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

Abstract

Glycemic-induced stress is a major culprit contributing to oxidative insult that has far-reaching effects in diabetic cataract worldwide. In an attempt to prevent/delay cataract, many therapeutic agents have been identified, and among these, natural dietary sources have gained pharmacological significance. Hence, we investigated the efficacy of the methanolic garlic extract against diabetic cataract in Wistar rats. Methanolic garlic extract scavenged the transition metal ion-generated H(2)O(2) with an IC(50) of 768.8 +/- 1.76 mug/ml, showing its potential ability as an antioxidant. We have noticed lenticular opacity and oxidative damage in streptozotocin (STZ)-induced hyperglycemic rats. This is evident by the elevation of Ca(2+), Cu(2+), Na(+), Mg(2+), thiobarbituric acid reacting substances (TBARS), and carbonyl content and increased activities of polyol enzymes, glutathione peroxidase (GPx), superoxide dismutase (SOD), and up regulation of iNOS transcript and protein aggregation/cross-linking followed by a decrease in reduced glutathione (GSH), K(+) content, and tryptophan fluorescence in the cataractous lenses of STZ-induced diabetic rats. Garlic administration in a dose-dependent manner attenuated the glycemia-mediated oxidative stress as all the parameters have been found normalized more or less to that of control rats and thus delaying the progression of the lens opacity. We conclude that garlic extract has hypoglycemic and anti oxidant properties that can delay the progression of cataract as revealed in this study.

Regulation of iNOS Expression by NF-κB in Human Lens Epithelial Cells Treated With High Levels of Glucose

“…Production of the ONOO À species and its derivatives, whose oxidative capacity is 2000-fold stronger than H 2 O 2 , can lead to a severe oxidative stress reaction, causing extensive damage to lens epithelial cells. 27,28 Over-expression of iNOS had been detected in various eye diseases, 20,[32][33][34][35][36][37] as reported in our previous study. 45 It is widely acknowledged that NF-jB is the major upstream regulator of iNOS.…”

“…30,31 Increased expression of iNOS has been detected in many eye diseases. 20,[32][33][34][35][36][37] Previous research has revealed that both NF-jB and iNOS expression are increased in the LECs of Zucker fatty rats. 38 However, it remains unclear whether NF-jB regulates iNOS expression in human LECs at high glucose levels.…”

Current Trends in the Pharmacotherapy of Cataracts

“…Commonly used as a seasoning worldwide, the therapeutic potential of garlic has been reported to include anti-tumor, cardioprotective, anti-diabetic, antimicrobial, amongst others [247]. In addition to delaying onset of streptozotocin-induced cataract in Wistar rats, the methanolic Allium sativum (garlic) extract mitigated hypoglycemia-induced oxidative stress associated with the disease in a dose-dependent manner and restored lenticular SOD and GSH-Px activities and GSH content [248]. In other studies, the flavonoid-rich, aqueous extract of Allium cepa (onion), preserved optical clarity in selenite-treated Wistar Albino rats, in vivo.…”

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“…Herbal dietary supplementation having diverse antioxidants, fibers, minerals, [164] antiglycant, which show inhibitory activity against α-amylase and α-glucosidase [165] can easily control carbohydrate metabolism in humans. [166] Further, inclusion of white vegetables such as garlic (Allium sativum) provides [167,168] in daily diet provides better diabetic control in T2D patients. [169] Natural components found in garlic oil [170] and its ingredients [171] found more beneficial to control T2D mellitus [172] because they possess antihyperglycemic, antihyperlipidemic, anti-inflammatory, and adenosine deaminase-lowering effects in patients and cut down obesity.…”