Antimicrobial activity of selected Eastern Cape medical plants
- Authors: Mohlakoana, Keneuoe
- Date: 2010
- Subjects: Materia medica, Vegetable -- South Africa , Drug resistance in microorganisms -- South Africa , Anti-infective agents -- South Africa , Antibiotics
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10120 , http://hdl.handle.net/10948/1199 , Materia medica, Vegetable -- South Africa , Drug resistance in microorganisms -- South Africa , Anti-infective agents -- South Africa , Antibiotics
- Description: Bacterial resistance to antibiotics has been a great problem for many years. The degree of resistance and the speed with which resistance develops varies with different organisms and different drugs. Enzymes called β-lactamases are produced by bacteria and are one mechanism in which bacteria develop antimicrobial resistance. Gram-negative bacteria producing enzymes called ESBLs because of their wide substrate range are of a particular concern in nosocomial infections. In many countries people still use traditional medicine derived from plants as an alternative to the Western medicine due to increased cost of Western medicine and microbial resistance of antibiotic treatments. Biologically active compounds isolated from plants species are used in herbal medicine. Because of the high prevalence of the ESBLs and their increasing resistance to the antibiotics, this research study was done to test the antimicrobial activities of selected medicinal plants of the Eastern Cape; G. incanum, D. angustifolia and E. autumnalis which were traditionally used to treat various infections. The in vitro antimicrobial activity of three different extracts (acetone, methanol & distilled water) and the traditional preparations of the three plants were tested against the selected strains of ESBL-producing bacteria, non β-lactamase producers and the different fungal species. The extracts were screened against 26 Gram-positive bacterial strains, 53 Gram-negative bacterial strains and 15 fungal strains. The Gram-positive bacteria included strains from S. aureus, B. cereus and E. faecalis. The Gram-negative bacteria included strains from E. ii coli, E. cloacae, K. pneumoniae, P. aeruginosa and Acinetobacter spp. The fungal strains included 9 strains of Candida albicans and a single strain of each of the following opportunistic fungi, Mucor sp, Geotrichium sp, Penicillium sp, Fusarium sp and Rhizopus sp. The agar dilution assay was used for the antimicrobial screening of the plants extracts and for the determination of the MICs. The Ames test was performed for the determination of probable carcinogenicity of the extracts of G. incanum and D. angustifolia. The distilled water extracts followed by acetone extracts of the plants revealed the highest antimicrobial activity against the different microbial strains. The extracts of G. incanum followed by the extracts of D. angustifolia inhibited the highest number of microbial strains. The extracts of E. autumnalis did not show any antimicrobial activity against all the pathogens in this study. More of the Gram-positive bacteria were inhibited by the plant extracts. The lowest MIC was obtained with Gram-positive bacteria. The bacterial strains of E. faecalis and P. aeruginosa were not inhibited by any of the plants extracts in the agar dilution assay yet Acinetobacter species which are MDR were inhibited by the distilled water and methanol extracts of G. incanum. A single strain of Mucor sp was the only spore forming fungi that was inhibited by the distilled water extracts of G. incanum. None of the plants extracts showed any mutagenic effects on the TA100 S. typhimurium strains incorporated on the Ames test. Apart from revealing of new antimicrobial agents that may be used against resistant organisms, the proper use of antimicrobial agents should be recommended. The study has highlighted a need for further investigations on the properties of the medicinal plants used in this study.
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- Date Issued: 2010
Leonotis leonurus: the anticoagulant and antidiabetic activity of Leonotis leonurus
- Authors: Mnonopi, Nandipha
- Date: 2010
- Subjects: Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , Diabetes -- Alternative treatment -- South Africa , Plant bioactive compounds , Leonotis leonurus -- Physiological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10323 , http://hdl.handle.net/10948/1194 , Medicinal plants -- South Africa , Materia medica, Vegetable -- South Africa , Diabetes -- Alternative treatment -- South Africa , Plant bioactive compounds , Leonotis leonurus -- Physiological aspects
- Description: Commercial marrubiin, aqueous and organic extracts of Leonotis leonurus were tested in vitro for their anticoagulant and antiplatelet activities. The aqueous extract inhibited platelet aggregation by 69.5 percent (100 μg/mL), while the organic extract (100 μg/mL) and marrubiin (5 μg/mL) showed 92.5 percent and 91.6 percent inhibition, respectively, by inhibiting the binding of fibrinogen to glycoprotein IIb/IIIa receptor in a concentration dependent manner. The extracts significantly prolonged activated partial thromboplastin time compared to untreated plasma controls. Fibrin and D-Dimer formation were drastically decreased. The extracts and marrubiin concentration-dependently inhibited calcium mobilization induced by collagen and thrombin. The formation of thromboxane A2 was also significantly reduced by both the extracts and marrubiin. Protein secretion and platelet adhesion were significantly reduced by both the extracts and marrubiin. The organic extract and marrubiin showed a more pronounced effect than the aqueous extracts in all the in vitro assays. The ex-vivo animal model confirmed the results obtained in vitro. Similar to the in vitro studies, activated partial thromboplastin time clotting time was prolonged by marrubiin and the number of aggregated platelets were significantly reduced relative to aspirin. The findings reflect that marrubiin largely contributes to the organic extract's anticoagulant and antiplatelet effect in vitro. INS-1 cells were cultured under normo- and hyperglycaemic conditions. Marrubiin and the two Leonotis leonurus extracts were screened for anti-diabetic activity in vitro. The stimulatory index of INS-1 cells cultured under hyperglycaemic conditions was significantly increased by 60 percent and 61 percent (p<0.01; n=5) in cells exposed to the organic extract (10 μg/mL) and marrubiin (500 ng/mL), respectively, relative to the normoglycaemic conditions. The gene expression of insulin was significantly increased by 76.5 and 71 percent, and of glucose transporter-2 by 93 and 92.5 percent for marrubiin and the organic extract, respectively, under the same conditions stipulated above (p<0.01; n=4). The extract and marrubiin similarly showed an increase in respiratory rate under hyperglycaemic conditions. Marrubiin increased insulin secretion, HDL-cholesterol, while it decreased total cholesterol, LDL-cholesterol and the atherogenic index in the in vivo rat model.
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- Date Issued: 2010