UWCScholar :: Browsing by Author "Joubert, Jacques"

Browsing by Author "Joubert, Jacques"

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Additional regulatory review pathways can facilitate faster dossier approvals in South Africa
(University of the Western Cape, 2019) Mattew, Ilona; Joubert, Jacques
The objective of the study was to perform a comparative review of pathways, timelines and improvements of countries with markets that the South African Health Products Authority (SAHPRA) benchmark themselves against. Furthermore, this study intends to identify the factors that improved and accelerated submissions and approval process in investigated countries and potential introduction of these strategies into the South African market.
Antimycobacterial Activity, Synergism, and Mechanism of Action Evaluation of Novel Polycyclic Amines against Mycobacterium tuberculosis
(Advances in Pharmacological and Pharmaceutical Sciences, 2021-06) Kapp, Erika; Joubert, Jacques; Sampson, Samantha, L; Malan, Sarel, F; Sharma, Rajan; Warner, Digby, F; Seldon, Ronnett; Jordaan, Audrey; de Vos, Margaretha
Mycobacterium tuberculosis has developed extensive resistance to numerous antimycobacterial agents used in the treatment of tuberculosis. Insufficient intracellular accumulation of active moieties allows for selective survival of mycobacteria with drug resistance mutations and accordingly promotes the development of microbial drug resistance. Discovery of compounds with new mechanisms of action and physicochemical properties that promote intracellular accumulation, or compounds that act synergistically with other antimycobacterial drugs, has the potential to reduce and prevent further drug resistance. To this end, antimycobacterial activity, mechanism of action, and synergism in combination therapy were investigated for a series of polycyclic amine derivatives. Compound selection was based on the presence of moieties with possible antimycobacterial activity, the inclusion of bulky lipophilic carriers to promote intracellular accumulation, and previously demonstrated bioactivity that potentially support inhibition of efflux pump activity. The most potent antimycobacterial demonstrated a minimum inhibitory concentration (MIC99) of 9.6 μM against Mycobacterium tuberculosis H37Rv. Genotoxicity and inhibition of the cytochrome bc1 respiratory complex were excluded as mechanisms of action for all compounds. Inhibition of cell wall synthesis was identified as a likely mechanism of action for the two most active compounds (14 and 15). Compounds 5 and 6 demonstrated synergistic activity with the known Rv1258c efflux pump substrate, spectinomycin, pointing to possible efflux pump inhibition. For this series, the nature of the side chain, rather than the type of polycyclic carrier, seems to play a determining role in the antimycobacterial activity and cytotoxicity of the compounds. Contrariwise, the nature of the polycyclic carrier, particularly the azapentacycloundecane cage, appears to promote synergistic activity. Results point to the possibility of combining an azapentacycloundecane carrier with a side chain that promotes antimycobacterial activity to develop dual acting molecules for the treatment of Mycobacterium tuberculosis.
Chalcone and curcumin hybrids of indole propargylamines as multifunctional neuroprotective agents
(University of the Western Cape, 2020) Musakwa, Lovetone; Joubert, Jacques; Malan, Sarel
Neurodegenerative disorders (NDs) are a range of chronic brain disorders that includes amongst others motor function loss. Parkinson’s disease (PD) is one of the common NDs that has an insidious onset and diagnosed when dopaminergic neurons in the substantia nigra are already lost. The loss creates a deficiency of the dopamine (neurotransmitter) thereby causing neurochemical imbalance resulting in the signs and symptoms of PD. NDs overlap at multiple levels so some of the symptoms overlap as well. NDs currently have no cure yet and current drug therapies only improve the quality of life of the patients by targeting the symptoms mainly. Treatment of PD currently involves different classes of drugs and depending on the stages of the disease, some drugs can be only used as an adjunct therapy. Anti-oxidants and monoamine oxidase inhibitors (MAO-I) are part of the treatment options.
Common defciencies found in generic Finished Pharmaceutical Product (FPP) applications submitted for registration to the South African Health Products Regulatory Authority (SAHPRA)
(Springer Nature, 2022) Moeti, Lerato; Litedu, Madira; Joubert, Jacques
The aim of the study was to investigate the common defciencies observed in the Finished Pharmaceutical Product (FPP) section of generic product applications submitted to SAHPRA. The study was conducted retrospectively over a 7-year period (2011–2017) for products that were fnalised by the Pharmaceutical and Analytical pre-registration Unit.There were 3148 fnalised products in 2011–2017, 667 of which were sterile while 2089 were non-sterile. In order to attain a representative sample for the study, statistical sampling was conducted. Sample size was obtained using the statistical tables found in literature and confrmed by a sample size calculation with a 95% confdence level. The selection of the products was according to the therapeutic category using the multi-stage sampling method called stratifed-systematic sampling. This resulted in the selection of 325 applications for non-sterile products and 244 applications for sterile products. Subsequently, all the defciencies were collected and categorised according to Common Technical Document (CTD) subsections of the FPP section (3.2.P).
Common Deficiencies Found in the Active Pharmaceutical Ingredient (API) Section of Non-sterile Generic Products Submitted for Registration by SAHPRA
(Springer Science and Business Media Deutschland GmbH, 2023) Moeti, Lerato; Joubert, Jacques
Purpose: This research study aims to determine the qualitative and quantitative common deficiencies included in the API section of dossiers submitted to SAHPRA. The study was conducted retrospectively over a 7-year period (2011–2017) for non-sterile generic products that were finalised by the Pharmaceutical and Analytical pre-registration Unit. In this period, the restricted part of the CTD was evaluated when needed therefore this was not conducted on all applications. The requirement to evaluate the restricted part for all applications was initiated in January 2020, thus, a separate study has been conducted to identify the common deficiencies in the restricted part. Methods: There were 2089 applications finalised between 2011 and 2017 and in order to attain a representative sample for the study, the multi-stage statistical sampling called the ‘stratified systematic sampling’ was selected as the method of choice. Sample size was obtained using the statistical tables found in the literature and confirmed by a sample size calculation with a 95% confidence level, resulting in the selection of 325 applications. Subsequently, all the deficiencies were collected and categorised according to CTD subsections. For the restricted part study, all new applications evaluated between January to May 2020 were used. Results: A total of 1130 deficiencies were collected from 325 applications sampled. The majority of the identified deficiencies were from Module 3.2.S.3.1 (19.38%) on characterisation, Module 3.2.S.1.3 (19.11%) on general properties, Module 3.2.S.4.1 (10.44%) on specifications and Module 3.2.S.4.3 (8.32%) on validation of analytical methods. The study on the restricted parts included the five most common deficiencies that SAHPRA has identified, which are similar to those observed from the 2011–2017 applications. This confirms that the quality of the evaluations has been maintained over the years. Comparison of the deficiencies with those reported by other agencies such as the USFDA, EMA, WHOPQTm and TFDA are discussed with similarities clearly outlined. Conclusions: The most common deficiencies observed by SAHPRA were extensively discussed. These findings could serve as a guidance for API manufacturers to submit better quality APIMFs which will improve turnaround times for registration and accelerate access to medicines for patients. © 2021, The Drug Information Association, Inc.
Crystal structure, Hirshfeld surface analysis and DFT studies of 5-(adamantan-1-yl)-3-[(4- chlorobenzyl)sulfanyl]-4-methyl4H-1,2,4-triazole, a potential 11βHSD1 inhibitor
(Scientific Reports, 2019) Joubert, Jacques; Al-Wahaibi, Lamya; Blacque, Olivier
5-(Adamantan-1-yl)-3-[(4-chlorobenzyl)sulfanyl]-4-methyl-4H-1,2,4-triazole (4) was identifed as a potential 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) inhibitor and this paper describes the in-depth structural analysis thereof. Compound 4 was synthesized in a 92% yield and its 3D-structure confrmed by single-crystal X-ray difraction. Hirshfeld surface analysis indicated that H…H, C-H…C, C-H…Cl and especially C-H…N hydrogen bond interactions are the primary contributors to the intermolecular stabilisation in the crystal. In order to explore the properties of 4, free from the infuence of the crystal feld, density functional theory (DFT) calculations were conducted. Results indicated that the DFT optimized geometry of 4 produced a conformer (4a) that is signifcantly diferent from the crystal structure. Further experiments confrmed that the crystal structure is not the absolute minimum conformation. This indicated that the crystal packing forces has signifcantly infuenced the conformation thereof. Frontier molecular orbital energies and net atomic charges were also calculated to elucidate the electronic properties of 4a. These results provided insight into areas of the molecule that may present with the ability to form binding interactions at the 11β-HSD1 active site. Molecular docking experiments revealed important intermolecular interactions between 4a and 11β-HSD1. These results indicate that 4 may be considered for further drug design endeavors.
Crystal structure, hirshfeld surface analysis and dft studies of 5-(adamantan-1-yl)-3-[(4-chlorobenzyl)sulfanyl]-4-methyl-4h-1,2,4-triazole, a potential 11β-hsd1 inhibitor
(Scientific Reports, 2019) Joubert, Jacques
5-(Adamantan-1-yl)-3-[(4-chlorobenzyl)sulfanyl]-4-methyl-4H-1,2,4-triazole (4) was identified as a potential 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) inhibitor and this paper describes the in-depth structural analysis thereof. Compound 4 was synthesized in a 92% yield and its 3D-structure confirmed by single-crystal X-ray diffraction.
Discovery of 9-phenylacridinediones as highly selective butyrylcholinesterase inhibitors through structure-based virtual screening
(Elsevier, 2020) Joubert, Jacques; Kapp, Erika
Butyrylcholinesterase (BuChE) is considered a promising drug target as it plays an important role in the pro-gression of late stage Alzheimer’s disease (AD). Two compound libraries were selected and 64 124 aminecontaining moieties were screened using a hierarchical virtual screening protocol to discover new selectiveBuChE inhibitors. From these and subsequent docking experiments, 9-phenylacridinedione (9-PAD) was iden-tified as a promising scaffold for selective inhibition of BuChE. Selected top dock scored 9-PADs were assayedand compounds3and6exhibited potent and highly selective human BuChE inhibition (IC50: 98 nM and 142 nM,respectively). Both molecules were also predicted to show sufficient brain permeability, not have any substantialtoxicities, especially hepatotoxicity, and no significantinvitrocytotoxicity against SH-SY5Y neuroblastoma cellsat concentrations up to 100 μM. These findings indicate that 9-PAD is a promising lead structure for the de-velopment of agents able to treat late stage AD.
Discovery of heat shock protein90 inhibitors using structured-based virtual screening
(University of the Western Cape, 2023) Ngcagawule, Siyasanga; Joubert, Jacques
Alzheimer's disease (AD) is the most common irreversible dementia, caused by accumulation of protein aggregates in the central nervous system, with symptoms that include memory loss and behavioural abnormalities. Cholinesterase inhibitors (ChEIs) and N-methyl-D-aspartate receptor (NMDAR) antagonists are current treatment options for mild to moderate AD. These agents are not used to cure the illness, but rather as symptomatic therapy. Heat Shock Protein (HSP90), is one of the molecular chaperones that plays a role in AD pathogenesis. HSP90’s main function is to regulate the heat shock factor-1 (HSF-1) transcription factor, which is the key regulator of the heat shock response. Inhibition of HSP90 activates HSF-1 and the subsequent induction of heat shock proteins such as HSP70, HSP40 and HSP27. Such protein assist the folding of newly synthesized or misfolded proteins, preventing their aggregation. Therefore, HSP90 inhibitors protect against protein toxicity and reduces brain aggregate to form in AD. The HSP90 protein crystal structure (PDB ID; 2bz5) was used to dock a diverse structural database of about 12 000 amine containing compounds from the Maybridge Screening Collection using Fast Rigid Exhaustive Docking (FRED). The top five hundred-docked compounds were viewed using Visualization & Communication of Modeling Results (VIDA), and the top 50 compounds were analysed for important binding interactions and low Chemgausse4 scores. Ten of these compounds were selected based on their interaction profile with the desired HSP90 active site amino acids. Thereafter, the ten MayBridge compounds were drawn on Sigma-Aldrich and searched for structures that show at least 70% similarity, to the selected MayBridge compounds.
The implementation of a risk based assessment approach by the South African Health pProducts Regulatory Authority (SAHPRA)
(Springer, 2023) Moeti, Lerato; Litedu, Madira; Joubert, Jacques
An extensive backlog of pending regulatory decisions is one of the major historical challenges that the South African Health Products Regulatory Authority (SAHPRA) inherited from the Medicine Control Council (MCC). Revising and implementing new regulatory pathways is one of the strategic mechanisms that SAHPRA employs to circumvent this problem. To alleviate the backlog, the use of a new review pathway termed the risk-based review on the scientifc quality and bioequivalence assessments was explored. The objective of the study was to articulate the risk-based assessment (RBA) pathway, to determine robust criteria for the classifcation of the levels of risk for medicines, and to defne the improved process to be followed in the assessment and approval of medicines.
Investigation of common deficiencies observed in scientific assessments and the implementation of a new robust review pathway, the risk-based assessment approach, by the South African Health Regulatory Authority, SAHPRA
(University of the Western Cape, 2022) Moeti, Lerato Petunia; Joubert, Jacques
The main objective of this study is to improve patient access to medicines. The research is two-fold, the first component promotes transparency between the South African Health Products Regulatory Authority (SAHPRA), pharmaceutical companies, manufacturers and clinical research organisations by investigating deficiencies in scientific assessments of medicines submitted for approval. The common deficiencies from the regional, Active Pharmaceutical Ingredient (API), Finished Pharmaceutical Product (FPP) and Bioequivalence study sections of dossiers submitted to SAHPRA were qualitatively and quantitatively investigated. The investigation was conducted retrospectively between 2011 to 2017 for non-sterile and sterile generic products finalised by the P&A pre-registration Unit. To strengthen the conclusions, up-to-date data was also collected between 2020-2021 to confirm the consistency of the findings.
Microwave-assisted methods for the synthesis of pentacyclo[5.4.0.02,6.03,10.05,9]undecylamines
(Elsevier, 2013) Joubert, Jacques; Sharma, Rajan; Onani, Martin O.; Malan, Sarel F.
Efficient methodologies for the preparation of pentacyclo[5..4.0.02,6.03,10.05,9]undecane (PCU) amine derivatives are described via microwave-assisted synthesis. The obtained results revealed that microwave-assisted synthetic procedures under controlled conditions (power, temperature and time) are very convenient, high yielding, efficient and low-cost methods for the preparation of PCU amine derivatives. The new methods show several advantages including operational simplicity, good performance, significant reduction in reaction time, less by-product formation and easier purification.
Multi-targeted directed ligands for Alzheimer’s disease: design of novel lead coumarin conjugates
(Taylor & Francis, 2018) Repsold, B.P.; Malan, Sarel F.; Joubert, Jacques; Oliver, D.W.
Alzheimer’s Disease (AD) is a neurodegenerative disease characterized by central nervous system insults with progressive cognitive (memory, attention) and non-cognitive (anxiety, depression) impairments. Pathophysiological events affect predominantly cholinergic neuronal loss and dysfunctions of the dopaminergic system. The aim of the current study was to design multi-targeted directed lead structures based on the coumarin scaffold with inhibitory properties at two key enzymes in disease relevant systems, i.e. acetylcholinesterase (AChE) and monoamine oxidase B (MAO-B). Conventional and microwave synthetic methods were utilized to synthesize coumarin scaffoldbased novel morpholino, piperidino, thiophene and erucic acid conjugates. Biological assays indicated that the coumarin–morpholine ether conjugate BPR 10 was the most potent hMAO-B inhibitor. The coumarin–piperidine conjugates BPR 13 and BPR 12 were the most potent inhibitors of eeAChE at 100 μM and 1 μM, respectively. Molecular modelling studies were conducted with Accelrys® Discovery Studio® V3.1.1 utilising the published hMAO-B (2V61) and hAChE (4EY7) crystal structures. Compound BPR 10 occupies both the entrance and substrate cavities of the active site of MAO-B. BPR 13 resides in both the peripheral anionic site (PAS) and the catalytic anionic site (CAS) of hAChE. This study demonstrated that the coumarin scaffold serves as a promising pharmacophore for MTDLs design.
Novel adamantane-chloroquinolin conjugates to overcome plasmodium falciparum chloroquine resistance
(University of the Western Cape, 2017) Yvette, Mofenge Opute; Joubert, Jacques; Malan, Sarel
Malaria poses devastating health and socioeconomic outcomes on global health especially among pregnant women and children below the age of 5 in endemic areas. This is exacerbated by Plasmodium falciparum resistance to available antimalarial drugs, especially chloroquine (CQ), which was the drug of choice for many years against the blood stage of malaria.
Novel norbornane derivatives as potential neuroprotective agents
(University of Western Cape, 2020) Egunlusi, Ayodeji Olatunde; Joubert, Jacques; Malan, Sarel
Neurodegenerative disorders are characterised by progressive loss of the brain’s physiological functions as a result of gradual degeneration of neurons in the central nervous system. Even though they are classified as diseases of the elderly, occurrence earlier in life is possible, but that would suggest the influence of genetic and/or environmental factors. Due to the continuous rise in modernisation and industrialisation over the years, there has been an increase in incidence and prevalence of neurodegenerative disorders. With the advances in technology and life expectancy, the rates of the common forms (Alzheimer’s disease and Parkinson’s disease), are expected to increase exponentially by 2050. Unfortunately, there is still no clinically approved treatment or therapy to slow down or halt the degenerative process as most registered drugs only offer symptomatic relief. Confounding this issue is the lack of definite mechanism of neurodegeneration, which is still poorly defined and not completely understood. Nonetheless, the pathology of most neurodegenerative disorders is believed to be a combination of interrelated processes that eventually leads to neuronal cell death. Among the postulated processes, the impact of excitotoxicity mediated by NMDA receptor over-activation is prominent and it is implicated in virtually all neurodegenerative disorders. With this basic insight, it is believed that molecules capable of inhibiting NMDA receptors and associated calcium channels, without affecting the normal physiological functions of the brain, could potentially serve as good neuroprotective drugs. Competitive and uncompetitive blockers (MK-801 and ketamine) have been explored, but none were clinically accepted due to undesirable side effects such as hallucinations, sedation and depression. However, NGP1-01, a polycyclic cage molecule, has been shown to be neuroprotective through modulation of NMDA receptors and voltage gated calcium channels and attenuation of MPP+ -induced toxicity. A similar approach could be useful in the design and development of new neuroprotective drugs. The aim of this study was to synthesise a series of open and rearranged cage-like molecules and explore their neuroprotective potential in neuroblastoma SH-SY5Y cells. The proposed structures, with norbornane scaffolds that contained different moieties, were designed to structurally resemble NGP1-01 and MK-801. Once synthesised, the compounds were purified and characterised, and were evaluated for their biological activities. Compounds were first screened for cytotoxicity at different concentrations. Thereafter, they were evaluated for neuroprotective effects against MPP+ -induced excitotoxicity and for calcium flux modulatory effects on NMDA receptor and voltage gated calcium channels. The norbornane derivatives were synthesised and characterised, and all final products were afforded in sufficient yields. All compounds with the exception of two compounds displayed good cytotoxic profiles towards the SH-SY5Y neuroblastoma cells at 10 µM, 50 µM and 100 µM concentrations as they demonstrated percentage cell viabilities close to 100% (control treated cells). Only two compounds showed percentage cell viability of 51% and 59% at 100 µM. Utilising the same cell line, all compounds, tested at 10 µM, attenuated MPP+ -induced toxicity after 24 hours of exposure to a neurotoxin. This was evident in the 23% to 53% enhancement (significant with p < 0.05) in cell viability when compared to the MPP+ only treated cells. In comparison to known NMDA receptor and/or voltage gated calcium channel blockers (MK-801, NGP1-01 or nimodipine), the synthesised compounds demonstrated mono or dual inhibition of calcium channels as they effectively attenuated calcium influx by blocking NMDA receptors and/or voltage gated calcium channels expressed in neuroblastoma SHSY5Y cells. This group of compounds were found to be more potent NMDA receptor inhibitors, probably due to similarities with MK-801 and memantine, than voltage gated calcium channel inhibitors. All compounds demonstrated moderate to good calcium inhibitory effects at NMDA receptors in the range of 23% to 70% while a selected few displayed very little or no activity at the voltage gated calcium channels. In conclusion, 27 compounds with norbornane scaffolds were successfully synthesised and evaluated for cytotoxicity and neuroprotection. The abilities of the synthesised compounds to protect neurons from the neurotoxin MPP+ and reduce calcium flux into neuronal cells were successfully demonstrated. These characteristics are essential in neuroprotection as they may prove significant in halting or slowing down the disease progression. The compounds showing a good cytotoxicity profile, neuroprotective effects and ability to reduce calcium overload, could potentially act as neuroprotective agents with good safety profiles or contribute as lead structures to the development and design of structurally related molecules that could clinically benefit people with neurodegenerative disorders.
Novel tricycloundecane derivatives as potential N-methyl-Daspartate receptor and calcium channel inhibitors for neuroprotection
(University of the Western Cape, 2014) Egunlusi, Ayodeji Olatunde; Joubert, Jacques; Malan, Sarel
This study focused on the synthesis of a series of novel tricycloundecane derivatives and evaluation of these compounds for neuroprotection using the fluorescent ratiometric calcium assay that indicates the ability of the test compounds to inhibit NMDA receptors and VGCC. The cycloaddition reaction between p-benzoquinone and monomerised dicyclopentadiene yielded tricycloundeca- 4,9-diene-3,6-dione which was used as the base structure and further derivatised. These derivatives were conjugated with benzylamine to form a series of imines and amines. A total of 10 compounds were synthesised for evaluation of inhibition of calcium influx through NMDA receptor channels and voltage-gated calcium channels. The structures were confirmed using NMR, IR and MS. On the proton NMR, the characteristic AB-quartet system was observed in the region of 1-2 ppm for all the compounds and the aromatic moiety was observed between 6.5-7.5 ppm for the novel polycyclic amines. These, with other functional groups, were used to confirm the individual structures
Polycyclic compounds as carriers for neuroactive non- steroidal anti-inflammatory drugs
(University of the Western Cape, 2017) Abaniwonda, Modupe; Joubert, Jacques
Recent scientific findings have highlighted the beneficial roles of polycyclic cage compounds in neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Further interest into the chemistry of these compounds is stimulated by their remarkable ability to improve the pharmacokinetics profile of known neuroprotective agents. As potent lipophilic scaffolds, they can be employed to target the brain delivery of desired compounds. Inflammation is a key mediator of neuronal cell's degeneration as activated microglia and other inflammatory mediators propagate oxidative damage and neuronal loss. Epidemiological and clinical evidence suggests that non-steroidal anti-inflammatory drugs (NSAIDs) slow down the progression and onset of neurodegenerative diseases. The beneficial effects of NSAIDs in ND can be attributed to their ability to inhibit cyclooxygenase enzymes thereby halting the biosynthesis of prostaglandins (PG) which are powerful mediators of inflammation. NSAIDs also inhibit the expression of pro- inflammatory genes. Despite their potential neuroprotective activity, NSAIDs are poorly lipophilic due to the presence of polar carboxylic acid groups and will therefore ionise at physiological pH, deterring them from reaching the desired site of action in the central nervous system (CNS).
Polycyclic propargylamine derivatives as multifunctional neuroprotective agents
(University of the Western Cape, 2018) Zindo, Frank T.; Joubert, Jacques; F. Malan, Sarel
The abnormal death of neurons in the central nervous system of individuals suffering from neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease, Huntington’s disease and amyotrophic lateral sclerosis, takes place by an intrinsic cell suicide programme known as apoptosis. This process is triggered by several stimuli, and consists of numerous pathways and cascades which lead to the death of neuronal cells. It is this multifactorial nature of neurodegenerative diseases that has over the years seen many researchers develop compounds that may serve as multi-target directed ligands (MTDLs) which could potentially confer neuroprotection by acting simultaneously on different receptors and target sites implicated in neurodegeneration. This study was aimed at developing MTDLs that may serve as neuroprotective agents by simultaneously (a) inhibiting N-methyl D-aspartate receptors (NMDAR) and blocking L-type voltage gated calcium channels (VGCC) thus regulating the Ca2+ influx mediated excitotoxic process; (b) inhibiting the monoamine oxidase enzymes A and -B (MAO-A/B) thus allowing increase in dopamine levels in the central nervous system and reducing the levels of the highly oxidative products produced by the activity of these enzymes; (c) possessing anti-apoptotic activity to halt the neuronal cell death process. In designing the compounds we focused on the structures of rasagiline and selegiline, two well-known MAO-B inhibitors and proposed neuroprotective agents, and of NGP1-01, a known VGCC blocker and NMDAR antagonist. The first series of compounds (reported in research article 1, Chapter 3), comprised polycyclic propargylamine and acetylene derivatives. Compounds 12, 15 and 16 from this series showed promising VGCC and NMDA receptor channel inhibitory activity ranging from 18 % to 59 % in micromolar concentrations, and compared favourably to the reference compounds. In the MAO-B assay, compound 10 exhibited weak MAO-B inhibition of 73.32 % at 300 μM. The rest of the series showed little to no activity on these target sites, despite showing significant anti-apoptotic activity. This suggested the compounds in this series to be exhibiting their neuroprotective action through some other mechanism(s) unexplored in this study.
Regulatory registration timelines of generic medicines in South Africa: Assessment of the performance of SAHPRA between 2011 and 2022
(Springer, 2023) Moeti, Lerato; Litedu, Madira; Joubert, Jacques
Various regulatory authorities are experiencing backlogs of applications which result in delayed access to medicines for patients. The objective of this study is to critically assess the registration process utilised by SAHPRA between 2011 and 2022 and determine the fundamental root causes for the formation of a backlog. The study also aims to detail the remedial actions that were undertaken which resulted in the development of a new review pathway termed the risk-based assessment approach for regulatory authorities experiencing backlogs to implement. A sample of 325 applications was used to evaluate the end-to-end registration process employed for the Medicine Control Council (MCC) process between 2011 and 2017; 129 applications were used for the backlog clearance project (BCP) between 2019 and 2022; 63 and 156 applications were used for the risk-based assessment (RBA) pilot studies in 2021 and 2022, respectively. The three processes are compared, and the timelines are discussed in detail.
Selection, synthesis and evaluation of novel drug-like compounds from a library of virtual compounds designed from natural products with antiplasmodial activities
(University of the Western Cape, 2020) Pokomi, Rostand Fankam; Joubert, Jacques; Malan, Sarel; Egieyeh, Samuel
Malaria is an infectious disease which continues to kill more than one million people every year and the African continent accounts for most of the malaria death worldwide. New classes of medicine to combat malaria are urgently needed due to the surge in resistance of the Plasmodium falciparum (the parasite that causes malaria in humans) to existing antimalarial drugs. One approach to circumvent the problem of P. falciparum resistance to antimalarial drugs could be the discovery of novel compounds with unique scaffolds and possibly new mechanisms of action. Natural products (NP) provide a wide diversity of compounds with unique scaffolds, as such, a library of virtual compounds (VC) designed from natural products with antiplasmodial activities (NAA) can be a worthy starting point.

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