Preventive Effect ofTephrosia purpureaon Selenite-Induced Experimental Cataract

The protective effect of pomegranate peel aqueous extract on selenite-induced cataract in rats

The present study was performed to evaluate the preventive effect of pomegranate peel extract on sodium-induced cataract in rats. Sprague-Dawley suckling male rats were divided into four groups: group C: rats received no treatment, group P: rats received pomegranate peel aqueous extract (PPE) orally, group Se: rats received an injection of sodium selenite, group Se + P: rats received PPE and sodium selenite concomitantly. After 4 weeks, rats were sacrificed, and their lenses were homogenized and evaluated for biochemical parameters and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In the Se group, developed cataract with significant lens opacity was observed. Other changes in enzymatic and non-enzymatic antioxidants, oxidative parameters, solubility of proteins, in NO and Ca levels and the electrophoresis pattern of proteins were observed in lenses of the Se group compared to control groups. After the preventive administration of PPE, most of these parameters were normalized due to antioxidant and anti-inflammatory activities of the extract. PRACTICAL APPLICATIONS: Cataract is one of the leading causes of vision impairment among the elderly, and surgery is the major therapeutic step taken to cure it. However, surgery has its limitations and complications. Therefore, prevention of cataract development, especially in high-risk individuals, can be better than cure. Pomegranate peel extract has a high potential to prevent cataract in these people.

Natural Antioxidant Activities of Plants in Preventing Cataractogenesis

A cataract is a condition that causes 17 million people to experience blindness and is the most significant cause of vision loss, around 47.9%. The formation of cataracts is linked to both the production of reactive oxygen species (ROS) and the reduction of endogenous antioxidants. ROS are highly reactive molecules produced by oxygen. Examples of ROS include peroxides, super-oxides, and hydroxyl radicals. ROS are produced in cellular responses to xenobiotics and bacterial invasion and during mitochondrial oxidative metabolism. Excessive ROS can trigger oxidative stress that initiates the progression of eye lens opacities. ROS and other free radicals are highly reactive molecules because their outer orbitals have one or more unpaired electrons and can be neutralized by electron-donating compounds, such as antioxidants. Examples of natural antioxidant compounds are vitamin C, vitamin E, and beta-carotene. Numerous studies have demonstrated that plants contain numerous antioxidant compounds that can be used as cataract preventatives or inhibitors. Natural antioxidant extracts for cataract therapy may be investigated further in light of these findings, which show that consuming a sufficient amount of antioxidant-rich plants is an excellent approach to cataract prevention. Several other natural compounds also prevent cataracts by inhibiting aldose reductase and preventing apoptosis of the eye lens.

Role of the renin-angiotensin system in the development of cataract formation in angiotensin-II-induced experimental rats

Previously, we established several facts regarding hypertension-associated cataractogenesis. As a follow-on study, we evaluated the role of the renin-angiotensin system (RAS) in angiotensin-II (Ang-II)-induced cataract formation in experimental hypertensive rats. Sprague-Dawley male albino rats (150-180 g) were used for the present experiment. The animals were divided into four groups, with six animals in each group. During the 12 weeks of the experimental protocol, the normal group received sterile water (1 ml/kg/day, subcutaneously (sc), and the Ang-II control group received angiotensin (1 mg/kg/day) subcutaneously. The ARB (O) group received olmesartan (2 mg/kg/day) orally, and the ARB (T) group received two drops of olmesartan (5 mM) topically on the cornea; concurrently, both groups were treated with Ang-II (1 mg/kg/day, sc) to induce hypertension. Biweekly, the systolic and the diastolic blood pressures were recorded, and the eyes were examined; moreover, cataractogenic parameters, such as oxidative stress markers and protein contents in the lenses, were evaluated after completion of the experimental protocol. Twelve weeks of olmesartan administered, orally or topically, significantly reduced the progression of cataract formation and restored antioxidants, lipid peroxidation, nitrite content, and protein contents in the lenses of the mice in groups O and T, respectively, as compared with those in the Ang-II control group. On the basis of our results, we conclude that the ocular RAS exacerbates the lenticular oxidative stress that may lead to cataract formation. The results showed that the RAS has an independent and important role in cataract formation under hypertensive conditions.

Biochemical Evidence Indicates the Preventive Effect of Resveratrol and Nicotinamide in the Treatment of STZ-induced Diabetic Cataract

PURPOSE

High glucose level is a strong initiator of both oxidative stress and DNA damage to various cellular proteins. This activates the poly ADP-ribose polymerase (PARP) enzyme, which is responsible for disturbing physiological energy metabolic homeostasis. The present study aimed to elucidate the association between stress and the PARP pathway by using resveratrol (RSV) and nicotinamide (NAM, PARP inhibitor) to treat diabetic cataract.

METHOD

Albino rats were used for the experimental study. A single streptozotocin administration (55 mg/kg, i.p.) prompted diabetes in the animals. The experimental groups were the normal group (non-diabetic) and the diabetic groups: the diabetic control animals (group D), the diabetic animals treated with RSV at 40 mg/kg/day, i.p. (D+ RSV group), NAM at 100 and 300 mg/kg/day, i.p. (D+ NAM100, D+ NAM300 groups, respectively), and a combination of RSV and NAM i.p. (D+ RSV+NAM100 = Combi 1 group, D+ RSV+NAM300 = Combi 2 group). Glucose levels and the eyes were examined biweekly; various cataractogenic parameters in the lenses were examined after completion of the eight-week experimental protocol.

RESULTS

Compared to diabetic control, RSV monotherapy significantly decreased hyperglycemia and other lenticular alterations. NAM at the high dose only showed beneficial effects without altering the blood glucose level, lenticular aldose reductase (AR) activity, and sorbitol content, primarily restored the lenticular NAD level and decreased oxidative stress in diabetic rats. These findings regarding NAM treatment indicate that a pathway other than the antioxidant defense system and the polyol pathway, which might be due to PARP inhibition, is involved in diabetic cataracts. Moreover, compared to RSV monotherapy, combination treatments were effective.

CONCLUSION

These results indicate that hyperglycemia and oxidative-osmotic-nitrosative stress play central roles in the pathophysiology of diabetic cataracts. Moreover, our study also revealed that concurrent treatment with the RSV and NAM may prove useful in the pharmacotherapy of diabetes and its secondary complications such as cataract.

Citrus hystrix leaf extract attenuated diabetic-cataract in STZ-rats

Diabetic cataract causes severe vision loss. This study evaluated the effects of hesperidin-standardized Citrus hystrix leaf flavonoids-rich extract (CLE) on diabetic-cataract development. Streptozotocin-induced diabetic rats were orally given 150 and 300 mg CLE/kg body-weight. These were compared with non-treated diabetic or healthy rats as controls, over 8 weeks. The CLE gradually attenuated fasting blood glucose (FBG), biomarkers for inflammation (Tumor necrosis factor alpha TNF-α; prostaglandin E2 PGE2); vascular permeability, (Vascular endothelial growth factor VEGF); and oxidative stress, (malondialdehyde MDA). The diabetic cataract was significantly mitigated by the 150 mg CLE/kg dose. Good correlations were found between cataract incidence with FBG (r²  = 0.90), serum PGE2 (r²  = 0.91), MDA (r²  = 0.99), VEGF (r²  = 0.71), but not with TNF-α levels (r²  = 0.49) suggesting the serum FBG, PGE2, MDA, and possibly the VEGF levels may help to predict the cataract risks. The CLE mitigated cataract probably by attenuating hyperglycaemia, inflammation, lens fluid influx, vascular leakage, lens osmotic-imbalance, and fibers over-hydration. PRACTICAL APPLICATIONS: The study shows the flavonoids-rich Citrus hystrix leaf consumption, effectively attenuated diabetes (fasting blood glucose) and mitigated diabetic cataract. It help reduce diabetes-related hyperglycaemia, oxidative stress, inflammation, and vascular leakage. The evidences were the CLE consumptions reduced the serum biomarkers tumor necrosis factor-alpha TNF-α; prostaglandin E2 PGE2, vascular endothelial growth factor (VEGF), and malondialdehyde (MDA). The C. hystrix leaf contains hesperidin, apiin, diosmin, saponarin, apigetrin, rutin and xanthotoxol, and other flavonoid glucosides. The study also showed good correlations between cataract incidence with fasting blood glucose FBG (r²  = 0.90), serum PGE2 (r²  = 0.91), and MDA (r²  = 0.99), and less closely with VEGF (r²  = 0.71) suggesting these serum biomarkers may help predict cataract risks. The CLE indicated cataract mitigation properties probably by attenuating FBG, inflammation, lens fluid influx, lens osmotic-imbalance, and fibers over-hydration.

A comprehensive review on ethnomedicine, phytochemistry, pharmacology, and toxicity of Tephrosia purpurea (L.) Pers

Tephrosia purpurea (L.) Pers. is a well-known plant in Ayurveda and named "Sarwa wranvishapaka" for its property to heal wounds. Traditionally, it is practiced for impotency, asthma, dyspepsia, hemorrhoids, syphilis gonorrhea, rheumatism, enlargement of kidney and spleen. It is an important component of herbal preparations like Tephroli and Yakrifti used to cure liver disorders. Various phytocompounds including pongamol, purpurin, purpurenone, tephrosin, bulnesol, tephrostachin, β-sitosterol, and so on have been reported. Modern pharmacological studies have shown that the plant have wound healing, antileishmanial, anticarcinogenic, antimicrobial, antioxidant, hepatoprotective, antifertility, antispermatogenic, anti-diarrheal, diuretic, and insecticidal properties. Acetylcholinesterase inhibitory action reported from this plant aids its utilization for the development of drugs for Alzheimer's and dementia neurological disorders. Among the known active compounds of T. purpurea, tephrostachin is responsible for antiplasmodial activity, tephrosin, pongaglabol, and semiglabrin exerts antiulcer activity while quercetin, rutin, β-sitosterol, and lupeol are mainly responsible for its anti-inflammatory and anti-cancer properties. From different toxicological studies, concentrations up to 2,000 mg/kg were considered safe. The present review comprehensively summarizes the ethnomedicine, phytochemistry, pharmacology, and toxicology of T. purpurea. Further research on elucidation of the structure-function relationship among active compounds, understanding of multi-target network pharmacology and clinical applications will intensify its therapeutic potential.

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.

Protective Effects of Trimetazidine in Retarding Selenite-Induced Lens Opacification

Purpose: Cataracts are the leading cause of vision loss worldwide, and the over-production of reactive oxygen species (ROS) is the foremost underlying cause of cataracts. Reducing ROS levels can efficiently prevent lens opacification, as evidenced by many studies. Here, we inhibited ROS overproduction with trimetazidine (TMZ), which is an antioxidant, to explore the therapeutic effects of TMZ and the mechanism of lens opacification.Materials and methods: Sodium selenite-induced cataract formation resulted in a significant loss of lens transparency. This effect could be efficiently rescued by TMZ, which was further found to be an inhibitor of ROS production, as determined by assaying oxidative stress-related parameters (SOD activity, MDA, ·OH and H₂O₂ levels) during cataract formation. The experimental protocols involving animal research were approved by the Animal Care and Ethics Committee of Wenzhou Medical University and conducted according to the Association for Research in Vision and Ophthalmology under the guidelines of the Animal Welfare Act (SYXK 2015-0009).Results: Our study found that TMZ can retard the onset and progression of lens opacification in vivo in experiments using Sprague-Dawley (SD) suckling rats and can rescue the morphology of HLEB₃ cells in vitro. The flow cytometry and DNA fragmentation assays showed that TMZ could prevent sodium selenite-induced apoptosis. The western blot analysing showed that the levels of apoptosis-associated Bcl-2 and Nrf2 were dramatically decreased following the sodium selenite treatment. In addition, the bisulfate DNA sequencing revealed that the demethylation of CpGs in the promoter region of Keap1 was stimulated, and that this demethylation could be inhibited by TMZ by rescuing the Nrf2 expression level.Conclusions: Our findings indicate that the antioxidant TMZ strongly reduces ROS production, which ultimately delays the progression of cataract formation, suggesting that treatment with TMZ represents a novel, promising antioxidant protection to retard cataract formation.

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.

Protective effect of Tephrosia purpurea in diabetic cataract through aldose reductase inhibitory activity

PURPOSE

Tephrosia purpurea (T. purpurea) has been reported to prevent cataract formation in senile cataract model as well as proven effective in STZ induced type 1 diabetes. Aldose reductase (AR) is a key enzyme in the intracellular polyol pathway responsible for the development of diabetic cataract.

OBJECTIVE

To investigate the effects of T. purpurea in the light of inhibition of aldose reductase enzyme in polyol pathway.

METHODS

We studied the effects of alcoholic extract and flavonoid fraction of T. purpurea in streptozotocin (STZ, 45mg/kg, i.v.)-induced type I diabetic cataract in rats. The animals were divided into five groups as control, control treated with alcoholic and flavonoid fraction, diabetic control and diabetic treated with alcoholic and flavonoid fraction. In-vitro aldose reductase inhibitory activity was also evaluated. Further, molecular docking study was performed with crystal structure of aldose reductase and its known chemical constituents of the plant.

RESULTS

The IC₅₀ value of alcoholic extract for aldose reductase inhibition was found to be 209.13μg/ml, and that of flavonoid fraction was found to be 46.73μg/ml. Administration of STZ produced significantly abnormal levels of serum glucose, serum insulin, soluble protein and antioxidants in the lens homogenate. Treatment with alcoholic extract and flavonoid fraction of T. purpurea were able to normalize these levels. Some of the active constituents of T. purpurea showed significant interactions with aldose reductase enzyme in molecular docking studies.

CONCLUSIONS

Our data suggested that both the extracts might be helpful in delaying the development of diabetic cataract due to the presence of rutin and quercetin. This beneficial effect may be due to its significant inhibition of aldose reductase enzyme and anti-oxidant activity.

Cataract

Cataract is the leading cause of reversible blindness and visual impairment globally. Blindness from cataract is more common in populations with low socioeconomic status and in developing countries than in developed countries. The only treatment for cataract is surgery. Phacoemulsification is the gold standard for cataract surgery in the developed world, whereas manual small incision cataract surgery is used frequently in developing countries. In general, the outcomes of surgery are good and complications, such as endophthalmitis, often can be prevented or have good ouctomes if properly managed. Femtosecond laser-assisted cataract surgery, an advanced technology, can automate several steps; initial data show no superiority of this approach over current techniques, but the results of many large clinical trials are pending. The greatest challenge remains the growing 'backlog' of patients with cataract blindness in the developing world because of lack of access to affordable surgery. Efforts aimed at training additional cataract surgeons in these countries do not keep pace with the increasing demand associated with ageing population demographics. In the absence of strategie that can prevent or delay cataract formation, it is important to focus efforts and resources on developing models for efficient delivery of cataract surgical services in underserved regions. For an illustrated summary of this Primer, visit: http://go.nature.com/eQkKll.