Biological Activity of Extracts of Red and Yellow Fruits of Cornus mas L.-An In Vitro Evaluation of Antioxidant Activity, Inhibitory Activity against α-Glucosidase, Acetylcholinesterase, and Binding Capacity to Human Serum Albumin

Although extracts are broadly used in order to support the treatment of numerous diseases, only in a limited number of cases is the process of applying and establishing their mechanisms of action scientifically analyzed. Fruits of Cornelian cherry are an abundant source of iridoids, anthocyanins, flavonols and phenolic acids. The aim of the present study was to evaluate the in vitro bioactivity of red and yellow Cornelian cherry fruits’ extracts. The biological potential of extracts, in a broad sense, involved antioxidant activity in relation to phosphatidylcholine liposomes, inhibitory ability against α-glucosidase and acetylcholinesterase enzymes, as well as interactions with human serum albumin. Studies showed that both extracts were more effective in protecting liposome membranes against free radicals produced by AAPH in an aqueous environment due to the fact that they can be better eliminated by the hydrophilic components of the extracts than those produced by UVB radiation. Extracts exhibited inhibitory activity against acetylcholinesterase and α-glucosidase, wherein loganic acid extract showed noncompetitive inhibition of the enzyme. Moreover, extracts binded to albumin mainly through hydrogen bonds and van der Waals forces. Taken together, red and yellow cherry fruits’ extracts exhibit diverse biological properties and can be exploited as a source of natural therapeutic agents.

Loganic Acid, an Iridoid Glycoside Extracted from Cornus mas L. Fruits, Reduces of Carbonyl/Oxidative Stress Biomarkers in Plasma and Restores Antioxidant Balance in Leukocytes of Rats with Streptozotocin-Induced Diabetes Mellitus

The various complications related to diabetes are due to the alteration in plasma components and functional activity of blood cells, hence the search for preventive remedies that would ameliorate the clinical condition of patients is a relevant problem today. The main aim of the present study was to examine the antidiabetic potency and antioxidant effects of loganic acid (LA) in blood of diabetic rats. LA showed a restoration of balance between functioning of antioxidant defense system and oxidative stress in leukocytes without notable effects on blood glucose levels when administered orally to rats (20 mg/kg b.w./day) for 14 days. LA ameliorated antioxidant status in leukocytes, as indicated by increasing the content of reduced glutathione and activities of catalase, glutathione peroxidase and glutathione reductase along with decreasing levels of intracellular reactive oxygen species. In addition, we observed the ability of LA to protect against formation and accumulation of glycation and oxidation protein products and malondialdehyde derivates in plasma. Therefore, LA showed antioxidant properties that may have beneficial effects under diabetes. Such results may represent LA as one of the plant components in the development of new drugs that will correct metabolic and functional disorders in leukocytes under diabetes.

Antidiabetic and Antioxidative Potential of the Blue Congo Variety of Purple Potato Extract in Streptozotocin-Induced Diabetic Rats

This study was designed to evaluate the effects of purple potato extract of the Blue Congo variety (PP) on diabetes and its antioxidant activities after two-week administration tostreptozotocin (STZ)-induced diabetic rats. The activities of PP were evaluated at a dose of 165 mg/kg body weight (b.w.) by estimating biochemical changes in blood plasma and through a histopathological study of kidney, muscles, and liver tissue. We evaluated the effect of treatment with extract on glucose level, glycated hemoglobin, activities of enzymatic antioxidants (including superoxide dismutase, glutathione peroxidase, and catalase), and lipid peroxidation. Moreover, we determined advanced glycation end-products (AGEs), advanced oxidation protein products (AOPPs), and the level of oxidative modified proteins (OMPs) as markers of carbonyl-oxidative stress in rats with diabetes. Using high-performance liquid chromatography, we identified five anthocyanins and six phenolic acids in the extract from Blue Congo with the dominant acylated anthocyanin as petunidin-3-p-coumaroyl-rutinoside-5-glucoside. The administration of Blue Congo extract lowered blood glucose, improved glucose tolerance, and decreased the amount of glycated hemoglobin. Furthermore, PP demonstrated an antioxidative effect, suppressed malondialdehyde levels, and restored antioxidant enzyme activities in diabetic rats. After administration of PP, we also noticed inhibition of OMP, AGE, and AOPP formation in the rats' blood plasma.

Agmatine Prevents Oxidative-nitrative Stress in Blood Leukocytes Under Streptozotocin-induced Diabetes Mellitus

Changes in cellular metabolism, development of oxidative-nitrative stress and intensification of glycation and lipid peroxidation (LPO), are significant processes that occur during diabetes mellitus (DM)-associated chronic hyperglycemia. These processes contribute to deviations in the structural organization and functional activity of leukocytes. The development of oxidative-nitrative stress in peripheral blood cells during DM can be prevented by agmatine, an endogenous metabolite of L-arginine, which is a nitric oxide synthase (NOS) inhibitor, and possesses hypoglycemic properties. The administration of agmatine to animals with DM lead to the inhibition of both constitutive and inducible NOS in leukocytes, which in turn decreased total nitrite/nitrate (NOx) levels. Additionally, we observed corresponding increases in reduced glutathione content and activity of antioxidant enzymes (SOD, CAT, GPx, GR), along with decreased levels of the thiobarbituric acid reactive substance, advanced oxidation protein products (AOPPs) and advanced glycosylation end-products (AGEs) as compared to the non-treated diabetic group. Our results indicate that treatment of diabetic animals with agmatine restores redox homeostasis and a balances antioxidant defence system enzymes in leukocytes. This corrective effect on the functional capacity of leukocytes is exerted by preventing oxidative-nitrative stress in animals with DM.

Antidiabetic effects of extracts of red and yellow fruits of cornelian cherries (Cornus mas L.) on rats with streptozotocin-induced diabetes mellitus

The effects of extracts of red and yellow fruits of cornelian cherries have been evaluated in rats with streptozotocin-induced diabetes mellitus.