Medicinal properties and micromorphology of Rauvolfia caffra Sond.
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Date
2017
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Abstract
Medicinal plants are effective treatments for various ailments and conditions due to the fact that they are easily accessible, cost effective, trusted and have little to no side effects. Plants produce bioactive or secondary compounds that serve as a defence mechanism to deter pests, attract pollinators and continue to assist in the survival of the species. These compounds or phytochemicals are useful to humans in the form of natural medicine, Rauvolfia caffra Sond. (Apocynaceae) is no exception. The traditional use of the bark is to alleviate skin ailments. A decoction of the bark is consumed for the treatment of abdominal discomfort, abscesses, pneumonia and fever. The research problem is that R. caffra has not been fully documented and the traditional uses cannot be supported scientifically. Furthermore, micromorphological characteristics remain to be described. This is a key component since R. caffra synthesizes latex and transports it through laticifers. The micromorphological characteristics were described by stereomicroscopy, scanning electron microscopy, light microscopy and histochemical tests on the leaves and petioles. This detected the presence of laticifers. To investigate the medicinal value, preliminary phytochemistry and antibacterial screening was performed on crude extracts of the stems and leaves. Methanol, chloroform and hexane were used as solvents of extraction and the classes of compounds detected were alkaloids, glycosides, sterols, flavones and flavonones. Thin layer chromatography provided a visualization of the classes of compounds present. The methanolic stem extract was found to inhibit seven strains of bacteria including E. coli and methicillin-resistant Staphylococcus aureus. The findings do not discredit the traditional utilization of this plant. Additionally, silver nitrate was combined with the crude methanol and water extracts of the stem and leaves to determine if silver nanoparticles (AgNPs) can be formed using a protocol that is safe, not toxic to the environment and simple to carry out. Three different mixing ratios (1:1, 1:2 and 1:4) were used to discover the optimum conditions for synthesis and the extracts screened for their antibacterial activity. The AgNPs synthesized ranged from15.84nm to 34.99nm in diameter which falls within a range that is preferred in nanoscience. The water stem 1:4 AgNPs was found to inhibit two different strains of bacteria, viz. methicillin-resistant Staphylococcus aureus and Klebsiella pneumonia. Rauvolfia caffra does have the potential to be used in drug formulation and in nanotechnology to treat prevalent health problems in South Africa.
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Masters Degree. University of KwaZulu-Natal, Durban.