Effect of methanolic extract of Allium sativum (AS) in delaying cataract in STZ-induced diabetic rats

Lebanese Medicinal Plants with Ophthalmic Properties

Lebanon benefits from a rich biodiversity, with medicinal and aromatic plants (MAPs) representing an important part of the country's natural wealth; however, limited data are available documenting medicinal plants being employed in eye health. This review is the first to document Lebanese medicinal plants with ophthalmic characteristics and phytochemistry that might be beneficial in the development of new, accessible, and efficient ocular medications. In this study, we searched for studies on ocular therapeutic plants using known resources, including PubMed, ScienceDirect, and Google Scholar, and confirmed these plants' presence within the Lebanese flora. The efficacy of 52 species from 28 families, including two endemic species (Crepis libanotica and Salvia libanotica), has been documented. Their Latin names, regional names, ocular medical applications, the plant parts used, and preparation forms are detailed below. The largest number of species belongs to the Lamiaceae family (21%), followed by Asteraceae (14%) and Solanaceae (7%). The most commonly used plant parts are the stems, leaves, and seeds. Ocular treatments fall into several categories: inflammation, infection, irritation, dry-eye, eyewash, the prevention or delay of cataracts, and general eye problems. A significant percentage (68%) of the medicinal plants target the anterior part of the eye. Some of the reported plants can be harmful to the eyes and should be handled with caution. The Lebanese medicinal plants listed, constituting a local heritage with global importance, could be used for treating ophthalmic ailments and require special screening and preservation.

Effect of epigallocatechin gallate in green tea on preventing lens opacity and αB-crystallin aggregation in rat model of diabetes

AIM

To evaluate the effect of epigallocatechin gallate (EGCG) in preventing lens opacity and the aggregation of lens αB-crystallin in model rats of diabetes mellitus (DM).

METHODS

This experimental study included Wistar rats for DM as in vivo models and divided into 5 groups. The treatment groups were administered EGCG by orally for 20d and were then assessed for their degree of lens opacity with binocular microscope and lens αB-crystallin expression from Western blot analyze.

RESULTS

Pearson correlation test and regression analysis on EGCG exposure and final random blood sugar (RBS) obtained a significance level of P<0.05. EGCG exposure can significantly lower RBS with an R ² of 0.5634 (56.34%). The same analysis on EGCG exposure and the degree of lens opacity obtained a significance level of P<0.05 and increased exposure to EGCG can significantly lower the degree of lens opacity with an R ² of 0.8577 (85.77%). Correlation analysis between EGCG and the expression of lens αB-crystallin can be concluded that the higher the EGCG exposure administered, the higher the native lens αB-crystallin expression and the lower the aggregate lens αB-crystallin expression. There was also significant effect in which every 1 mg/kg body weight dose of EGCG can increase the native lens αB-crystallin expression by 0.0063 and decrease the aggregate lens αB-crystallin expression by 0.0076.

CONCLUSION

The administration of EGCG at a dose of 300, 600, and 1200 mg shows a significant effect on preventing lens opacity and aggregation of αB-crystallin in diabetic rat models and this research could be a biomolecular prevention of cataract.

Current Trends in the Pharmacotherapy of Cataracts

Cataracts, one of the leading causes of preventable blindness worldwide, refers to lens degradation that is characterized by clouding, with consequent blurry vision. As life expectancies improve, the number of people affected with cataracts is predicted to increase worldwide, especially in low-income nations with limited access to surgery. Although cataract surgery is considered safe, it is associated with some complications such as retinal detachment, warranting a search for cheap, pharmacological alternatives to the management of this ocular disease. The lens is richly endowed with a complex system of non-enzymatic and enzymatic antioxidants which scavenge reactive oxygen species to preserve lens proteins. Depletion and/or failure in this primary antioxidant defense system contributes to the damage observed in lenticular molecules and their repair mechanisms, ultimately causing cataracts. Several attempts have been made to counteract experimentally induced cataract using in vitro, ex vivo, and in vivo techniques. The majority of the anti-cataract compounds tested, including plant extracts and naturally-occurring compounds, lies in their antioxidant and/or free radical scavenging and/or anti-inflammatory propensity. In addition to providing an overview of the pathophysiology of cataracts, this review focuses on the role of various categories of natural and synthetic compounds on experimentally-induced cataracts.

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.

Hypoglycemic and antioxidant effects of oral administration of garlic extract in the livers of type 1 diabetic rats

Background Liver dysfunction is a predominant complication of diabetes. Herbal remedies such as garlic are commonly used for reducing diabetic complications. In this study the effect of garlic extract on glucose level, liver enzymes activities in the serum and nitric oxide (NO) level, oxidative stress status, and histology in the liver tissues of streptozotocin-induced diabetes (type 1) was investigated. Methods Twenty-four adult male Wistar rats were randomized and divided into four groups: control rats, diabetic rats, diabetic rats treated with garlic, and garlic-treated normal rats. Glucose level and liver enzymes activities were determined by colorimetric assay in the serum. NO levels by Griess method, oxidative stress parameters including malondialdehyde (MDA), total oxidative status (TOS), and total antioxidant capacity (TAC) by spectrophotometric method, and histopathological examination by hematoxylin and eosin staining method were evaluated in the liver tissues. Results Glucose level, liver enzymes activities, MDA, TOS, and NO levels were increased and TAC level decreased significantly in diabetic rats in comparison with control rats (p<0.01); whereas, after oral administration of garlic, glucose level, liver enzymes activities, MDA, TOS, and NO levels were decreased and TAC level increased significantly near to the normal levels (p<0.05). Conclusion The results showed the hypoglycemic and antioxidant effects of garlic in the livers of type 1 diabetic rats.

Ameliorative Influence of Dietary Fenugreek (Trigonella foenum-graecum) Seeds and Onion (Allium cepa) on Eye Lens Abnormalities via Modulation of Crystallin Proteins and Polyol Pathway in Experimental Diabetes

PURPOSE AND METHODS

Hyperglycemia-induced osmotic and oxidative stress is thought to be involved in the pathogenesis of diabetes-related secondary complications including cataract. In continuation of our previous observation of the ameliorative influence of these spices on hyperglycemia, attendant metabolic abnormalities, and oxidative stress in tissues of diabetic rats, the beneficial influence of dietary (10%) fenugreek seeds, (3%) onion, or their combination was investigated on diabetes-induced alteration in the eye lens of streptozotocin-induced diabetic rats.

RESULTS

Animals maintained on these spices showed significantly countered oxidative stress markers (reactive oxygen species, lipid peroxidation and protein carbonyl), advanced glycation end products, and expression of their receptor in the eye lens. Increased activity of polyol pathway enzymes, their protein, and mRNA expression was significantly countered in the cataractogenic lens as a result of these dietary interventions. Altered crystallin (αA and αB) distribution profile, their expression, activity of carbohydrate metabolizing enzymes, and antioxidant status were significantly annulled by these dietary treatments. Physical and visual observation of the photomicrographs of the lenses of treated rats indicated that these dietary interventions delayed cataractogenesis in diabetic rats.

CONCLUSIONS

Overall, the present investigation evidenced a beneficial modulation of the progression of cataractogenesis by dietary fenugreek seeds and onion, implicating their potential in ameliorating cataract in diabetics.

Ameliorative Effects of Allium sativum Extract on iNOS Gene Expression and NO Production in Liver of Streptozotocin + Nicotinamide-Induced Diabetic Rats

Diabetes mellitus (DM) is one of the most prevalent diseases in the world, which is strongly associated with liver dysfunction. Hyperglycemia, through an oxidative stress pathway, damages various tissues. Herbal medicine is a good candidate to ameliorate hyperglycemia and oxidative stress. In this study, the effects of aqueous Allium sativum (garlic) extract (AGE) on gene expression of inducible nitric oxide synthases (iNOS) and production of nitric oxide (NO) were evaluated in the liver tissue of diabetic rats. Four groups of rats contained normal control rats, garlic control rats (AGE), Streptozotocin (STZ) + nicotinamide-induced diabetic rats (DM), and diabetic rats treated with garlic (DM + AGE). Glucose levels and liver enzymes activities were determined by colorimetric assay in the serum. Gene expression of iNOS by real-time PCR, NO levels by Griess method, oxidative stress parameters by spectrophotometric method and histopathological examination by hematoxylin and eosin staining method were evaluated in the liver tissues. Glucose levels, activities of liver enzymes, oxidative stress markers, iNOS gene expression, and NO production increased significantly in diabetic rats in comparison with control rats, whereas after oral administration of garlic, these parameters decreased significantly, close to the normal levels. Hence, the beneficial effects of garlic on the liver injury of diabetes could be included in the hypoglycaemic and antioxidant properties of garlic via a decrease in gene expression of iNOS and subsequent NO production.

Medicinal plants used for ophthalmological problems in Navarra (Spain)

ETHNOPHARMACOLOGICAL RELEVANCE

Several plants have been found to have effective against number of ophthalmological problems in Navarra.

MATERIAL AND METHODS

Information was collected using semi-structured ethnobotanical interviews with 686 informants in 267 locations. In order to confirm the pharmacological application of the uses more cited by the informants, a literature review was conducted.

RESULTS

A total of 57 pharmaceutical uses were reported, for 19 plants and 13 families, mainly represented by Asteraceae. The most frequently used parts were inflorescences, flowers, aerial parts, leaves and flowered aerial parts. The related affections fell into eleven categories: bloodshot eyes, watery eyes and wounds, improve vision, irrited eyelids, rheums and styes, tired eyes, conjunctivitis, eyewash, ocular problems in general. The most cited plants were: Chamaemelum nobile (L.) All., Santolina chamaecyparissus L. ssp. squarrosa (DC.) Nyman, Sambucus nigra L. ssp. nigra, Rosa agrestis Savi and Calendula officinalis L. None of them have been pharmacologically validated by Official International Organisms. From the therapeutic point of view, Allium sativum L., Foeniculum vulgare Mill., C. officinalis, and S. chamaecyparissus ssp. squarrosa deserve special attention, because ethnobotanical and pharmacological studies suggest that these medicinal plants are effective for ophthalmological problems.

CONCLUSIONS

The present study constitutes a good basis for further phytochemical and pharmacological research of these four plants, which could be of interest in the design of new inexpensive, effective and safe drugs. The remaining plants are needed to be screened through standard pharmacological and clinical procedures for their activities.