Antioxidant and anticholinesterase potentials of the methanol extract of Alstonia boonei stem bark and its fraction.
Abstract
Background: Alstonia boonei is a plant known for its medicinal values in the treatment and management of a vast number of ailments. This study investigated the in vitro antioxidant and anti-cholinesterase potential of the methanol extract (ME) of the plant, its dichloromethane derived fraction (DF), ethyl acetate derived fraction (EF) and aqueous derived fraction (AF).Methodology: The antioxidant potential of the extracts was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and metal ion chelating assays. Anti-cholinesterase analysis was performed following the procedure put forward by Ellman, (1961). All other assays were estimated using standard methods. Results: The study showed that ethyl acetate component has the highest amount of phytochemicals tested for, with phenolics being the highest constituent at 1176.88 ± 6.51mg/100g. The methanol extract and its fraction showed significant free radical scavenging potentials with IC50 values of 8.98 ± 0.01 µg/ml, 16.49 ± 0.45 µg/ml, 6.67 ± 1.05 µg/ml and 8.39 ± 0.4 µg/ml for the ME, DF, EF and AF respectively compared to that of the ascorbic acid standard (AAS), 21.69 ± 0.13 µg/ml. The methanol extract showed the highest metal chelating potential (IC50 = 7.53 ± 0.37 µg/ml). The aqueous fraction of the methanol extract presented the most cholinesterase inhibitory potential with an IC50 value of 543 ± 25.39 µg/ml. Results also showed that the methanol extract has the least effect (IC50 = 702 ± 22.7µg/ml) compared to that of galantamine standard (IC50 = 1.42 ± 0.17 µg/ml).Conclusions: These findings present Alstonia boonei as a medicinal plant with likely usage in the therapeutic alleviation of symptoms associated with Alzheimer’s disease.
Keywords: Alstonia boonei, antioxidant, anticholinesterase, phytochemicals, Alzheimer’s disease