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

In vitro antioxidant and ex vivo anti-cataract activity of ethanolic extract of Cineraria maritima: a traditional plant from Nilgiri hills

Background

Cineraria maritima has a long history of use in the treatment of cataract and other eye-related problems in the homeopathic system of medicines. High oxidative stress is one of the major underlying causes of cataract which results in the precipitation of natural protein present in the lenses with aging. This research has been carried out to determine the anti-cataract activity of C. maritima by performing various antioxidant techniques such as 1,1-diphenyl-2-picrylhydrazyl, nitric oxide, hydrogen peroxide, and studies in oxidative stress–induced ex vivo cataract model.

Results

Results of the study conducted in the ethanolic extract of aerial parts (leaves and stems) of C. maritima revealed the presence of various phytoconstituents such as alkaloids, phenols, flavonoids, etc. Total phenol and total flavonoid content was found to be 6.31 ± 0.06 % w/w and 2.14 ± 0.09% w/w respectively, which revealed that the plant contains a good amount of these compounds and hence possesses good antioxidant activity. Furthermore, IC50 values obtained from all the methods gave strong evidence regarding the antioxidant potential of this plant. Anti-cataract activity was also investigated using goat eye lenses and promising results were obtained which speak voluminously about its anti-cataract potential and support its well-prescribed use.

Conclusion

Results obtained with this study clearly supported the significant antioxidant potential and anti-cataract activity of this plant. Further, this plant demands great attention for the development of suitable novel dosage forms for the effective treatment of cataract.

The quest for homeopathic and nonsurgical cataract treatment

PURPOSE OF REVIEW

Age-related cataract occurs when crystallin proteins in the lens partially unfold and subsequently aggregate. Physicians and traditional healers alike have been exploring pharmacologic cataract treatment for hundreds of years. Currently, surgery is the only effective treatment. However, there are an abundance of homeopathic and alternative remedies that have been suggested as treatment for cataract. This article reviews the current understanding of cataract development and discusses several homeopathic remedies purported to treat age-related cataract. Additionally, we will present an overview of evidence regarding the development of pharmacologic cataract reversal therapies.

RECENT FINDINGS

Some homeopathic therapies have been shown to prevent cataract development in experimental models. More studies are required to elucidate the potential medicinal and toxic properties of the various alternative therapies. However, in recent years, scientists have begun to investigate substances that address cataract by reversing lens protein aggregation. One such compound, lanosterol, was reported to reverse cataract opacity in vitro and in animal models. Subsequently, 25-hydroxycholesterol and rosmarinic acid were identified as having similar properties.

SUMMARY

Although challenges and uncertainties remain, further research has the potential to lead to the development of a nonsurgical therapeutic option for age-related cataract.

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.

In vitro antioxidant and anticataractogenic potential of silver nanoparticles biosynthesized using an ethanolic extract of Tabernaemontana divaricata leaves

Silver nanoparticles (AgNPs) have been found useful in biological systems and in medicine since they possess a large surface area to volume ratio, which confers on them several unique properties. In the present study, AgNPs that had been biosynthesized using an ethanolic extract of Tabernaemontana divaricata leaf were evaluated for putative antioxidant potential and efficacy in preventing experimental in-vitro selenite-induced opacification of the ocular lens (cataractogenesis). The antioxidant potential of the AgNPs was evaluated in-vitro by looking for radical-scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydrogen peroxide (H₂O₂) free radicals as well as by determining reducing power. The anticataractogenic potential of the AgNPs was evaluated in an in-vitro model of selenite-induced cataractogenesis in five groups of Wistar rat lenses cultured in Dulbecco's modified Eagle's medium (DMEM) for 24h: Group I lenses (negative control) were cultured in DMEM alone; Group II lenses were exposed to sodium selenite alone (100μM); Group III lenses were exposed simultaneously to sodium selenite and the T. divaricata extract (250μg/ml); Group IV lenses were exposed simultaneously to sodium selenite and the biosynthesized AgNPs (125μg/ml); and Group V lenses were exposed to the AgNPs alone. In these lenses, gross morphological changes, as well as activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione-S-transferase (GST), and levels of reduced glutathione (GSH) and malondialdehyde (MDA), were determined. In-vitro, the AgNPs (which were spherical in shape with an average diameter ranging from 15 to 50nm) showed potent and concentration-dependent radical-scavenging activity on DPPH and H₂O₂ free radicals as well as reducing power. The gross morphological changes seen in the cultured rat lenses were: all eight control (Group I) lenses remained transparent; dense opacification was noted in all eight selenite-challenged untreated (Group II) lenses; in selenite-challenged, simultaneously T. divaricata extract-treated (Group III) lenses, no opacification occurred in seven of eight (87.5%) lenses and only minimal opacification in one (12.5%) lens; all the eight Group IV (selenite-challenged, simultaneously AgNPs-treated) lenses did not show any opacification; and all the eight Group V lenses (exposed to AgNPs alone) remained as transparent as control lenses. The mean activities of CAT, SOD, GPx and GST, and the mean levels of GSH, were significantly (p<0.05) lower in Group II lenses than those in Groups I, III, IV and V lenses, while the mean MDA level was significantly (p<0.05) higher in Group II lenses than those in Groups I, III, IV and V lenses; oxidative damage possibly occurred in Group II lenses, whereas this appears to have been prevented in Groups III and IV lenses. These observations suggest that the T. divaricata leaf ethanolic extract, and also the AgNPs biosynthesized using the T. divaricata extract, possess effective in-vitro antioxidant activity and the potential to prevent experimental selenite-induced opacification in cultured Wistar rat lenses.

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.

Preventive and Protective Effect of Nishamalaki in STZ Induced Diabetic Complications in Wistar Rats

INTRODUCTION

Diabetes is a metabolic disease of vital health importance because of the complications associated with it. Clinical trials and animal studies have demonstrated the anti-hyperglycaemic effect of Nishamalaki. Present study was planned to evaluate the protective potential of Nishamalaki on diabetic complication in rats.

AIM

To study the Nephro-protective effect and to assess the protective potential on retinal changes of Nishamalaki in diabetic wistar rats.

MATERIALS AND METHODS

Diabetes induced with 60 mg/kg of Streptozotocin and 110 mg/kg Nicotinamide IP. Nishamalaki, a combination of Curcuma longa and Emblica officinalis administered orally with honey. Rats divided into six groups, control and diabetic rats with blood glucose above 250 mg/dl were divided into 5 groups. After 8 weeks test animals were treated with Nishamalaki, Enalapril and control with saline for 30 days. Biochemical parameters measured like Serum BSL, BUN and Creatinine and rats were observed for development of cataract. Rats sacrificed and kidney samples were taken to examine histopathological changes.

RESULTS

Blood Urea Nitrogen and Creatinine values were significantly (p<0.01) reduced in Nishamalaki group than control group. Nishamalaki showed the protective effect on kidney pathology as seen on histopathology by near normal glomerular and tubular structures. Control group showed shrunken glomerulus and tubular vacuolations. In Nishamalaki group immature sub capsular cataract with mild lenticular opacity were seen compared to the mature cataract with significant lenticular opacity and corneal vascularisation in control group.

CONCLUSION

Nishamalaki showed protective effect on development of Nephrotoxicity and it has also delayed the progression of cataract in rats.

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.

C-phycocyanin modulates selenite-induced cataractogenesis in rats

The present investigation is aimed to evaluate the anticataractogenic potential of C-phycocyanin (C-PC), extracted and purified from Spirulina platensis. Enucleated rat lenses were maintained in vitro in Dulbecco's modified Eagle medium (DMEM). Group I contained DMEM, Group II and Group III contained 100 μM of sodium selenite, Group III was subdivided into three viz IIIa, IIIb, IIIc supplemented with 100, 150, 200 μg of C-PC respectively. In the in vivo study, on tenth day post partum: Group I rat pups received an intraperitoneal injection of saline, Group II, IIIa, IIIb, and IIIc rat pups received a subcutaneous injection of sodium selenite (19 μmol/kg bodyweight) Group IIIa, IIIb, IIIc also received an intraperitoneal injection of 100, 150, 200 mg/kg body weight of C-PC, respectively, from postpartum days 9-14. On termination of the experiment, the lenses from both in vitro and in vivo studies were subjected to morphological examination and subsequently processed to estimate the activities of antioxidant enzymes namely superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, levels of reduced glutathione and lipid peroxidation products. Sodium selenite-exposed, C-PC-treated rat lenses (Group IIIc), showed significant restoration of antioxidant enzyme activity (p < 0.05) when compared to their counterpart Group II. Group IIIc conserved the levels of GSH and lipid peroxidation products at near to normal levels as compared with Group II. Results conclude the possible role of C-PC in modulating the antioxidant enzyme status, thereby retarding sodium selenite-induced cataract incidence both in vitro and in vivo.