Phenolic composition, antioxidant and acetylcholinesterase inhibitory activities of Sclerocarya birrea and Harpephyllum caffrum (Anacardiaceae) extracts
2010
Moyo, Mack | Ndhlala, Ashwell R. | Finnie, Jeffrey F. | Van Staden, Johannes
Total phenolic content, proanthocyanidins, gallotannins, flavonoids, and antioxidant activities of Sclerocarya birrea and Harpephyllum caffrum methanolic extracts were evaluated using in vitro assays. S. birrea young stem extract contained the highest levels of total phenolic content (14.15±0.03mg GAE/g), flavonoids (1.21±0.01mg CE/g) and gallotannins (0.24±0.00mg GAE/g). H. caffrum stem bark extract had the highest content of proanthocyanidins (1.47%). The EC ₅₀ values of the extracts in the DPPH free radical scavenging assay ranged from 4.26 to 6.92μg/ml, compared to 6.86μg/ml for ascorbic acid. A dose-dependent linear curve was obtained for all extracts in the ferric-reducing power assay. Dichloromethane and methanol extracts exhibited dose-dependent acetylcholinesterase inhibitory activity. Similarly, all extracts exhibited high antioxidant activity comparable to butylated hydroxytoluene based on the rate of β-carotene bleaching (84.1-93.9%). The two Anacardiaceae species provide a source of natural antioxidants and acetylcholinesterase inhibitors, and may be beneficial to the health of consumers.
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