an investigation into the antibacterial activities of medicinal plants ...

CHAPTER 3
METHODOLOGICAL JUSTIFICATION
This study is aimed at the investigation of different extractions and traditional
preparations of medicinal plants for in vitro antibacterial activity and scientifically
justifying certain traditional uses of these plants. The bacteria used in this study are
clinical isolates from burn wound patients obtained from the National Health
Laboratory Services (NHLS) in Port Elizabeth.
The selection of methods and techniques for investigating the in vitro antibacterial
activity of medicinal plants can be a challenging task when faced with the various
methods employed in literature. The different requirements of the selected bacteria
and the traditional uses of the medicinal plants formed the basis for selecting the
methods used in this research.
3.1 Medicinal plants
The medicinal plants (Bulbine frutescens, Leonotis leonurus, Melianthus major,
Zantedeschia aethiopica) were selected based on their traditional therapeutic uses
as described in literature. The selected medicinal plants are traditionally used in the
Eastern Cape region for treating burns and skin conditions (Van Wyk et al., 1997;
Van Wyk & Gericke, 2000). Although different parts of a plant may show varying
antibacterial activity (Essawi & Srour, 2000), leaves were reported as the most
frequently used plant part for treating wounds in the Eastern Cape Province, South
Africa (Grierson & Afolayan, 1999b).
Fresh plant leaves that were easily accessible on a regular basis from the site of
collection were used for extracting different active compounds. The plant leaves
were crushed into fine leave particles in order to obtain a large surface area for
solvent extraction. Although the interfering water content of fresh plants may pose
problems when there is a delay between collection and processing (George et al.
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