TITLE:
The in Vitro Antioxidant Capacities of Hydroalcoholic Extracts from Roots and Leaves of Smallanthus sonchifolius (Yacon) Do Not Correlate with Their in Vivo Antioxidant Action in Diabetic Rats
AUTHORS:
Ana Carla Broetto Biazon, Mariana Marques Nogueira Wendt, Júlia Rosa Moreira, Cristiane Vizioli Castro Ghizoni, Andreia Assunção Soares, Sandra da Silva Silveira, Anacharis Babeto de Sá-Nakanishi, Ciomar Aparecida Bersani Amado, Rosane Marina Peralta, Adelar Bracht, Jurandir Fernando Comar
KEYWORDS:
Smallanthus sonchifolius, Yacon, Streptozotocin-Induced Diabetes, Liver Oxidative Status
JOURNAL NAME:
Journal of Biosciences and Medicines,
Vol.4 No.2,
February
19,
2016
ABSTRACT: Leaf and root extracts
of Smallanthus sonchifolius (yacon), have antihyper-glycemic activity and antioxidant properties. The present
study aims to compare the in vivo hepatic antioxidant activity of hydroalcoholic
extracts of yacon leaves and roots in rats with streptozotocin-induced diabetes
in terms of their in vitro antioxidant capacity. Rats were treated
during 14 days with 1060 mg·Kg-1 root extract or 400 mg·Kg-1 leaf extract. The latter was richer
in phenolics and possessed a much higher in vitro antioxidant activity. Both extracts
prevented hyperglycemia in diabetic rats. The liver of diabetic rats presented increased
levels of protein carbonyls and ROS and decreased activities of antioxidant enzymes.
Treatment with both root and leaf extracts restored the protein carbonyl levels
to normality. The root extract also restored the ROS levels to normality, but the
leaf extract was not effective. The root extract was also more effective in restoring
the activity of at least two important antioxidant enzymes (glucose 6-phosphate
dehydrogenase and glutathione peroxidase). In terms of the antioxidant load (which
was 17 times lower in the root extract treatment), the in vivo action of the root
extract was more effective than the leaf extract in reducing the hepatic oxidative
stress that accompanies diabetes.