In Vitro Antioxidant and Acetylcholinesterase-Inhibitory Activities of Avena Sativa L. Whole-Plant Extracts and Fractions

Background: Avena sativa L. (oat) has a history of use in preparations associated with cognitive function and mood. However, systematic evaluation of chemically differentiated whole-plant extracts and fractions for antioxidant and acetylcholinesterase (AChE)-inhibitory activity is limited. Objective: To evaluate the hydrogen peroxide-scavenging and AChE-inhibitory activities of successive whole-plant extracts of A. sativa and fractions prepared from the most active extract, and to relate the observed activity to preliminary phytochemical findings. Methods: Dried whole-plant material was extracted successively with n-hexane, chloroform and methanol using Soxhlet extraction; the residual marc was decocted with water. The methanol extract was subsequently partitioned with n-hexane, ethyl acetate and 1-butanol. Preliminary phytochemical screening was performed using standard procedures. Hydrogen peroxide-scavenging activity was assessed by a modified Dehpour method, and AChE inhibition was evaluated using the Ellman assay. Ascorbic acid and donepezil were used as reference compounds, respectively. Results: The methanol extract (ME) showed the strongest hydrogen peroxide-scavenging activity among the crude extracts (IC50, 1.06 mg/mL) and the strongest AChE inhibition (IC50, 42.48 µg/mL). Among the fractions tested, the ethyl acetate fraction (EAF) showed the greatest activity in both assays, with IC50 values of 0.95 mg/mL for hydrogen peroxide scavenging and 20.83 µg/mL for AChE inhibition. The EAF was reported to contain flavonoids and tannins on preliminary phytochemical screening. Conclusion: The methanol extract and, particularly, its ethyl acetate fraction demonstrated promising in vitro antioxidant and AChE-inhibitory activities relative to the other A. sativa preparations examined. These findings support further chemical characterization and mechanistic investigation. The results are preliminary and do not establish anti-dementia efficacy or clinical benefit.