Browsing by Author "Klaasen, Jeremy"

Now showing 1 - 6 of 6
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    Additive antibacterial activity of naringenin and antibiotic combinations against multidrug resistant Staphylococcus aureus
    (Academic Journals, 2015) Ng'uni, Tiza; Mothlalamme, Thato; Daniels, Raymond; Klaasen, Jeremy; Fielding, Burtram C.
    Methicillin-resistant Staphylococcus aureus has been causing numerous problems in the health care sector. This is mainly due to its ability to develop resistance to a number of antibiotics used to treat staphylococcal infections. Medicinal plants have been used to treat various ailments over the years and are generating a lot of interest as alternative treatment options. Naringenin is a plant derived flavonoid that possesses antibacterial properties, among others. This study assessed the effect of combinations of naringenin and four antibiotics against two Staphylococcus aureus strains. The minimum inhibitory concentrations were determined using the disk diffusion and broth microdilution assays. In the disk diffusion assay, naringenin did not inhibit bacterial growth, nor did it enhance the antibacterial activity of the antibiotics in the combination study. This was attributed to its slow rate of diffusion out of the disks. On the contrary, in the broth microdilution assay, naringenin exhibited additive effects when combined with the antibiotics (at sub-inhibitory concentrations). These results show the potential of naringenin as an antibacterial agent. Furthermore, the additive effects observed at low naringenin concentrations showed that it can potentially be used in combination with antibiotics against multidrug resistant bacteria.
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    Importance and relevance of phytochemicals present in Galenia Africana
    (Hindawi, 2022) Heredia, Dario; Green, Ivan; Klaasen, Jeremy
    Many people in developing countries rely primarily on medicinal plants as their main source of healthcare, particularly for the treatment of skin infections. Despite the widespread use of medicinal plants, there is a lack of literature describing the relevance and risks of exposure of the phytochemicals present. Galenia africana has been used traditionally in the form of pastes, decoctions, and lotions to treat wounds and other skin-related ailments. -is is a report on the phytochemical composition of G. africana and a review on the pharmacological importance and relevance of these phytochemicals. -e major groups of phytochemicals identified in G. africana extracts were aliphatics, aliphatic triterpenoids, fatty acids, flavonoids, and phenolic and tocopherol compounds. -ese have been found to exhibit medicinal properties, thus highlighting the need to assess the safety of G. africana for topical application. -e information related to the safety of the various compounds could indicate the potential risks related to accidental intake of the extract upon topical product applications. -is report concludes that the quantities of the phytochemicals present in G. africana should not cause undue risk to human health, which provides comfort to pursue future work on using and developing G. africana as a therapeutic agent.
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    Isolation and Partial Characterization Serine Protease Inhibitors from Triticum aestivum cv' Witwol
    (University of the Western Cape, 2001) Morse, Monique; Bradley, Graeme; Klaasen, Jeremy
    Plant diseases and plant pests are major constraints to plant growth and development, resulting in severe crop losses annually. Plant pathogens can be a variety of things, living and non-living. Non-living pathogens exist as physical conditions that plants are exposed to- climatic conditions can cause damage to plants and there are various agricultural practices that can also be harmful to the plant. Living pathogens are called parasitic or infectious diseases and are extremely contagious and can spread from plant to plant very quickly. Insects, nematodes, mites and higher animals can be considered as pathogens, as are slime mold, bacteria, fungi and parasitic higher plants. Viruses and viroids are also considered pathogens (URL ). Fungal diseases, in particular, severely limit the production of major crops, as do insect crop pests. Effective control of pathogens has led to widespread use of chemical fungicides and insecticides, but with potentially deleterious environmental and human health consequences associated with this practice, strategies to utilize natural host plant resistance mechanisms for disease control are being pursued (Yun e/ a1.,1997). The agrochemical industry has been actively looking for less damaging ways to control insect pests, and has introduced a number of more environmentally friendly pesticides. In addition, alternative strategies for pathogen and pest control have been pursued, such as biological control, and the use of plant varieties with inherent resistance
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    Real-time assessment of Candida biofilm disruption by Galenia africana
    (2022-05-25) Stuurman, Keith; Abrantes, Pedro Miguel dos Santos; Klaasen, Jeremy; Africa, Charlene Wilma Joyce
    Candida species often cause opportunistic infections in immunocompromised patients and are able to form highly structured biofilms that protect the yeast cells from the external environment and the action of antimicrobials. The use of fluconazole, a routinely dispensed antifungal in the treatment of localised and systemic Candida infections, often leads to treatment failure due to drug resistance. This increases patient morbidity and mortality and justifies the need for effective and accessible treatment alternatives. Galenia africana is an indigenous South African plant with proven antifungal properties and no toxicity to mammalian cells. In this study the activity of a G. africana aqueous extract against C. albicans and C. glabrata biofilms before and after biofilm formation was tested using the xCELLigence impedance-based real-time biofilm monitoring system. The presence of G. africana resulted in a dose-dependent decrease in biofilm formation in both Candida species and was found to be effective in preventing Candida biofilm formation and disrupting existing Candida biofilms. This is the first reported study to use an impedance-based system to monitor the real-time biofilm formation of Candida species in the presence of a medicinal plant extract.
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    Testing of eight medicinal plant extracts in combination with kresoxim-methyl for integrated control of botrytis cinerea in apples
    (MDPI, 2015) Fielding, Burtram C.; Knowles, Cindy-Lee; Vries, Filicity A.; Klaasen, Jeremy
    Botrytis cinerea is a fungus that causes gray mold on many fruit crops. Despite the availability of a large number of botryticides, the chemical control of gray mold has been hindered by the emergence of resistant strains. In this paper, tests were done to determine the botryticidal efficacy of selected plant extracts alone or combined with kresoxim-methyl. In total, eight South African medicinal plants viz Artemisia afra, Elyptropappus rhinocerotis, Galenia africana, Hypoxis hemerocallidea, Siphonochilus aetheopicus, Sutherlandia frutescens, Tulbaghia violacea and Tulbaghia alliacea were screened. Allium sativum, a plant species known to have antifungal activity, was included in the in vivo studies. For the in vitro studies, synergistic interactions between the plant extracts and the kresoxim-methyl fungicide were tested with radial growth assays. Data indicated synergistic inhibitory effects between the fungicide and the plant extracts. Next, different doses of plant extracts combined with kresoxim-methyl were used for decay inhibition studies on Granny Smith apples. Synergistic and additive effects were observed for many of the combinations. Even though this study was done using only one strain of B. cinerea, results showed that the tested indigenous South African plant species possess natural compounds that potentiate the activity of kresoxim-methyl.
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    Tyrosinase and melanogenesis inhibition by indigenous African plants: A review
    (Multidisciplinary Digital Publishing Institute (MDPI), 2020) Opperman, Laurentia; De Kock, Maryna; Klaasen, Jeremy
    The indiscriminate use of non-regulated skin lighteners among African populations has raised health concerns due to the negative effects associated with skin lightener toxicity. For this reason, there is a growing interest in the cosmetic development of plants and their metabolites as alternatives to available chemical-derived skin lightening formulations. Approximately 90% of Africa’s population depends on traditional medicine, and the continent’s biodiversity holds plant material with various biological activities, thus attracting considerable research interest. This study aimed to review existing evidence and document indigenous African plant species capable of inhibiting the enzyme tyrosinase and melanogenesis for potential incorporation into skin lightening products.