Screening of antioxidants and anti-diabetic activities of some hypoglisemic plants

Diabetes mellitus (DM) is a very important disease initially characterized by disturbance in glucose homeostasis balance. There are 171 million people in worldwide with diabetes. This number will be more than double in 2030. Each year approximately 3.2 million people die due to diabetes and its complications. It means that six deaths every minutes. In this thesis, the antioxidant and antidiabetic effects of ethanol:water extracts of plants, which are used traditionally to treat diabetes, Juglans regia, Teucrium polium, Piperis longum, Rheum ribes, Apium graveolens, Artemissia absinthium, Cuscuta babylonica and Artemissia millefolium were investigated. These plants are used by local herbalists to ameliorate diabetes complications. When total phenolics, flavonoids and antioxidant activities of each plant extract are examined, it was found that the quantities total phenolics, flavonoids and antioxidant activities increase by the order of J. regia, T. polium, R. ribes, C. babylonica, A. graveolens, A. millefolium, P. longum and A. absinthium. Diabetes induce oxidative stres, which increases free radical production. Therefore, because of free radicals levels are high in diabetes mellitus, in the present study, our first aim was to investigate the radical scavenging activities of plant extracts. For this purpose, the radical scavenging activities of plant extracts on reactive oxygen species such as hydroxyl radical, and synthetic types such as DPPH and ABTS radicals were examined. The protective ability of plant extract against lipid peroxidation, DNA and protein oxidation were also investigated. We also investigated of antidiabetic effects of J. regia and T. polium extracts. For this purpose, an in vitro BSA-glucose model system was used to evaluate glycation reaction. The inhibition activities of J. regia and T. polium extracts on advanced glycation end products formation were examined.-Amylase and -glucosidase are key enzymes involved in the digestion of carbohydrates. Therefore, -amylase and -glucosidase enzyme inhibitory effects of J. regia and T. polium extracts were also studied. Consequently, it was found that the ethanol:water extracts of J.regia and T.polium have inhibated reactive oxygen species, lipid peroxidation, DNA and protein oxidation and also both AGE products and -amylase and -glucosidase enzymes respectively. Therefore, they can be effective in the treatment of diabetes. Keywords: Antioxidant, Antidiabetic, Diabetes Mellitus, AGE, Juglans regia, Teuricum polium