Anticholinesterase and antioxidant activity of Drynaria quercifolia and its ameliorative effect in scopolamine-induced memory impairment in mice.

Drynaria quercifolia is an epiphytic fern distributed all over Bangladesh with traditional use in treating neurological disorders and other ailments. Although several pharmacological activities of D. quercifolia have been investigated, the neuroprotective potential of this plant is still unexplored. In this study, we evaluated the in vitro anticholinesterase and antioxidant activities of D. quercifolia and the neuroprotective effect in scopolamine-induced memory-impaired mouse model. The crude methanol extract (DCM) of the plant was fractionated to prepare n-hexane (DHF), chloroform (DCF), ethyl acetate (DEF), and aqueous (DAF) factions. All the fractions were evaluated for anticholinesterase activity by modified Ellman's method and the antioxidant activity by several in vitro assays such as DPPH and hydroxyl free radicals scavenging, reducing power, and inhibition of brain lipid peroxidation. The effect of the most active fractions (both DCF and DEF) on learning and memory was assessed in scopolamine-induced mouse model of memory-impairment by Morris water maze tasks. Biochemical assays were performed in brain tissue. The active compound was isolated and characterized by chromatographic, spectroscopic, and molecular docking methods. Phytochemical analysis demonstrated a high content of phenolic and flavonoid in DEF. In vitro studies revealed a strong antioxidant power of DEF and anticholinesterase activity of DCF. Both the DCF and DEF significantly (P˂0.05) reduced the escape latency time in the Morris's water maze tasks, and increased the time spent in the northeast quadrant in the probe trial. Biochemical data demonstrated that treatment with DCF and DEF at different doses significantly (P˂0.0001) inhibited acetylcholinesterase activity, restored GSH levels, and reduced MDA levels in the brain of scopolamine-induced memory-impaired mice, indicating the protective effect of D. quercifolia , possibly by acetylcholinesterase inhibition and oxidative stress prevention. Chromatographic methods of separation led to he isolation of catechin and protocatechuric acid from DEF and 3,4-dihydroxy benzoic acid from DCF. The structure of the compounds was determined by studies of their 1H-NMR spectra. Molecular docking as well as in vitro study suggests the anticholinesterase and antioxidant activity of the isolated compounds. Our study suggested that the extracts of D. quercifolia , due to anticholinesterase and antioxidant activity, ameliorate the scopolamine-induced memory impairment in mice and thus may represent therapeutics in the treatment of Alzheimer's disease. [Display omitted] • The chloroform and ethyl acetate fraction of Drynaria quercifolia rhizome exhibited considerable anticholinesterase and antioxidant activity in vitro. • Both the fractions significantly improved learning and memory in scopolamine-induced memory-impaired mice via cholinesterase & lipid peroxidation inhibition activity, and non-enzymes augmentation. • The predominant compounds were found to be 3, 4-dihydroxybenzoic acid in the chloroform fraction, and catechin & 2, 3, 4-trihydroxybenzoic acid in the ethylacetate fraction, which were responsible for both anticholinesterase and antioxidant activities as evidenced from in vitro and molecular docking studies. • These results support the traditional use of D. quercifolia in the neurological disorder and suggest that both the chloroform and ethyl acetate fraction of the plant may represent therapeutics in the prevention or treatment of AD. [ABSTRACT FROM AUTHOR]