Palladium-α-lipoic acid complex attenuates alloxan-induced hyperglycemia and enhances the declined blood antioxidant status in diabetic rats

Amelioration of Metal-Induced Cellular Stress by α-Lipoic Acid and Dihydrolipoic Acid through Antioxidative Effects in PC12 Cells and Caco-2 Cells

α-Lipoic acid (ALA) and its reduced form dihydrolipoic acid (DHLA) are endogenous dithiol compounds with significant antioxidant properties, both of which have the potential to detoxify cells. In this study, ALA (250 μM) and DHLA (50 μM) were applied to reduce metal (As, Cd, and Pb)-induced toxicity in PC12 and Caco-2 cells as simultaneous exposure. Both significantly decreased Cd (5 μM)-, As (5 μM)-, and Pb (5 μM)-induced cell death. Subsequently, both ALA and DHLA restored cell membrane integrity and intracellular glutathione (GSH) levels, which were affected by metal-induced toxicity. In addition, DHLA protected PC12 cells from metal-induced DNA damage upon co-exposure to metals. Furthermore, ALA and DHLA upregulated the expression of survival-related proteins mTOR (mammalian target of rapamycin), Akt (protein kinase B), and Nrf2 (nuclear factor erythroid 2-related factor 2) in PC12 cells, which were previously downregulated by metal exposure. In contrast, in Caco-2 cells, upon co-exposure to metals and ALA, Nrf2 was upregulated and cleaved PARP-1 (poly (ADP-ribose) polymerase-1) was downregulated. These findings suggest that ALA and DHLA can counterbalance the toxic effects of metals. The protection of ALA or DHLA against metal toxicity may be largely due to an enhancement of antioxidant defense along with reduced glutathione level, which ultimately reduces the cellular oxidative stress.

Alpha-lipoic acid: A possible pharmacological agent for treating dry eye disease and retinopathy in diabetes

Alpha-lipoic acid (ALA) is a naturally occurring dithiol micronutrient which acts as a cofactor for mitochondrial enzyme activity. Due to its potential antioxidant activity, it is considered as "universal antioxidant". Previous studies reported the pharmacological benefits of ALA such as glycaemic control, improved insulin sensitivity and alleviation of diabetic complications such as neuropathy and cardiovascular diseases. Dry eye disease and retinopathy are prevalent in diabetic patients. Experimental studies demonstrated the beneficial effects of ALA in dry eye and diabetic retinopathy. ALA can prevent the dry eye by down regulating the expression of matrix metalloproteinase-9 in the corneal epithelial cells and activating the antioxidant status of the ocular surface. Furthermore, its direct antioxidant effect can also prevent oxidative stress-induced corneal surface erosion and lachrymal gland damage. ALA prevents diabetic retinopathy through inhibition of O-linked β-N-acetylglucosamine transferase and nuclear factor-kappa B activity and alleviation of oxidative stress. It can activate the nuclear factor erythroid-2-related factor 2 and AMP-activated protein kinase in retinal ganglion cells. Clinical trials conducted in pre-retinopathic diabetic patients showed ALA with genistein and vitamins could protect the retinal cells and decline the inflammatory effect in diabetic patients. However, studies are scant to explore its beneficial effects in dry eye disease and diabetic retinopathy. Therefore, this review article discusses an update on the role of ALA in dry eye disease and diabetic retinopathy, two ocular diseases prevalent in diabetic patients.

Chronic treatment of (R)-α-lipoic acid reduces blood glucose and lipid levels in high-fat diet and low-dose streptozotocin-induced metabolic syndrome and type 2 diabetes in Sprague-Dawley rats

(R)‐ α ‐lipoic acid (ALA), an essential cofactor in mitochondrial respiration and a potential antioxidant, possesses a wide array of metabolic benefits including anti‐obesity, glucose lowering, insulin‐sensitizing, and lipid‐lowering effects. In this study, the curative effects of ALA (100 mg/kg) on a spectrum of conditions related to metabolic syndrome and type 2 diabetes (T2D) were investigated in a high‐fat diet (HFD)‐fed and low‐dose streptozotocin (STZ)‐induced rat model of metabolic syndrome and T2D. The marked rise in the levels of glucose, triglycerides, total‐cholesterol, LDL‐cholesterol, and VLDL‐cholesterol in the blood of HFD‐fed and low‐dose STZ‐injected rats were significantly reduced by ALA treatment. Furthermore, ALA treatment significantly increased the serum HDL‐cholesterol levels and tended to inhibit diabetes‐induced weight reduction. Mathematical computational analysis revealed that ALA also significantly improved insulin sensitivity and reduced the risk of atherosclerotic lesions and coronary atherogenesis. This study provides scientific evidence to substantiate the use of ALA to mitigate the glucose and lipid abnormality in metabolic syndrome and T2D.

Therapeutic potency of saponin rich aqueous extract of Scoparia dulcis L. in alloxan induced diabetes in rats

Background:

Diabetes mellitus is major metabolic disorders of carbohydrate metabolism. This leads to alter the multiple organ system.

Aims:

To investigate the antidiabetic and antioxidant effects of the saponin rich aqueous extract of Scoparia dulcis (SRE-SD) using alloxan-induced hyperglycemic rat model.

Material and Methods:

The single dose of alloxan was injected for the induction of diabetes in rats. The SRE-SD and glibenclamide were administered for 15 consecutive days from the 3^rd day of alloxan administration. Quantity of food and water intake was measured at day 0, and 18. Further, body weight was recorded and blood samples were collected at different time intervals that is, day 0, 3, 8, 13, and 18. The oxidative biomarkers (i.e. thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) and nitrite (NO²⁻) levels were also estimated in the serum sample.

Results:

The SRE-SD showed a remarkable dose and time-dependent changes in alloxan-induced rise in the level of food consumption and water intake, serum glucose level, TBARS, NO²⁻ and fall in the level of GSH. Further, significant attenuation was observed at 20 and 30 mg/kg of SRE-SD treated group.

Conclusions:

These findings demonstrate that SRE-SD has both antidiabetic and antioxidant effects on the experimental model of diabetes in rat.

Beneficial effects of silibinin against the progression of metabolic syndrome, increased oxidative stress, and liver steatosis in Psammomys obesus, a relevant animal model of human obesity and diabetes

BACKGROUND

Insulin resistance and oxidative stress are major pathogenic mechanisms leading to chronic liver diseases in diabetic subjects. The gerbil Psammomys obesus is a unique model of nutritional diabetes resembling the disease in humans. This study investigated whether the natural ingredient silibinin, known as hepatoprotective, could decrease oxidative stress and reduce liver damage in obese gerbils.

METHODS

Control animals were fed their vegetable-based low caloric diet while two other rat groups ingested a high calorie diet for 14 weeks. Silibinin, or its vehicle, was administrated by gastric intubation (100 mg/kg per day) from the 7th week of treatment, which corresponds to an established insulin resistance state. At the end of the experiments, the hepatic biochemical profile, markers of oxidative stress in either plasma or liver tissue, and histological alterations were examined.

RESULTS

Diabetic P. obesus displayed many metabolic disturbances (hyperinsulinemia, hyperglycemia, dyslipidemia), which were aggravated for the last 8 weeks. These events were coupled with greater oxidative stress (decline in glutathione, rise in lipoperoxidation). In addition, glutathione peroxidase activity was reduced while the level of superoxide dismutase was elevated. Interestingly, treatment with silibinin alleviated most of the metabolic defects, especially high triglyceride levels, reduced insulin resistance and largely restored antioxidant status. Also, Masson's trichrome staining revealed distinct steatosis, yet silibinin partially reversed this manifestation.

CONCLUSION

Silibinin affords substantial protection against the progression of insulin resistance in Type 2 diabetes mellitus for P. obesus by hampering the oxidative process and improving hepatic metabolism.