Abstract
BackgroundSeveral plants traditionally used in treatment of a variety of infections in South Africa are reported in ethnobotanical surveys. Many of these plants including Ziziphus mucronata subsp. mucronata lack scientific reports to support their medicinal importance.MethodsThe antioxidant activities and phenolic contents of the acetone, ethanol and aqueous extracts of the stems of Z. mucronata subsp. mucronata were evaluated using in vitro standard methods. The total phenol, total flavonoids and proanthocyanidin content were determined spectrophotometrically. Quercetin, Tannic acid and catechin equivalents were used for these parameters. The antioxidant activities of the stem bark extracts of this plant were determined by ABTS, DPPH, and ferrous reducing antioxidant property (FRAP) methods.ResultsThe quantity of the phenolic compounds, flavonoids and proanthocyanidins detected differ significantly in the various extracts. The phenolics were significantly higher than the flavonoids and proanthocyanidin contents in all the extracts investigated. The ferric reducing ability and the radical scavenging activities of the extracts were very high and dose-dependent. The ethanol extract had the highest antioxidant activity, followed by the acetone extract while the aqueous extract was the least active. Reacting with ABTS, the 50% inhibitory concentrations (IC50) were (0.0429 ± 0.04 mg/ml) for aqueous, (0.0317 ± 0.04 mg/ml) for acetone and (0.0306 ± 0.04 mg/ml) for ethanol extracts while they inhibited DPPH radical with 50% inhibitory concentration (IC50) values of 0.0646 ± 0.02 mg/ml (aqueous), 0.0482 ± 0.02 mg/ml (acetone) and 0.0422 ± 0.03 mg/ml (ethanol).ConclusionsA correlation between the antioxidant activity and the total phenolic contents of the extracts indicated that phenolic compounds were the dominant contributors to the antioxidant activity of the plant. This study, therefore, demonstrated that Z. mucronata subsp. mucronata has strong antioxidant property and free radical scavenging capability.
Highlights
Several plants traditionally used in treatment of a variety of infections in South Africa are reported in ethnobotanical surveys
Phytochemical compositions In this study, the result showed that the amount of total phenolic content, flavonoids and proanthocyanidins differ significantly among the various extracts of the Z. mucronata subsp. mucronata (Figure 1)
The values of total phenolic contents varied from 24.72 ± 0.01 to 31.96 ± 0.01 mg GAE/100 g dry weight of plant material
Summary
Collection of plant material The bark materials of Z. mucronata subsp. mucronata were collected from the plant growing within the University of Fort Hare campus in Alice, South Africa. 0.5 ml of 2% AlCl3 ethanol solution was added to 0.5 ml of extract and allowed to stand for 60 min at room temperature before the absorbance was measured at 420 nm. The changes in colour from deep-violet to light-yellow were measured at 517 nm wavelength using 95% methanolic solution as a reference solution This was related to the absorbance of the control without the plant extracts. Plant extracts (1 ml) were allowed to react with 1 ml of the ABTS+ solution and the absorbance was taken at 734 nm after 7 min using the spectrophotometer. Though the activity is expressed as 50% inhibitory concentration (IC50) [25,26], IC50 was calculated based on the percentage of ABTS radicals scavenged. The Pearson correlation analysis was performed between antioxidant activity and total phenolic content
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