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Seven commonly known medicinal plants from Zimbabwe were analysed for their antioxidant activity as well as their total phenolic content. The plant samples used in this study were Albizia amara, Elionurus muticus, Heteropyxis natalensis, Hoslundia opposita, Lippia javanica, Ocimum urticifolia and Warburgia salutaris. The plant samples were extracted using 70% ethanol. The 2,2-diphenyl-1-picrylhydrazyl radical assay was used to determine the antioxidant activity of the plant extracts, while the Folin-Ciocalteu method was used to determine the total phenolic content. The antioxidant activities of the plant extracts ranged from 95.84 ± 0.50% for E. muticus to 5.31 ± 4.47% for H. opposita. Total phenolics in the plant extract estimated as tannic acid equivalent (TAE) ranged from 0.098 ± 0.005 mg per 100 g for H. natalensis to 0.024 ± 0.006 TAE for H. opposita. There was a poor correlation (R ¼ 0.522) between total phenolic content and antioxidant activity in the plant samples. The results indicate the presence of phenolic compounds as well as significant antioxidant activity.

Polysaccharide was isolated from Cordia abyssinica and its effect, at differing concentrations, on its emulsifying ability was determined. Emulsions of vegetable oil containing up to 1% of the polysaccharide in phosphate pH 7.4 buffer, were prepared by using a hand piston homogenizer. Emulsification was assessed by diluting samples of the emulsions in sodium dodecyl sulphate and measuring absorbance at 500 nm. Addition of increasing concentrations of the polysaccharide up to 1% enhanced emulsification and emulsion stability. Above 1% concentration the polysaccharide solutions were too viscous for making emulsions conveniently. At a constant concentration of the polysaccharide, addition of up to a 1% concentration of salt enhanced emulsion formation. Further addition of salt above 1% resulted in no further changes in emulsifying ability, but the stability of the emulsions formed decreased on increasing the concentration of salt above 1%. The effect of pH on emulsifying ability was investigated by preparing emulsions using buffers of different pH, from pH 3 to pH 13. The polysaccharide had poor emulsifying ability below pH 7. Emulsifying ability increased with pH between pH 7 and 11. At pH above 11 there was a decrease in emulsifying ability.

Amaranthus hybridus, Brachiaria brizantha and Panicum maximum are wild cereal grains that have been consumed mainly in times of drought especially in the Manicaland Province, which is the worst-hit province in Zimbabwe whenever there are droughts. Methanolic extract solutions were prepared from sun-dried A. hybridus, B. brizantha and P. maximum grains. We studied the phenolic compound content and antioxidant properties including high-performance liquid chromatography, 1-diphenyl-2-pierylhydrazyl radical scavenging and reducing power. B. brizantha was found to contain the highest phenolic compound concentration of 3.180 Ϯ 0.072 mgGA/100 mg, while A. hybridus was found to have the least phenolic compound concentration of 1.127 Ϯ 0.133 mgGA/100 mg. The grains were found to contain caffeic acid, ferulic acid, p-coumaric acid, p-hydroxybenzoic acid and protocatechuic acid. P. maximum had the highest DPPH scavenging capacity and the highest reducing power as well. A. hybridus had the least reducing power and required 20.33 mg of sample equivalent per milliliter to reduce Fe 3+ to Fe

SummaryThe phenolic compound content and profiles of three wild fruits found in Zimbabwe were tentatively identified using the traditional colorimetric methods and high-performance liquid chromatography (HPLC). The fruits assayed were: Ximenia caffra, Artobotrys brachypetalus and Syzygium cordatum. Ximenia caffra fruit peels contained the highest amounts of total phenolics amounting to 1205 lg g)1 in fresh weight, flavonols amounting to 27 lg g )1 and phenolic acids on HPLC tentative identification showed higher concentrations compared with the profiles of the other fruits. Syzygium cordatum fruit peels contained the least amounts of phenolics amounting to 20 lg g)1, flavonols amounting to 8 lg g )1 and phenolic acids' HPLC profiles showed low concentrations. Comparing the peels and pulps of all the fruits, we detected more total phenolics in the peels of X. caffra as high as 1205 lg g )1 and the pulps had 228 lg g)1, more flavonols and phenolic acids while the peels of S. cordatum fruits contained the least with a total phenolic acid content of 20 lg g )1, and had more flavonols in the pulps than the peels, 11 lg g)1 and 8 lg g)1, respectively. Ximenia caffra contained 1.2% and about 1% dry weight condensed tannins in peels and pulps, respectively. In S. cordatum we detected 0.2% and 0.3% dry weight condensed tannins in the peels and pulps, respectively.