA-treated groups compared to DM animals. It was concluded that UDCA decreased the incidence of diabetic cataract by maintaining the antioxidant status, reducing the endoplasmic reticulum stress, and suppressing the structural changes of soluble lens proteins.

Ameliorative effects of taurine against diabetes: a review

Diets in rats and humans have shown promising results. Taurine improved glucagon activity, promoted glycemic stability, modified glucose levels, successfully addressed hyperglycemia via advanced glycation end-product control, improved insulin secretion and had a beneficial effect on insulin resistance. Taurine treatment performed well against oxidative stress in brain, increased the secretion of required hormones and protected against neuropathy, retinopathy and nephropathy in diabetes compared with the control. Taurine has been observed to be effective in treatments against diabetic hepatotoxicity, vascular problems and heart injury in diabetes. Taurine was shown to be effective against oxidative stress. The mechanism of action of taurine cannot be explained by one pathway, as it has many effects. Several of the pathways are the advanced glycation end-product pathway, PI3-kinase/AKT pathway and mitochondrial apoptosis pathway. The worldwide threat of diabetes underscores the urgent need for novel therapeutic measures against this disorder. Taurine (2-aminoethane sulfonic acid) is a natural compound that has been studied in diabetes and diabetes-induced complications.

Effect of taurine on cell proliferation and apoptosis human lung cancer A549 cells

To investigate the effects of taurine on cell proliferation and apoptosis, the human lung cancer A549 cell line and xenograft tumors in nude mice were used. The effects of taurine on cell proliferation and apoptosis were observed at time points of 24, 48 and 72 h after treatment using an MTT assay to detect the survival rate, and flow cytometry to detect the apoptotic rate. Western blot analysis was performed to examine the levels of p53 upregulated modulator of apoptosis (PUMA), BCL2, apoptosis regulator (Bcl-2) and BCL2-associated X, apoptosis regulator (Bax) in A549 cells. The level of PUMA, Bax and Bcl-2 proteins in the mouse xenograft tumors treated with taurine and/or exogenous PUMA were assessed by immunohistochemistry, with taurine suppressing the proliferation of the human lung cancer A549 cell line in a concentration-dependent manner, and it significantly enhanced the apoptosis rate at all concentrations. Taurine induced the significant upregulation of PUMA and Bax, but led to downregulation of Bcl-2. In comparison to the control group, taurine treatment markedly reduced the volume and weight of A549-derived xenograft tumors in nude mice. Expression of PUMA and Bax were upregulated in the xenograft tumors following taurine treatment, whereas Bcl-2 was downregulated. In addition, the inhibitory effect of taurine and exogenous PUMA on tumor growth was significantly higher than that of a single treatment of taurine or exogenous PUMA. It can therefore be concluded that taurine can inhibit cell proliferation of the human lung cancer A549 cell line and the growth of the xenograft tumors, whereas PUMA serves an important role in taurine-induced growth suppression.

The Benefits of the Citrus Flavonoid Diosmin on Human Retinal Pigment Epithelial Cells under High-Glucose Conditions

We investigate diosmin for its effect on the ARPE-19 human retinal pigment epithelial cells exposed to high glucose, a model of diabetic retinopathy (DR). After incubation for 4 days with a normal (5 mmol/L) concentration of D-glucose, ARPE-19 cells were exposed separately to normal or high concentrations of D-glucose (30 mmol/L) with or without diosmin at different concentrations (0.1, 1, 10 μg/mL) for another 48 h. Next, we assessed cell viability, reactive oxygen species (ROS) generation and antioxidant enzyme activities. In order to examine the underlying molecular mechanisms, we meanwhile analyzed the expressions of Bax, Bcl-2, total and phosphorylated JNK and p38 mitogen-activated protein kinase (MAPK). Diosmin dose dependently enhanced cell viability following high glucose treatment in ARPE-19 cells. The activities of superoxide dismutase and glutathione peroxidase, as well as the levels of reduced glutathione were decreased, while it was observed that levels of ROS in high glucose cultured ARPE-19 cells increased. High glucose also disturbed Bax and Bcl-2 expression, interrupted Bcl-2/Bax balance, and triggered subsequent cytochrome c release into the cytosol and activation of caspase-3. These detrimental effects were ameliorated dose dependently by diosmin. Furthermore, diosmin could abrogate high glucose-induced apoptosis as well as JNK and P38 MAPK phosphorylation in ARPE-19 cells. Our results suggest that treatment ARPE-19 cells with diosmin halts hyperglycemia-mediated oxidative damage and thus this compound may be a candidate for preventing the visual impairment caused by DR.

Prophylactic role of taurine and its derivatives against diabetes mellitus and its related complications

Taurine is a conditionally essential amino acid present in the body in free form. Mammalian taurine is synthesized in the pancreas via the cysteine sulfinic acid pathway. Anti-oxidation and anti-inflammation are two main properties through which it exerts its therapeutic effects. Many studies have shown its excellent therapeutic potential against diabetes mellitus and related complications like diabetic neuropathy, retinopathy, nephropathy, hematological dysfunctions, reproductive dysfunctions, liver and pancreas related complications etc. Not only taurine, a number of its derivatives have also been reported to be important in ameliorating diabetic complications. The present review has been aimed to describe the importance of taurine and its derivatives against diabetic metabolic syndrome and related complications.

Cataracts and strabismus associated with hand rearing using artificial milk formulas in Bengal tiger (Panthera tigris spp tigris) cubs

The aim of this investigation is to describe the potential contributing nutritional factors involved in the development of ophthalmic and dermatologic changes in four Bengal tiger (Panthera tigris spp tigris) cubs fed an artificial milk formula. The affected animals were compared with two other tiger cubs that had been nursed by their dam naturally. After the first clinical signs appeared, the tiger cubs underwent ophthalmic evaluation. Severe symmetric generalized alopecia over the trunk, sparing the head and distal portion of the front and rear limbs, bilateral cataracts and strabismus were noticed. Milk and blood from the mother, as well as blood from the healthy and affected cubs were collected in order to evaluate complete blood counts, serum chemistry values, and amino acid levels. The amino acid concentrations in the artificial formula were also evaluated for comparison to the milk from the dam. The concentration of taurine, arginine, phenylalanine, tryptophan and histidine were very low in the artificial formulas as compared to the dam´s milk. The tiger cubs that received the artificial formula had lower levels of the amino acids listed previously as compared to those that nursed from the dam naturally. Taurine, as well as arginine, phenylalanine, tryptophan and histidine deficiency appeared to be possible causes of the development of skin problems, cataracts and strabismus in the tiger cubs fed with these particular artificial milk replacers. In the future, special attention should be given in order to make sure that adequate levels of these amino acids are present in artificial milk for tiger cubs.

Magnesium taurate prevents cataractogenesis via restoration of lenticular oxidative damage and ATPase function in cadmium chloride-induced hypertensive experimental animals

Previously we found that hypertension potentiates the risk the cataractogenesis. In the present study, we investigated the protective effects of magnesium taurate (MgT) on hypertension and associated lenticular damages against cadmium chloride (CdCl₂)-induced hypertensive animals. Male Sprague-Dawley albino rats (150-180g) were assigned to five experimental groups (n=6). Among the five groups, normal group received 0.3% carboxymethyl cellulose (10ml/kg/day, p.o.). Hypertension control group received CdCl₂ (0.5mg/kg/day, i.p.). Tests and standard groups received MgT (3 and 6mg/kg/day, p.o.) and amlodipine (3mg/kg/day, p.o.) concurrently with CdCl₂ respectively_, for six consecutive weeks. Blood pressure, heart rate, and eyes were examined biweekly, and pathophysiological parameters in serum and eye lenses were evaluated after six weeks of the experimental protocol. The chronic administration of MgT concurrently with CdCl₂ significantly restored the blood pressure, serum and lens antioxidants (CAT, SOD, GPx, and GSH), MDA level, and ions (Na⁺, K⁺, and Ca²⁺). Additionally, MgT treatment led to significant increase in the lens proteins (total and soluble), Ca²⁺ ATPase, and Na⁺K⁺ ATPase activity as compared to hypertension control group. Ophthalmoscope observations indicated that MgT treatments delayed the progression of cataract against the hypertensive state. The study shows that MgT prevents the progression of cataractogenesis via restoration of blood pressure, lenticular oxidative damages, and lens ATPase functions in the hypertensive state. The results suggest that MgT supplement may play a beneficial role to manage hypertension and associated cataractogenesis.

Cinnamaldehyde Attenuates Cataractogenesis via Restoration of Hypertension and Oxidative Stress in Fructose-Fed Hypertensive rats

OBJECTIVES

Several studies have revealed that systemic hypertension is strongly associated with cataractogenesis. However, the pathophysiology and treatment is often unclear. In this study, we evaluated the anti-cataractogenic effect of cinnamaldehyde (CA), a natural organic compound, in rats with fructose-induced hypertension.

METHODS

The rats were divided into six groups. For six weeks, the normal group received a suspension of 0.5% carboxy methyl cellulose (10 mL/kg/day, p.o.) while five other groups received a 10% (w/v) fructose solution in their drinking water to induce hypertension. By the end of the third week hypertension had been induced in all the animals receiving fructose. From the beginning of the fourth week to the end of the sixth week, one of those five groups (control) continued to receive only 10% (w/v) fructose solution, one group (standard) received ramipril (1 mg/kg/day, p.o.) plus 10% (w/v) fructose solution, and three groups (experimental) received CA at doses of 20, 30, and 40 mg/kg/day p.o., plus 10% (w/v) fructose solution. Blood pressure was measured weekly using a non-invasive blood pressure apparatus. After six weeks, the animals were sacrificed, and the anti-cataractogenic effects on the eye lenses were evaluated.

RESULTS

Administration of fructose elevated both the systolic and the diastolic blood pressures, which were significantly reduced by CA at all dose levels. In the control group, a significant increase in the malonaldehyde (MDA) level and decreases in the total protein, Ca(2+)adenosine triphosphate (ATP)ase activity, glutathione peroxidase, catalase, superoxide dismutase and glutathione levels, as compared to the normal group, were observed. Administration of CA at all doses significantly restored the enzymatic, non-enzymatic, antioxidants, total protein, and Ca(2+)ATPase levels, but decreased the MDA level, as compared to the control group.

CONCLUSION

The present study revealed that CA modulated the antioxidant parameters of the serum and lens homogenates in hypertension-induced cataractogenic animals.

Hypertension potentiates cataractogenesis in rat eye through modulation of oxidative stress and electrolyte homeostasis

Purpose

To evaluate modes of cataractogenesis in the hypertensive state by using different hypertensive animal models, including fructose, cadmium chloride (CdCl₂), N_ω-nitro-l-arginine methyl ester (l-NAME), and two-kidney, one clip (2K1C) method.

Methods

Male Sprague–Dawley albino rats (150–180 g) were divided into different groups, each group containing six animals. Hypertension was induced in animals via six weeks administration of fructose (10% solution in drinking water), CdCl₂ (0.5 mg/kg/day, i.p.), and l-NAME (20 mg/kg/day, p.o.) in their respective groups and NaCl (0.9% solution in drinking water) in the 2K1C group. The Ramipril-treated group (2 mg/kg/day, orally) served as a standard group for the 2K1C animal model. Blood pressure was measured biweekly using non-invasive blood pressure system. The biochemical parameters in serum and eye lenses were evaluated after six weeks of the experimental protocol.

Results

Hypertensive animal models showed significant induction of systolic and diastolic blood pressure and modulation of oxidative stress through depletion of antioxidants, including glutathione peroxidase, catalase, superoxide dismutase, glutathione, and elevation of malondialdehyde in serum and eye lenses. A significant elevation of ionic contents (Na⁺ and Ca²⁺) and reduction of total protein and Ca²⁺ ATPase activity in eye lenses were observed in all hypertensive animal models except l-NAME when compared with the normal group. The significant restoration of the antioxidants, Malondialdehyde (MDA) total protein, and ionic contents in the eye lenses concomitant with reduction of blood pressure were observed in the ramipril-treated group as compared to the 2K1C animal model. The results indicate that the fructose, CdCl_2, and 2K1C models showed pronounced cataractogenic effects in the rat eye lenses.

Conclusion

Based on our findings, it can be concluded that systemic hypertension significantly increases the risk of cataract formation in the rat eyes via modulation of the antioxidant defense mechanism and electrolyte homeostasis.

Switching to instant black coffee modulates sodium selenite-induced cataract in rats

The influence of daily consumption of some common beverages on the development of cataract in rats was investigated. Total phenol content was determined in the beverages and an oral standardized dose of total phenols from each beverage was given to the treated rats. Weaned male albino rats were used and divided into five groups (n=7). Rats were fed Ain 93G and administered the standardized dose of instant coffee, black tea and hibiscus beverages for 30 days. On day 14 all rats were injected with a single dose of sodium selenite (Na₂SeO₃) 15 µmol/kg bodyweight, except the control groups NC (negative control, did not receive Na₂SeO₃) and PC (positive control, was already injected on day 1 of the study). The rats were continued on Ain 93G and the standardized dose for another 16 days. Positive control rats were used. Total phenols were 210, 40, and 44 mg/g dry weight gallic acid equivalent in black coffee, black tea, and hibiscus, respectively. Decreased levels (statistically significant P<0.05) of malondialdehyde, total nitric oxide, Ca-ATPase, tumor necrosis factor-α, interleukin-1β, superoxide dismutase, and conversely, increased levels (statistically significant P<0.05) of total protein, reduced glutathione, catalase were found in the lenses of the coffee group compared to PC. There are co-phenol substances in the instant black coffee that promoted coffee to be the most effective beverage.

Damaging effects of hyperglycemia on cardiovascular function: spotlight on glucose metabolic pathways

The incidence of cardiovascular complications associated with hyperglycemia is a growing global health problem. This review discusses the link between hyperglycemia and cardiovascular diseases onset, focusing on the role of recently emerging downstream mediators, namely, oxidative stress and glucose metabolic pathway perturbations. The role of hyperglycemia-mediated activation of nonoxidative glucose pathways (NOGPs) [i.e., the polyol pathway, hexosamine biosynthetic pathway, advanced glycation end products (AGEs), and protein kinase C] in this process is extensively reviewed. The proposal is made that there is a unique interplay between NOGPs and a downstream convergence of detrimental effects that especially affect cardiac endothelial cells, thereby contributing to contractile dysfunction. In this process the AGE pathway emerges as a crucial mediator of hyperglycemia-mediated detrimental effects. In addition, a vicious metabolic cycle is established whereby hyperglycemia-induced NOGPs further fuel their own activation by generating even more oxidative stress, thereby exacerbating damaging effects on cardiac function. Thus NOGP inhibition, and particularly that of the AGE pathway, emerges as a novel therapeutic intervention for the treatment of cardiovascular complications such as acute myocardial infarction in the presence hyperglycemia.

Screening of microorganisms from deep-sea mud for Antarctic krill (Euphausia superba) fermentation and evaluation of the bioactive compounds

Twelve kinds of strains were isolated from deep-sea mud which can use Antarctic krill powder as the sole carbon/nitrogen source. These strains were identified by 16s rDNA sequence analysis and grouped into eight different genera, including Bacillus, Shewanella, Psychrobacter, Klebsiella, Macrococcus, Aeromonas, Acinetobacter, and Saccharomyces. After fermentation of Antarctic krill powder using these strains, bioactive compounds including total phenolics, free amino acids, and enzyme activities were investigated. Meanwhile, antioxidant activities of the fermentation liquors were also detected. Results showed that bioactive compounds could be effectively produced through fermentation process by these strains, of which three strains (Bacillus subtilis OKF04, Macrococcus caseolyticus OKF09, and Aeromonas veronii OKF10) could produce more than 650 mg/L total phenolics or 2000 mg/L total free amino acids. In terms of enzyme activities, almost all of the strains showed protease activity and amylase activity, but only Bacillus cereus OKF01 and Bacillus megaterium OKF05 performed lipase activity and chitinase activity, respectively. All of the fermentation liquors showed antioxidant activity, within which Bacillus megaterium OKF05, Macrococcus caseolyticus OKF09, and Aeromonas veronii OKF10 displayed it more prominently. These results demonstrate that the Antarctic krill powder could be effectively converted by microorganisms isolated from deep-sea mud for production of bioactive compounds mixture.

Taurine induces the apoptosis of breast cancer cells by regulating apoptosis-related proteins of mitochondria

Taurine (Tau), the most abundant free amino acid in humans has numerous potential health benefits through its antioxidant and anti-inflammatory properties. However, limited studies have assessed its effect on tumors and the antitumor mechanism remains unknown. The present study investigated the cellular and molecular changes induced by Tau, leading to the induction of apoptosis in human breast cancer cell lines MCF-7 and MDA-MB-231. MCF-7 is p53 proficient (p53+/+) and MDA-MB-231 is a p53 null mutant (p53-/-). Cell proliferation and viability were assessed by MTT. Flow cytometry and hoechst33342 fluorescent staining were employed to detect apoptosis. Spectrophotometry was used to detect caspase-3 activity. Reverse transcription-polymerase chain reaction and western blot analysis were used to detect the levels of mRNA and proteins of p53-upregulated modulator of apoptosis (PUMA), Bax and Bcl-2. Finally, the affect of Tau on the growth of MDA-MB-231-cell-nude mice xenografts was examined. In the study, Tau inhibited growth and induced apoptosis of the two cell lines in a concentration- and time-dependent manner. Notably, the inhibitory effect of Tau on p53-/- cancer cells was clearly significant compared to the p53+/+ cancer cells. Further studies showed that Tau promoted apoptosis in human breast cancer cells and inhibited the growth of tumor in nude mice by inducing the expression of PUMA, which further up- and downregulated the expression of Bax and Bcl-2 protein, giving rise to increased activation of caspase-3. Collectively, these results indicate that Tau is a potent candidate for the chemotherapy of breast cancer through increasing the PUMA expression independent of p53 status.

Mechanism of taurine-induced apoptosis in human colon cancer cells

Taurine (Tau) has been shown to possess cancer therapeutic effect through induction of apoptosis, while the underlying molecular mechanism of its anti-cancer effect is not well understood. PUMA (p53-upregulated modulator of apoptosis) plays an important role in the process of apoptosis induction in a variety of human tumor cells in both p53-dependent and -independent manners. However, whether PUMA is involved in the process of Tau-induced apoptosis in cancer cells has not been well studied. In the present study, we treated human colorectal cancer cells HT-29 (mutant p53) and LoVo (wild-type p53) with different concentrations of Tau, which led to the repression of cell proliferation and induction of apoptosis in both cell lines. Meanwhile, we also observed the increased expression of PUMA and high Bax/Bcl-2 ratios. To determine the role of PUMA in Tau-induced apoptosis, we used small interfering RNA interference to suppress PUMA expression. As a result, apoptosis was decreased in response to Tau treatment. All these results indicated that PUMA plays a critical role in Tau-induced apoptosis pathway in human colorectal cancer cells. Demonstration of the molecular mechanism involved in the anti-tumor effect of Tau may be useful in the therapeutic target selection for p53-deficient colorectal cancer.

Ellagic acid protects against carrageenan-induced acute inflammation through inhibition of nuclear factor kappa B, inducible cyclooxygenase and proinflammatory cytokines and enhancement of interleukin-10 via an antioxidant mechanism

There are several hypotheses that explain the process of acute inflammation, including free radical overproduction, pro-inflammatory enzyme activation, and release of pro-inflammatory cytokines. In this study, the protective role of ellagic acid against carrageenan-induced acute inflammation was assessed. In addition, the immunomodulatory action, the antioxidant effects, and the role of COX-2 and NF-κB were also investigated. Inflammation was induced by the injection of 100 μl of 1.5% carrageenan solution. Ellagic acid (10, 25, 50, 100 and 200mg/kg), indomethacin (10 mg/kg), meloxicam (4 mg/kg), and saline, were injected 2h before carrageenan injection. The percentage inhibition in the paw weight was calculated. Paws, MDA, NO, GSH, IL-1β, TNF-α, IL-10 and NF-κB mRNA expression were estimated. Formalin fixed hind paws were used for histopathological examination and immunohistochemical staining for COX-2 expression. Ellagic acid, meloxicam and indomethacin reduced paws, edema, MDA and NO formation. In addition, all of them restored the depleted GSH contents in the paws. Ellagic acid, meloxicam and indomethacin reduced NF-κB mRNA expression. Ellagic acid ameliorated COX-2 expression; meloxicam inhibited while indomethacin failed. Both ellagic acid and meloxicam increased IL-10 while indomethacin did not. The docking study revealed a high affinity of ellagic acid towards COX-2. Ellagic acid exhibited a potent anti-inflammatory effect against carrageenan-induced inflammation. The mechanisms of ellagic acid induced protection were proved to be due to reduction of NO, MDA, IL-1β, TNF-α, COX-2 and NF-κB expression and induction of GSH and IL-10 production.

Effects of magnesium taurate on the onset and progression of galactose-induced experimental cataract: in vivo and in vitro evaluation

Cataract, a leading cause of blindness, is characterized by lenticular opacities resulting from denaturation of lens proteins due to activation of calcium-dependent enzyme, calpain. Magnesium (Mg(2+)) plays an important role not only in maintaining a low lenticular calcium (Ca(2+)) and sodium concentration but also in preserving the lens redox status. Taurine has also been shown to reduce lenticular oxidative stress. Present study evaluated the anticataract effects of magnesium taurate in vivo and in vitro. Among the five groups of 9 Sprague Dawley rats each, two groups received 30% galactose diet with topical (GDMT) or oral treatment (GDMO) with magnesium taurate. Two groups received 30% galactose diet with topical (GDT) or oral vehicle (GDO). Remaining 1 group received normal diet (ND). Weekly slit lamp examination was done during 21 days experimental period and then all rats were sacrificed; Ca/Mg ratio and antioxidant parameters including reduced glutathione (GSH), catalase and superoxide dismutase (SOD) activities were measured in the isolated lenses using ELISA. In the in vitro study, 2 groups of 10 normal rat lenses were incubated in Dulbecco's Modified Eagle's Medium (DMEM) with galactose while 1 similar group was incubated in DMEM without galactose. In one of the groups, galactose containing medium was supplemented with magnesium taurate. After 48 h of incubation, lenses were photographed and Ca(2+)/Mg(2+) ratio and antioxidant parameters were measured as for in vivo study. The in vivo study, at the end of experimental period, demonstrated delay in the development of cataract with a mean opacity index of 0.53 ± 0.04 and 0.51 ± 0.03 in GDMO (p < 0.05 versus GDO) and GDMT (p < 0.01 versus GDT) respectively. Histopathological grading showed a lower mean value in treated groups, however, the differences from corresponding controls were not significant. Lenticular Ca(2+)/Mg(2+) ratio with a mean value of 1.20 ± 0.26 and 1.05 ± 0.26 in GDMO and GDMT was significantly lower than corresponding controls (p < 0.05) and in GDMT no significant difference was observed from ND. Lenticular GSH and catalase activities were significantly lower and SOD activity was significantly higher in all galactose fed groups. However, in GDMT, GSH and catalase were significantly higher than corresponding control with mean values of 0.96 ± 0.30 μmol/gm lens weight and 56.98 ± 9.86 μmol/g lens protein respectively (p < 0.05 for GSH and p < 0.01 for catalase). SOD activity with mean values of 13.05 ± 6.35 and 13.27 ± 7.61 units/mg lens protein in GDMO and GDMT respectively was significantly lower compared to corresponding controls (p < 0.05) signifying lesser upregulation of SOD due to lesser oxidative stress in treated groups. In the in vitro study, lenses incubated in magnesium taurate containing medium showed less opacity and a lower mean Ca(2+)/Mg(2+) ratio of 1.64 ± 0.03, which was not significantly different from lenses incubated in DMEM without galactose. Lens GSH and catalase activities were restored to normal in lenses incubated in magnesium taurate containing medium. Both in vivo and in vitro studies demonstrated that treatment with magnesium taurate delays the onset and progression of cataract in galactose fed rats by restoring the lens Ca(2+)/Mg(2+) ratio and lens redox status.

Protective effects of taurine against alloxan-induced diabetic cataracts and refraction changes in New Zealand White rabbits

The present study examined the protective effects of taurine on alloxan-induced diabetic cataracts and lens damage in male New Zealand White rabbits. The animals were randomly divided into three treatment groups: (1) normal control (vehicle administration); (2) diabetes (100 mg/kg alloxan administration); and (3) diabetes + taurine (1% [w/v] taurine dissolved in drinking water and alloxan administration). The results showed that alloxan-induced diabetes caused significant (p < 0.05) hyperglycemia, hyperopic refraction shifts, cataract formation and lens damage compared with the normal control group. In contrast, the administration of taurine for 24 weeks significantly ameliorated the alloxan-induced elevated levels of blood glucose, level of hyperopic refraction error shifts in the eyes and progression of diabetic cataract formation in the lens in rabbits. Moreover, histopathology showed that the taurine supplement reduced the incidence of lens lesions induced by hyperglycemia. Overall, the studies demonstrate that taurine exhibits potent protective effects against alloxan-induced diabetic cataracts and refraction changes in rabbits.

Radiation protection following nuclear power accidents: a survey of putative mechanisms involved in the radioprotective actions of taurine during and after radiation exposure

There are several animal experiments showing that high doses of ionizing radiation lead to strongly enhanced leakage of taurine from damaged cells into the extracellular fluid, followed by enhanced urinary excretion. This radiation-induced taurine depletion can itself have various harmful effects (as will also be the case when taurine depletion is due to other causes, such as alcohol abuse or cancer therapy with cytotoxic drugs), but taurine supplementation has been shown to have radioprotective effects apparently going beyond what might be expected just as a consequence of correcting the harmful consequences of taurine deficiency per se. The mechanisms accounting for the radioprotective effects of taurine are, however, very incompletely understood. In this article an attempt is made to survey various mechanisms that potentially might be involved as parts of the explanation for the overall beneficial effect of high levels of taurine that has been found in experiments with animals or isolated cells exposed to high doses of ionizing radiation. It is proposed that taurine may have radioprotective effects by a combination of several mechanisms: (1) during the exposure to ionizing radiation by functioning as an antioxidant, but perhaps more because it counteracts the prooxidant catalytic effect of iron rather than functioning as an important scavenger of harmful molecules itself, (2) after the ionizing radiation exposure by helping to reduce the intensity of the post-traumatic inflammatory response, and thus reducing the extent of tissue damage that develops because of severe inflammation rather than as a direct effect of the ionizing radiation per se, (3) by functioning as a growth factor helping to enhance the growth rate of leukocytes and leukocyte progenitor cells and perhaps also of other rapidly proliferating cell types, such as enterocyte progenitor cells, which may be important for immunological recovery and perhaps also for rapid repair of various damaged tissues, especially in the intestines, and (4) by functioning as an antifibrogenic agent. A detailed discussion is given of possible mechanisms involved both in the antioxidant effects of taurine, in its anti-inflammatory effects and in its role as a growth factor for leukocytes and nerve cells, which might be closely related to its role as an osmolyte important for cellular volume regulation because of the close connection between cell volume regulation and the regulation of protein synthesis as well as cellular protein degradation. While taurine supplementation alone would be expected to exert a therapeutic effect far better than negligible in patients that have been exposed to high doses of ionizing radiation, it may on theoretical grounds be expected that much better results may be obtained by using taurine as part of a multifactorial treatment strategy, where it may interact synergistically with several other nutrients, hormones or other drugs for optimizing antioxidant protection and minimizing harmful posttraumatic inflammatory reactions, while using other nutrients to optimize DNA and tissue repair processes, and using a combination of good diet, immunostimulatory hormones and perhaps other nontoxic immunostimulants (such as beta-glucans) for optimizing the recovery of antiviral and antibacterial immune functions. Similar multifactorial treatment strategies may presumably be helpful in several other disease situations (including severe infectious diseases and severe asthma) as well as for treatment of acute intoxications or acute injuries (both mechanical ones and severe burns) where severely enhanced oxidative and/or nitrative stress and/or too much secretion of vasodilatory neuropeptides from C-fibres are important parts of the pathogenetic mechanisms that may lead to the death of the patient. Some case histories (with discussion of some of those mechanisms that may have been responsible for the observed therapeutic outcome) are given for illustration of the likely validity of these concepts and their relevance both for treatment of severe infections and non-infectious inflammatory diseases such as asthma and rheumatoid arthritis.

The potential usefulness of taurine on diabetes mellitus and its complications

Taurine (2-aminoethanesulfonic acid) is a free amino acid found ubiquitously in millimolar concentrations in all mammalian tissues. Taurine exerts a variety of biological actions, including antioxidation, modulation of ion movement, osmoregulation, modulation of neurotransmitters, and conjugation of bile acids, which may maintain physiological homeostasis. Recently, data is accumulating that show the effectiveness of taurine against diabetes mellitus, insulin resistance and its complications, including retinopathy, nephropathy, neuropathy, atherosclerosis and cardiomyopathy, independent of hypoglycemic effect in several animal models. The useful effects appear due to the multiple actions of taurine on cellular functions. This review summarizes the beneficial effects of taurine supplementation on diabetes mellitus and the molecular mechanisms underlying its effectiveness.

Different experimental approaches in modelling cataractogenesis: An overview of selenite-induced nuclear cataract in rats

Cataract, the opacification of eye lens, is the leading cause of blindness worldwide. At present, the only remedy is surgical removal of the cataractous lens and substitution with a lens made of synthetic polymers. However, besides significant costs of operation and possible complications, an artificial lens just does not have the overall optical qualities of a normal one. Hence it remains a significant public health problem, and biochemical solutions or pharmacological interventions that will maintain the transparency of the lens are highly required. Naturally, there is a persistent demand for suitable biological models. The ocular lens would appear to be an ideal organ for maintaining culture conditions because of lacking blood vessels and nerves. The lens in vivo obtains its nutrients and eliminates waste products via diffusion with the surrounding fluids. Lens opacification observed in vivo can be mimicked in vitro by addition of the cataractogenic agent sodium selenite (Na₂SeO₃) to the culture medium. Moreover, since an overdose of sodium selenite induces also cataract in young rats, it became an extremely rapid and convenient model of nuclear cataract in vivo. The main focus of this review will be on selenium (Se) and its salt sodium selenite, their toxicological characteristics and safety data in relevance of modelling cataractogenesis, either under in vivo or in vitro conditions. The studies revealing the mechanisms of lens opacification induced by selenite are highlighted, the representatives from screening for potential anti-cataract agents are listed.

Taurine plays a beneficial role against cadmium-induced oxidative renal dysfunction

The present study has been carried out to investigate the role of taurine (2-aminoethanesulfonic acid), a conditionally essential amino acid, in ameliorating cadmium-induced renal dysfunctions in mice. Cadmium chloride (CdCl(2)) has been selected as the source of cadmium. Intraperitoneal administration of CdCl(2 )(at a dose of 4 mg/kg body weight for 3 days) caused significant accumulation of cadmium in renal tissues and lessened kidney weight to body weight ratio. Cadmium administration reduced intracellular ferric reducing/antioxidant power (FRAP) of renal tissues. Levels of serum marker enzymes related to renal damage, creatinine and urea nitrogen (UN) have been elevated due to cadmium toxicity. Cadmium exposure diminished the activities of enzymatic antioxidants, superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx) and glucose-6-phosphate dehydrogenase (G6PD) as well as non-enzymatic antioxidant, reduced glutathione (GSH) and total thiols. On the other hand, the levels of oxidized glutathione (GSSG), lipid peroxidation, protein carbonylation, DNA fragmentation, concentration of superoxide radicals and activities of cytochrome P450 enzymes (CYP P450s) have been found to increase due to cadmium intoxication. Treatment with taurine (at a dose of 100 mg/kg body weight for 5 days) before cadmium intoxication prevented the toxin-induced oxidative impairments in renal tissues. The beneficial role of taurine against cadmium-induced renal damage was supported from histological examination of renal segments. Vitamin C, a well-established antioxidant was used as the positive control in the study. Experimental evidence suggests that both taurine and vitamin C provide antioxidant defense against cadmium-induced renal oxidative injury. Combining all, results suggest that taurine protects murine kidneys against cadmium-induced oxidative impairments, probably via its antioxidative property.

Cadmium-induced neurological disorders: prophylactic role of taurine

The present study was conducted to investigate whether the conditionally essential amino acid taurine could play any protective role against the potent neurotoxin cadmium (Cd)-induced oxidative impairment in mice brain. Cd administration in the form of CdCl(2 )(at a dose of 4 mg kg(-1) body weight for 3 days, orally) increased the intracellular accumulation of metallic Cd, reactive oxygen species and super oxide radicals. The toxin also augmented the extent of lipid peroxidation, protein carbonylation and the levels of glutathione disulfide. Activities of the antioxidant enzymes and the levels of reduced glutathione as well as total thiols have been significantly decreased due to Cd exposure. In addition, the toxin also caused significant DNA degradation (as evidenced from DNA smearing and diphenylamine reaction). Oral administration of taurine (at a dose of 100 mg kg(-1) body weight for 5 days) was found to be very effective in the prevention of Cd-induced oxidative impairment in the brain tissue of experimental mice. In addition, taurine treatment could also prevent the reduction in the in vivo antioxidant power linearly up to a dose of 100 mg kg(-1) body weight. The preventive role of taurine against Cd-induced cerebral oxidative damage was supported by the observation under scanning electron microscope as well as histological examination of brain segments. To validate the experimental results, a well-known water soluble antioxidant, vitamin C, was used as the positive control in the study. In all, the results suggest that taurine plays a beneficial role against Cd-induced cerebral oxidative stress.