Thesis (M.Sc. (Agriculture)) --University of Limpopo, 2006 / Refer to document / National Research Foundation (NRF) and Cannon Collins Educational Trust Fund of Southern Africa (CCETSA)

There is an increasing interest in ethnomedical and ethnoveterinary practices, especially as it relates to the use of medicinal plants for treating various ailments. As a result, the current trend in government health authorities is to integrate herbal medicine with primary healthcare. This arises because nearly 80% of people in the developing world, particularly those from rural communities where modern drugs are unaffordable, inaccessible or, unavailable, depend on phytomedicine for primary healthcare. Despite this, however, most medical and veterinary professionals distrust herbal medicines due to concerns of scientific evidence of efficacy and safety. Hence, there is need for their validation, before herbal medicines gain wider acceptance and use. Traditional healers and rural farmers use extracts of Peltophorum africanum (a medicinal plant wide-spread in southern Africa and other tropical regions), to treat diarrhoea, helminths and abdominal parasites, dysentery, HIV-AIDS, acute and chronic pain, anxiety and depression, infertility, and to promote well-being and resistance to diseases. To evaluate these ethnobotanical leads, dried leaves, bark and root from mature P. africanum (Fabaceae) trees were extracted with acetone, ethanol, dichloromethane and hexane. Chromatograms were made on silica gel plates. Thin layer chromatograms (TLC) were sprayed with 0.2% 2, 2-diphenyl-1-picryl hydrazyl (DPPH) for qualitative screening for antioxidants. Quantification of antioxidant activity was done in comparison with L-ascorbic acid and Trolox (6-hydroxy-2, 5, 7, 8-tetranethylchromane-2-carboxylic acid). With regard to the extracts, minimum inhibitory concentrations (MIC) were determined for Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Enterococcus faecalis. The total antibacterial activity (TAA), signifying the volume to which active compounds present in 1 g of plant material can be diluted and still inhibit bacterial growth, was also determined. In vitro anthelmintic activity was evaluated by effects of acetone extracts on the egg hatching and larval development of parasitic nematodes Haemonchus contortus and Trichostrongylus colubriformis. The eggs and larvae of the two parasites were incubated in various concentrations of the leaf, bark and root extracts for two and five days respectively. Furthermore the efficacies of the acetone extracts were tested on lambs artificially induced with H. contortus and T. colubriformis infections. Toxicity was performed in brine shrimp and MTT assay on Vero monkey kidney cells. The extracts had substantial activity against both Gram-positive and Gram-negative bacteria, with MIC values of 0.08 mg ml-1 for Staphylococcus aureus and 0.16 mg ml-1 for Pseudomonas aeruginosa ; the corresponding TAA values were 1263 and 631 ml g-1. The acetone extracts the bark, and root of P. africanum had higher antioxidant activity than L-ascorbic acid (Vitamin-C) and Trolox (6-hydroxy-2, 5, 7, 8-tetramethylchromane-2-carboxylic acid), a synthetic vitamin-E analogue, and much higher than Ginkgo biloba extract (EGb 761). The standardized extract of Ginkgo biloba (EGb 761) is widely employed for its significant benefit in neurological disorders. The respective EC50 for the P. africanum root , bark and leaf extracts, L-ascorbic acid, and EGb761 were 3.82 µg ml-1, 4.37 µg ml-1, 6.54 µg ml-1, 5.04 µg ml-1, and 40.72 µg ml-1. The extracts inhibited egg hatchability and larval development (from L1 to infective stage L3) of both H. contortus and T. colubriformis (both parasitic nematodes of ruminants) at concentrations of 0.2-1.0 mg ml-1. The plant extracts, at concentrations of 5-25 mg ml-1 completely lysed larval forms (L1) and eggs of the nematodes. In all assays, the root extracts had higher antibacterial, antioxidant and anthelmintic activity than the bark and leaf. Although the extracts were safe and non-toxic, the reduction in faecal egg and adult worm counts in lambs infected with H. contortus and T. colubriformis was not statistically significant (P=0.073). From the acetone extracts of the root, a brownish crystalline compound, bergenin was isolated. Bergenin was also assayed for toxicity with brine shrimp and Vero monkey kidney cells like the extracts, where the compound was found to be not toxic. In a disc diffusion test, the inhibitory activition of bergenin was determined for the bacteria E. coli, P. aeruginosa, Mycobacterium vaccae, and the fungi Sporobolomyces salmonicolor and Penicillium notatum. Bergenin had reasonable antimicrobial activity against S. salmonicolor, moderate activity against M. vaccae, E. coli and P. aeruginosa, but non inhibitory against P. notatum. P. africanum extracts have therefore, potential for treatment of infection-related diseases by either directly inhibiting bacterial growth or by stimulating the immune system of the host. The traditional use of P. africanum concoctions against diarrhoea, dysentery and unthriftness, may be also due to anthelmintic activity as these signs are consistent with parasitic astroenteritis. Antioxidants are also important in boosting the immunity, critical in the management of helminthosis. There is ample scientific and empirical evidence supporting the use of plantderived antioxidants in the control of human immunodeficiency virus (HIV) and neurological diseases. Synergistic activity of plant antioxidants has been proposed as a mechanism by which viral replication and immune cell killing in HIV infection can be inhibited. Antioxidants may have neuro-protective (preventing apoptosis), as well as neuro-regenerative roles. Due to the high antioxidant activity of its extracts, P. africanum has prospects in the chemotherapy of HIV and management or control of neurodegenerative diseases. Thus there is great potential of P. africanum extracts in medicine. Further isolation and bioassay characterization of bioactive compounds from P. africanum is recommended as well as refinement of in vivo tests in target livestock, or clinical trials. Better methods of plant extraction easily adaptable to rural communities for sustainable exploitation of the tree, may have to be devised especially those using the leaves instead of bark or root. / Thesis (PhD(Paraclinical Sciences))--University of Pretoria, 2007. / Paraclinical Sciences / unrestricted

Urginea sanguinea, Aloe marlothii, Elephantorrhiza elephantina and Rhoicissus tridentate are all plants utilized for the management of tick borne diseases in the Madikwe area of North-west province. These plants, in certain concoctions, are believed to be effective against “seme”, “gala” and “Bolwetsi jwa mothlapo o moshibidu” which we have assumed to represent heartwater, gallsickness and redwater from circumstantial epidemiological data available. To obtain a representative extract, which would be indicative of the general activity of the plant, only acetone or methanol extracts were tested for the presence of antimicrobial, antiparasitic or anti-oxidant activity within that specific plant. Activity in all cases made use of either an in vitro biological assay or more specific chemical tests, which were validated in all cases. Ehrlichia ruminantium, Babesia caballi and Theileria equi, all grown in specific cell cultures, were used as a model for evaluating the efficacy against the common protozoan and rickettsial diseases caused by these organisms in livestock. Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Escherichia coli, four human nosocomial infectious agents, were used as an indicator for the presence of antibacterial activity against these common animal bacterial pathogens. Diphenyl-picrylhydrazyl and the trolox equivalent anti-oxidant chemical assays were used to determine anti-oxidant activity, which although not curative, may aid in the recovery from an infection by stimulating the immune system. The activities demonstrated among the various plants and organisms were not consistent. E. elephantine extracts were the most effective, with activity demonstrable in all biological and chemical screening assays. Although R. tridentate demonstrated poor activity (> 100 ìg/ml) against the tick-borne parasites, the plant extract did demonstrate significant anti-oxidant activity. U. sanguinea extracts showed good activity in both the antibacterial and anti-rickettsial assays (EC50 = 44.49 ng/ml), which may be due to the presence of the toxic bufadienolides present within the plant. A. marlothii possessed significant anti-rickettsial activity (EC50= 111.4 µg/ml) and to a lesser degree antibacterial activity. The results of the study support the use of these plants against heartwater, gallsickness and redwater, which gives credence for the traditional use against “Seme, Gala, and Bolwetsi jwa mothlapo o moshibidu”. Further studies are required to isolate and determine the structure of the active compounds of these plants as well as to confirm the safety and efficacy of the extracts against disease conditions in livestock. Copyright / Urginea sanguinea, Aloe marlothii, Elephantorrhiza elephantina and Rhoicissus tridentata word tradisioneel gebruik vir die bekamping van siektes deur bosluise oorgedra in die Madikwe gebied van die Noordwes provinsie. Ekstrakte van hierdie species word gebruik teen “seme”, “gala” en “Bolwetsi jwa mothlapo o moshibidu” wat waarskynlik op hartwater, galsiekte and rooiwater dui volgens die beskikbare epidemiologiese data. Asetoon en metanol ekstrakte is gebruik vir die bepaling van antimikrobiese, antiparasitiese en antioksidant aktiwiteite in verskillende species deur gevalideerde in vitro metodes. Selkulture van Ehrlichia ruminantium, Babesia caballi en Theileria equi, , is in ‘n model gebruik om die doeltreffendheid van ekstrakte teen algemene siektes deur protozoa en ricketsias te bepaal. Vier algemene menslike nosokomiale patogene Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Escherichia coli, is gebruik om antibakteriese aktiwiteit van ekstrakte te bepaal. Difeniel-pikrielhidrasiel en die trolox ekwivalente anti-oksidant essajeermetode is gebruik om anti-oksidantaktiwiteit te bepaal. Antioksidante mag herstel na infeksies bespoedig deur stimulering van die immuunstelsel. Daar was ‘n groot verskil in die aktiwiteite tussen die verskillende ekstrakte en organismes. E. elephantina ekstrakte was die mees doeltreffende met die biologiese and chemiese bepalings. R. tridentata het sterk anti-oksidantaktiwiteit gehad, maar het lae aktiwiteit (> 100 µg/ml) teen bosluis-oorgedraagde parasiete gehad. U. sanguinea ekstrakte was aktief in beide die antibakteriese en anti-riketsiale bepalings (EC50 = 44.49 ng/ml), wat moontlik toegeskryf kan word aan die giftige bufadienoliede teenwoordig in hierdie species. A. marlothii ekstrakte het betekenisbolle anti-riketsiale aktiwiteit (EC50 = 111.4 µg/ml) maar slegs geringe antibakteriese aktiwiteit gehad. Hierdie resultate bevestig die moontlike waarde van hierdie species teen hartwater, galsiekte and rooiwater, en ondersteun die tradisionele etnoveterinêre gebruik teen “Seme, Gala, and Bolwetsi jwa mothlapo o moshibidu”. Verdere studies word benodig om die 5 aktiewe verbindings te isoleer en te karakteriseer en om die veiligheid en doeltreffendheid van ekstrakte teen hierdie siektes in vee te bevestig. / Dissertation (MSc (Veterinary Science))--University of Pretoria, 2004. / Paraclinical Sciences / unrestricted