Browsing by Author "Nkala, Bongani Alphouse."

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The cytotoxic effects, anti-iflammatory, antioxidant, antibacterial, and antidiabetic properties of eight selected South African plants for medicinal purposes.
(2020) Nkala, Bongani Alphouse.; Mbongwa, Hlengiwe Prosperity.; Qwebani-Ogunleye, Tozama.
People from the Southern African region have been using the fauna and flora of the region in their homes for millennia to treat all sorts of ailments and complaints with great success. This knowledge transfer was done through ’apprenticeships’ and oral communication. Certain communities consider medicinal plants to be safer than drugs and that they can treat more than one ailment. This study investigated cytotoxic effect, antimicrobial, anti-inflammatory, antioxidant, and antidiabetic properties of eight selected South African plants for medicinal purposes. Plant species were collected from the Walter Sisulu National Botanical-Gardens and were extracted with 90% methanol (1 g/10 ml) and concentrate to 10 mg/ml. Antimicrobial activities were determined by the microplate dilution method to establish the ability of the plant extracts to inhibit or kill pathogenic organisms with minimal inhibitory concentrations and minimum bactericidal concentration. Cytotoxicity effects were determined with Alamar blue and crystal violet cell viability assays, against C2C12 and RAW 264.7 cells. Anti-inflammatory effects were identified with stimulated lipopolysaccharide RAW 264.7 cells, and nitric oxide inhibition was measured with Griess reagent assay. The estimation of preliminary phytochemical, antioxidant (DPPH and ABTS radical scavenging), and alpha-amylase inhibition were determined with standard methods. The plant extracts inhibition and bactericidal effects were observed against all bacteria, namely: Lippia javanica (0.25±0.00 to 1.13±0.29 mg/ml); Ziziphus mucronata leaf (0.44±0.00 to 1.00±0.00 mg/ml); Erythrina lysistemon (0.44±0.00 to 1.08±0.00 mg/ml) and Schkuhria pinnata (0.5±0.00 to 1.34±0.00 mg/ml). All plant extracts exhibited flavonoids, phenols, terpenoids, and coumarins. The antioxidant inhibition was observed above 80% for Schkuhria pinnata, Lippia javanica, Clerodendrum myricoides, and Erythrina lysistemon. Also, these plant species exhibited an alpha-amylase inhibitory effect of 80%. The IC50 values were > 1000 μg/ml. All plant extracts demonstrated some degree of an antiinflammatory effect. However, Clerondendrum myricoides (35% - 89%), Lippia javanica (26% - 77%), Erythrina lysistemon (23% - 76%), Schkuhria pinnata (27% - 65%), and Vernonia oligocephala (16% - 58%) with IC50 value >1000 μg/ml, exhibited a marked antiinflammatory effect. Therefore, the presence of phenolic, flavonoids, anti-inflammatory, antioxidants, and α-amylase properties are potential solutions towards the management of diabetes and other chronic inflammatory diseases. Keywords: medicinal plants, antimicrobial, cytotoxicity, anti-inflammatory, antidiabetic, antioxidant.
Toxicological analysis of house dust collected from selected Durban residental buildings.
(2009) Nkala, Bongani Alphouse.; Gqaleni, Nceba.
Indoor air quality is described as the chemical, physical and biological characteristics of air in a residential or occupational indoor environment. In residential settings, there are many contributions to indoor pollution levels namely; human activities, biological sources and outdoor air. There has been increased focus on house dust due to its potential to contain biological and chemical pollutants in indoor environments. These have the potential to cause harm to human health. The purpose of this study was to conduct toxicological analysis of house dust collected from inside selected Durban residential buildings. The objectives of this study were to isolate, identify and quantify mould occurrence in house dust samples; to measure the occurrence of heavy metals (arsenic, lead and mercury) in house dust; and to analyse the cytotoxicity of house dust on human lung bronchus carcinoma epithelial line (A549) and human lung bronchus virus transformed epithelial cell line (BBM). One hundred and five house dust samples were obtained from households that participated in the South Durban Health Study. In each home, a sample of settled dust was collected, using standardized protocols, then sieved and individually packed into polystyrene bags. The samples were taken from three surface areas namely; living room couches, bed mattresses, and carpets. Well documented methods were used for the isolation, identification and quantification of mould. The samples for heavy metals analysis were sent to Umgeni Water (chemistry laboratory, Pietermaritzburg) where standardised methods were used. Human cell lines were treated with five different dilutions of each house dust extract. Cell viability was assessed using the MTT assay. Toxic effects of house dust extract were analyzed, following house dust extract treatment and cells were stained with double dye (annexin-V- and propidium iodide) and analysed with flow cytometry, and fluorescent microscope. Cytokines were analysed by Microbionix (Neuried, German) using a Luminex®100 plate reader for multiplex human cytokines analysis. There were (n=128) mould types isolated and (n=105) were identified, of which (n=10) were predominately isolated moulds. This was further confirmed by Allerton Provincial Laboratory in Pietermaritzburg. Among the isolated genera in all three surface areas, Rhizopus spp and Penicillium spp were widely distributed throughout surface areas in greater proportion. The overall highest mean which was reported in this study and expressed in colony forming unit per gram (CFU/g) for Penicillium spp ranged (3400 - 62316 CFU/g) obtained from living room couches, followed by Rhizopus spp (5200 - 15990 CFU/g). The mould results were compared with the South African Occupational Health and Safety Act (OHSA) 85 of 1993 as amended suggested guidelines of 1,000, 000 CFU/g. The findings of this study suggest the moulds in the homes studied were below the suggested guideline. However, this does not imply that the indoor conditions are unsafe or hazardous. Instead, the findings act as an indicator of moulds presence indoors. The type of airborne mould, its concentration and extent of exposure and the health status of the occupants of a building will determine the health effects on an individual. Heavy metals were detected in the dust in the following ascending order: arsenic (As) ranged from 1.3 ug/g -18.4 ug/g (mean, 4.26 ug/g), lead (Pb) ranged from 28.0 - 872 ug/g (mean 171.66 ug/g), and mercury (Hg) ranged from 0.6 -19.0 ug/g (mean, 2.22 ug/g). The mean concentration of lead in the dust was within the range of Canadian National Classification guidelines on residential contamination (500 ug/g). There was numerous numbers of samples in this study that exceeded these guidelines. The mean concentration of arsenic was within residential soil guidelines (20 ug/g). Mercury was within limits when compared with Global Hg project guidelines of soil/residential (6.6 ug/g), thought some of samples were notably above this mean. The ability of house dust extract to lower the cell viability which was slightly above 80% (prior treatment) to less than 50% (post treatment) in both cells was observed in this study. The findings in this study showed that dust extract are toxic to human cell lines, and cells undergone a degree of apoptosis and necrosis 62% (A549) and 99% (BBM). The cytokines serve an important role in the non-specific defence external against insults. It was observed that A549 cells up-regulated the release of IL-6 and IL-8 pro-inflammatory cytokines and under-regulated the release of other cytokines analysed (IL-4, IL-13, and TNF-a). BBM cells released IL-4, IL-8 and IL-13 within limit of detection. The presence of moulds in these sampled indoor household dusts, which is comparable with findings elsewhere indoors, show that moulds act as an indicator for building conditions such as dampness, which supports mould growth. Individuals, whether they are sensitized or not, may develop allergic reactions towards spores, thus the elevated numbers of spores quantified in this study are of concern. Some of the heavy metals reported in this study were higher or marginally higher than international norms and guidelines. The findings in this study strongly suggest that house dust extract is toxic to human lung cell lines. It must be noted, however, that this study may not reflect all that happens when a human lung is exposed to house dust. The findings of this study could contribute to the development of South African indoor air guidelines. In conclusion further study needed to be undertaken with respect to air pollution disease such as allergic; the reason being this study shown the reduced expression of cytokines that are involved in allergic inflammation.