Six flavonoids were isolated from Brickellia arguta and identified using chemical and spectral methods. The isolation and spectral data of a new flavonoid, 6- methoxykaempferol 3-O-beta-D- robinobioside (3), are reported for the first time. Three of these flavonoids were tested and showed inhibition of rat lens aldose reductase.

Aldehyde Reductase↗

PubMedDate not supplied

Flavonoids from Brickellia glutinosa.

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Aldehyde Reductase↗

PubMedDate not supplied

Green tea (Camellia sinensis) protects against selenite-induced oxidative stress in experimental cataractogenesis.

Cataract is the leading cause of blindness worldwide. It is a multifactorial disease primarily associated with oxidative stress produced by free radicals. The protection offered by various antioxidants in cataract development is well established. Polyphenolic compounds present in green tea (Camellia sinensis) are reported to possess antioxidant property in various pathological conditions. The present study was undertaken to evaluate the anticataract potential of green tea leaf (GTL) extract in the development of lens opacification. Enucleated rat lenses were randomly divided into normal, control and treated groups and incubated for 24 h at 37 degrees C. Oxidative stress was induced by sodium selenite in the culture medium of the two groups (except the normal group). The medium of the treated group was additionally supplemented with GTL extract. After incubation, lenses were subjected to glutathione and malondialdehyde estimation. Enzyme activity of superoxide dismutase, catalase and glutathione peroxidase was also measured in different sets of the experiment. In vivo cataract was induced in 9-day-old rat pups of both control and treated groups by a single subcutaneous injection of sodium selenite. The treated pups were injected GTL extract intraperitoneally prior to selenite challenge and continued for 2 consecutive days thereafter. Cataract incidence was evaluated on 16th postnatal day by slit lamp examination. There was positive modulation of biochemical parameters in the organ culture study. Green tea was also found to reduce the incidence of selenite cataract in vivo. The results suggest that green tea possesses significant anticataract potential and acts primarily by preserving the antioxidant defense system.

Animals↗

PubMedDate not supplied

Establishment of the mouse as a model animal for the study of diabetic cataracts.

The purpose of the present study was to investigate the suitability of using the mouse, a species known to have a low lens aldose reductase activity, as a model animal for studying the pathogenesis of diabetic cataract. Earlier studies with diabetic rats whose cataract development is much faster can only partially explain the etiology of cataracts in humans where lens aldose reductase is substantially low. CD-1 mice were injected intraperitoneally with streptozotocin according to Rossini's method. Blood glucose levels were estimated after 7 days, and animals having blood glucose between 300 and 400 mg/dl were selected for further experiments. Development of lenticular opacity was followed by examining the animals every 3-4 weeks by direct ophthalmoscopy, slitlamp examination and Scheimpflug photography. Additionally, the animals were sacrificed at appropriate intervals, eyes enucleated and subjected to morphological studies. The presence of refractive changes and early cataract in the diabetic mice was initially ascertained by the distorted appearance of the grid pattern when seen through the isolated lenses. Early cataracts were visible on slitlamp examination and by ophthalmoscopy as early as 3-4 weeks after the establishment of diabetes. Advanced opacity was clearly documentable by photography after 5-6 months. Similar to that in other species, a single layer of anterior epithelial cells abutting the anterior capsule was seen in the histological sections of normal mouse lenses. On the contrary, the epithelium in the diabetic lens was multilayered, and numerous nucleated cells were visible in the superficial anterior cortex. These studies therefore suggest that further studies with mice may throw additional light on the contribution of diabetes in the pathogenesis of cataracts in low lens aldose reductase models.

Animals↗

PubMedDate not supplied

Attenuation and delay of diabetic cataracts by antioxidants: effectiveness of pyruvate after onset of cataract.

Cataract is one of the most significant vision-impairing complications of diabetes. The present study examined the feasibility of inhibiting cataract formation by treatment with pyruvate, a metabolite known to effectively scavenge reactive species of oxygen and inhibit protein glycation, both known to be involved in the genesis of diabetic cataracts. In addition, pyruvate stimulates tissue metabolism, which is depressed with the onset of cataract formation. The objective of our experiments was to determine if this compound could be effective in offsetting the progress of cataract, specifically if administered after the diabetes-induced lens changes have begun, as opposed to the previous reports wherein it has been reported to delay cataract formation if administered prophylactically with the immediate onset of diabetes. Diabetes was induced by intraperitoneal administration of streptozotocin to mice. Lens transparency was assessed by slit lamp examination and its photography. ATP was determined enzymatically by reacting it with luciferin-luciferase mixture and measuring the fluorescence intensity. The findings described herein are in accordance with this possibility. The incidence of cataract in the group of diabetic animals, where treatment with pyruvate was initiated after the initial lens changes set in, was significantly lower at all times of observation in comparison to the untreated diabetic group. In addition, the severity of opacities in the pyruvate-treated group, when present, was much minor, the transparency of these cases being close to that in the control animals. The ophthalmic findings are supported biochemically by ATP levels, which were significantly higher in the pyruvate group in comparison to the untreated group. The present findings emphasize the clinical usefulness of initiating treatment with anti-oxidants and metabolic agonists even when the lens changes are detected at the time of the diabetes diagnosis. The latter usually comes much later than the onset of visual aberrations. Prophylaxis is not an absolute requirement.

Adenosine Triphosphate↗