Indian secondary school youths' understanding of sexual violence in their community in the age of HIV and AIDS: a participatory video approach
- Authors: Mahadev, Rekha
- Date: 2014
- Subjects: Sex crimes , Indian youth -- Education (Secondary) , AIDS (Disease) , HIV infections
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/7522 , vital:21793
- Description: This study focuses on Indian secondary school youths’ understanding of sexual violence in their community in the age of HIV and AIDS, and the contribution that participatory video can make to address sexual violence. South Africa, apart from having the highest HIV prevalence in the world, also has the highest incidence of sexual violence. South African society often appears complacent about the high levels of sexual violence. In the Indian community, especially among the youth, sexual violence is also cause for concern. Much effort and energy has been expended in educating learners about sexual violence and HIV and AIDS with the objective of raising awareness of the dangers of engaging in risky sexual behaviour, and ultimately to empower and influence positive behaviour change. Because HIV prevalence in the Indian population is on the rise, Indian youth’s particular vulnerability is the reason for focusing on how they understand sexual violence in the age of AIDS. Besides the paucity of research on Indian youth and sexual violence, the methodologies which have been used produced research which is descriptive in nature and hence a methodological shift from traditional methodologies to a participatory visual methodology which has the potential for critically engaging the Indian youth on the issues of sexual violence, could contribute to research which has a social change focus. This qualitative research therefore uses a visual participatory methodology within a critical research paradigm, to explore and contribute to addressing the problem of sexual violence in the age of HIV and AIDS. The participants in the study, a sample of 20 Indian learners (10 boys and 10 girls), from a secondary school in Durban which has predominantly Indian learners, was purposively selected from Grade 11 classes. Participatory video enabled them to voice how they understand sexual violence and in doing so move towards reflecting on their own agency. The theory of triadic influence with its three streams, i.e. cultural attitudinal, social normative and intrapersonal, was used to make meaning of the findings. It also provided a frame for a fourth path, namely the preventive intervene. While participatory video enabled exploring Indian youths’ understanding of sexual violence in their community in the age of AIDS, it at the same time enabled them to reflect on, and perhaps begin to disrupt their understanding of the cultural attitudinal, social normative and the intrapersonal influences and how these influence their thinking about sexual violence. Two a priori themes were established prior to the analysis, to respond to how Indian youths understand sexual violence in the age of AIDS, and how participatory video can address sexual violence. The findings suggest that their understanding of sexual violence stems from a culture of concealment in which veiling sexual violence is the norm; that the vulnerability of youth increases as the experience of pressure from peers to engage in sexual violence increases; and that sexual violence is traumatising. The use of participatory video increased the youths’ reflexivity and created a space for them to explore how to take action. The findings imply that addressing sexual violence with Indian youth should begin with interrogating the cultural norms of masculinities and femininities, and the cultural practices rooted in traditional structures of the family and community which perpetuate gender disparities and the restriction of the autonomy of women and girls. Addressing issues of vulnerability and sexual violence should be the focus of all school and community interventions to ensure learners’ well-being and ability to resist negative peer pressure. These interventions should encourage self-reflection and raise social awareness through active participation and in so doing bring about social change in the Indian community. Vigorous participatory interventions which draw on the voices of the Indian youth as agents of social change in addressing sexual violence in the age of HIV and AIDS, is therefore urgent. The significance of this study as research as intervention is useful in enabling the exploration - with the Indian youth - of how cultural and religious norms, gender disparity, Indian masculinities and femininities, and social peer pressure feed into youth’s understanding of sexual violence and at the same time getting them to begin rethinking, challenging and disrupting these understandings where necessary. The study demonstrates that engaging youth affords them an opportunity to draw from their own experiences and through their own voices and actions create knowledge through participatory video, thereby making a contribution to visual methodologies and research around sexual violence and HIV and AIDS in their world.
- Full Text:
- Date Issued: 2014
- Authors: Mahadev, Rekha
- Date: 2014
- Subjects: Sex crimes , Indian youth -- Education (Secondary) , AIDS (Disease) , HIV infections
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/7522 , vital:21793
- Description: This study focuses on Indian secondary school youths’ understanding of sexual violence in their community in the age of HIV and AIDS, and the contribution that participatory video can make to address sexual violence. South Africa, apart from having the highest HIV prevalence in the world, also has the highest incidence of sexual violence. South African society often appears complacent about the high levels of sexual violence. In the Indian community, especially among the youth, sexual violence is also cause for concern. Much effort and energy has been expended in educating learners about sexual violence and HIV and AIDS with the objective of raising awareness of the dangers of engaging in risky sexual behaviour, and ultimately to empower and influence positive behaviour change. Because HIV prevalence in the Indian population is on the rise, Indian youth’s particular vulnerability is the reason for focusing on how they understand sexual violence in the age of AIDS. Besides the paucity of research on Indian youth and sexual violence, the methodologies which have been used produced research which is descriptive in nature and hence a methodological shift from traditional methodologies to a participatory visual methodology which has the potential for critically engaging the Indian youth on the issues of sexual violence, could contribute to research which has a social change focus. This qualitative research therefore uses a visual participatory methodology within a critical research paradigm, to explore and contribute to addressing the problem of sexual violence in the age of HIV and AIDS. The participants in the study, a sample of 20 Indian learners (10 boys and 10 girls), from a secondary school in Durban which has predominantly Indian learners, was purposively selected from Grade 11 classes. Participatory video enabled them to voice how they understand sexual violence and in doing so move towards reflecting on their own agency. The theory of triadic influence with its three streams, i.e. cultural attitudinal, social normative and intrapersonal, was used to make meaning of the findings. It also provided a frame for a fourth path, namely the preventive intervene. While participatory video enabled exploring Indian youths’ understanding of sexual violence in their community in the age of AIDS, it at the same time enabled them to reflect on, and perhaps begin to disrupt their understanding of the cultural attitudinal, social normative and the intrapersonal influences and how these influence their thinking about sexual violence. Two a priori themes were established prior to the analysis, to respond to how Indian youths understand sexual violence in the age of AIDS, and how participatory video can address sexual violence. The findings suggest that their understanding of sexual violence stems from a culture of concealment in which veiling sexual violence is the norm; that the vulnerability of youth increases as the experience of pressure from peers to engage in sexual violence increases; and that sexual violence is traumatising. The use of participatory video increased the youths’ reflexivity and created a space for them to explore how to take action. The findings imply that addressing sexual violence with Indian youth should begin with interrogating the cultural norms of masculinities and femininities, and the cultural practices rooted in traditional structures of the family and community which perpetuate gender disparities and the restriction of the autonomy of women and girls. Addressing issues of vulnerability and sexual violence should be the focus of all school and community interventions to ensure learners’ well-being and ability to resist negative peer pressure. These interventions should encourage self-reflection and raise social awareness through active participation and in so doing bring about social change in the Indian community. Vigorous participatory interventions which draw on the voices of the Indian youth as agents of social change in addressing sexual violence in the age of HIV and AIDS, is therefore urgent. The significance of this study as research as intervention is useful in enabling the exploration - with the Indian youth - of how cultural and religious norms, gender disparity, Indian masculinities and femininities, and social peer pressure feed into youth’s understanding of sexual violence and at the same time getting them to begin rethinking, challenging and disrupting these understandings where necessary. The study demonstrates that engaging youth affords them an opportunity to draw from their own experiences and through their own voices and actions create knowledge through participatory video, thereby making a contribution to visual methodologies and research around sexual violence and HIV and AIDS in their world.
- Full Text:
- Date Issued: 2014
The effectiveness of social support mechanisms provided to HIV and AIDS opharns: the case of Tembisa child and family welfare society, Gauteng
- Authors: Khumalo, Princess Sengeziwe
- Date: 2013
- Subjects: Child welfare -- South Africa -- Gauteng -- Case studies , HIV infections -- South Africa -- Gauteng , Children of AIDS patients -- Services for South Africa -- Gauteng , AIDS (Disease)
- Language: English
- Type: Thesis , Masters , M SW
- Identifier: vital:11761 , http://hdl.handle.net/10353/d1005633 , Child welfare -- South Africa -- Gauteng -- Case studies , HIV infections -- South Africa -- Gauteng , Children of AIDS patients -- Services for South Africa -- Gauteng , AIDS (Disease)
- Description: The study was aimed at investigating the effectiveness of social support mechanisms provided to HIV and AIDS orphans in Tembisa, Gauteng Province. An interview guide was designed and it guided the in-depth interviews with HIV and AIDS affected and infected orphans. In addition, a focus group was run with the social workers and the children‟s caregivers. Empirical findings gathered were based on the qualitative information from the participants. The findings indicated that social support systems were effective although there were various challenges facing their smooth running. Firstly social support provided to orphans is mainly provided by caregivers, social workers, schools and the government. Secondly for some, the support is not entirely enough to help them cope with life. The minority of the orphans indicated that they were not even aware that they were orphaned. The study therefore recommends that social workers and caregivers be trained on how to be effective social support systems for HIV and AIDS orphans. Furthermore psycho-social support groups need to be more informational and inclusive of HIV and AIDS orphans.
- Full Text:
- Date Issued: 2013
- Authors: Khumalo, Princess Sengeziwe
- Date: 2013
- Subjects: Child welfare -- South Africa -- Gauteng -- Case studies , HIV infections -- South Africa -- Gauteng , Children of AIDS patients -- Services for South Africa -- Gauteng , AIDS (Disease)
- Language: English
- Type: Thesis , Masters , M SW
- Identifier: vital:11761 , http://hdl.handle.net/10353/d1005633 , Child welfare -- South Africa -- Gauteng -- Case studies , HIV infections -- South Africa -- Gauteng , Children of AIDS patients -- Services for South Africa -- Gauteng , AIDS (Disease)
- Description: The study was aimed at investigating the effectiveness of social support mechanisms provided to HIV and AIDS orphans in Tembisa, Gauteng Province. An interview guide was designed and it guided the in-depth interviews with HIV and AIDS affected and infected orphans. In addition, a focus group was run with the social workers and the children‟s caregivers. Empirical findings gathered were based on the qualitative information from the participants. The findings indicated that social support systems were effective although there were various challenges facing their smooth running. Firstly social support provided to orphans is mainly provided by caregivers, social workers, schools and the government. Secondly for some, the support is not entirely enough to help them cope with life. The minority of the orphans indicated that they were not even aware that they were orphaned. The study therefore recommends that social workers and caregivers be trained on how to be effective social support systems for HIV and AIDS orphans. Furthermore psycho-social support groups need to be more informational and inclusive of HIV and AIDS orphans.
- Full Text:
- Date Issued: 2013
Factors influencing university students' use of HIV voluntary counselling and testing services : an analysis using the health belief model
- Authors: Musemwa, Shingisai
- Date: 2011
- Subjects: Health Belief Model , AIDS (Disease) , College students
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9867 , http://hdl.handle.net/10948/1448 , Health Belief Model , AIDS (Disease) , College students
- Description: Human Immune Virus (HI)V /Acquired Immune Deficiency Syndrome (AIDS) has emerged as the most devastating epidemic that the world has experienced. Voluntary counselling and testing (VCT) has proven to be an effective way of preventing and controlling HIV. South African universities provide free VCT services on their campuses; however, these facilities are underused. The study’s objectives were to use the components of the health belief model (HBM) to explore and describe the factors that influenced the decision made by university students who have gone for VCT. The sample consisted of five male students. Data was collected through one-on-one in depth interviews, which were recorded. Data was analysed using thematic analysis, and the components of the HBM were used as codes for the data. Themes were generated for each component. The results indicated that perceived severity, perceived benefits and cues to action played a role in influencing the participants’ decision to go for VCT. In addition, results show that perceived susceptibility had little influence on their decision to go for VCT. Even though participants acknowledged barriers to VCT, they reported that the perceived benefits for VCT outweighed the barriers, and the decision to go for VCT was made. Participants suggested that to increase uptake of VCT on their campus, the university could improve current VCT campaigns, introduce rewards for VCT and introduce couples VCT.
- Full Text:
- Date Issued: 2011
- Authors: Musemwa, Shingisai
- Date: 2011
- Subjects: Health Belief Model , AIDS (Disease) , College students
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9867 , http://hdl.handle.net/10948/1448 , Health Belief Model , AIDS (Disease) , College students
- Description: Human Immune Virus (HI)V /Acquired Immune Deficiency Syndrome (AIDS) has emerged as the most devastating epidemic that the world has experienced. Voluntary counselling and testing (VCT) has proven to be an effective way of preventing and controlling HIV. South African universities provide free VCT services on their campuses; however, these facilities are underused. The study’s objectives were to use the components of the health belief model (HBM) to explore and describe the factors that influenced the decision made by university students who have gone for VCT. The sample consisted of five male students. Data was collected through one-on-one in depth interviews, which were recorded. Data was analysed using thematic analysis, and the components of the HBM were used as codes for the data. Themes were generated for each component. The results indicated that perceived severity, perceived benefits and cues to action played a role in influencing the participants’ decision to go for VCT. In addition, results show that perceived susceptibility had little influence on their decision to go for VCT. Even though participants acknowledged barriers to VCT, they reported that the perceived benefits for VCT outweighed the barriers, and the decision to go for VCT was made. Participants suggested that to increase uptake of VCT on their campus, the university could improve current VCT campaigns, introduce rewards for VCT and introduce couples VCT.
- Full Text:
- Date Issued: 2011
Prevalence of Escherichia coli O157:H7 in water and meat and meat products and vegetables sold in the Eastern Cape Province of South Africa and its impact on the diarrhoeic conditions of HIV/AIDS patients
- Authors: Abong'o, Benard Omondi
- Date: 2008
- Subjects: Foodborne diseases , Diarrhea , Escherichia coli , HIV infections , AIDS (Disease) , Bacterial diseases
- Language: English
- Type: Thesis , Doctoral , PhD (Microbiology)
- Identifier: vital:11263 , http://hdl.handle.net/10353/87 , Foodborne diseases , Diarrhea , Escherichia coli , HIV infections , AIDS (Disease) , Bacterial diseases
- Description: Water and food borne Escherichia coli O157:H7 could be one of the pathogens posing high health risk to patients suffering from Acquired Immunodeficiency Syndrome (AIDS) because of its incrimination in diarrhoea cases in AIDS patients. The present study, which was conducted between March 2005 and August 2006, investigated the prevalence of E. coli O157:H7 in water, meat and meat products and vegetables and its impact on diarrhoeic conditions of confirmed and non-confirmed HIV/AIDS patients in the Amathole District in the Eastern Cape Province of South Africa. The water samples used in the study were obtained from stand pipes supplying treated drinking water to communities residing in Fort Beaufort, Alice, Dimbaza and Mdantsane whereas borehole waters were sampled from Ngwenya and Kwasaki. The meat and meat products and vegetable samples were purchased from shops, butcheries, supermarkets and open air markets in Fort Beaufort, Alice and Mdantsane. The stool swabs used in the study were obtained from HIV/AIDS and outpatient clinics at Frere Hospital in East London. A total of 180 each of water, meat and meat products and vegetable samples and another 360 stool samples were analyzed for E. coli O157:H7. Presumptive E. coli O157 was isolated from the samples by culture-based methods and confirmed using Polymerase Chain Reaction techniques. Anti-biogram as well as risk assessment were also carried out using standard methods. The viable counts of presumptive E. coli O157 for water samples ranged between 3.3 × 104 and 1.71 × 105 CFU/ml, and between 1.8 × 104 and 5.04 × 106 CFU/g for meat and meat products, whereas those for vegetables ranged between 1.3 × 103 and 1.6 × 106 CFU/g. The counts of presumptive E. coli O157 for the water and vegetable samples were not significantly different whereas those for meat and meat products were found to be significantly different (P ≤ 0.05). The prevalence rates of presumptive E coli O157 in meat and meat products was 35.55 percent (64/180), and 25.55 percent (46/180) and 21.66 percent (39/180) for water and vegetables respectively. Prevalence of presumptive E. coli O157 in the stool samples of HIV/AIDS patients was 36.39 percent (131/360), of which 56.5 percent (74/131) and 43.5 percent (57/131) were from stools of confirmed and non-confirmed HIV/AIDS patients, respectively. Molecular analysis of representative presumptive E. coli O157 indicated that 10.29 percent (4/39) of vegetables; 14.81 percent (4/27) of water and 38.46 percent (5/13) of meat and meat products carried E. coli O157:H7. Also 36 percent (9/25) and 17.24 percent (5/29) of the stool samples were positive for E. coli O157:H7. Antimicrobial susceptibility profile revealed that all of the E. coli O157:H7 isolated from water, meat and meat products and vegetables as well as those isolated from stools of confirmed and non-confirmed HIV/AIDS patients were resistant (R) to gentamycin and erythromycin. However, 75 percent (20/27) of these isolates were resistant (R) to ampicillin and tetracycline whereas approximately 25 percent (6/27) were resistant (R) to nalidixic acid, ceftriaxone, and chloramphenicol. All the isolates (27/27) were susceptible (S) to amikacin. Probability of risk of E. coli O157:H7 infection was high for confirmed HIV/AIDS patients than for the non-confirmed HIV/AIDS patients. Estimated probability of risk of E. coli O157:H7 due to ingestion of water was 1.00 for 100 confirmed and non-confirmed HIV/AIDS patients. Risk due to meat and meat products was estimated at 0.27 and 0.20 and for vegetables at 0.21 and 0.15 per 100 confirmed and non-confirmed HIV/AIDS patients. The findings of this study predicted a possible link between E. coli O157:H7 isolated from drinking water, meat and meat products and vegetables and diarrhoeic conditions in both confirmed and non-confirmed HIV/AIDS patients, and concludes that confirmed HIV/AIDS patients can be at higher risk of contracting water and food borne E. coli O157:H7 than nonconfirmed HIV/AIDS patients. It is thus recommended that proper water treatment and food handling, maximum food and water safety and sanitation as well as personal body hygiene should be maintained, in order to prevent E. coli O157:H7 infections. Education initiatives and active surveillance of E. coli O157:H7 should be taken by all the stake-holders working directly or indirectly towards ensuring enduring sound public health.
- Full Text:
- Date Issued: 2008
- Authors: Abong'o, Benard Omondi
- Date: 2008
- Subjects: Foodborne diseases , Diarrhea , Escherichia coli , HIV infections , AIDS (Disease) , Bacterial diseases
- Language: English
- Type: Thesis , Doctoral , PhD (Microbiology)
- Identifier: vital:11263 , http://hdl.handle.net/10353/87 , Foodborne diseases , Diarrhea , Escherichia coli , HIV infections , AIDS (Disease) , Bacterial diseases
- Description: Water and food borne Escherichia coli O157:H7 could be one of the pathogens posing high health risk to patients suffering from Acquired Immunodeficiency Syndrome (AIDS) because of its incrimination in diarrhoea cases in AIDS patients. The present study, which was conducted between March 2005 and August 2006, investigated the prevalence of E. coli O157:H7 in water, meat and meat products and vegetables and its impact on diarrhoeic conditions of confirmed and non-confirmed HIV/AIDS patients in the Amathole District in the Eastern Cape Province of South Africa. The water samples used in the study were obtained from stand pipes supplying treated drinking water to communities residing in Fort Beaufort, Alice, Dimbaza and Mdantsane whereas borehole waters were sampled from Ngwenya and Kwasaki. The meat and meat products and vegetable samples were purchased from shops, butcheries, supermarkets and open air markets in Fort Beaufort, Alice and Mdantsane. The stool swabs used in the study were obtained from HIV/AIDS and outpatient clinics at Frere Hospital in East London. A total of 180 each of water, meat and meat products and vegetable samples and another 360 stool samples were analyzed for E. coli O157:H7. Presumptive E. coli O157 was isolated from the samples by culture-based methods and confirmed using Polymerase Chain Reaction techniques. Anti-biogram as well as risk assessment were also carried out using standard methods. The viable counts of presumptive E. coli O157 for water samples ranged between 3.3 × 104 and 1.71 × 105 CFU/ml, and between 1.8 × 104 and 5.04 × 106 CFU/g for meat and meat products, whereas those for vegetables ranged between 1.3 × 103 and 1.6 × 106 CFU/g. The counts of presumptive E. coli O157 for the water and vegetable samples were not significantly different whereas those for meat and meat products were found to be significantly different (P ≤ 0.05). The prevalence rates of presumptive E coli O157 in meat and meat products was 35.55 percent (64/180), and 25.55 percent (46/180) and 21.66 percent (39/180) for water and vegetables respectively. Prevalence of presumptive E. coli O157 in the stool samples of HIV/AIDS patients was 36.39 percent (131/360), of which 56.5 percent (74/131) and 43.5 percent (57/131) were from stools of confirmed and non-confirmed HIV/AIDS patients, respectively. Molecular analysis of representative presumptive E. coli O157 indicated that 10.29 percent (4/39) of vegetables; 14.81 percent (4/27) of water and 38.46 percent (5/13) of meat and meat products carried E. coli O157:H7. Also 36 percent (9/25) and 17.24 percent (5/29) of the stool samples were positive for E. coli O157:H7. Antimicrobial susceptibility profile revealed that all of the E. coli O157:H7 isolated from water, meat and meat products and vegetables as well as those isolated from stools of confirmed and non-confirmed HIV/AIDS patients were resistant (R) to gentamycin and erythromycin. However, 75 percent (20/27) of these isolates were resistant (R) to ampicillin and tetracycline whereas approximately 25 percent (6/27) were resistant (R) to nalidixic acid, ceftriaxone, and chloramphenicol. All the isolates (27/27) were susceptible (S) to amikacin. Probability of risk of E. coli O157:H7 infection was high for confirmed HIV/AIDS patients than for the non-confirmed HIV/AIDS patients. Estimated probability of risk of E. coli O157:H7 due to ingestion of water was 1.00 for 100 confirmed and non-confirmed HIV/AIDS patients. Risk due to meat and meat products was estimated at 0.27 and 0.20 and for vegetables at 0.21 and 0.15 per 100 confirmed and non-confirmed HIV/AIDS patients. The findings of this study predicted a possible link between E. coli O157:H7 isolated from drinking water, meat and meat products and vegetables and diarrhoeic conditions in both confirmed and non-confirmed HIV/AIDS patients, and concludes that confirmed HIV/AIDS patients can be at higher risk of contracting water and food borne E. coli O157:H7 than nonconfirmed HIV/AIDS patients. It is thus recommended that proper water treatment and food handling, maximum food and water safety and sanitation as well as personal body hygiene should be maintained, in order to prevent E. coli O157:H7 infections. Education initiatives and active surveillance of E. coli O157:H7 should be taken by all the stake-holders working directly or indirectly towards ensuring enduring sound public health.
- Full Text:
- Date Issued: 2008
Studies directed towards the synthesis of chromone carbaldehyde-derived HIV-1 protease inhibitors
- Authors: Molefe, Duduzile Mabel
- Date: 2008
- Subjects: Protease Inhibitors , HIV infections , HIV (Viruses) , AIDS (Disease) , Proteolytic enzymes , Heterocyclic compounds -- Derivatives , Chemical kinetics , Nuclear magnetic resonance spectroscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4526 , http://hdl.handle.net/10962/d1015542
- Description: A series of chromone-3-carbaldehydes have been prepared using Vilsmeier-Haack methodology while a corresponding series of chromone-2-carbaldeydes have been synthesized via the Kostanecki-Robinson reaction. Baylis-Hillman reactions have been conducted on both series of chromone carbaldehydes using three different catalysts, viz., 1,4-diazabicyclo(2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]undec- 7-ene (DBU) and 3-hydroxyquinuclidine (3HQ), and acrylonitrile, methyl acrylate and methyl vinyl ketone as the activated alkenes. These reactions have typically (but not always!) afforded both normal Baylis-Hillman and dimeric products. Attention has also been given to the use of 1-methyl-2-pyrrolidine (1-NMP), an ionic liquid, to replace normal organic solvents, and it has been found that, in the presence of DABCO, chromone-3-carbaldehydes afford the dimeric products alone. Reactions of chromone-3-carbaldehydes with methyl vinyl ketone have yielded unexpected, novel adducts, which appear to arise from preferential attack at C(2) in the chromone nucleus. Research on chromone-2-carbaldeydes under Baylis-Hillman conditions has also resulted in the formation of some interesting products instead of the expected Baylis-Hillman adducts. The Baylis-Hillman products have been explored as substrates for aza-Michael reactions using various amino derivatives including protected amino acids in the presence of the tetrabutylammonium bromide (TBAB) and the ionic liquid, 3-butyl-1- methylimidazoleboranetetrafluoride (BmimBF₄), as catalysts. The aza-Michael products have been targeted as truncated ritonavir analogues for investigation as potential HIV -1 protease inhibitors, and representative compounds have been subjected to enzyme inhibition assays to explore the extent and type of inhibition. Lineweaver-Burk and Dixon plots have indicated competitive inhibition in one case as well as non-competitive inhibition in another, and the inhibition constants (Ki) have been compared with that of the ritonavir. Computer modelling studies have also been conducted on selected chromonecontaining derivatives, using the ACCELRYS Cerius² platform. Interactive docking of the chromone-containing ligands into the HIV -1 protease receptor site, using the Ligandfit module, has indicated the importance of hydrogen-bonding interactions mediated by bridging water molecules situated in the receptor cavity. NMR spectroscopy has been used to elucidate complex and competing mechanistic pathways involved in the Baylis-Hillman reactions of selected 2-nitrobenzaldehydes with MVK in the presence of DABCO - reactions which afford the normal BaylisHillman product, the MVK dimer and syn- and anti-Baylis-Hillman type diadducts. The kinetic data confirm the concomitant operation of two pathways and reveal that, in the initial stage of the reaction, the product distribution is kinetically controlled, whereas in the latter stage, thermodynamic control results in the consumption of the normal Baylis-Hillman product and predominance of the anti-diadduct.
- Full Text:
- Date Issued: 2008
- Authors: Molefe, Duduzile Mabel
- Date: 2008
- Subjects: Protease Inhibitors , HIV infections , HIV (Viruses) , AIDS (Disease) , Proteolytic enzymes , Heterocyclic compounds -- Derivatives , Chemical kinetics , Nuclear magnetic resonance spectroscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4526 , http://hdl.handle.net/10962/d1015542
- Description: A series of chromone-3-carbaldehydes have been prepared using Vilsmeier-Haack methodology while a corresponding series of chromone-2-carbaldeydes have been synthesized via the Kostanecki-Robinson reaction. Baylis-Hillman reactions have been conducted on both series of chromone carbaldehydes using three different catalysts, viz., 1,4-diazabicyclo(2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]undec- 7-ene (DBU) and 3-hydroxyquinuclidine (3HQ), and acrylonitrile, methyl acrylate and methyl vinyl ketone as the activated alkenes. These reactions have typically (but not always!) afforded both normal Baylis-Hillman and dimeric products. Attention has also been given to the use of 1-methyl-2-pyrrolidine (1-NMP), an ionic liquid, to replace normal organic solvents, and it has been found that, in the presence of DABCO, chromone-3-carbaldehydes afford the dimeric products alone. Reactions of chromone-3-carbaldehydes with methyl vinyl ketone have yielded unexpected, novel adducts, which appear to arise from preferential attack at C(2) in the chromone nucleus. Research on chromone-2-carbaldeydes under Baylis-Hillman conditions has also resulted in the formation of some interesting products instead of the expected Baylis-Hillman adducts. The Baylis-Hillman products have been explored as substrates for aza-Michael reactions using various amino derivatives including protected amino acids in the presence of the tetrabutylammonium bromide (TBAB) and the ionic liquid, 3-butyl-1- methylimidazoleboranetetrafluoride (BmimBF₄), as catalysts. The aza-Michael products have been targeted as truncated ritonavir analogues for investigation as potential HIV -1 protease inhibitors, and representative compounds have been subjected to enzyme inhibition assays to explore the extent and type of inhibition. Lineweaver-Burk and Dixon plots have indicated competitive inhibition in one case as well as non-competitive inhibition in another, and the inhibition constants (Ki) have been compared with that of the ritonavir. Computer modelling studies have also been conducted on selected chromonecontaining derivatives, using the ACCELRYS Cerius² platform. Interactive docking of the chromone-containing ligands into the HIV -1 protease receptor site, using the Ligandfit module, has indicated the importance of hydrogen-bonding interactions mediated by bridging water molecules situated in the receptor cavity. NMR spectroscopy has been used to elucidate complex and competing mechanistic pathways involved in the Baylis-Hillman reactions of selected 2-nitrobenzaldehydes with MVK in the presence of DABCO - reactions which afford the normal BaylisHillman product, the MVK dimer and syn- and anti-Baylis-Hillman type diadducts. The kinetic data confirm the concomitant operation of two pathways and reveal that, in the initial stage of the reaction, the product distribution is kinetically controlled, whereas in the latter stage, thermodynamic control results in the consumption of the normal Baylis-Hillman product and predominance of the anti-diadduct.
- Full Text:
- Date Issued: 2008
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