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Biological activities of Cremaspora triflora (Thonn.) K. Schum (Rubiaceae) extract, fractions and an isolated compound on selected fungi and bacteria and the determination of the mode of action using Electron Microscopy
Thesis (PhD (Paraclinical Sciences))--University of Pretoria, 2016.
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2026
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| access_status_str | Open Access |
| author2 | Botha, Francien Susanna S. |
| author_browse | Botha, Francien Susanna S. |
| author_facet | Botha, Francien Susanna S. |
| collection | Thesis |
| description | Thesis (PhD (Paraclinical Sciences))--University of Pretoria, 2016. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/110071 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:37:13.330Z |
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| publishDate | 2026 |
| publishDateRange | 2026 |
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| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/110071 Biological activities of Cremaspora triflora (Thonn.) K. Schum (Rubiaceae) extract, fractions and an isolated compound on selected fungi and bacteria and the determination of the mode of action using Electron Microscopy Botha, Francien Susanna S. leokonti@yahoo.com Eloff, Jacobus Nicolaas Elisha, Ishaku Leo Cremaspora triflora Hentriacontane Electron microscopy Antimicrobial activity Ultrastructural changes Thesis (PhD (Paraclinical Sciences))--University of Pretoria, 2016. Medicinal plants have been used for many years to flavour and conserve food, to treat health disorders and to prevent diseases. Medicinal plants may be described as biosynthetic laboratories for the production of secondary metabolites, which includes tannins, flavonoids, anthraquinones, alkaloids, glycosides, etc., which exert physiological and therapeutic effects. Currently, there are numerous scientifically confirmed data on medicinal plants effective against pathogenic microorganisms resistant to antimicrobials. The preliminary investigation involved the screening and evaluation of the leaves of nine South African medicinal plants using standard methods. The selected plants were Heteromorpha arborescens (Spreng.) Chan. & Schltdl, Bolusanthus speciosus (H. Bolus) Harms, Maesa lanceolata Forssk, Elaeodendron croceum (Thunb.) DC, Pittosporum viridiflorum Sims, Hypericum roeperianum G.W. Schimp.ex A.Rich. Var. roeperianum, Morus mesozygia Stapf ex A.Chev., Cremaspora triflora (Thonn.) K.Schum. and Calpurnia aurea (Aiton) Benth ssp aurea. There are traditional claims of their uses in the treatment of various infections in humans and animals and a record of excellent activity against Escherichia coli from the Phytomedicine database of the University of Pretoria. The anti-inflammatory activity determination of the acetone extracts, using nitric oxide production, indicated inhibition of nitric oxide production in a dose-dependent manner in the LPS-stimulated RAW 264.7 macrophages. E. croceum and C. aurea extracts had strong activity against 15-lipoxygenase with IC50 values at 26.23 and 34.70 _g/mL respectively. Morus mesozygia and Heteromorpha arborescens extracts had good in vitro antiprotein denaturation activity with IC50 values at 11.89 and 53.78 _g/mL. The free radical scavenging activity of the extracts in DPPH assays ranged from 7.72 to 154.77 _g/mL. Trolox equivalent antioxidant capacity (TEAC) and FRAP values ranged from 0.06 to 1.32 and 0.06 to 0.99 respectively. Results from this study support the traditional use of the selected medicinal plants in the management of arthritis and other inflammatory conditions. The free radical scavenging capacity of the extracts might be an indication of their immune-boosting potential. The minimal inhibitory concentration (MIC) values of the crude extracts against Gram-positive (Staphylococcus aureus, Enterococcus faecalis and Bacillus cereus) and Gram-negative (Escherichia coli, Salmonella Typhimurium and Pseudomonas aeruginosa) bacteria indicated that the extracts were active against most of these pathogens with MIC values ranging from 0.02 to 0.52 mg/ml. Enterococcus faecalis and S. Typhimurium was resistant to the extracts. Cremaspora triflora and Maesa lanceolata leaf extracts were more potent than the other extracts against Gram-positive and Gram-negative pathogens, Biological activities of Cremaspora triflora (Thonn.) K. Schum (Rubiaceae) extract, fractions and an isolated compound on selected fungi and bacteria and the determination of the mode of action using Electron Microscopy xxix with mean MICs of 0.07 mg/ml and 0.09 mg/ml respectively. Extracts of Maesa lanceolata and Hypericum roeperianum were the most efficacious, with total antibacterial activity (TAA) at 1417.16 and 963.29 ml/g respectively. All, except extracts of Maesa lanceolata, Elaeodendron croceum and Calpurnia aurea were relatively non-cytotoxic with LC50 >20 _g/ml. Cremaspora triflora had good selectivity index (SI) values against S. aureus and E. coli, with SI=2.87 and 1.15 respectively. Hypericum roeperianum had SI=1.10 against B. cereus. Bioautography revealed 1-6 visible bioactive compounds that are non-polar. These findings indicate that some of the extracts have good potential for therapeutic use against the bacterial pathogens. The in vitro antibacterial activity of the acetone leaf extracts were determined against Bacillus anthracis Sterne strain. Excellent MIC values were observed for the following plant species: M. lanceolata (0.02 mg/ml), B. speciosus, H. roeperianum, M. mesozygia (0.04 mg/ml) and P viridiflorum (0.08 mg/ml). The total antibacterial activity of the extracts ranged from 92 to 5562 ml/g. The cytotoxicity determined on Vero cells indicated that most of the extracts were relatively non-toxic compared to doxorubicin. The selectivity index (SI) ranged from 0.02 to 1.66. Further investigation of these plant extracts may lead to the development of new therapeutic agents to protect humans or animals against anthrax. The in vitro antifungal activity of the acetone crude leaf extracts against Candida albicans ranged from 0.31-1.25 mg/ml, indicating poor activity against C. albicans. However, against Cryptococcus neoformans, the MIC ranged from 0.08 to 0.63 mg/ml. The extracts of Cremaspora triflora, Bolusanthus speciosus, Calpurnia aurea and Morus mesozygia had good activity with MIC of 0.08 mg/ml respectively. All extracts were tested against six enteropathogenic bacteria namely, Enterobacter cloacae, Proteus mirabilis, Klebsiella pneumoniae, Escherichia coli, Salmonella serotype Typhimurium and Stenotrophomonas maltophilia isolated from commercial poultry eggs. All the tested pathogens were sensitive to Cremaspora triflora extracts with MIC at 0.08 mg/ml, except Proteus mirabilis, which was less sensitive with MIC of 0.63 mg/ml. Consequently, crude extracts of C. triflora were separated into different fractions using solvent-solvent partitioning. A total of five fractions were collected from acetone crude extracts of the leaves of C. triflora. These fractions include hexane, chloroform, butanol, 35% methanol and water fractions respectively. The fractions were tested for antimicrobial activity using the microdilution and bioautography methods. All the fractions showed various degrees of activity against the tested bacteria, Staphylococcus aureus, Enterococcus faecalis, Bacillus cereus, Salmonella Typhimurium, Escherichia coli, Pseudomonas aeruginosa and two fungal agents, Candida albicans and Cryptococcus neoformans. The hexane fraction and chloroform fractions had the best activity against the tested pathogens. The safety of the fractions Biological activities of Cremaspora triflora (Thonn.) K. Schum (Rubiaceae) extract, fractions and an isolated compound on selected fungi and bacteria and the determination of the mode of action using Electron Microscopy xxx was determined using Vero cells and bovine dermal cells. All fractions were non-toxic to the tested cell lines and had good selectivity index. Column chromatography of the hexane fraction was carried out and an active compound (1) was isolated. The mode of action of the hexane fraction and the compound on both bacterial and fungal pathogens were evaluated using scanning and transmission electron microscopy. The mode of action of the hexane fraction and the isolated compound on the bacterial and fungal pathogens is due to damage of the cytoplasmic inclusions of the organisms. The isolated compound was non-toxic to Vero cell and bovine dermal cells. The mode of action of hexane and the compound (1) identified as hentriacontane from the leaves of C. triflora, was attributed to their lipophilic nature which allows them to diffuse through the cell envelope and disrupt the cell membrane. The resultant effect is the morphological and ultrastructural deformities. SEM revealed rough surfaces, wrinkled and shrunken cells, protrusions, pleomorphic appearance. TEM micrographs showed cells with disorganised cytoplasm, disintegrated cytoplasmic contents, disrupted cell membrane and in Enterococcus faecalis cell wall damage with the leakage of cytoplasmic contents. Both hexane and hentriacontane were all able to trigger germ tube formation, an indication of stress effect on Candida albicans. Generally, both extracts and the isolated compound were able to affect the metabolic, reproduction functions and other physiologic functions of the cells. This is the first report of this kind of investigation on Candida albicans, Enterococcus faecalis, Stenotrophomonas maltophilia, and Salmonella serotype Typhimurium from the hexane fraction and hentriacontane from the leav Paraclinical Sciences PhD (Paraclinical Sciences) 2026-05-15T17:26:14Z 2026-05-15T17:26:14Z 17/01/26 2016 Thesis http://hdl.handle.net/2263/110071 en application/pdf |
| spellingShingle | Cremaspora triflora Hentriacontane Electron microscopy Antimicrobial activity Ultrastructural changes Biological activities of Cremaspora triflora (Thonn.) K. Schum (Rubiaceae) extract, fractions and an isolated compound on selected fungi and bacteria and the determination of the mode of action using Electron Microscopy |
| title | Biological activities of Cremaspora triflora (Thonn.) K. Schum (Rubiaceae) extract, fractions and an isolated compound on selected fungi and bacteria and the determination of the mode of action using Electron Microscopy |
| title_full | Biological activities of Cremaspora triflora (Thonn.) K. Schum (Rubiaceae) extract, fractions and an isolated compound on selected fungi and bacteria and the determination of the mode of action using Electron Microscopy |
| title_fullStr | Biological activities of Cremaspora triflora (Thonn.) K. Schum (Rubiaceae) extract, fractions and an isolated compound on selected fungi and bacteria and the determination of the mode of action using Electron Microscopy |
| title_full_unstemmed | Biological activities of Cremaspora triflora (Thonn.) K. Schum (Rubiaceae) extract, fractions and an isolated compound on selected fungi and bacteria and the determination of the mode of action using Electron Microscopy |
| title_short | Biological activities of Cremaspora triflora (Thonn.) K. Schum (Rubiaceae) extract, fractions and an isolated compound on selected fungi and bacteria and the determination of the mode of action using Electron Microscopy |
| title_sort | biological activities of cremaspora triflora thonn k schum rubiaceae extract fractions and an isolated compound on selected fungi and bacteria and the determination of the mode of action using electron microscopy |
| topic | Cremaspora triflora Hentriacontane Electron microscopy Antimicrobial activity Ultrastructural changes |
| url | http://hdl.handle.net/2263/110071 |