Preventive effect of onion juice on selenite-induced experimental cataract

Effects of Laurus Nobilis Eye Drop on Selenite-Induced Cataract Formation and Oxidative Stress-Related Parameters in Rabbits: An Experimental Study

PURPOSE

To evaluate the protective role of Laurus Nobilis eye drops on selenite-induced cataracts in suckling rabbits.

METHODS

Fifteen male albino suckling rabbits with no signs of ocular inflammation were randomly assigned to three groups: controls (Group A), sodium-selenite group (Group B) and sodium-selenite plus Laurus Nobilis group (Group C). By selenite treatment, cataract formation was experimentally induced and then graded. The grade of oxidative stress was defined in the lens, measuring the concentration of malondialdehyde, alpha-tocopherol, oxidized glutathione, ascorbic acid and hydrogen peroxide, and in blood samples as levels of alpha-tocopherol and malondialdehyde.

RESULTS

Mean lens concentrations of GSSG, H2O2, and MDA levels in group B were significantly higher than in both group C and control. Ascorbic acid and alpha-tocopherol concentrations were lower in group B than in both group C and A. As plasma oxidative status markers, the level of MDA was higher in group B respected group C and A. The mean alpha-tocopherol levels in group B were significantly lower than in both group A and group C.

CONCLUSIONS

In animals treated with Laurus Nobilis-based eye drops, inflammation was inhibited, and lipid peroxidation was significantly reduced. Laurus nobilis leaves extract represents a good source of antioxidant components that may contrast sodium selenite-induced cataractogenesis in suckling rabbits.

Insights into the cumulative effect of Colletotrichum gloeosporioides and Fusarium acutatum causing anthracnose-twister disease complex of onion

Colletotrichum is an important plant pathogenic fungi that causes anthracnose/-twister disease in onion. This disease was prevalent in the monsoon season from August to November months and the symptoms were observed in most of the fields. This study aimed to investigate the pathogenicity and cumulative effect, if any of Colletotrichum gloeosporioides and Fusarium acutatum. The pot experiment was laid out to identify the cause responsible for inciting anthracnose-twister disease, whether the Colletotrichum or Fusarium or both, or the interaction of pathogens and GA3. The results of the pathogenicity test confirmed that C. gloeosporioides and F. acutatum are both pathogenic. C. gloeosporioides caused twisting symptoms independently, while F.acutatum independently caused only neck elongation. The independent application of GA3 did not produce any symptoms, however, increased the plant height. The combined treatment of C. gloeosporioides and F. acutatum caused twisting, which enhanced upon interaction with GA3 application giving synergistic effect. The acervuli were found in lesions infected with C. gloeosporioides after 8 days of inoculation on the neck and leaf blades. Symptoms were not observed in untreated control plants. Koch's postulates were confirmed by reisolating the same pathogens from the infected plants.

A Review of the Prospective Effects of Spacing and Varieties on Onion Yield and Yield Components (Allium cepa L.) in Ethiopia

Onion (Allium cepa L.) is the most important commercial vegetable crop widely grown throughout the world. It is also an important bulb crop in Ethiopia. However, its production and productivity are restricted by different factors, including biotic and abiotic stresses. This review investigates the potential impacts of spacing and varieties on onion yield and yield components in Ethiopia. Countries around the world are producing onion for its nutritional value, medicinal properties, minerals, proteins, and carbohydrates. In terms of production, onion ranks second only after tomatoes. The average onion yield in Ethiopia is estimated to be 8.8 tons/ha, while in the world, it is approximately 19.7 tons/ha. Inappropriate spacing and inadequate onion varieties are some of the limitations widely described for yield variation in Ethiopia. Thus, to control the size, shape, and yield of onion bulbs, spacing determination and variety improvement are some of the techniques currently employed in Ethiopia. Adama red, Bombay red, and red creole are some of the known varieties in the country, and the intrarow spacings for Adama red and Bombay red are reported to be 4 cm and 6 cm, respectively. Different spacing between onion plants affects how much they produce and other factors such as size and quality, depending on the variety. It is important to assess whether changing spacing makes sense from both a farming and economic standpoint, alongside considering other agricultural methods.

Investigating the therapeutic potential of Allium cepa extract in combating pesticide exposure induced ocular damage

The ocular surface is subject to a range of potentially hazardous environmental factors and substances, owing to its anatomical location, sensitivity, and physiological makeup. Xenobiotic stress exerted by chronic pesticide exposure on the cornea is primarily responsible for ocular irritation, excessive tear production (hyper-lacrimation), corneal abrasions and decreased visual acuity. Traditional medicine hails the humble onion (Allium cepa) for its multi-faceted properties including but not limited to anti-microbial, antioxidant, anti-inflammatory and wound healing. However, there is a lacuna regarding its impact on the ocular surface. Thereby, the current study investigated whether topical application of crude extract of Allium cepa aided in mitigating pesticide-induced damage to the ocular surface. The deleterious effects of pesticide exposure and their mitigation through the topical application of herbal extract of Allium cepa were analysed initially through in vitro evaluation on cell lines and then on the ocular surface via various in-vivo and ex-vivo techniques. Pathophysiological alterations to the ocular surface that impacted vision were explored through detailed neurophysiological screening with special emphasis on visual acuity wherein it was observed that the murine group treated with topical application of Allium cepa extract had comparable visual capacity to the non-pesticide exposed group. Additionally, SOD2 was utilized as an oxidative stress marker along with the expression of cellular apoptotic markers such as Bcl-xL to analyse the impact of pesticide exposure and subsequent herbal intervention on oxidative stress-induced corneal damage. The impact on the corneal epithelial progenitor cell population (ABCG2 and TERT positive cells) was also flowcytometrically analysed. Therefore, from our observations, it can be postulated that the topical application of Allium cepa extract might serve as an effective strategy to alleviate pesticide exposure related ocular damage.

Screening of short-day onions for resistance to Stemphylium leaf blight in the seed-to-bulb stage (stage I) and bulb-to-seed stage (stage II)

Stemphylium leaf blight, caused by Stemphylium vesicarium, is a very important fungal disease in onions since its epidemics are able to affect both the bulb yield and the seed quality. The aim of this study was to screen onion genotypes at stage I (seed to bulb) and further screen the identified resistant and susceptible genotypes at stage II (bulb to seed). One hundred and fifty-seven genotypes were screened against SLB under artificially inoculated field conditions. Results revealed a significant variation among the morphological and biochemical traits studied. Correlation studies revealed a significant and negative correlation between percent disease incidence (PDI), pseudostem width, neck thickness, and dry matter. Fifteen genotypes were identified as moderately resistant, and the rest were categorized as susceptible. Bulbs of the genotypes, identified as moderately resistant, were again screened for resistance in stage II. All the genotypes were categorized as moderately susceptible. Biochemical analysis revealed that total foliar phenol content, pyruvic acid, catalase, and peroxidase increased up to 20 days after inoculation (DAI) and thereafter declined. Protein content was highest in the initial stage and declined at 10, 20, and 30 DAI. The higher biochemical activity was observed in moderately resistant category genotypes compared with the susceptible ones. Correlation analysis showed a highly significant and negative correlation of PDI with total foliar phenol content (TFPC), pyruvic acid, catalase, peroxidase, and protein content. To conclude, it was observed that screening against SLB should be done at both the stages (stage I and Stage II) to identify resistant onion genotypes. Direction selection for genotypes with high dry matter, higher phenols, and enzymes may be an alternative pathway to select genotypes for a robust resistance breeding program.

Medicinal plants effective in the treatment of glaucoma from the perspective of traditional Persian medicine

Traditional Persian medicine (TPM) is one of the richest medical schools in the world, which has nurtured valuable books. From Ibn Sina's law to Heravi's successful medicinal facts, all emphasize the treatment of various diseases, especially eye diseases based on herbal medicines, as well as their prevention. In this study, by reviewing the authoritative books of Traditional Persian Medicine, we are looking for medicinal plants so that they can be used in the treatment of glaucoma or glaucoma. the purpose of this study is not to express the complete cure of glaucoma, but this article seeks to classify plants that from the perspective of Traditional Persian Medicine can be used as complementary medicine alongside conventional medical treatments. Methods and Materials: This is a summative qualitative content analysis that focused on Traditional Persian Medicine (TPM) texts from 2th to 13th AH centuries. Literature was searched during centuries 4th to 13th AH, and after described of glaucoma, extracting and classifying plants. Results: The scholars of TPM have opinions in the field of recognizing, describing and treating eye diseases and defining practical words. In almost all books of general Persian PM, the diagnosis and treatment of eye diseases have been discussed. Glaucoma in Traditional Persian Medicine is called “black water”. Conclusion: Unlike other medical schools in the world, in addition to treating diseases, Persian medicine has a strong recommendation to prevent the occurrence of disease and also to strengthen the body's visual powers by using 6 principles of maintaining health along with herbal medicines"

Topical onion juice mitigates the morphological alterations of the cornea in the aged male rats

Aging is associated with structural and functional changes of the cornea. Fresh onion juice contains phenolic compounds and flavonoids that may provide an anti-aging effect. The aim of this study was to assess the ability of the onion juice to ameliorate these aging changes. Rats were grouped as adult and aged groups. Rats of both groups received eye drops of diluted onion juice in their right eyes every 8 hours for 12 weeks, while the left ones were served as control eyes. The corneas of both eyes underwent histopathological, immunohistochemical and morphometric assessments, in addition to measuring their intraocular pressure (IOP). The aged group exhibited a significantly elevated IOP, decreased tear secretion, degenerated corneal epithelium and endothelium, surface erosions and stromal edema with irregular collagen fibers. Administration of onion juice led to lowering of IOP, significant increase in tearing, restoration of most of epithelial, endothelial and stromal integrity, and increased epithelial, keratocystic and endothelial cell densities. Immunohistochemically, the epithelium and endothelium revealed positive immune reactions for both epidermal growth factor receptor (EGFR) and paired box protein-6 (PAX6) in the control and onion-treated corneas of the adult group, while these immune reactions were negative in the untreated aged ones. Onion drops in aged corneas showed a positive immune reaction for EFGR and PAX6 involving the epithelial and endothelial layers. In conclusion, topical onion juice improves corneal aging changes through its direct effect, and indirectly through lowering IOP and enhancing tear secretion.

Useful Medicinal Plants for Vision Impairment in Traditional Iranian Medicine

Vision impairment is an important general health issue that imposes many costs on governments and the health system every year. Despite the decline in infectious eye diseases, which has reduced the vision impairment and blindness over the past two decades, vision impairment is still a major health problem in some parts of the world. In traditional medicine books, visual weakness is referred to as "any disturbance in the act of seeing ". Many medicinal herbs have been mentioned in books of Traditional Iranian medicine (TIM) for the management of vision impairment. The aim of this study is to review the medicinal plants mentioned in TIM, which are considered effective for the treatment of vision impairment or its enhancement. In this library-based study, medicinal plants effective in the treatment of vision impairment were searched using 6 valid sources of traditional medicine, including Makhzan ol-Adawiya, The Canon of Medicine, Tuhfat al-Momenin, Al-Abniyah An Haqaiq al-adwiya, Al-Shamil Fi al-Sana'at al-tebiyah, and Ekhtiarate Badiee. This was done in 10 steps (finding keywords, searching for resources, preparing a single list, finding synonyms, classifying, reviewing, extracting plants from compositions, summarizing, scoring and sorting based on the obtained score). A total of 89 medicinal plants were extracted, most of which had a hot and dry temperament. Based on the obtained score, 12 plants got the highest scores (10 and above). The extracted plants can be the basis for further clinical studies to make new effective drugs for the prevention and treatment of vision impairment.

Inhibition of copper-induced aggregation of human γD-crystallin by rutin and studies on its role in molecular level for enhancing the chaperone activity of human αA-crystallin by using multi-spectroscopic techniques

Oxidative aggregation of γ-crystallins induced by copper in aged lens increases the lens opacity and causes cataract formation. Therefore, chelation of free Cu²⁺ by small molecules can inhibit metal-mediated aggregation of γ-crystallin. In this work, the inhibition potency of several naturally occurring flavonoid compounds was studied against aggregation of human γD-crystallin (HGD) mediated by copper ions. Among them, rutin demonstrated ~20% inhibition of HGD aggregation induced by Cu²⁺ through its metal chelation ability. Not only that, the chaperone activity of lens chaperone, human αA-crystallin (HAA) was found to be enhanced in the presence of rutin. Subsequently, the molecular interactions between HAA and rutin were investigated using fluorescence and CD spectroscopy to understand the molecular basis of the chaperone activity enhancement by rutin. Quenching of HAA fluorescence by rutin with a quenching constant in the order of ~10⁵ M^-1 depicts a complexation between them. Entropy driven process of complexation between HAA and rutin suggests significant involvement of hydrophobic interactions. Fluorescence resonance energy transfer between protein and ligand can occur at a distance of 2.73 nm. Synchronous fluorescence and circular dichroism spectroscopy revealed that protein-ligand interaction does not cause any notable conformational changes in HAA. Experimental observations have been well substantiated by docking.

Medicinal Plants and Natural Products Used in Cataract Management

Cataract is the leading reason of blindness worldwide and is defined by the presence of any lens opacities or loss of transparency. The most common symptoms of cataract are impaired vision, decreased contrast sensitivity, color disturbance, and glare. Oxidative stress is among the main mechanisms involved in the development of age-related cataract. Surgery through phacoemulsification and intraocular lens implantation is the most effective method for cataract treatment, however, there are chances of serious complications and irreversible loss of vision associated with the surgery. Natural compounds consisting of antioxidant or anti-inflammatory secondary metabolites can serve as potential leads for anticataract agents. In this review, we tried to document medicinal plants and plant-based natural products used for cataract treatment worldwide, which are gathered from available ethnopharmacological/ethnobotanical data. We have extensively explored a number of recognized databases like Scifinder, PubMed, Science Direct, Google Scholar, and Scopus by using keywords and phrases such as “cataract”, “blindness”, “traditional medicine”, “ethnopharmacology”, “ethnobotany”, “herbs”, “medicinal plants”, or other relevant terms, and summarized the plants/phytoconstituents that are evaluated in different models of cataract and also tabulated 44 plants that are traditionally used in cataract in various folklore medical practices. Moreover, we also categorized the plants according to scientific studies carried out in different cataract models with their mechanisms of action.

The anti-cataract molecular mechanism study in selenium cataract rats for baicalin ophthalmic nanoparticles

PURPOSE

The objective of this study was to investigate the effects of the solid lipid nanoparticles of baicalin (BA-SLNs) on an experimental cataract model and explore the molecular mechanism combined with bioinformatics analysis.

MATERIALS AND METHODS

The transparency of lens was observed daily by slit-lamp and photography. Lenticular opacity was graded. Two-dimensional gel electrophoresis (2-DE) was employed to analyze the differential protein expression modes in each group. Proteins of interest were subjected to protein identification by nano-liquid chromatography tandem mass spectrometry (LC-MS/MS). Bioinformatics analysis was performed using the Ingenuity Pathway Analysis (IPA) online software to comprehend the biological implications of the proteins identified by proteomics.

RESULTS

At the end of the sodium selenite-induced cataract progression, almost all lenses from the model group developed partial nuclear opacity; however, all lenses were clear and normal in the blank group. There was no significant difference between the BA-SLNs group and the blank group. Many protein spots were differently expressed in 2-DE patterns of total proteins of lenses from each group, and 65 highly different protein spots were selected to be identified between the BA-SLNs group and the model group. A total of 23 proteins were identified, and 12 of which were crystalline proteins.

CONCLUSION

We considered crystalline proteins to play important roles in preserving the normal expression levels of proteins and the transparency of lenses. The general trend in the BA-SLN-treated lenses' data showed that BA-SLNs regulated the protein expression mode of cataract lenses to normal lenses. Our findings suggest that BA-SLNs may be a potential therapeutic agent in treating cataract by regulating protein expression and may also be a strong candidate for future clinical research.

Protection of human γB-crystallin from UV-induced damage by epigallocatechin gallate: spectroscopic and docking studies

The transparency of the human eye lens depends on the solubility and stability of the structural proteins of the eye lens, the crystallins. Although the mechanism of cataract formation is still unclear, it is believed to involve protein misfolding and/or aggregation of proteins due to the influence of several external factors such as ultraviolet (UV) radiation, low pH, temperature and exposure to chemical agents. In this article, we report the study of UV induced photo-damage (under oxidative stress) of recombinant human γB-crystallin in vitro in the presence of the major green tea polyphenol, (-)-epigallocatechin gallate (EGCG). We have shown that EGCG has the ability to protect human γB-crystallin from oxidative stress-induced photo-damage.

Green tea flavanols protect human γB-crystallin from oxidative photodamage

Age related cataract is a major cause of visual loss worldwide that is a result of opacification of the eye lens proteins. One of the major reasons behind this deterioration is UV induced oxidative damage. The study reported here is focused on an investigation of the oxidative stress induced damage to γB-crystallin under UV exposure. Human γB-crystallin has been expressed and purified from E. coli. We have found that epicatechin gallate (ECG) has a higher affinity towards the protein compared to epigallocatechin (EGC). The in vitro study of UV irradiation under oxidative damage to the protein in the presence of increasing concentrations of GTPs is indicative of their effective role as potent inhibitors of oxidative damage. Docking analyses show that the GTPs bind to the cleft between the domains of human γB-crystallin that may be associated with the protection of the protein from oxidative damage.

Identification of phytoconstituents and in-vitro evaluation of the putative anticataractogenic effect of an ethanolic root extract of Leucas aspera

Modern herbal medicine has played a significant role in treating oxidative stress and related complications. In the present investigation, gas chromatography-mass spectrometric analysis of ethanolic extracts of the leaf and of the root of Leucas aspera (L. aspera) (Willd.) Link separately showed the presence of various phytoconstituents; major components have already been reported to possess various biological, including antioxidant, activities. Of the two extracts analyzed, the root extract exhibited more potential antioxidant activity than did the leaf extract. Since this finding correlated with more perceptible amounts of antioxidant components being detected in the ethanolic extract of L. aspera root, the root extract was evaluated for possible anticataractogenic potential in cultured Wistar rat lenses. Following incubation of Wistar rat lenses for 24h at 37°C in Dulbecco's modified Eagle's medium (DMEM), gross morphological examination revealed that none of the eight lenses incubated in DMEM alone (Group I) exhibited any opacification (Grade 0), whereas all eight lenses incubated in DMEM that contained sodium selenite (100μM selenite/ml of DMEM) (Group II) exhibited thick opacification (Grade +++). In contrast, only one out of eight lenses incubated in DMEM containing sodium selenite (100μM selenite/ml of DMEM) and simultaneously exposed to the L. aspera root extract (300μg/ml of DMEM) (Group III) exhibited a slight degree of opacification (Grade +) after 24h incubation, while the remaining seven lenses did not show any opacification (Grade 0). The mean activities of catalase, superoxide dismutase, glutathione peroxidase and glutathione-S-transferase and the mean level of reduced glutathione were all significantly (p<0.05) higher in Group III lenses than the mean values in Group II lenses. The mean concentration of malondialdehyde in Group III lenses was significantly (p<0.05) lower than that in Group II lenses. Further, significantly (p<0.05) lower mean mRNA transcript levels of the genes encoding αA- and βB1-crystallins, as well as significantly lower mean levels of the αA- and βB1-crystallin proteins themselves, were observed in Group II lenses. However, in Group III lenses, the mean mRNA transcript levels of the crystallin genes, and the mean protein levels, were essentially similar to those noted in normal control (Group I) lenses. The results of the present study suggest that in selenite-challenged Wistar rat lenses simultaneously exposed to an ethanolic extract of L. aspera root, lenticular opacification was prevented by mean activities of enzymatic antioxidants, mean levels of reduced glutathione and malondialdehyde mean expression levels of genes encoding αA- and βB1-crystallins, and mean levels of the crystallin proteins themselves, being maintained at near normal levels. Further studies are required to confirm whether the ethanolic extract of the root of L. aspera can be developed for pharmacological management of cataract.

Identification of Novel Source of Resistance and Differential Response of Allium Genotypes to Purple Blotch Pathogen, Alternaria porri (Ellis) Ciferri

Purple blotch, caused by Alternaria porri (Ellis) Cifferi, is a serious disease incurring heavy yield losses in the bulb and seed crop of onion and garlic worldwide. There is an immediate need for identification of effective resistance sources for use in host resistance breeding. A total of 43 Allium genotypes were screened for purple blotch resistance under field conditions. Allium cepa accession 'CBT-Ac77' and cultivar 'Arka Kalyan' were observed to be highly resistant. In vitro inoculation of a selected set of genotypes with A. porri, revealed that 7 days after inoculation was suitable to observe the disease severity. In vitro screening of 43 genotypes for resistance to A. porri revealed two resistant lines. An additional 14 genotypes showed consistent moderate resistance in the field as well as in vitro evaluations. Among the related Allium species, A. schoenoprasum and A. roylei showed the least disease index and can be used for interspecific hybridization with cultivated onion. Differential reaction analysis of three A. porri isolates (Apo-Chiplima, Apn-Nasik, Apg-Guntur) in 43 genotypes revealed significant variation among the evaluated Allium species (P = 0.001). All together, the present study suggest that, the newly identified resistance sources can be used as potential donors for ongoing purple blotch resistance breeding program in India.

Hypercholesterolemia-induced ocular disorder: Ameliorating role of phytotherapy

The ocular region is a complex structure that allows conscious light perception and vision. It is of ecto-mesodermal origin. Cholesterol and polyunsaturated fatty acids are involved in retinal cell function; however, hypercholesterolemia and diabetes impair its function. Retinal damage, neovascularization, and cataracts are the main complications of cholesterol overload. Dietary supplementation of selected plant products can lead to the scavenging of free reactive oxygen species, thereby protecting the ocular regions from the damage of hypercholesterolemia. This review illustrates the dramatic effects of increased cholesterol levels on the ocular regions. The effect of phytotherapy is discussed in relation to the different regions of the eye, including the retina, cornea, and lens.

Prevention of Selenite-Induced Cataratogenesis by Ginkgo biloba Extract (Egb761) in Wistar Rats

OBJECTIVE

To investigate whether Ginkgo biloba extract retards selenite-induced cataractogenesis in Wistar rat pups.

METHODS

On postpartum day eight, Group I rat pups (n = 12) received an intraperitoneal injection of physiological saline. Groups II and III rat pups (n = 12) received a subcutaneous injection of sodium selenite. Group III also received an intraperitoneal injection of G. biloba extract once daily on postpartum days 9-14. Both eyes of each pup were examined from postpartum day 16 up to day 30. After sacrifice, encapsulated pup lens were analyzed for mean activities of catalase, superoxide dismutase, glutathione peroxidase (GPx), glutathione S-transferase and glutathione reductase. In addition, the mean concentrations of reduced glutathione (GSH) and malondialdehyde were analyzed in samples of lens and serum.

RESULTS

Dense lenticular opacification occurs 100% in Group II, but only minimal opacification occurs in three pups of Group III (25%), no opacification in 75% of Group III, none in Group I. Compared with Groups I and III, Group II rat showed lower lenticular antioxidant enzyme activity, lower level of GSH, and higher level of malondidehyde (mean ± standard deviation SD, p < 0.05 respectively).

CONCLUSIONS

The treatment with G. biloba extract is effective against oxidative stress - a crucial factor of cataractogenesis in rat pups, possibly by preventing depletion of antioxidant enzymes and by inhibiting lipid peroxidation.

Hydrogen saline prevents selenite-induced cataract in rats

PURPOSE

The aim of this study was to investigate the potential antioxidative effect and mechanism for the protective effects of hydrogen saline on selenite-induced cataract in rats.

METHODS

Sprague-Dawley rat pups were divided into the following groups: control (Group A), selenite induced (Group B), and selenite plus hydrogen saline treated (Group C). Rat pups in Groups B and C received a single subcutaneous injection of sodium selenite (25 μmol/kg bodyweight) on postnatal day 12. Group C also received an intraperitoneal injection of H2 saline (5 ml/kg bodyweight) daily from postnatal day 8 to postnatal day 17. The development of cataract was assessed weekly by slit-lamp examination for 2 weeks. After sacrifice, extricated lenses were analyzed for activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione S-transferase, levels of malondialdehyde, reduced glutathione (GSH), and total sulfhydryl contents.

RESULTS

The magnitude of lens opacification in Group B was significantly higher than in Group A (p<0.05), while Group C had less opacification than Group B (p<0.05). Compared with Group B, the mean activities of the antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione S-transferase, levels of GSH, and total sulfhydryl contents were higher, whereas the level of malondialdehyde was lower following treatment with hydrogen saline(p<0.05).

CONCLUSIONS

This is an initial report showing that hydrogen saline can prevent selenite-induced cataract in rats. It acts via maintaining antioxidant enzymes and GSH, protecting the sulfhydryl group, and inhibiting lipid peroxidation.

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.

The effect of apricots on the experimental cataract model formed by sodium selenite

This study was designed in order to investigate whether sun dried apricots have a preventive effect on the experimental cataract model formed by sodium selenite in rats. Fifty-nine Spraque-Dawley rat pups were divided into three groups. Group 1 (control group) consisted of twenty rat pups, born from the rats nourished ad libitum. Group 2 consisted of 18 newborn rats, born from the rats nourished ad libitum with 10% sun dried natural apricots. Group 3 consisted of 21 newborn rats, born from the rats nourished ad libitum. Subcutaneous (30nmol/gr) sodium selenite injection was applied to all the newborn rats except the control group (Group 1) on postpartum day 10. Cataract development was graded by slit-lamp examination and photography. Encapsulated lenses were analyzed for reduced glutathione (GSH) and malondialdehyde (MDA), a marker of lipid per oxidation. Lenses were also analyzed for total nitrite (TN). The presence of oxidative stress in selenite cataract development and its prevention by sun dried apricots.

Bioactive derivatives of curcumin attenuate cataract formation in vitro

In this study, curcumin derivatives salicylidenecurcumin (CD1) and benzalidenecurcumin (CD2)] were prepared, and their biological activity was compared in in vitro selenite-induced cataract model. The antioxidant activity was studied using DPPH radical scavenging assay. Knoevenagel condensates of curcumin exhibited higher DPPH radical scavenging activity compared with curcumin. The anticataractogenic potential of curcumin derivatives was analyzed using lens organ culture method. The activity of antioxidant enzymes and calcium homeostasis was reversed to near normal levels following treatment in organ cultured rat lenses. These results indicated that curcumin and its derivatives--CD1 and CD2--are beneficial against selenite-induced cataract in vitro. Of these, CD1 is having higher bioactive potential compared with curcumin and CD2.

Avicenna and cataracts: a new analysis of contributions to diagnosis and treatment from the canon

BACKGROUND

Physicians in ancient Persia played an important role in the development of medicine in the medieval era. One of the most influential figures of this era was Abu Ali Sina or Ibn Sina, known as Avicenna in the western world. The author of more than 200 books on medicine and philosophy, Avicenna followed and further expanded on the tradition of western philosophy and medicine introduced by Aristotle, Hippocrates and Galen. Few researchers have looked into the different medical issues in his best known work, the Canon of Medicine, particularly with regard to ophthalmology. In this analysis, Avicenna's views on and contributions to the diagnosis and treatment of cataracts in his Canon were elucidated.

METHODS

We first reviewed an electronic copy of the Canon and then reviewed other important sources in traditional medicine including the Kamel-al-Sanaeh, Al-Havi (Continents) and Zakhireh-kharazmshahi, available in the Avicenna Special Traditional Medicine Library of Shiraz University of Medical Sciences. We also searched Medline, Embase, Scopus, Iranmedex and Science Iranian Database (SID) with these keywords: "traditional medicine," "Avicenna," "cataract", "Canon", "history", "ophthalmology" and "eye disorders".

RESULTS

According to the Canon, nozul-al-maa or cataract is an obstructive disease in which external moisture accumulates between the aqueous humor and the corneal membrane and prevents images from entering the eye. Avicenna classified cataracts on the basis of size, density and color. According to size, he identified two types of cataracts including complete and partial obstruction. According to the Canon, surgical intervention was necessary only for certain indications. Avicenna believed that opacity in the initial stages of cataract could be diminished by medicines and foods, and described several medicines for cataracts. He believed that surgery should be postponed until the liquid accumulation stopped, and the cataract reached its mature state. After surgery, according to Avicenna, the patient should avoid headache-inducing situations because headaches could lead to edema of the layers of the eye. He further emphasized that the patient's psychological status played an important role in the success of surgery.

CONCLUSION

An important aspect of Avicenna's contribution to the medical management of cataracts was that he believed they could be cured by medication and nutrition in their early stages without the need for surgery. He also considered the patient's mental status as an important factor contributing to the postoperative prognosis. Our review of Avicenna's writings on eye disorders in the Canon of Medicine suggests that he had a rigorous approach to the diagnosis and management of patients suffering from eye disorders.

Protein misfolding and aggregation in cataract disease and prospects for prevention

The transparency of the eye lens depends on maintaining the native tertiary structures and solubility of the lens crystallin proteins over a lifetime. Cataract, the leading cause of blindness worldwide, is caused by protein aggregation within the protected lens environment. With age, covalent protein damage accumulates through pathways thought to include UV radiation, oxidation, deamidation, and truncations. Experiments suggest that the resulting protein destabilization leads to partially unfolded, aggregation-prone intermediates and the formation of insoluble, light-scattering protein aggregates. These aggregates either include or overwhelm the protein chaperone content of the lens. Here, we review the causes of cataract and nonsurgical methods being investigated to inhibit or delay cataract development, including natural product-based therapies, modulators of oxidation, and protein aggregation inhibitors.

Prevention of selenite-induced cataractogenesis by an ethanolic extract of Cineraria maritima: an experimental evaluation of the traditional eye medication

In the present study, the antioxidant potential of an ethanolic extract of Cineraria maritima and its efficacy in preventing selenite-induced cataractogenesis were assessed in vitro and in vivo. In the in vitro phase of the study, lenses dissected out from the eyes of Wistar rats were incubated for 24 h at 37 °C in Dulbecco's modified Eagle medium (DMEM) alone (group I), in DMEM containing 100 μM of selenite only (group II), or in DMEM containing 100 μM of selenite and 300 μg/ml C. maritima extract added at the same time (group III). Gross morphological examination of the lenses revealed dense opacification in group II, minimal opacification in group III, and no opacification in group I lenses. The mean activities of the antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase were significantly lower in group II than in group I or group III lenses, while malondialdehyde concentration was significantly higher in group II lenses than in group I and group III lenses. In the in vivo phase of the study, dense opacification of lenses was noted in all rat pups (100%) that had received a single subcutaneous injection of sodium selenite alone (19 μM/kg body weight) on postpartum day 10, whereas cataract formation occurred in only 33.3% of rat pups that had received selenite as well as an intraperitoneal injection of the extract of C. maritima (350 mg/kg body weight) for five consecutive days. These observations suggest that the ethanolic extract of C. maritima may prevent experimental selenite-induced cataractogenesis.

Evaluation of anticataract potential of Triphala in selenite-induced cataract: In vitro and in vivo studies

Triphala (TP) is composed of Emblica officinalis, Terminalia chebula, and Terminalia belerica. The present study was undertaken to evaluate its anticataract potential in vitro and in vivo in a selenite-induced experimental model of cataract. In vitro enucleated rat lenses were maintained in organ culture containing Dulbecco’s Modified Eagles Medium alone or with the addition of 100μM selenite. These served as the normal and control groups, respectively. In the test group, the medium was supplemented with selenite and different concentrations of TP aqueous extract. The lenses were incubated for 24 h at 37°C. After incubation, the lenses were processed to estimate reduced glutathione (GSH), lipid peroxidation product, and antioxidant enzymes. In vivo selenite cataract was induced in 9-day-old rat pups by subcutaneous injection of sodium selenite (25 μmole/kg body weight). The test groups received 25, 50, and 75 mg/kg of TP intraperitoneally 4 h before the selenite challenge. At the end of the study period, the rats’ eyes were examined by slit-lamp. TP significantly (P < 0.01) restored GSH and decreased malondialdehyde levels. A significant restoration in the activities of antioxidant enzymes such as superoxide dismutase (P < 0.05), catalase (P < 0.05), glutathione peroxidase (P < 0.05), and glutathione-s-transferase (P < 0.005) was observed in the TP-supplemented group compared to controls. In vivo TF 25mg/kg developed only 20% nuclear cataract as compared to 100% in control. TP prevents or retards experimental selenite-induced cataract. This effect may be due to antioxidant activity. Further studies are warranted to explore its role in human cataract.

Natural flavonoids as potential multifunctional agents in prevention of diabetic cataract

Cataract is one of the earliest secondary complications of diabetes mellitus. The lens is a closed system with limited capability to repair or regenerate itself. Current evidence supports the view that cataractogenesis is a multifactorial process. Mechanisms related to glucose toxicity, namely oxidative stress, processes of non-enzymatic glycation and enhanced polyol pathway significantly contribute to the development of eye lens opacity under conditions of diabetes. There is an urgent need for inexpensive, non-surgical approaches to the treatment of cataract. Recently, considerable attention has been devoted to the search for phytochemical therapeutics. Several pharmacological actions of natural flavonoids may operate in the prevention of cataract since flavonoids are capable of affecting multiple mechanisms or etiological factors responsible for the development of diabetic cataract. In the present paper, natural flavonoids are reviewed as potential agents that could reduce the risk of cataract formation via affecting multiple pathways pertinent to eye lens opacification. In addition, the bioavailability of flavonoids for the lens is considered.

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.

Prevention of selenite-induced cataractogenesis in Wistar albino rats by aqueous extract of garlic

PURPOSE

The main aim of this study was to evaluate the inhibitory impacts of the aqueous extract of garlic (Ga) on the formation of cataract induced by sodium selenite (Se).

METHODS

Thirty-two Wistar albino rat pups (4 equal groups: G1, G2, G3, and G4) were treated as follows: G1, subcutaneous (s.c.) and intraperitoneal (i.p.) injection of normal saline (0.3 mL) on postpartum (day 10); G2, i.p. injection of aqueous extract of garlic (1 mL/kg body weight) and s.c. injection of normal saline (0.3 mL) on postpartum (day 10); G3, s.c. injection of sodium selenite (20 nmol/g body weight) and i.p. injection of normal saline (0.3 mL) on postpartum (day 10); and G4, s.c. injection of sodium selenite (20 nmol/g body weight) and i.p. injection of aqueous extract of garlic (1 mL/kg body weight) on postpartum (day 10). Daily i.p. injections of aqueous extract of garlic (in G2 and G4) and normal saline (in G1 and G3) were continued for 14 days. The development of cataract was assessed over a period of 2 weeks after injection of sodium selenite. For further examination, the rats' lenses were removed and analyzed for glutathione (GSH), malondialdehyde (MDA) levels, and superoxide dismutase (SOD), glutathione peroxidase (GPX) activities.

RESULTS

In G3 (Se-treated group), all rats developed grade 3 cataract in both eyes. However, in G1 (untreated control group), G2 (Ga-treated group), and G4 (Ga-Se-treated group), the lenses in both eyes of all rats remained clear (P < 0.0001). This clinical finding was associated with higher GSH level and GPX, SOD activities and lower level of MDA in the Se- and Ga-treated group (G4) compared with SS-treated group (G3) rat lenses (P < 0.003).

CONCLUSIONS

Intraperitoneal injection of the Ga in rat model appeared to effectively prevent Se-induced cataract, thus such herbal remedy may be considered for treatment of cataract.

Prevention of selenite-induced cataractogenesis by rutin in Wistar rats

PURPOSE

To investigate whether rutin retards selenite-induced cataractogenesis in Wistar rat pups.

METHODS

On postpartum day ten, Group I rat pups received an intraperitoneal injection of saline. Group II and III rat pups received a subcutaneous injection of sodium selenite. Group III also received an intraperitoneal injection of rutin once daily on postpartum days 9-14. Both eyes of each pup were examined from day 16 up to postpartum day 30. After sacrifice, extricated pup lenses were analyzed for mean activities of catalase, superoxide dismutase, glutathione peroxidase, glutathione S-transferase, and glutathione reductase. In addition, the mean concentrations of reduced glutathione (GSH) and of malondialdehyde were analyzed in samples of lenses and hemolysate.

RESULTS

There was dense lenticular opacification in all of Group II, minimal opacification in 33.3% of Group III, no opacification in 66.7% of Group III, and no opacification in Group I. Significantly lower mean activities of lenticular antioxidant enzymes were noted in Group II, compared to Group I and III. Significantly lower mean concentrations of GSH and higher mean concentrations of malondialdehyde were noted in samples of hemolysate and lens from Group II, compared to the values in Group I and III.

CONCLUSION

Rutin prevents experimental selenite-induced cataractogenesis in rat pups, possibly by preventing depletion of antioxidant enzymes and of GSH, and by inhibiting lipid peroxidation.