Dietary curcumin prevents ocular toxicity of naphthalene in rats

SUMO1-regulated DBC1 promotes p53-dependent stress-induced apoptosis of lens epithelial cells

Deleted in breast cancer 1 (DBC1) was initially identified from a homozygously deleted region in human chromosome 8p21. It has been well established that DBC1 plays a dual role during cancer development. Depending on the physiological context, it can promote or inhibit tumorigenesis. Whether it plays a role in lens pathogenesis remains elusive. In the present study, we demonstrated that DBC1 is highly expressed in lens epithelial cells from different vertebrates and in retina pigment epithelial cells as well. Moreover, DBC1 is SUMOylated through SUMO1 conjugation at K591 residue in human and mouse lens epithelial cells. The SUMOylated DBC1 is localized in the nucleus and plays an essential role in promoting stress-induced apoptosis. Silence of DBC1 attenuates oxidative stress-induced apoptosis. In contrast, overexpression of DBC1 enhances oxidative stress-induced apoptosis, and this process depends on p53. Mechanistically, DBC1 interacts with p53 to regulate its phosphorylation status at multiple sites and the SUMOylation of DBC1 enhances its interaction with p53. Together, our results identify that DBC1 is an important regulator mediating stress-induced apoptosis in lens, and thus participates in control of lens cataractogenesis.

Expression of αA-crystallin (CRYAA) in vivo and in vitro models of age-related cataract and the effect of its silencing on HLEB3 cells

AIM

To investigate the expression of αA-crystallin (CRYAA) in age-related cataract (ARC) models and its role in lens epithelial cells (LECs).

METHODS

We used Flow cytometry to detect the apoptosis and cell cycle in HLEB3 cells and Real-time fluorescence quantitative polymerase chain reaction to detect the expression of CRYAA mRNA in HLEB3 and in rabbit lens. The expression of CRYAA in HLEB3 cells and rabbit lenses as well as the proteins related to apoptosis and autophagy in transfected cells were detected by western blotting. The lens structure in rabbits was investigated using hematoxylin-eosin staining. Protein thermostability assay was performed to detect the thermal stability of rabbit lens proteins. CCK- 8 assay was used to detect the viability of transfected cells, and the transfection was recorded by fluorescence photography.

RESULTS

Hydrogen peroxide can promote apoptosis and arrest the cell cycle in HLEB3 cells, and naphthalene can cause cataract formation and damage the structure of the lens in rabbits. Both ARC models can reduce the expression of CRYAA. The expression of CRYAA silencing increased apoptosis and autophagy in HLEB3 cells.

Recent progress and research trend of anti-cataract pharmacology therapy: A bibliometric analysis and literature review

Cataract is the leading cause of blindness worldwide. Cataract phacoemulsification combined with intraocular lens implantation causes great burden to global healthcare, especially for low- and middle-income countries. Such burden would be significantly relieved if cataracts can effectively be treated or delayed by non-surgical means. Excitingly, novel drugs have been developed to treat cataracts in recent decades. For example, oxysterols are found to be able to innovatively reverse lens clouding, novel nanotechnology-loaded drugs improve anti-cataract pharmacological effect, and traditional Chinese medicine demonstrates promising therapeutic effects against cataracts. In the present review, we performed bibliometric analysis to provide an overview perspective regarding the research status, hot topics, and academic trends in the field of anti-cataract pharmacology therapy. We further reviewed the curative effects and molecular mechanisms of anti-cataract drugs such as lanosterol, metformin, resveratrol and curcumin, and prospected the possibility of their clinical application in future.

MAB21L1 promotes survival of lens epithelial cells through control of αB-crystallin and ATR/CHK1/p53 pathway

The male abnormal gene family 21 (mab21), was initially identified in C. elegans. Since its identification, studies from different groups have shown that it regulates development of ocular tissues, brain, heart and liver. However, its functional mechanism remains largely unknown. Here, we demonstrate that Mab21L1 promotes survival of lens epithelial cells. Mechanistically, Mab21L1 upregulates expression of αB-crystallin. Moreover, our results show that αB-crystallin prevents stress-induced phosphorylation of p53 at S-20 and S-37 through abrogating the activation of the upstream kinases, ATR and CHK1. As a result of suppressing p53 activity by αB-crystallin, Mab21L1 downregulates expression of Bak but upregulates Mcl-1 during stress insult. Taken together, our results demonstrate that Mab21L1 promotes survival of lens epithelial cells through upregulation of αB-crystallin to suppress ATR/CHK1/p53 pathway.

Curcumin, the active substance of turmeric: its effects on health and ways to improve its bioavailability

Turmeric (Curcuma longa L.) is a spice utilized widely in India, China, and Southeast Asia as an aromatic stimulant, a food preservative, and coloring material. The commonly used names of turmeric are castor saffron, turmeric, and saffron root. Turmeric is a yellow-orange polyphenolic natural substance derived from C. longa rhizomes. It has been used to treat common inflammatory diseases, tumors, biliary diseases, anorexia, cough, topical wounds, diabetic injuries, liver disorders, rheumatism, and sinusitis. Extensive studies on the biological properties and pharmacological consequences of turmeric extracts have been conducted in recent years. Curcumin, the primary yellow biocomponent of turmeric, has anti-inflammatory, antioxidant, anticarcinogenic, antidiabetic, antibacterial, antiprotozoal, antiviral, antifibrotic, immunomodulatory, and antifungal properties. Defense assessment tests showed that curcumin is tolerated well at high doses, without adverse effects. Thus, curcumin is a highly active biological material with the potential to treat different diseases in modern medicine. This review article focuses on curcumin's biological characteristics. The most popular methods for curcumin encapsulation are also discussed. Several effective techniques and approaches have been proposed for curcuminoid capsulation, including nanocomplexing, gelation, complex coacervation, electrospraying, and solvent-free pH-driven encapsulation. This review also highlights curcumin's chemical properties, allowing the readers to expand their perspectives on its use in the development of functional products with health-promoting properties. © 2021 Society of Chemical Industry.

Soursop juice enhanced seminal antioxidant defence and semen quality of rabbit bucks in extremely dry climatic condition of Southwestern Nigeria

Heat induced stress associated with dry climatic conditions in the tropics does have adverse effects reproduction in rabbits, and this in-turn impacts negatively on the income of rabbit farmers. However, natural products might prove to be a reliable, safe and cheap remedy for ameliorating reproductive such anomalies in rabbits. The potential of soursop for mitigating heat induced reproductive deficiency in rabbit bucks was investigated during the peak of dry climatic conditions in southwestern Nigeria. Sixty mixed breed (New Zealand white x Chinchilla) adult rabbit bucks were allotted to five treatments of four replicates (3 bucks per replicate) each in a completely randomized design. Soursop (Annona muricata) fruit was processed into juice using standard procedures and was designated as soursop juice. The juice was administered orally daily per kg body weight (BW), 0.55ml/kgBW distilled water (control), 0.55 ml/kgBW soursop juice, 1.11 ml/kgBW soursop juice, 1.67 ml/kgBW soursop juice and 2.22 ml/kgBW soursop juice to designated treatments 1 to 5, respectively for 56 days. Semen samples were collected with an improvised artificial vagina on the 28th and 56th day of the study, semen quality and seminal oxidative status were evaluated using standard procedures. Results showed that rabbit buck exposed to heat stress had lower semen quality, seminal antioxidants and increased seminal lipid peroxidation. However, the consumption of soursop juice lowered lipid peroxidation and enhanced (p < 0.05) antioxidant production in the seminal fluid of heat-stressed bucks than bucks on control group. Bucks' semen quality and antioxidant status peaks in heat-stressed bucks gavaged 2.22 ml/kgBW soursop juice and gives 100% recovery from the effects of heat induced stress. It can be concluded that 2.22 ml/kgBW soursop juice administered for 56 days did enhance spermatozoa quality and mitigated lipid peroxidation by improving antioxidant capacity of male rabbits in a dose dependent manner on extremely dry climatic conditions.

MicroRNA-124 regulates lens epithelial cell apoptosis by affecting Fas alternative splicing by targeting polypyrimidine tract-binding protein in age-related cataract

BACKGROUND

Age-related cataract (ARC) is a primary cause of visual blindness worldwide. Lens epithelial cell (LEC) apoptosis, in which Fas plays an essential role, is a vital cytological basis for cataractogenesis. However, the regulatory mechanism of Fas-dependent LEC apoptosis is not well understood. This study aimed to investigate whether MicroRNA (miRNA)-124 can regulate LEC apoptosis by targeting polypyrimidine tract-binding protein (PTB) and thereby affecting Fas alternative splicing in ARC.

METHODS

Lens capsule samples from patients with ARC and cornea donors with a transparent lens were collected. HLE-B3 cells were cultured and treated with hydrogen peroxide (H₂ O₂ ) to establish an apoptosis model in LECs. The expression of miRNA-124, PTB, Fas, and Fas isoforms in tissues and cell lines was assessed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blotting, polyacrylamide gel electrophoresis, and flow cytometry. The miRNA-124 mimic and inhibitor were transfected into HLE-B3 cells, and the effects of the miRNA-124/PTB/Fas pathway in LECs were assessed by analysis of their related targets.

RESULTS

High expression of miRNA-124 and membrane Fas (mFas) mRNA and decreased PTB expression were observed in the lens capsule samples. In cells undergoing H₂ O₂ -induced apoptosis, mFas expression was increased, accompanied by decreased PTB and increased miRNA-124 expression. Subsequently, miRNA-124 upregulation suppressed PTB expression, elevated the mFas level without affecting total Fas expression and promoted apoptosis; miRNA-124 downregulation exerted the opposite effects.

CONCLUSION

This study revealed that miRNA-124 promotes LEC apoptosis in ARC by upregulating mFas through targeted inhibition of PTB. Moreover, the identification of the miRNA-124/PTB/Fas pathway provides novel insight into Fas-dependent LEC apoptosis.

Development of Animal Models for Lens and Corneal Diseases Using N-Methyl-N-Nitrosourea

Purpose

N-methyl-N-nitrosourea (MNU) is an alkylating toxicant with potent mutagenic ability. This study was designed to induce apoptosis in lens epithelial cells (LECs) and corneal endothelial cells (CECs) via MNU administration. We sought to build ocular disease models of cataract and corneal endothelial decompensation.

Methods

MNU was delivered into the intraperitoneal cavities of neonatal rats and the anterior chambers of adult rabbits. The MNU-treated animals were then subjected to a series of functional and morphological analyses at various time points.

Results

MNU treatment induced pervasive apoptosis of LECs and CECs. These effects were dose and time dependent. Mature cataracts were found in neonatal rats 3 weeks after MNU treatment. Histological analysis revealed that MNU toxicity induced swelling, vacuolation, and liquefaction in lens fibers of MNU-treated rats. Pentacam examination showed that the average density of rat lens increased significantly after MNU administration. Terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) analysis showed pervasive apoptotic staining in the lenses of MNU-treated rats. In rabbit eyes, intracameral treatment with MNU induced corneal edema and significantly increased central corneal thickness, which peaked at P14. Morphological and immunohistochemical analysis showed that CECs were effectively ablated in the MNU-treated rabbits. The expression of 8-OHdG increased significantly in the cornea of MNU-treated rabbits, compared with vehicle-treated controls.

Conclusions

MNU is sufficient to induce ocular cell apoptosis in animal models. These models of MNU-induced cataract and corneal endothelial decompensation represent valuable tools for efforts to develop relevant therapies.

The potential health benefits of dietary natural plant products in age related eye diseases

In the past decade, there has been a tremendous increase in the number of cases of age-related eye diseases such as age-related macular degeneration (AMD), cataract, diabetic retinopathy and glaucoma. These diseases are the leading causes of visual impairment and blindness all over the world and are associated with many pathological risk factors such as aging, pollution, high levels of glucose (hyperglycaemia), high metabolic rates, and light exposure. These risk factors lead to the generation of uncontrollable reactive oxygen species (ROS), which causes oxidative stress. Oxidative stress plays a crucial role in the pathogenesis of age-related eye diseases through the activation of nuclear factor kappa B (NF-κB), vascular endothelial growth factor (VEGF), and lipid peroxidation, which leads to the production of inflammatory cytokines, angiogenesis, protein and DNA damages, apoptosis that causes macular degeneration (AMD), cataract, diabetic retinopathy and glaucoma. This review provides updated information on the beneficial effects of dietary natural plant products (DPNPs) against age-related eye diseases. In this review, supplementation of DPNPs demonstrated preventive and therapeutic effects on people at risk of or with age-related eye diseases due to their capacity to scavenge free radicals, ameliorate inflammatory molecules, neutralize the oxidation reaction that occurs in photoreceptor cells, decrease vascular endothelial growth factor and the blood-retinal barrier and increase the antioxidant defence system. However, further experiments and clinical trials are required to establish the daily doses of DPNPs that will safely and effectively prevent age-related eye diseases.

Resveratrol delay the cataract formation against naphthalene-induced experimental cataract in the albino rats

Oxidative stress-induced toxicity plays a major role in ocular diseases such as retinal degeneration, age-related cataract (ARC) formation and macular dystrophy. In this study, we explored the possible role of resveratrol (RSV) at the different dose levels (10, 20 and 40 mg/kg/day, ip) in an experimental model of naphthalene (1 g/kg/day, po)-induced age-related cataracts. Morphological changes in the eyes of the rats in two groups, the RSV and the ARC groups, were monitored weekly, and biochemical parameters in the lenses were assessed after completion of the experimental work. A comparison between the rats in the two groups showed that treatments at RSV doses of 20 and 40 mg/kg/day significantly retarded lenticular opacity, restored antioxidants (CAT, SOD, GPX, GSH), Ca²⁺ ATPase function, and protein contents, and reduced lipid peroxidation in the lenses of the animals in the RSV group. The treatment with resveratrol at a dose of 10 mg/kg/day did not show any anti-cataractogenic effects. Based on the results of our investigation, we conclude that supplemental doses of resveratrol at 40 mg/kg/day effectively prevent cataract formation associated with the aging via increased soluble protein contents and Ca²⁺ homeostasis, apart from the antioxidant restoration. The results demonstrate that RSV treatment may be considered as a promising preventive or supplemental measure for delaying and/or preventing the formation of ARCs.

Some Biological Properties of Curcumin: A Review

Curcumin (diferuloyl methane), a small-molecular weight compound isolated from the roots of Curcuma longa L. (family Zingiberaceae), has been used traditionally for centuries in Asia for medicinal, culinary and other purposes. A large number of in vitro and in vivo studies in both animals and man have indicated that curcumin has strong antioxidant, anti-carcinogenic, anti-inflammatory, anti-angiogenic, antispasmodic, antimicrobial, anti-parasitic and other activities. The mechanisms of some of these actions have recently been intensively investigated. Curcumin inhibits the promotion/ progression stage of carcinogenesis by induction of apoptosis and the arrest of cancer cells in the S, G2/M cell cycle phase. The compound inhibits the activity of growth factor receptors. The anti-inflammatory properties of curcumin are mediated through their effects on cytokines, lipid mediators, eicosanoids and proteolytic enzymes. Curcumin scavenges the superoxide radical, hydrogen peroxide and nitric oxide, and inhibits lipid peroxidation. These actions may be the basis for many of its pharmacological and therapeutic properties.

Curcumin is a nutraceutical of low toxicity, which has been used successfully in a number of medical conditions that include cataracts, cystic fibrosis, and prostate and colon cancers.

Ocular non-P450 oxidative, reductive, hydrolytic, and conjugative drug metabolizing enzymes

Metabolism in the eye for any species, laboratory animals or human, is gaining rapid interest as pharmaceutical scientists aim to treat a wide range of so-called incurable ocular diseases. Over a period of decades, reports of metabolic activity toward various drugs and biochemical markers have emerged in select ocular tissues of animals and humans. Ocular cytochrome P450 (P450) enzymes and transporters have been recently reviewed. However, there is a dearth of collated information on non-P450 drug metabolizing enzymes in eyes of various preclinical species and humans in health and disease. In an effort to complement ocular P450s and transporters, which have been well reviewed in the literature, this review is aimed at presenting collective information on non-P450 oxidative, hydrolytic, and conjugative ocular drug metabolizing enzymes. Herein, we also present a list of xenobiotics or drugs that have been reported to be metabolized in the eye.

Curcumin, A Potential Therapeutic Candidate for Anterior Segment Eye Diseases: A Review

Curcumin, the major curcuminoid of the turmeric, has been extensively used in many countries since ancient time for preventing and/or treating a multitude of diseases. This review is to illustrate the researches on the properties of curcumin and its potential therapeutic efficacy in major anterior segment eye diseases. The bio-medical potential of curcumin is restricted because of its low solubility and digestive bioavailability. This review will discuss promising research in improving curcumin bioavailability through structural modification. In vitro and in vivo research made progress in studying the beneficial effects of curcumin on major anterior segment eye diseases, including anti-angiogenesis effect in corneal diseases; anti-inflammation or anti-allergy effects in dry eye disease, conjunctivitis, anterior uveitis; anti-proliferation and pro-apoptosis effects in pterygium; anti-oxidative stress, anti-osmotic stress, anti-lipid peroxidation, pro-apoptosis, regulating calcium homeostasis, sequestrating free radicals, protein modification and degradation effects in cataracts; neuroprotective effects in glaucoma. Curcumin exhibited to be a potent therapeutic candidate for treating those anterior segment eye diseases.

miR‑34a suppresses proliferation and induces apoptosis of human lens epithelial cells by targeting E2F3

microRNA (miRNA) is abnormally expressed in numerous diseases, and it was intimately associated with cell proliferation and apoptosis. However, the mechanism by which miRNAs control cataractogenesis remains unclear. In the current study, it was demonstrated that miR-34a was highly expressed in the cataractous lens by stem-loop reverse transcription-quantitative polymerase chain reaction. Trying to investigate the role of miR-34a in human lens epithelial cells, miR-34a mimics were transfected into SRA01/04 cells, and this suppressed proliferation and induced apoptosis. Subsequently, E2F3 was confirmed as a direct target of miR-34a. Downregulation of E2F3 by small interfering (si) RNA siE2F3 resulted in proliferation inhibition and apoptosis of SRA01/04 cells. Furthermore, it was demonstrated that miR-34a and siE2F3 downregulated E2F3 expression at a protein level. In summary, the current study demonstrated that miR-34a suppressed the proliferation and induced apoptosis of SRA01/04 cells by downregulating E2F3. These observations provide novel insights with potential therapeutic applications for the treatment of cataracts.

Prospects of curcumin as an additive in storage solutions: a study on erythrocytes

BACKGROUND/AIM

Curcumin, a naturally occurring antioxidant, shows a wide variety of medicinal properties. The possibility of utilizing curcumin as an additive in storage solutions of blood has not been explored. The purpose of this study was to analyze the effect of curcumin on erythrocytes during storage.

MATERIALS AND METHODS

Blood obtained from rats was stored (4 °C) for 20 days in citrate-phosphate-dextrose-adenine-1 solution. Samples were divided into four groups: 1) Controls; 2) Curcumin 10 mM; 3) Curcumin 30 mM; and 4) Curcumin 60 mM. Every fifth day, hemoglobin, superoxide, antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase (GSH-Px)), lipid peroxidation (conjugate dienes and malondialdehyde (MDA)), protein oxidation (advanced oxidation protein products (AOPP) and sulfhydryls (P-SH)), and hemolysis were analyzed.

RESULTS

Hemoglobin was successfully maintained, while superoxide dismutase increased initially and decreased towards the end of storage. Superoxide, catalase, GSH-Px, conjugate dienes, and AOPP were lower in the curcumin groups than they were in the controls. MDA was higher in the curcumin groups than in the controls. P-SH increased in the curcumin groups, while hemolysis increased in all groups.

CONCLUSION

Curcumin maintained hemoglobin and modulated antioxidant enzymes throughout storage. However, curcumin could not protect all proteins and lipids from oxidative damage completely. This study opens up new avenues for using curcumin, in combination with other antioxidants, as a component in storage solutions.

The Comparative Studies of Binding Activity of Curcumin and Didemethylated Curcumin with Selenite: Hydrogen Bonding vs Acid-Base Interactions

In this report, the in vitro relative capabilities of curcumin (CCM) and didemethylated curcumin (DCCM) in preventing the selenite-induced crystallin aggregation were investigated by turbidity tests and isothermal titration calorimetry (ITC). DCCM showed better activity than CCM. The conformers of CCM/SeO3(2-) and DCCM/SeO3(2-) complexes were optimized by molecular orbital calculations. Results reveal that the selenite anion surrounded by CCM through the H-bonding between CCM and selenite, which is also observed via IR and NMR studied. For DCCM, the primary driving force is the formation of an acid-base adduct with selenite showing that the phenolic OH group of DCCM was responsible for forming major conformer of DCCM. The formation mechanisms of selenite complexes with CCM or DCCM explain why DCCM has greater activity than CCM in extenuating the toxicity of selenite as to prevent selenite-induced lens protein aggregation.

Botanical compounds: effects on major eye diseases

Botanical compounds have been widely used throughout history as cures for various diseases and ailments. Many of these compounds exhibit strong antioxidative, anti-inflammatory, and antiapoptotic properties. These are also common damaging mechanisms apparent in several ocular diseases, including age-related macular degeneration (AMD), glaucoma, diabetic retinopathy, cataract, and retinitis pigmentosa. In recent years, there have been many epidemiological and clinical studies that have demonstrated the beneficial effects of plant-derived compounds, such as curcumin, lutein and zeaxanthin, danshen, ginseng, and many more, on these ocular pathologies. Studies in cell cultures and animal models showed promising results for their uses in eye diseases. While there are many apparent significant correlations, further investigation is needed to uncover the mechanistic pathways of these botanical compounds in order to reach widespread pharmaceutical use and provide noninvasive alternatives for prevention and treatments of the major eye diseases.

Antioxidants and cataract

The major causes for cataract formation are free radicals, and these free radicals are neutralized by the presence of endogenous antioxidants in the eye. Using xenobiotics, it has been confirmed that free radicals mediate the formation of cataract. Two cataract model-selenite model and the diabetic cataract model-have been developed to study the pathophysiology of cataract formation due to free radicals and the role of antioxidants during the process of cataractogenesis. This review focuses on natural compounds with antioxidant properties that could actually be applied as an interventional strategy on a large scale and are also relatively inexpensive. A brief overview of plants with antioxidant properties that in addition possess potential anti-cataract properties has been discussed. In addition to plants, three natural compounds (curcumin, vitamin C and vitamin E), on which a lot of data exist showing anti-cataract and antioxidant activities, have also been discussed. These antioxidants can be supplemented in the diet for a better defence against free radicals. Studies on vitamin C and vitamin E have proved that they are capable of preventing lipid peroxidation, thereby preventing the generation of free radicals, but their efficacy as anti-cataract agent is questionable. Unlike vitamins C and E, curcumin is well established as an anti-cataract agent, but the issue of curcumin bioavailability is yet to be addressed. Nanotechnology proves to be a promising area in increasing the curcumin bioavailability, but still a lot more research needs to be done before the use of curcumin as an effective anti-cataract agent for humans.

Phytochemicals in ocular health: Therapeutic potential and delivery challenges

Diabetic retinopathy (DR) and age-related macular degeneration (AMD) are the leading causes of blindness in adults. The impact of these conditions on the quality of life is increasing in significance with a rise in life expectancy. The role of hyperglycemia, oxidative stress and inflammatory responses in the development and/or progression of DR and AMD, and several other sight threatening ocular diseases, is well established. In proliferative retinopathy, signals sent by the retina for nourishment, triggers the growth of fragile and abnormal blood vessels. Changes in ocular pressure may lead to rupture of these blood vessels causing severe vision problems. Recent in vitro and preclinical studies demonstrate that certain phytochemicals possessing potent antioxidant and anti-inflammatory activity and ocular blood flow enhancing properties may be very useful in the treatment of, or as a prophylactic measure for, DR and AMD. Apart from these properties they have also been investigated for their anti-bacterial, hormonal, enzyme stimulation, and anti-angiogenic activities. The attractive aspect of these potential therapeutic candidates is that they can act on multiple pathways identified in the etiology of DR, AMD, cataract and other ocular diseases. However, results from clinical trials have been somewhat ambiguous, raising questions about the concentrations of these bioflavonoids achieved in the neural retina following oral administration. Unfortunately, as of date, an efficient noninvasive means to deliver therapeutic agents/candidates to the back-of-the eye is still not available. This review examines some of these promising natural agents and discusses the challenges encountered in delivering them to the posterior segment ocular tissues through the oral route.

The Protective Effect of Curcumin on Ionizing Radiation-induced Cataractogenesis in Rats

OBJECTIVE

The aim of the study was to determine the protective effect of curcumin against ionizing radiation-induced cataract in the lens of rats.

MATERIAL AND METHODS

Rats were divided into six groups. Group 1: Control, Group 2: Dimethyl sulfoxide (DMSO), Group 3: DMSO+curcumin, Group 4: Irradiation, Group 5: Irradiation+DMSO, Group 6: Irradiation+DMSO+curcumin. A 15 Gy total dose was given to 4, 5, 6 groups for radiation damage. Curcumin (100 mg/kg) was dissolved in DMSO and given by intragastric intubation for 28 days. At the end of the experiment, lenses were graded and enucleated. The lenticular activity of the antioxidant enzymes, total antioxidant and glutathione peroxidase (GSH-Px), and the malondialdehyde (MDA) were measured.

RESULTS

100% Cataract was seen in the irradiation group. Cataract rate fell to 40% and was limited at grade 1 and 2 in the curcumin group. In the irradiation group, antioxidant enzyme levels were decreased, MDA levels were increased. There was an increase in antioxidant enzyme levels and a significant decrease in MDA in the group which was given curcumin.

CONCLUSION

Curcumin has antioxidant and radioprotective properties and is likely to be a valuable agent for protection against ionizing radiation. Hence, it may be used as an antioxidant and radioprotector against radiation-induced cataractogenesis.

Determination of cytotoxic and genotoxic effects of naphthalene, 1-naphthol and 2-naphthol on human lymphocyte culture

Naphthalene, a bicyclic aromatic hydrocarbon, has toxic effects on animals and humans. Although recent studies stressed on the genotoxic and cytotoxic effects of naphthalene and its metabolites on eukaryotic cells, there is a big controversy among the results of these studies. The aim of this study is to investigate the effects of naphthalene and its metabolites on the cytotoxicity and genotoxicity in the human lymphocytes in the culture. The genotoxic and cytotoxic effects of naphthalene and its metabolites, 1-naphthol and 2-naphthol, were studied using cytotoxicity test (lactate dehydrogenase and cell proliferation (WST-1) assays) and DNA fragmentation assay (terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay). Naphthalene and its metabolites had no significant cytotoxic effect on treated samples when compared with untreated ones. This result was also confirmed by WST-1 assay. In the TUNEL assay, DNA fragmentation was induced significantly by all concentrations of naphthalene and 2-naphthol and 50 and 100 µM concentrations of 1-naphthol ( p < 0.05 or 0.001). In the DNA fragmentation, the most effective dose of 2-naphthol (63%) was 100 µM, when compared with negative control group (13%). These results suggest that naphthalene and its metabolites, 1-naphthol and 2-naphthol, may cause DNA damage on human lymphocytes.

Excessive milk intake as a risk factor, probably associated with oxidative stress, in experimental naphthalene-initiated cataract in rats

AIM

To determine whether a diet containing excessive amounts of milk aggravates naphthalene-initiated cataracts in a common animal model of age-related human cataract.

METHODS

Ninety Sprague-Dawley rats were fed a natural diet supplemented with either water (group A), normal amounts of milk (group B), excessive amounts of milk (group C), naphthalene plus water (group D), naphthalene plus normal amounts of milk (group E), naphthalene plus excessive amounts of milk (group F). Cataract development was monitored weekly using a slit lamp and lens gray value analysis. Concentrations of reactive oxygen species (ROS), reduced glutathione (GSH) and malondialdehyde (MDA) in rat lenses were measured to determine the role of oxidative stress in cataract induction.

RESULTS

By week 4, the cortical gray value was significantly higher in group F than that in group D, and the cortical gray value was significantly higher in group D than in group A. However, by week 8, no significant differences were observed among groups C, F, B, E and A. ROS concentrations in lenses of rats of groups C and F were slightly higher than in those of groups B, E and A, but ROS concentrations in group F were significantly higher than in the other groups receiving naphthalene (i.e. groups D and E). GSH concentrations in group F were significantly lower than in the other groups. MDA concentrations in group F were significantly higher than in the other groups receiving naphthalene, indicating increased lipid peroxidation induced by naphthalene plus excessive intake of milk.

CONCLUSIONS

Our results provide quantitative evidence that excessive intake of milk aggravates naphthalene-initiated cataracts, which is probably due to oxidative damage caused by increased ROS.

Rescue of photoreceptor degeneration by curcumin in transgenic rats with P23H rhodopsin mutation

The P23H mutation in the rhodopsin gene causes rhodopsin misfolding, altered trafficking and formation of insoluble aggregates leading to photoreceptor degeneration and autosomal dominant retinitis pigmentosa (RP). There are no effective therapies to treat this condition. Compounds that enhance dissociation of protein aggregates may be of value in developing new treatments for such diseases. Anti-protein aggregating activity of curcumin has been reported earlier. In this study we present that treatment of COS-7 cells expressing mutant rhodopsin with curcumin results in dissociation of mutant protein aggregates and decreases endoplasmic reticulum stress. Furthermore we demonstrate that administration of curcumin to P23H-rhodopsin transgenic rats improves retinal morphology, physiology, gene expression and localization of rhodopsin. Our findings indicate that supplementation of curcumin improves retinal structure and function in P23H-rhodopsin transgenic rats. This data also suggest that curcumin may serve as a potential therapeutic agent in treating RP due to the P23H rhodopsin mutation and perhaps other degenerative diseases caused by protein trafficking defects.

p53 codon 271 CGT to CAT mutant fraction does not increase in nasal respiratory and olfactory epithelia of rats exposed to inhaled naphthalene

A 2-year rat tumor bioassay testing whole body exposure to naphthalene (NA) vapor found a significant increase in nasal respiratory epithelial adenomas in male rats and in olfactory epithelial neuroblastomas in female rats. To obtain mechanistic insight into NA-induced nasal carcinogenesis, NA dose-response was characterized in nasal epithelium using a tumor-relevant endpoint. Specifically, levels of p53 codon 271 CGT to CAT mutation were measured in nasal respiratory and olfactory epithelium of NA-exposed male and female rats by allele-specific competitive blocker-PCR (ACB-PCR). Male and female, 8-9 week-old F344 rats (5 rats/group) were exposed to 0, 0.1, 1.0, 10, and 30ppm NA vapor for 13 weeks (6h/day, 5 days/week). The geometric mean p53 mutant fraction (MF) levels in nasal epithelium of control treatment groups ranged between 2.05 × 10(-5) and 3.05 × 10(-5). No significant dose-related changes in p53 mutant fraction (MF) were observed in the olfactory or respiratory epithelia of female rats. However, statistically significant treatment-related differences were observed in male respiratory and olfactory epithelium, with the p53 MF in the respiratory epithelium of male rats exposed to 30ppm NA significantly lower than that in controls. Further, a significant trend of decreasing p53 MF with increasing dose was observed in the male respiratory epithelium. Of the tissue types analyzed, respiratory epithelium is the most sensitive to the cytotoxic effects of NA, suggesting cytotoxicity may be responsible for the loss of p53 mutation. Because ACB-PCR has been used successfully to detect the effects of known mutagenic carcinogens, the absence of any significant increases in p53 MF associated with NA exposure adds to the weight of evidence that NA does not operate through a directly mutagenic mode of action.

Decreased chaperone activity of alpha-crystallins in naphthalene-induced cataract possibly results from C-terminal truncation

Naphthalene-induced cataract has been extensively used to test potential anticataract drugs. Because the morphology as well as the toxic manifestations of naphthalene-induced cataract are reported to be similar to that of age-related cataract, naphthalene cataractogenesis in rats has been used as a valuable animal model to study the aetiology of age-related cataract in humans. This study aimed to determine whether the molecular chaperone activity of the alpha-crystallins was altered in naphthalene-induced cataract, and to clarify the possible mechanism for these changes. The data showed that the chaperone activity of the alpha-crystallins decreased in naphthalene-induced cataract. By mass spectrometry, C-terminal truncation of 16 amino acids and other post-translational modifications such as acetylation, phosphorylation, oxidation and carbamylation of the alpha-crystallins were detected. Furthermore, the results suggested that, at the proteomics level, naphthalene-induced cataract is a valuable animal model for the study of age-related cataract in humans.

alpha-Lipoic acid alters post-translational modifications and protects the chaperone activity of lens alpha-crystallin in naphthalene-induced cataract

PURPOSE

To evaluate whether alpha-lipoic acid (LA) inhibits lens opacity of naphthalene-induced cataract by altering post-translational modifications (PTMs) and protecting the chaperone activity of alpha-crystallins.

METHODS

Forty-five Sprague-Dawley rats were divided into three groups: control, naphthalene, and naphthalene plus LA. Cataracts were induced by oral administration of 1 g naphthalene/kg body weight/day. Rats in the naphthalene plus LA group were also fed 30 mg LA/day. The development of naphthalene-initiated cataract was monitored every week by slit lamp microscopy for nine weeks, then the lens proteins were separated by HPLC, and peaks corresponding to alpha-crystallins were resolved on 2-DE. The spots of 2-DE were subjected to mass spectrometry to identify PTMs. Chaperone activity of alpha-crystallins was measured by heat-induced aggregation of betaL-crystallin.

RESULTS

The lenses of rats fed with naphthalene plus LA exhibited less light scattering than that fed with only naphthalene at three weeks after treatment (P < 0.01). C-terminal truncated alphaA crystallin was detected in naphthalene-induced cataract and was abrogated by LA treatment. Several other post-translational modifications were identified including methylation, phosphorylation, acetylation, carbamylation, and oxidation.

CONCLUSIONS

Our data are the first to show PTM changes induced by naphthalene in rat lenses. Our findings also indicate that LA can inhibit naphthalene-induced lens opacity by altering PTM and protecting the chaperone activity of alpha-crystallins.

Targeting inflammation-induced obesity and metabolic diseases by curcumin and other nutraceuticals

Extensive research within the past two decades has revealed that obesity, a major risk factor for type 2 diabetes, atherosclerosis, cancer, and other chronic diseases, is a proinflammatory disease. Several spices have been shown to exhibit activity against obesity through antioxidant and anti-inflammatory mechanisms. Among them, curcumin, a yellow pigment derived from the spice turmeric (an essential component of curry powder), has been investigated most extensively as a treatment for obesity and obesity-related metabolic diseases. Curcumin directly interacts with adipocytes, pancreatic cells, hepatic stellate cells, macrophages, and muscle cells. There, it suppresses the proinflammatory transcription factors nuclear factor-kappa B, signal transducer and activators of transcription-3, and Wnt/beta-catenin, and it activates peroxisome proliferator-activated receptor-gamma and Nrf2 cell-signaling pathways, thus leading to the downregulation of adipokines, including tumor necrosis factor, interleukin-6, resistin, leptin, and monocyte chemotactic protein-1, and the upregulation of adiponectin and other gene products. These curcumin-induced alterations reverse insulin resistance, hyperglycemia, hyperlipidemia, and other symptoms linked to obesity. Other structurally homologous nutraceuticals, derived from red chili, cinnamon, cloves, black pepper, and ginger, also exhibit effects against obesity and insulin resistance.

Effect of curcumin on selenite-induced cataractogenesis in Wistar rat pups

PURPOSE

The present study was aimed at investigating the possible antioxidant potential of curcumin at a dose of 75 mg/kg body weight on selenite-induced cataract in experimental rat pups.

METHODS

Group I: Control rat pups receiving physiological saline; Group II: Selenite-induced group (15 microM/kg body wt); Group III: Selenite-induced group co-treated with curcumin (single dose of curcumin orally 75 mg/kg body wt); Group IV: Selenite-induced animals post-treated (after 24 hrs) with curcumin at a dose mentioned for group III; Group V: Rat pups were pretreated with curcumin (dose as mentioned in Group III), 24 hrs before the administration of selenite. Encapsulated lenses liver, kidney, and serum were analyzed for antioxidant enzymes and malondialdehyde, a marker of lipid peroxidation.

RESULTS

Intraperitoneal injection of sodium selenite (15 microM/kg body wt) to 8-10-day-old rat pups led to severe oxidative stress in eye lens as evidenced by enhanced LPO levels that led to cataract formation. Sodium selenite also led to decrease in activities of SOD, GST, GPx, CAT with simultaneous decrease in the levels of GSH, vitamin C, and vitamin E. Treatment with curcumin (75 mg/kg body wt) led to a significant decrease in the levels of LPO, enzymic antioxidants, and nonenzymic antioxidants, which were similar to that of control.

CONCLUSIONS

Curcumin suppressed selenite-induced oxidative stress and cataract formation in rat pups. The presence of oxidative stress in selenite cataract development and its prevention by curcumin support the possibility that the natural consumption of curcumin in food can help prevent the onset of senile cataract.

Sustained oxidative stress inhibits NF-kappaB activation partially via inactivating the proteasome

NF-kappaB is a family of important transcription factors involved in many cellular functions, such as cell survival, proliferation, and stress responses. Many studies indicate that NF-kappaB is a stress-sensitive transcription factor and its activation is regulated by reactive oxygen species. In previous studies, we and others demonstrated that this transcription factor can be activated by transient oxidative stress. However, the effects of sustained oxidative stress on NF-kappaB activation are not clear. The objective of this study was to determine the effects of sustained oxidative stress on NF-kappaB activation and to elucidate the signaling events affected by sustained oxidative stress. Human lens epithelial cells (HLEC) that were subjected to 4 h of continuous influx of hydrogen peroxide were used to investigate the effects of sustained oxidative stress on NF-kappaB activation. The data showed that, unlike transient oxidative stress, sustained exposure of HLEC to physiologically relevant levels of H(2)O(2) (50-100 microM for 4 h) did not induce the degradation of I-kappaB and activation of NF-kappaB, but attenuated TNFalpha-induced degradation of I-kappaB and activation of NF-kappaB. Sustained exposure of HLEC to these levels of H(2)O(2) also inactivated proteasome activity by 50-80%. Consistent with the role of the proteasome in degradation of I-kappaB and activation of NF-kappaB, treatment of HLEC with proteasome inhibitors also attenuated TNFalpha-induced I-kappaB degradation and NF-kappaB activation. The data also indicate that activation of NF-kappaB is essential for the cells to recover from oxidative stress. Inhibiting NF-kappaB activation during recovery from transient oxidative stress significantly reduced the cell viability. Together, these data indicate that sustained oxidative stress may inactivate the proteasome and subsequently inhibit NF-kappaB activation by impeding the degradation of I-kappaB. The oxidative inactivation of the proteasome and subsequent impairment of NF-kappaB activation may contribute to the death of lens epithelial cells, a common feature associated with cataract.

CURCUMIN: THE INDIAN SOLID GOLD

Turmeric, derived from the plant Curcuma longa, is a gold-colored spice commonly used in the Indian subcontinent, not only for health care but also for the preservation of food and as a yellow dye for textiles. Curcumin, which gives the yellow color to turmeric, was first isolated almost two centuries ago, and its structure as diferuloylmethane was determined in 1910. Since the time of Ayurveda (1900 Bc) numerous therapeutic activities have been assigned to turmeric for a wide variety of diseases and conditions, including those of the skin, pulmonary, and gastrointestinal systems, aches, pains, wounds, sprains, and liver disorders. Extensive research within the last half century has proven that most of these activities, once associated with turmeric, are due to curcumin. Curcumin has been shown to exhibit antioxidant, anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer activities and thus has a potential against various malignant diseases, diabetes, allergies, arthritis, Alzheimer's disease, and other chronic illnesses. These effects are mediated through the regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other enzymes. Curcumin exhibits activities similar to recently discovered tumor necrosis factor blockers (e.g., HUMIRA, REMICADE, and ENBREL), a vascular endothelial cell growth factor blocker (e.g., AVASTIN), human epidermal growth factor receptor blockers (e.g., ERBITUX, ERLOTINIB, and GEFTINIB), and a HER2 blocker (e.g., HERCEPTIN). Considering the recent scientific bandwagon that multitargeted therapy is better than monotargeted therapy for most diseases, curcumin can be considered an ideal "Spice for Life".

Antioxidant effect of the marine algae Chlorella vulgaris against naphthalene-induced oxidative stress in the albino rats

Alcoholic extract of the marine algae Chlorella vulgaris was examined for its free radical scavenging effect with reference to naphthalene-induced lipid peroxidation in serum, liver, and kidney of rats. Initially, upon naphthalene intoxication (435 mg/kg body weight, intraperitoneally), the lipid peroxidation activity increased significantly (P < 0.001), and in contrast, the enzymic antioxidants (superoxide dismutase, catalase, glutathione peroxidase) and non-enzymic antioxidants (glutathione, ascorbic acid, and alpha-tocopherol) levels decreased remarkably. When the naphthalene stressed rats were treated with Chlorella vulgaris extract (70 mg/kg body weight, orally), the lipid peroxidation activity reduced significantly (P < 0.001) and the activities of both the enzymic and non-enzymic antioxidants increased reaching near control values. The minimum concentration (70 mg/l) of the extract that exhibited maximum (85%) free radical scavenging activity was chosen for the experimental study. The present results suggest that Chlorella vulgaris extract exerts its chemo-preventive effect by modulating the antioxidants status and lipid peroxidation during naphthalene intoxication.

Effects of curcumin on retinal oxidative stress and inflammation in diabetes

BACKGROUND

Oxidative stress and inflammation are implicated in the pathogenesis of retinopathy in diabetes. The aim of this study is to examine the effect of curcumin, a polyphenol with antioxidant and anti-inflammatory properties, on diabetes-induced oxidative stress and inflammation in the retina of rats.

METHODS

A group of streptozotocin-induced diabetic rats received powdered diet supplemented with 0.05% curcumin (w/w), and another group received diet without curcumin. The diets were initiated soon after induction of diabetes, and the rats were sacrificed 6 weeks after induction of diabetes. The retina was used to quantify oxidative stress and pro-inflammatory markers.

RESULTS

Antioxidant capacity and the levels of intracellular antioxidant, GSH (reduced form of glutathione) levels were decreased by about 30-35%, and oxidatively modified DNA (8-OHdG) and nitrotyrosine were increased by 60-70% in the retina of diabetic rats. The levels of interleukin-1beta (IL-1beta) and vascular endothelial growth factor (VEGF) were elevated by 30% and 110% respectively, and the nuclear transcription factor (NF-kB) was activated by 2 fold. Curcumin administration prevented diabetes-induced decrease in the antioxidant capacity, and increase in 8-OHdG and nitrotyrosine; however, it had only partial beneficial effect on retinal GSH. Curcumin also inhibited diabetes-induced elevation in the levels of IL-1beta, VEGF and NF-kB. The effects of curcumin were achieved without amelioration of the severity of hyperglycemia.

CONCLUSION

Thus, the beneficial effects of curcumin on the metabolic abnormalities postulated to be important in the development of diabetic retinopathy suggest that curcumin could have potential benefits in inhibiting the development of retinopathy in diabetic patients.

Oxidation, antioxidants and cataract formation: a literature review

PURPOSE

This review aims to provide a literature survey of the association between photo-oxidation of lens proteins and lipid peroxidation with the genesis of age-related cataract in laboratory studies using rodent models, in epidemiological and interventional studies in humans.

MATERIALS AND METHODS

A Medline search using initial search terms lens, oxidation, antioxidant, and diet was employed to search for research papers covering the areas noted above from 1995 to 2005. Literature cited in those papers was also reviewed to provide as comprehensive a coverage of research work as possible.

RESULTS

Lens protein photo-oxidation and lipid peroxidation are widely acknowledged as important steps in age-related cataractogenesis. Dietary antioxidants are central in retarding cataractogenesis, although most evidence for this is gained from laboratory-based work on relatively unphysiologic rodent cataract models, using antioxidant regimes that could not be sustained in clinical practice. Most research in humans is retrospective epidemiology although some interventional research has been undertaken, with mixed results.

CONCLUSIONS

Dietary antioxidants are likely to be important in retarding cataractogenesis in older animals and in humans. Work on companion animals could provide a valuable stepping stone between rodent-based laboratory work and human interventional studies.

Apoptosis in lens development and pathology

The ocular lens is a distinct system to study cell death for the following reasons. First, during animal development, the ocular lens is crafted into its unique shape. The crafting processes include cell proliferation, cell migration, and apoptosis. Moreover, the lens epithelial cells differentiate into lens fiber cells through a process, which utilizes the same regulators as those in apoptosis at multiple signaling steps. In addition, introduction of exogenous wild-type or mutant genes or knock-out of the endogenous genes leads to apoptosis of the lens epithelial cells followed by absence of the ocular lens or formation of abnormal lens. Finally, both in vitro and in vivo studies have shown that treatment of adult lens with stress factors induces apoptosis of lens epithelial cells, which is followed by cataractogenesis. The present review summarizes the current knowledge on apoptosis in the ocular lens with emphasis on its role in lens development and pathology.

Curcumin, an atoxic antioxidant and natural NFkappaB, cyclooxygenase-2, lipooxygenase, and inducible nitric oxide synthase inhibitor: a shield against acute and chronic diseases

BACKGROUND

The world suffers a tsunami of chronic diseases, and a typhoon of acute illnesses, many of which are associated with the inappropriate or exaggerated activation of genes involved in inflammation. Finding therapeutic agents which can modulate the inflammatory reaction is the highest priority in medical research today. Drugs developed by the pharmaceutical industry have thus far been associated with toxicity and side effects, which is why natural substances are of increasing interest.

METHODS

A literature search (PubMed) showed almost 1500 papers dealing with curcumin, most from recent years. All available abstracts were read. Approximately 300 full papers were reviewed.

RESULTS

Curcumin, a component of turmeric, has been shown to be non-toxic, to have antioxidant activity, and to inhibit such mediators of inflammation as NFkappaB, cyclooxygenase-2 (COX-2), lipooxygenase (LOX), and inducible nitric oxide synthase (iNOS). Significant preventive and/or curative effects have been observed in experimental animal models of a number of diseases, including arteriosclerosis, cancer, diabetes, respiratory, hepatic, pancreatic, intestinal and gastric diseases, neurodegenerative and eye diseases.

CONCLUSIONS

Turmeric, an approved food additive, or its component curcumin, has shown surprisingly beneficial effects in experimental studies of acute and chronic diseases characterized by an exaggerated inflammatory reaction. There is ample evidence to support its clinical use, both as a prevention and a treatment. Several natural substances have greater antioxidant effects than conventional vitamins, including various polyphenols, flavonoids and curcumenoids. Natural substances are worth further exploration both experimentally and clinically.

Human alphaA- and alphaB-crystallins bind to Bax and Bcl-X(S) to sequester their translocation during staurosporine-induced apoptosis

AlphaA- and alphaB-crystallins are distinct antiapoptotic regulators. Regarding the antiapoptotic mechanisms, we have recently demonstrated that alphaB-crystallin interacts with the procaspase-3 and partially processed procaspase-3 to repress caspase-3 activation. Here, we demonstrate that human alphaA- and alphaB-crystallins prevent staurosporine-induced apoptosis through interactions with members of the Bcl-2 family. Using GST pulldown assays and coimmunoprecipitations, we demonstrated that alpha-crystallins bind to Bax and Bcl-X(S) both in vitro and in vivo. Human alphaA- and alphaB-crystallins display similar affinity to both proapoptotic regulators, and so are true with their antiapoptotic ability tested in human lens epithelial cells, human retina pigment epithelial cells (ARPE-19) and rat embryonic myocardium cells (H9c2) under treatment of staurosporine, etoposide or sorbitol. Two prominent mutants, R116C in alphaA-crystallin and R120G, in alphaB-crystallin display much weaker affinity to Bax and Bcl-X(S). Through the interaction, alpha-crystallins prevent the translocation of Bax and Bcl-X(S) from cytosol into mitochondria during staurosporine-induced apoptosis. As a result, alpha-crystallins preserve the integrity of mitochondria, restrict release of cytochrome c, repress activation of caspase-3 and block degradation of PARP. Thus, our results demonstrate a novel antiapoptotic mechanism for alpha-crystallins.

Antioxidant role of glutathione S-transferases: protection against oxidant toxicity and regulation of stress-mediated apoptosis

It has been known that glutathione S-transferases (GSTs) can reduce lipid hydroperoxides through their Se-independent glutathione peroxidase activity and that these enzymes can also detoxify lipid peroxidation end products such as 4-hydroxynonenal (4-HNE). In this article, recent studies suggesting that the Alpha class GSTs provide a formidable defense against oxidative stress are critically evaluated and the role of these enzymes in the regulation of oxidative stress-mediated signaling is reviewed. Available evidence from earlier studies together with results of recent studies in our laboratories strongly suggests that lipid peroxidation products, particularly hydroperoxides and 4-HNE, are involved in the mechanisms of stress-mediated signaling and that it can be modulated by the Alpha class GSTs through the regulation of the intracellular concentrations of 4-HNE.