White tea (Camellia sinensis) consumption improves heart and brain glycolytic and oxidative profiles in prediabetic rats

Abstract

Diabetes mellitus (DM) is a major public health problem and its incidence is dramatically rising. Heart and brain are particularly susceptible to glucose fluctuations and hyperglycaemia-induced oxidative stress. Tea is widely consumed and studied; however, the antidiabetic properties of white tea (WT) remain largely unexplored. In this work, we hypothesized that the regular consumption of WT by prediabetic rats improved cardiac and cerebral cortex glycolytic and oxidative profiles. WT composition, and rats' heart and brain cortex glycolytic and oxidative profiles were determined. WT phytochemical profile was composed by glucose, sucrose, (-)-epicatechin, (-)-epigallocatechin, (-)-epigallocatechin-3-gallate, caffeine, L-theanine, alanine, and lactate, being (-)-epigallocatechin-3-gallate the major one. Prediabetic rats drinking water developed mild glycaemia, glucose intolerance and insulin resistance. In addition, prediabetes decreased lactate and acetate contents and lactate dehydrogenase (LDH) activity in cardiac tissue; while in brain cortex decreased lactate content and increased LDH activity. Prediabetes also decreased heart and brain cortex antioxidant capacities, increasing lipid peroxidation and protein oxidation. Consumption of WT improved glucose tolerance and insulin sensitivity in prediabetic rats. In the heart, WT increased alanine content and antioxidant capacity, and normalized LDH activity and lipid peroxidation. In the cerebral cortex, WT decreased lactate and alanine contents and normalized the antioxidant capacity, lipid peroxidation and protein oxidation. In conclusion, the regular consumption of WT improved the heart and brain metabolic and oxidative profiles in prediabetic rats, suggesting it as a good, safe and inexpensive strategy to prevent DM-related effects. Acknowledgements: This work was supported by FCT (PEst-C/SAU/UI0709/2014) co-funded by FEDER via Programa Operacional Factores de Competitividade – COMPETE/QREN.