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Medicinal uses of plants
Plants have been used as medicine from time immemorial and in several developing countries they are still the mainstay of health care (Hoareau and Da Silva 1999). According to Weiner and Weiner (1994) herbal medicine was human’s first line of defense before the dawn of history. We learnt the use of plants from instinct and from the observation of animals and birds. Through trial humans learnt which plants and preparations served them best. The knowledge was transferred to helping others and eventually rescuing his animals. Initially plants were collected from the wild. Later the plants were planted in herbal gardens and ultimately pharmaceutical companies isolated bioactive compounds from plants and then synthesised them chemically.
Distribution of heartwater
The disease occurs only where its vectors occur naturally. It occurs wide-spread in sub-Saharan Africa (Figure 1.2) and the eastern Caribbean Islands. In South Africa heartwater occurs in the northern provinces (Limpopo province and the northern part of North-west province as well as along the eastern coast down to Eastern Cape province (Figure 1.3).
Bacteria
The bacteria that were used as test organisms were obtained from the department of Microbiology and Pathology, University of Pretoria. These were Gram-positive (Bacillus cereus, Bacillus subtilis, Bacillus pumilus and Staphylococcus aureus) and Gram-negative (Enterobacter cloacae, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Serratia marcescens). They were maintained on a Nutrient Agar medium (Biolab).
Bacterial cultures for bioautography
Bacteria (B. cereus) were cultured in 50 ml nutrient medium as above and shaken for 24 hours (2.2.1.1). Each culture was divided into two portions in centrifuge tubes and centrifuged for 20 minutes at 3 000g (Dilika et al. 2000). One of the pellets was shaken in 50ml fresh nutrient medium. Fresh cultures were used for spraying onto thin layer chromatograms (TLC).
General Discussion
In general, plant extracts have low antibacterial activity though many of them are used in traditional medicine. McGaw et al. (2002) found that the minimum inhibitory concentration of the leaf extracts of Schotia brachypetala was lower than 10.0 mg ml-1 for both Gram positive and Gram-negative bacteria. A high antibacterial activity was recorded for Helichrysum odoratissimum with a MIC of 0.01 mg ml-1 against Gram-positive bacteria (Mathekga and Meyer 1998). Compretum zeyheri and C. erythrophyllum were reported to contain compounds with antibacterial activity higher than that of the antibiotics chloramphenicol and ampicillin (Kotze and Eloff 2002). The antibacterial activity of the extracts of the three plants (Drimia delagoansis, Petalidium oblongifolium and Ipomoea anadioides) investigated in this study varied. The minimum inhibitory concentration (MIC) values of their extracts were higher than 10.0 mg ml-1 for Gram-negative bacteria. The antibacterial activity of the extract from U.lydenburgensis was so low that it was decided not to proceed with isolation of bioactive compounds from it.
CHAPTER 1 Plant Uses in Ethnoveterinary medicines
1.2 Medicinal uses of plants
1.2.1 Ethnoveterinary plant use
1.3 Livestock diseases
1.3.1 Heartwater
1.3.1.1 The causative agent of heartwater
1.3.1.2 The heartwater vector
1.3.1.3 Distribution of heartwater
1.3.1.4 Diagnosis of heartwater
1.3.1.5 Control of heartwater
CHAPTER 2 The Antibacterial activity of Drimia delagoansis
2.1 Introduction
2.1.1 Bioactive compounds in the subfamily Urgineoidea Materials and Methods
2.2.1 Bacteria
2.2.1.1 Bacterial cultures for antibacterial activity
2.2.1.2 Bacterial cultures for bioautography
2.2.2 Plant material
2.2.3 Extraction
2.2.4 Agar-diffusion bioassay
2.3 Results and Discussion
2.4 References
CHAPTER 3 Antibacterial Activity of Petalidium oblongifolium and the Isolation of a Bioactive Compound
3.1 Introduction
3.2 Materials and Methods
3.2.1 Plant Material
3.2.1.1 Antibacterial activity of crude extract
3.2.2 Fractionation and isolation of bioactive compounds
3.2.2.1 Extraction
3.2.2.2 Fractionation
3.2.3 Structure elucidation of the isolated compound
CHAPTER 4 Antibacterial Activity of Ipomoea adenioides and the Isolation of Bioactive Compounds
4.2 Materials and Methods
4.2.1 Plant material
4.2.2 Bacteria
4.2.2.1 Antibacterial activity of extracts
4.2.2.2 Bacterial cultures for bioautography
4.2.3 Isolation of bioactive compounds
4.2.3.1 Extraction
CHAPTER 5 General Discussion
5.1 References
