Famine From Feast: Low Red Cell Vitamin C Levels in Diabetes

Protective role of Pleurotus florida against streptozotocin-induced hyperglycemia in rats: A preclinical study

Pleurotus florida (Mont.) Singer is a mushroom species known to be an antioxidant, immunomodulatory, and diuretic agent, reducing blood pressure and cholesterol. The aim of this study was to evaluate the in vivo potency of P. florida's anti-diabetic properties in rats affected by hyperglycemia induced by Streptozotocin (STZ) at 55 mg/kg (i.p.), characterized by oxidative stress impairment, and changes in insulin levels and lipid profile. After inducing hyperglycemia in the rats, they were treated with P. florida acetone and methanol extracts, orally administered for 28 days at doses of 200 mg/kg and 400 mg/kg body weight. The hyperglycemic control (DC) group showed significant increases (P < 0.05) in mean blood sugar, total cholesterol, triglycerides, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, blood urea nitrogen, lipid hydroperoxides, and malondialdehyde, compared to the normal control (NC) group The high-density lipoprotein cholesterol, serum insulin, superoxide dismutase, catalase, glutathione disulfide, glutathione peroxidase, reduced glutathione, guaiacol peroxidase, and vitamin E and C levels showed a significant decrease (P < 0.05) in DC group, compared to the NC group. Blood glucose levels, lipid profiles, and insulin levels improved significantly after 28 days of treatment, in the group treated with glibenclamide (an oral hypoglycemic drug, used as positive control), and in the groups treated with P. florida extracts. In DC group, the treatment with P. florida was found to prevent diabetes, according to histopathological studies of the kidneys, pancreas, and liver of rats. In conclusion, this study has shown that the treatment with P. florida decreased oxidative stress and glucose levels in the blood, as well as restoring changes in lipid profiles.

Vitamin C: the known and the unknown and Goldilocks

Vitamin C (Ascorbic Acid), the antiscorbutic vitamin, cannot be synthesized by humans and other primates, and has to be obtained from diet. Ascorbic acid is an electron donor and acts as a cofactor for fifteen mammalian enzymes. Two sodium-dependent transporters are specific for ascorbic acid, and its oxidation product dehydroascorbic acid is transported by glucose transporters. Ascorbic acid is differentially accumulated by most tissues and body fluids. Plasma and tissue vitamin C concentrations are dependent on amount consumed, bioavailability, renal excretion, and utilization. To be biologically meaningful or to be clinically relevant, in vitro and in vivo studies of vitamin C actions have to take into account physiologic concentrations of the vitamin. In this paper, we review vitamin C physiology; the many phenomena involving vitamin C where new knowledge has accrued or where understanding remains limited; raise questions about the vitamin that remain to be answered; and explore lines of investigations that are likely to be fruitful.