ACETYLCHOLINESTERASE ACTIVITY OF METHANOLIC EXTRACT OF THE LEAVES OF PSIDIUM GUINEENSE SWARTZ
prevalent cause of dementia, which is currently implicated in approximately 70% of the overall cases. This
irreversible neurological disorder is characterized by memory failure, cognitive dysfunction, behavioral
disturbances, difficulties in the activities of daily living and disorientation of time and place. The
“cholinergic hypothesis” states the degenerationof cholinergic neurons and the reduction in the
concentration of the neurotransmitter acetylcholine (ACh), which is involved in the learning and memory
processes in the central nervous system, contribute significantly to the cognitive decline associated with
old age and AD. Acetylcholinesterase (AChE) enzymatic inhibition is an important target for the
management of Alzheimer disease (AD) and AChE inhibitors are the mainstay drugs for its treatment.
Psidium Guineense Swartz, popularly known “guava-the-field”, is used in traditional medicine as antidiarrheal. Studies with leaves showed antibacterial activity the presence of tannins1. Objectives: The
present work has investigated the acetylcholinesterase activity "in vitro" of methanol extract from the
leaves of P. guineense. Material and Methods: Dried leaves of Psidium Guineense were exhaustively
extracted by maceration with methanol at room temperature. After filtration, evaporation of the solvent
under vacuum furnished the methanol extract. The enzymatic activity of acetylcholinesterase was
determined by the spectrophotometric method of Ellman et al. (1961)2 modified by Rhee et al. (2001)3
using male Wistar rats to obtain their brain structures (cortex and cerebellum). The protein was
determined previously and adjusted for each structure: cortex (0.5 mg/ml) and cerebellum (0.5 mg/ml).
Protein was measured by the Coomassie blue method according to Bradford (1976)4 using serum albumin
as standard. The extract was evaluated in the concentrations of 0,5; 2,5 and 4,0 mg/mL in methanol.
Results: The methanol extract of P. guineense showed in vitro inhibitory effect of the AchE activity in brain
structures, cortex (0,5 mg/mL; 1.69 µmol Ach.h-1.mg protein-1, 2,5 mg/mL; 8.94 µmol Ach.h-1.mg protein-
1 and 4,0 mg/mL; 13.30 µmol Ach.h-1.mg protein-1) and cerebellum (0,5 mg/mL; 4.01 µmol Ach.h-1.mg
protein-1, 2,5 mg/mL; 19.44 µmol Ach.h-1.mg protein-1 and 4,0 mg/mL; 33.08 µmol Ach.h-1.mg protein-1),
compared to the control. Discussion and Conclusion: P. guineense showed activity in enzyme
acetylcholinesterase (AChE) in cerebellum structure tested “in vitro”. However, future studies in “ex vivo”
models are necessary, serving as validation for the results found in this work.
Rodrigues, C.G. et al. Antibacterial activity of tannins from Psidium guineense Sw. (Myrtaceae). Journal
of Medicinal Plant Research. v. 8, n. 35, p. 1095-1100, 2014.
Ellman, G. L. A new and rapid colorimetric determination of acetylcholinesterase activity. Biochemical
Pharmacology. 7 ed., p. 88-95. 1961.
Rhee, I.K.; et al. Screening for acetylcholinesterase inhibitors from Amaryllidaceae using silica gel thinlayer chromatography in combination with bioactivity staining. Journal of Chromatography, v. 915, n. 2,
p. 217-223, 2001.
Bradford, M.M. A rapid and sensitive method for the quantitation of microgram quantities of protein
utilizing the principle of protein-dye binding. Analytical Biochemistry. 72ed. p. 248–254. 1976.
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