In recent times there has been great demand for natural products that have possible preventive action against diabetes and its secondary complications. Keeping this in mind, this study was undertaken to investigate the influence of the flavonoid, quercetin, on oxidative stress markers and the antioxidant defence system of hepatic and neuronal tissues from galactose-induced hyperglycaemic rats. Weanling male Wistar rats were treated with 30% galactose in AIN 93 diet (group B, n=8) to induce hyperglycaemia. Control rats received normal Stock AIN 93 diet (group A, n=8). The third set of rats received group B diet with quercetin at 400 mg/100 g diet (group C, n=8). Glucose levels and body weights were measured on a weekly basis for four weeks to monitor the hyperglycaemia induced by galactose feeding. Parameters involved in the pathogenesis of galactose-induced hyperglycaemia, which included organosomatic index, protein content, antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), tryptophan fluorescence, content of protein carbonyls, prooxidant malonaldehyde (MDA) and glutathione (GSH) in hepatic and neuronal tissues were determined at the end of the fourth week. The study suggest that quercetin counters the pro-oxidant effects of galactose-induced hyperglycaemic stress, as there was a significant reversal of changes with respect to body weights, organosomatic index of hepatic and neuronal tissues, lipid peroxidation, protein carbonyl content, reduced glutathione and activities of antioxidant enzymes. In addition, treatment with quercetin appears to reduce the osmotic stress induced by hyperglycaemia, as assessed by polyol pathway enzyme aldose reductase. These results imply that inclusion of quercetin in the diet controls, to some extent, galactose-induced hyperglycaemia and its attendant complications.

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Diabetes is a major socio-economical burden with serious health consequences. The reactive oxygen species generated in this pathology alters the internal milieu of the cellular systems paving way to metabolic disorders. In the present investigation garlic's dose-dependent protective action against streptozotocin (STZ)-induced oxidative stress in hepatic and intestinal tissues has been studied. Methanolic garlic extract scavenged the DPPH radical with an IC(50) of 424 +/- 4.4 microg/ml proving its efficient antioxidant property. Garlic administration at 250 and 500 mg/kg body wt. significantly normalized the blood glucose in the diabetic rats. Biochemical analysis revealed a pronounced oxidative stress in STZ-rats (G-II) consequent to hyperglycemia as seen by a significant (P < 0.05 and 0.01) rise in malondialdehyde, protein carbonyls; accumulation of glycation products; disintegration of protein integrity (tryptophan fluorescence) followed by a decrease in reduced glutathione, antioxidant (GPx and CAT) enzymes culminating in apoptosis. Garlic administration in a dose-dependent manner has been found to restore and normalize significantly the above changes and thus restoring a normal functional integrity. These beneficial effects are prominent with 500 mg/kg body wt. dosage of garlic in comparison with 250 mg/kg body wt. dosage. But, 500 mg/kg body wt. dosage is not totally free from side effects as the decrease in body weight and increased intestinal tissue apoptosis were also found in control rats administered with garlic extract at 500 mg/kg body wt. along with diabetic rats. Based on these findings it is suggested that consumption of garlic at a lower dose is beneficial in terms of defensive action against oxidative stress.

Metal complexes of divalent cobalt, nickel and copper and trivalent iron were synthesized using N-salicylidene-3-aminocoumarin as chelating agent. The ligand behaves as a monobasic ONO donor towards Co(II), Ni(II) and Cu(II) and as an ON as well as an ONO donor towards Fe(III). All the complexes have been proposed to have octahedral geometry on the basis of analytical, thermal conductivity, spectral and magnetic data. The complexes have been screened against Spodoptera litura; F (Lepidoptera: noctuiidae) for antifeeding and insect-growth-regulating activity. The results show appreciable insect-growth-regulating activity associated with metal complexation.

Galactosemic cataracts are characterized by electrolyte disturbances resulting in osmotic imbalance and loss of transparency. We have studied the defensive role of quercetin, a bioflavonoid, against the alterations of calcium (Ca2+), sodium (Na+), and potassium (K+) concentrations in galactose-induced cataract in a rodent model. The experimental study was conducted on weanling male Wistar rats with an average body weight of 34 +/- 0.9 g. Different groups received normal stock AIN 93 diet (group A, n = 8), AIN 93 diet with 30% galactose (group B, n = 8), and AIN 93 diet with 30% galactose + quercetin at 400 mg/100 g diet (group C, n = 8). Aldose reductase activity and protein content and concentrations of Ca2+, Na+, and K+ were determined in normal and cataractous lenses. Treatment with quercetin resulted in a significant decrease in Na+ and Ca2+ and aldose reductase levels and an increase in K+ and protein levels in galactosemic cataractous lenses. These results imply that inclusion of quercetin contributes to lens transparency through the maintenance of characteristic osmotic ion equilibrium and protein levels of the lens.