Don Grierson

Prof. Don Grierson


Research Focus & Metrics

Academic Career Length

16Years (2011-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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13 April 2012 in BMC Complementary and Alternative Medicine
Verified
Journal Article
Open access
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WOWilfred Mbeng Otang
Wilfred Mbeng Otang
DGDon Grierson
Don Grierson
RNRoland Ndip Ndip
Roland Ndip Ndip
Background: It has been observed that perturbations in the antioxidant defense systems, and consequently redox imbalance, are present in many tissues of HIV-infected patients. Hence, the exogenous supply of antioxidants, as natural compounds that scavenge free radicals, might represent an important additional strategy for the treatment of HIV infection. The aim of this study was therefore to analyse the phytochemical constituents and antioxidant potential ofGasteria bicolorHaw andPittosporum viridiflorumSims., two South African plants traditionally used for the management of opportunistic fungal infections (OFIs) in AIDS patients.Methods: Thein vitroantioxidant properties of the two plants were screened through DPPH (1,1-diphenyl-2-picrylhydrazyl), NO (nitric oxide), H2O2(hydrogen peroxide) radical scavenging effects and reducing power assays. Phytochemical studies were done by spectrophotometric techniques.Results: There were no significant differences in the flavonoid and proanthocyanidins contents between the leaves and bark extracts ofGasteria bicolorandPittosporum viridiflorumrespectively, while the total phenolic content of the bark extract ofP. viridiflorumwas significantly higher than that ofG. bicolorleaf. The acetone extracts of both plants indicated strong antioxidant activities.Conclusion: The results from this study indicate that the leaves and stem extracts ofGasteria bicolorandPittosporum viridiflorumrespectively possess antioxidant properties and could serve as free radical inhibitors, acting possibly as primary antioxidants. Since reactive oxygen species are thought to be associated with the pathogenesis of AIDS, and HIV-infected individuals often have impaired antioxidant defenses, the inhibitory effect of the extracts on free radicals may partially justify the traditional use of these plants in the management of OFIs in HIV patients in South Africa.

1 January 2012 in Pharmacognosy Magazine
Verified
Journal Article
Open access
PDF file
DGDon Grierson
Don Grierson
RNRoland N Ndip
Roland N Ndip
WOWilfred M Otang
Wilfred M Otang
Background : In South Africa where many patients are immunocompromised as a result of the AIDS pandemic, opportunistic fungal infections such as candidiasis caused mainly by Candida albicans are common. Arctotis arctotoides and Gasteria bicolor are two plants which are frequently and commonly used in traditional medicine in the treatment of HIV patients. Aim: The aim of this study was to investigate the antifungal activity of A. arctotoides and G. bicolor against opportunistic fungi common in HIV/AIDS patients. Materials and Methods: The agar diffusion and micro-dilution methods were used to determine the antifungal activities of the medicinal plant extracts against 10 opportunistic fungi. Results: All the hexane and acetone extracts were active against at least one of the fungi with zones of inhibition varying from 8 to 32 mm, while none of the aqueous extracts was active against any of the fungi. The inhibitory activity of the active extracts, based on the overall mean inhibition diameters, was in the order: A. arctotoides (hexane) > A. arctotoides (acetone) > G. bicolor (hexane) > G. bicolor (acetone). The most susceptible fungi, based on the overall mean diameter of growth inhibition, were Candida glabrata, C. krusei, and Microsporum canis, while Cyptococcus neoformans, Trycophyton tonsurans, and Microsporum gypseum were not susceptible to any of the extracts even at 5 mg/ml which was the highest concentration used. Conclusion: This study validates the use of these plants in traditional medicine in the treatment of secondary fungal infections in HIV/AIDS patients.

1 November 2014 in Journal of Ethnopharmacology
Verified
Journal Article
Closed access
WOWilfred M. Otang
Wilfred M. Otang
DGDon Grierson
Don Grierson
AAAnthony Afolayan
Anthony Afolayan

Verified
Journal Article
Open access
PDF file
WOWilfred M. Otang
Wilfred M. Otang
DGDon Grierson
Don Grierson
RNRoland N. Ndip
Roland N. Ndip
In this study, the effect of the acetone extract of Arctotis arctotoides (L.f.) O. Hoffm. (Asteraceae) on the growth and ultrastructure of some opportunistic fungi associated with HIV/AIDS was analyzed by means of scanning electron microscope (SEM). Remarkable morphological alterations in the fungal mycelia which were attributed to the loss of cell wall strength ranged from loss of turgidity and uniformity, collapse of entire hyphae to evident destruction of the hyphae. The elements responsible for giving the fungi their characteristic virulence were detected and quantified by energy dispersive X-ray microanalysis techniques. X-ray microanalysis showed the specific spectra of sodium, potassium and sulfur as the principal intersection of the four pathogenic fungi studied. Since these ions have the potential of fostering fungal invasion by altering the permeability of hosts’ membranes, their presence was considered inherent to the pathogenicity of the opportunistic fungi. Hence, these findings indicate the potential of the crude extract of A. arctotoides in preventing fungal invasion and subsequent infection of host’s membranes.