Antimicrobial activities of three medicinal plants against selected diarrheagenic pathogens
- Authors: Nkosi, Themba Johan
- Date: 2013
- Subjects: Anti-infective agents , Drug resistance in microorganisms , Materia medica, Vegetable
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10126 , http://hdl.handle.net/10948/d1020759
- Description: Diarrhea is a global concern that the United Nations Children’s Fund (UNICEF) and the World Health Organization (WHO), have confirmed to be the second major cause of death in children under the age of five. Major bacterial pathogens that cause diarrhea include Escherichia coli, Salmonella species, Shigella species and Staphylococcus aureus. Antibiotic therapy is recommended depending on the severity and presentation of the disease; however, the appearance of antibiotic-resistant bacteria is an emerging global threat to the ability to treat these bacterial infections. This situation could be overcome by the discovery of new natural antibiotics. Plants have been a source of medicine for centuries and have been used to treat diseases including diarrhea. This makes plants a natural potential target to study for their antibiotic properties. The objective of this study was to determine the antibiotic properties of medicinal plants against known pathogens that cause bacterial diarrhea. Three medicinal plants, Cassia abbreviata, Kigelia africana, and Geranium incanum were investigated for their antimicrobial properties against these strains of microorganisms: American Type Culture Collection (ATTC) and Clinical Strains (CS). The plant materials were ground into powder, which was then dissolved in methanol, acetone and distilled water to extract the active compounds. The plant extracts were then used to (i) determine their antibiotic activity, (ii) determine the minimum inhibitory concentration (MICs), (iii) analyze the thin layer chromatography (TLC) fingerprints, and (iv) analyze the autobiography assay. The results obtained in this study met the aim and objectives of this study. The antimicrobial activities of the selected plants were obtained as discussed in Chapter 2 and 3. These results indicated that the traditional plants could be used as antimicrobials. In the screening assays, the test microorganisms were inhibited by the plant extracts, when they were subjected to plant extracts. This was performed on Mueller Hinton agar as sensitivity testing, which revealed clear zones of inhibition. The MIC values for each plant extract were established which ranged from 0.101 to 13.3 mg/dl. The TLC analysis revealed the spots which contained the active compounds which inhibited the bacterial growth. A bioautography assay was performed on the TLC plates, which exposed the exact spots containing the active compound inhibiting the bacteria. These results are clearly consistent with what former scientists have observed. Detailed explanations on the results are in Chapter 3 and 4 of this paper. It is important to note that all the procedures performed in this study were in vitro assays. Some effective in vitro assay activity may not always result in the same effective in vivo activity, because some active compounds may be metabolized and degraded into inactive metabolites. For this reason, the in vitro results obtained in this study, may not reflect the true effectiveness of the compounds in in vivo trials. It is therefore advised that future scientists should take a step further in analyzing the plant extracts through in vivo assays. Further testing and study on these plants at an advanced molecular level will be beneficial in the medical fields in the search for new antibiotics to treat infectious diseases. Purification and further analysis of their products can be helpful in the production of pure natural medicines. This will discover the active ingredients and compounds responsible for inhibition of the microorganisms. This will make the compounds potential candidates for a scientific validation and analysis for future scientists to bring a new dawn in the fight against infectious diseases.
- Full Text:
- Date Issued: 2013
- Authors: Nkosi, Themba Johan
- Date: 2013
- Subjects: Anti-infective agents , Drug resistance in microorganisms , Materia medica, Vegetable
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10126 , http://hdl.handle.net/10948/d1020759
- Description: Diarrhea is a global concern that the United Nations Children’s Fund (UNICEF) and the World Health Organization (WHO), have confirmed to be the second major cause of death in children under the age of five. Major bacterial pathogens that cause diarrhea include Escherichia coli, Salmonella species, Shigella species and Staphylococcus aureus. Antibiotic therapy is recommended depending on the severity and presentation of the disease; however, the appearance of antibiotic-resistant bacteria is an emerging global threat to the ability to treat these bacterial infections. This situation could be overcome by the discovery of new natural antibiotics. Plants have been a source of medicine for centuries and have been used to treat diseases including diarrhea. This makes plants a natural potential target to study for their antibiotic properties. The objective of this study was to determine the antibiotic properties of medicinal plants against known pathogens that cause bacterial diarrhea. Three medicinal plants, Cassia abbreviata, Kigelia africana, and Geranium incanum were investigated for their antimicrobial properties against these strains of microorganisms: American Type Culture Collection (ATTC) and Clinical Strains (CS). The plant materials were ground into powder, which was then dissolved in methanol, acetone and distilled water to extract the active compounds. The plant extracts were then used to (i) determine their antibiotic activity, (ii) determine the minimum inhibitory concentration (MICs), (iii) analyze the thin layer chromatography (TLC) fingerprints, and (iv) analyze the autobiography assay. The results obtained in this study met the aim and objectives of this study. The antimicrobial activities of the selected plants were obtained as discussed in Chapter 2 and 3. These results indicated that the traditional plants could be used as antimicrobials. In the screening assays, the test microorganisms were inhibited by the plant extracts, when they were subjected to plant extracts. This was performed on Mueller Hinton agar as sensitivity testing, which revealed clear zones of inhibition. The MIC values for each plant extract were established which ranged from 0.101 to 13.3 mg/dl. The TLC analysis revealed the spots which contained the active compounds which inhibited the bacterial growth. A bioautography assay was performed on the TLC plates, which exposed the exact spots containing the active compound inhibiting the bacteria. These results are clearly consistent with what former scientists have observed. Detailed explanations on the results are in Chapter 3 and 4 of this paper. It is important to note that all the procedures performed in this study were in vitro assays. Some effective in vitro assay activity may not always result in the same effective in vivo activity, because some active compounds may be metabolized and degraded into inactive metabolites. For this reason, the in vitro results obtained in this study, may not reflect the true effectiveness of the compounds in in vivo trials. It is therefore advised that future scientists should take a step further in analyzing the plant extracts through in vivo assays. Further testing and study on these plants at an advanced molecular level will be beneficial in the medical fields in the search for new antibiotics to treat infectious diseases. Purification and further analysis of their products can be helpful in the production of pure natural medicines. This will discover the active ingredients and compounds responsible for inhibition of the microorganisms. This will make the compounds potential candidates for a scientific validation and analysis for future scientists to bring a new dawn in the fight against infectious diseases.
- Full Text:
- Date Issued: 2013
Photophysicochemical and photodynamic antimicrobial chemotherapeutic studies of novel phthalocyanines conjugated to silver nanoparticles
- Authors: Rapulenyane, Nomasonto
- Date: 2013 , 2013-06-10
- Subjects: Phthalocyanines , Photochemistry , Photochemotherapy , Cancer -- Photochemotherapy , Anti-infective agents , Escherichia coli , Nanoparticles , Silver , Zinc
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4291 , http://hdl.handle.net/10962/d1003912 , Phthalocyanines , Photochemistry , Photochemotherapy , Cancer -- Photochemotherapy , Anti-infective agents , Escherichia coli , Nanoparticles , Silver , Zinc
- Description: This work reports on the synthesis, characterization and the physicochemical properties of novel unsymmetrically substituted zinc phthalocyanines: namely tris{11,19, 27-(1,2- diethylaminoethylthiol)-2-(captopril) phthalocyanine Zn ((ZnMCapPc (1.5)), hexakis{8,11,16,19,42,27-(octylthio)-1-(4-phenoxycarboxy) phthalocyanine} Zn (ZnMPCPc(1.7)) and Tris {11, 19, 27-(1,2-diethylaminoethylthiol)-1,2(caffeic acid) phthalocyanine} Zn ((ZnMCafPc (1.3)). Symmetrically substituted counterparts (tetrakis(diethylamino)zinc phthalocyaninato (3.8), octakis(octylthio)zinc phthalocyaninato (3.9) and tetrakis (carboxyphenoxy)zinc phthalocyaninato (3.10) complexes) were also synthesized for comparison of the photophysicochemical properties and to investigate the effect of the substituents on the low symmetry Pcs. The complexes were successfully characterized by IR, NMR, mass spectral and elemental analyses. All the complexes showed the ability to produce singlet oxygen, while the highest triplet quantum yields were obtained for 1.7, 1.5 and 3.9 (0.80, 0.65 and 0.62 respectively and the lowest were obtained for 1.3 and 3.10 (0.57 and 0.47 respectively). High triplet lifetimes (109-286 μs) were also obtained for all complexes, with 1.7 being the highest (286 μs) which also corresponds to its triplet and singlet quantum yields (0.80 and 0.77 respectively). The photosensitizing properties of low symmetry derivatives, ZnMCapPc and ZnMCafPc were investigated by conjugating glutathione (GSH) capped silver nanoparticles (AgNP). The formation of the amide bond was confirmed by IR and UV-Vis spectroscopies. The photophysicochemical behaviour of the novel phthalocyanine-GSH-AgNP conjugates and the simple mixture of the Ag NPs with low the symmetry phthalocyanines were investigated. It was observed that upon conjugation of the phthalocyanines to the GSH-AgNPs, a blue shift in the Q band was induced. The triplet lifetimes and quantum yields improved upon conjugation as compared to the phthalocyanines (Pc) alone. Complex 1.5 triplet lifetimes increased from 109 to 148 and triplet quantum yield from 0.65 to 0.86 upon conjugation. Fluorescence lifetimes and quantum yields decreased for the conjugates compared to the phthalocyanines alone, due to the quenching caused by the Ag NPs. The antimicrobial activity of the zinc phthalocyanines (complexes 1.3 and 1.5) and their conjugates against Escherichia coli was investigated. Only 1.3 and 1.5 complexes were investigated because of the availability of the sample. In general phthalocyanines showed increase in antibacterial activity with the increase in phthalocyanines concentration in the presence and absence of light. The Pc complexes and their Ag NP conjugates showed an increase in antibacterial activity, due to the synergistic effect afforded by Ag NP and Pcs. Improved antibacterial properties were obtained upon irradiation. 1.5-AgNPs had the highest antibacterial activity compared to 1.3-AgNPs conjugate; these results are in agreement with the photophysical behaviour. This work demonstrates improved photophysicochemical properties of low symm
- Full Text:
- Date Issued: 2013
- Authors: Rapulenyane, Nomasonto
- Date: 2013 , 2013-06-10
- Subjects: Phthalocyanines , Photochemistry , Photochemotherapy , Cancer -- Photochemotherapy , Anti-infective agents , Escherichia coli , Nanoparticles , Silver , Zinc
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4291 , http://hdl.handle.net/10962/d1003912 , Phthalocyanines , Photochemistry , Photochemotherapy , Cancer -- Photochemotherapy , Anti-infective agents , Escherichia coli , Nanoparticles , Silver , Zinc
- Description: This work reports on the synthesis, characterization and the physicochemical properties of novel unsymmetrically substituted zinc phthalocyanines: namely tris{11,19, 27-(1,2- diethylaminoethylthiol)-2-(captopril) phthalocyanine Zn ((ZnMCapPc (1.5)), hexakis{8,11,16,19,42,27-(octylthio)-1-(4-phenoxycarboxy) phthalocyanine} Zn (ZnMPCPc(1.7)) and Tris {11, 19, 27-(1,2-diethylaminoethylthiol)-1,2(caffeic acid) phthalocyanine} Zn ((ZnMCafPc (1.3)). Symmetrically substituted counterparts (tetrakis(diethylamino)zinc phthalocyaninato (3.8), octakis(octylthio)zinc phthalocyaninato (3.9) and tetrakis (carboxyphenoxy)zinc phthalocyaninato (3.10) complexes) were also synthesized for comparison of the photophysicochemical properties and to investigate the effect of the substituents on the low symmetry Pcs. The complexes were successfully characterized by IR, NMR, mass spectral and elemental analyses. All the complexes showed the ability to produce singlet oxygen, while the highest triplet quantum yields were obtained for 1.7, 1.5 and 3.9 (0.80, 0.65 and 0.62 respectively and the lowest were obtained for 1.3 and 3.10 (0.57 and 0.47 respectively). High triplet lifetimes (109-286 μs) were also obtained for all complexes, with 1.7 being the highest (286 μs) which also corresponds to its triplet and singlet quantum yields (0.80 and 0.77 respectively). The photosensitizing properties of low symmetry derivatives, ZnMCapPc and ZnMCafPc were investigated by conjugating glutathione (GSH) capped silver nanoparticles (AgNP). The formation of the amide bond was confirmed by IR and UV-Vis spectroscopies. The photophysicochemical behaviour of the novel phthalocyanine-GSH-AgNP conjugates and the simple mixture of the Ag NPs with low the symmetry phthalocyanines were investigated. It was observed that upon conjugation of the phthalocyanines to the GSH-AgNPs, a blue shift in the Q band was induced. The triplet lifetimes and quantum yields improved upon conjugation as compared to the phthalocyanines (Pc) alone. Complex 1.5 triplet lifetimes increased from 109 to 148 and triplet quantum yield from 0.65 to 0.86 upon conjugation. Fluorescence lifetimes and quantum yields decreased for the conjugates compared to the phthalocyanines alone, due to the quenching caused by the Ag NPs. The antimicrobial activity of the zinc phthalocyanines (complexes 1.3 and 1.5) and their conjugates against Escherichia coli was investigated. Only 1.3 and 1.5 complexes were investigated because of the availability of the sample. In general phthalocyanines showed increase in antibacterial activity with the increase in phthalocyanines concentration in the presence and absence of light. The Pc complexes and their Ag NP conjugates showed an increase in antibacterial activity, due to the synergistic effect afforded by Ag NP and Pcs. Improved antibacterial properties were obtained upon irradiation. 1.5-AgNPs had the highest antibacterial activity compared to 1.3-AgNPs conjugate; these results are in agreement with the photophysical behaviour. This work demonstrates improved photophysicochemical properties of low symm
- Full Text:
- Date Issued: 2013
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