Improving effect of Actinidia arguta leaf on hyperglycemia-induced cognitive dysfunction

This study was performed to investigate the effect of ethyl acetate fraction from Actinidia arguta leaf (EFAL) in improving cognitive decline caused by hyperglycemia-induced oxidative stress. EFAL suppressed hyperglycemia and improved glucose tolerance in streptozotocin (STZ)-induced diabetic mice. In behavioral tests, cognitive dysfunction was present in diabetic mice, whereas cognitive function was improved by EFAL treatment. All serum oxidative damage markers decreased in the EFAL groups. Brain tissue analysis showed that the oxidative stress marker malondialdehyde (MDA) decreased and the antioxidant enzyme superoxide dismutase (SOD) increased with EFAL treatment compared with diabetic mice. In addition, the reduction of neurotransmitters and mitochondrial dysfunction were suppressed by EFAL. Improvement of the insulin signaling pathway with the reduction of Tau phosphorylation and decrease in amyloid beta (Aβ) by increasing IDE expression in EFAL group was also observed. Finally, oxo-dihydroxy-octadecenoic acid (oxo-DHODE), rutin, and kaempferol-3-O-rutinoside were identified as the main compounds of EFAL.