In vitro neuroprotective effects of the leaf and fruit extracts of Juglans regia L. (walnut) through enzymes linked to Alzheimer's disease and antioxidant activity.

Several extracts of the leaves and fruits of Juglans regia L. were assessed for their neuroprotective effects through antioxidant and anti-cholinesterase methods. Anticholinesterase activity was determined against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), the enzymes vital for Alzheimer's disease, at 50, 100 and 200 μg ml(-1). Antioxidant activity was tested using radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH), N,N-dimethyl-p-phenylenediamine (DMPD), superoxide (SO), nitric oxide (NO) and hydrogen peroxide (H(2)O(2)) radicals, as well as ferric ion-chelating capacity, ferric- and phosphomolybdenum-reducing antioxidant power at 500, 1000 and 2000 μg ml(-1). Total phenol and flavonoid quantification of the extracts was calculated. The extracts scavenged DPPH radical in varying degrees; however, they did not scavenge DPMD and H(2)O(2). Only the dichloromethane and water extracts were able to quench SO (10.09 ± 1.38%) and NO (24.09 ± 2.19%) radicals, respectively, at low level. The extracts showed either low or no BChE inhibition and no AChE inhibition.