Background: HIV/AIDS remains a major health concern worldwide and the number of people infected in Sub-Saharan Africa continues to increase. This despite increased awareness and availability of HIV drugs in most countries. The success of current HIV-1 drugs is overshadowed by the emergence of drug resistant viral strains and the adverse side-effects they may cause. It is these limitations and many more that drives the continuous search for better HIV treatments. Research into drug discovery and development using natural products is becoming better established. With natural products, there are endless opportunities for discovering novel compounds which either ends up as final drugs or as backbones of drug leads. Methods: In this thesis, sixteen Lamiaceae (mint) plants were investigated for inhibitory properties against HIV-1 as well as for beneficial immune enhancing effects. This family of plants is commonly used in traditional medicine preparations for the treatment of various ailments including those that are virus induced. Cytotoxicity of the plant material was determined using tetrazolium dyes and the results subsequently confirmed with flow cytometry and real-time cell analysis. Direct enzyme assays were used to determine the inhibitory properties of the extracts and isolated compounds against HIV-1 protease (PR), reverse transcriptase (RT) and integrase (IN). The effect of the plant materials was also evaluated in an in vitro model of chronic and latent infection by measuring HIV-1 p24 protein secretion of an infected cell line (U1) following treatment. Most HIV-infected individuals only seek treatment during the chronic stages of disease and latent reservoirs of the virus perpetuate treatment. The immune modulating properties were determined by quantitating the effects of plant extracts/compounds on Th1/2/17 cytokine production in human mononuclear cells using the cytometric bead array technology. Finally, anti-oxidant and anti-inflammatory properties were also assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide colorimetric assays respectively. Results and discussion: The 50% cytotoxic concentration (CC50) of the extracts was between 4.2 and 100 μg/ml. Of the sixteen, extracts from six plants (Ocimum labiatum, Ocimum serratum, Plectranthus barbatus, Plectranthus neochilus, Salvia apiana and Stachys byzantina) were active against HIV-1. Four plants (P. neochilus, O. serratum, S. apiana and S. byzantina) demonstrated moderate inhibitory properties against HIV-1 PR, RT and IN (40-49%) and three of these plants (O. serratum, S. apiana and S. byzantina) significantly (p<0.05) suppressed HIV-1 replication in U1 cells. The most exciting data was obtained from extracts of P. barbatus and O. labiatum which demonstrated inhibition classified as good (>50%) against HIV-1 PR (IC50s 62 ±0.2 and 49.8 ±0.4 μg/ml), reduced the production of pro-inflammatory cytokines at non-cytotoxic concentrations and demonstrated strong antioxidant properties (IC50 values 13 ±0.8 and 15.8 ±0.3 μg/ml). O. labiatum extract also suppressed HIV-1 expression in U1 cells, significantly (p<0.05). In addition, one of the extracts (P. ciliatus) had anti-cancer potential with CC50 values <10 μg/ml. O. labiatum extract was purified to yield a chlorophyll derivative, pheophytin-a (phy-a); triterpene isomers (3-hydroxy-4,6a,6b,11,12,14b-hexamethyl- 1,2,3,4,6,6a,6b,7,8,8a,9,10,11,12,12a,14,14a,14b-octadecahydropicene-4,8adicarboxylic acid), amyrin and a labdane diterpenoid (labda-8(17),12E,14-triene-2R,18- diol). Phy-a inhibited HIV-1 PR with an IC50 value of 44.4 ±1.5 μg/ml. The triterpenes activated latent HIV-1 (a serious obstacle in the eradication of the virus) while the diterpenoid reduced the production of pro-inflammatory cytokines. These activities were observed at non-toxic concentrations of these compounds. There is an ongoing search for novel compounds that are able to activate latent HIV-1 to use in conjunction with HAART. If the triterpenes were to progress to clinical use, their use would be in activating latent virus for eradication by existing treatments. Conclusion: The findings presented in this thesis provide some scientific explanation for the anecdotal success of some Lamiaceae plants used traditionally to manage HIV/AIDS. The findings also conform to recommendations by the scientific community regarding the validation of the beneficial effects of plant products used traditionally. / Thesis (PhD)--University of Pretoria, 2013. / gm2014 / Biochemistry / unrestricted

The immune-reactive sperm are kept separate from the body by epithelial barriers such as the blood-testis barrier (BTB). While these barriers are beneficial for the protection of sperm from toxicants, they can make treating these areas difficult due to preventing the entry of pharmacological agents. This is especially an issue in the treatment of HIV and Ebola infection based on the ample evidence that these viruses are able to survive and spread from within the male genital tract (MGT), but only a few antiviral drugs are known to access the MGT. Transporters that line the epithelial barriers of the MGT, especially the BTB, are important for determining whether or not a drug is able to penetrate into the MGT through transepithelial transport. Several nucleoside analogs (NSA), which are used to treat HIV infection and leukemias, are known to be able to accumulate in seminal plasma, which makes them a useful tool for understanding transepithelial transport for the BTB. The purpose of these studies is to characterize the transport profile for the MGT, in particular the BTB, to gain a better understanding of how xenobiotics, especially ones based on nucleosides, can access the MGT. The chief finding of this work is the discovery of a transepithelial transport pathway expressed by Sertoli cells that allows for the entry of nucleosides (necessary for germ cell development) and NSA into the MGT. This pathway depends on equilibrative nucleoside transporter (ENT) 1 uptake and ENT2 efflux and occurs in both rats and humans. These studies provide the foundation for being able to predict the penetration of novel drugs into the MGT.

MPH / Department of Public Health / HIV/AIDS is an overwhelming global pandemic that affects the country’s health-care system. In order to reduce HIV/AIDS morbidity and mortality, the World Health Organization has called on countries to provide earlier access to antiretroviral therapy. In order to comply with the World Health Organization’s call, South Africa has developed the National Consolidated Guidelines, which were aimed at increasing access to ART as well as reducing new infections through viral suppression. Although the new guidelines have been implemented, they have not been fully implemented, especially in rural-based Primary Health Care facilities. The researcher observed that women who were pregnant were not tested every three months, as prescribed by the HIV/AIDS guidelines. The aim of this study was to investigate Challenges faced by health professionals regarding the implementation of HIV/AIDS guidelines at PHC facilities of Vhembe District, South Africa. This study adopted a qualitative, explorative, descriptive and contextual approach targeting nurses working at rural-based primary health care facilities at Vhembe District. Face-to face in-depth, Semistructured interviews were conducted, audiotaped and transcribed verbatim. The study used non-probability quota sampling method to identify participants until data saturation was reached with 12 participants. The results revealed that nurses faced some challenges when implementing HIV/AIDS guidelines, including shortages of resources, poor technical support, poor infrastructure, work overload, patients starting ART while there are not ready, shortage of ART, late booking of antenatal care, and mothers’ denial of HIV positive status, HIV positive babies, and poor RPC after birth. Ethical considerations were observed throughout the study. The data collected was analyzed using interpretative phenomenological analysis and all measures to ensure trustworthiness of the study findings were ensured. Some recommendations were made based on the findings of the study / NRF

Pullulan is a non-ionic water-soluble polysaccharide which is produced from starch by the yeast-like fungus Aureobasidium pullulans. Pullulan is known for its non-toxicity and biocompatibility. Most pullulan modifications are intended to reduce its water solubility or to introduce charged or reactive groups for functionality. Polysaccharides that have been hydrophobically modified and contain carboxyl groups are commonly used in drug delivery systems because of their ability to provide pH-controlled drug release. We demonstrated in this dissertation the regioselective synthesis of a range of 6-carboxypullulan ethers that are promising anionic derivatives for drug delivery applications. These compounds have also shown impressive surfactant properties. Another class of pullulan derivatives was synthesized by regioselective introduction of amine and amide groups to the pullulan backbone. These chemical groups are known to play a fundamental role in the biological activity of important polysaccharides, such as chitin and chitosan, therefore, the pullulan derivatives synthesized herein, which are structural isomers of those polymers, possess great potential for biomedical applications. Clarithromycin (CLA) is an aminomacrolide antibiotic whose physical properties are fascinating and challenging. It has very poor solubility at neutral intestinal pH, but much higher solubility under acidic conditions. Therefore, CLA dissolves better in the stomach than in the small intestine; but CLA is also quite labile towards acid-catalyzed degradation. We report herein a study on amorphous solid dispersion (ASD) of CLA with promising carboxyl-containing cellulose derivatives, both as macro and nanoparticles. This approach was intended to improve CLA solubility in neutral media, to protect it from acid degradation, and thereby increase its uptake from the small intestine and ultimately its bioavailability. We have also prepared ASDs of selected anti-HIV drugs, ritonavir (RTV), efavirenz (EFV) and etravirine (ETR) with the cellulosic derivative carboxymethyl cellulose acetate butyrate (CMCAB). This polymer was efficient in stabilizing RTV and EFV in their amorphous form in the solid phase and all ASDs provided significant enhancement of drug solution concentration. / Ph. D.

Cardiovascular disease (CVD) is the leading cause of death worldwide and is partially attributed to perturbations in lipid metabolism. Xenobiotics, such as pharmaceutical drugs and environmental chemicals, have been associated with increased risk of CVD in multiple large-scale human population studies, but the underlying mechanisms remain poorly defined. We and others have identified several xenobiotics as potent agonists for the pregnane X receptor (PXR), a nuclear receptor that can be activated by numerous drugs as well as environmental and dietary chemicals. However, the role of PXR in mediating the pathophysiological effects of xenobiotic exposure in humans and animals remains elusive. The work herein identified several widely used pharmaceutical agents and endocrine disrupting chemicals as PXR-selective agonists such as drugs involved in HIV therapy and phthalates/phthalate substitutes, respectively. We investigated the role of amprenavir, an HIV protease inhibitor, and tributyl citrate, a phthalate substitute, on PXR-dependent alterations in lipoprotein metabolism. Acute exposure with either xenobiotic in mice elicited increases in the proatherogenic LDL-cholesterol levels in a PXR-dependent manner. PXR activation significantly induced expression of genes involved in intestinal lipid metabolism. Further, we went on to identify the intestinal cholesterol transporter, Niemann-Pick C1-Like 1 (NPC1L1), as a direct PXR-target gene. PXR activation also stimulated cholesterol uptake in both murine and human intestinal cells. Moreover, we provide evidence that the microsomal triglyceride transfer protein (MTP) may be a direct PXR-target gene. Taken together, these findings provide critical mechanistic insight into the role of xenobiotic-mediated PXR activation on lipid homeostasis and demonstrate a potential role of PXR in mediating adverse effects of xenobiotics on CVD risk in humans. In addition to PXR signaling, we investigated the role of IκB kinase β (IKKβ), a central coordinator of inflammation, in adipocyte progenitor cells. Targeting IKKβ in adipose progenitor cells resulted in decreased high fat diet (HFD)-elicited adipogenesis, while protecting mice from inflammation and associated insulin resistance. Consistently, we discovered that IKKβ inhibition by antisense oligonucleotides ablated HFD-induced adiposity, while protecting mice against associated metabolic disorders. In conclusion, targeting IKKβ with antisense therapy may present as a novel therapeutic approach to combat obesity and metabolic dysfunctions.