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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 scientific 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 classification of the levels of risk for medicines, and to define the improved process to be followed in the assessment and approval of medicines.In 2015, an extensive exercise was conducted by SAHPRA to identify the unknown status of in-process applications. The RBA pilot project commenced in 2016 and further piloted in 2021 using the knowledge gained from the 2016 study for optimisation of efficiency.By 2015 the backlog was quantified as 7902 applications in the pre-registration phase. The 2015 project entailed two phases. The initial phase was conducted to identify the status of 3505 in-process applications, which resulted in the registration of 198 applications. The second phase commenced in 2016 on 4397 applications not yet reviewed whereby the RBA approach was explored. With the developed criteria for risk classification and refined end-to-end registration process, the pilot resulted in a finalisation time with a median value of 90 calendar days and a median approval time of 109 calendar days. The throughput of the RBA pilot study conducted in 2021 was 68 calendar days finalisation time for the 63 applications used. These finalisation times are lower in comparison to the 501 calendar days for the current process employed by SAHPRA for the backlog clearance programme initiated in 2019. Both the 2016 and 2021 studies had similar approval times calculated from the date of allocation of scientific assessments. The reported evaluation timelines for both studies were within 6-7 h for a low-risk quality assessment, 9-10 h for a high-risk quality assessment, 7-8 h for a bioequivalence assessment, and 2-3 h for a biowaiver and initial response assessment.The refined processes used in the risk-based pilot studies to alleviate the SAHPRA backlog are described in detail. The process managed a reduction of the finalisation time to 68 calendar days in comparison to 501 calendar days for the current process that was employed by SAHPRA for the backlog clearance programme initiated in 2019. The RBA approach, therefore, reduces the finalisation and approval times for quality and bioequivalence assessments for regulatory authorities without compromising on the quality, safety and efficacy of the medicinal products. In addition, the approach provides a prototype solution to counteract the influx of medicinal product applications received by the regulatory authorities.

International audience; Like much of the developing world, sub-Saharan Africa (SSA) is facing a major challenge. This challenge is due to noncommunicable diseases (NCDs) whose rates are rising dramatically in SSA. Two conditions that frequently coexist head the list of NCDs as either established disease entities or risk factors for NCDs. These are hypertension and diabetes. Hypertension is the foremost cardiovascular condition. The objective of this scoping review is to examine peer-reviewed publications for the period 2009–2019 related to the detection and management of hypertension in SSA. We seek to define the issues confronted in managing hypertension in SSA, what measures have been implemented and evaluated, and what barriers and facilitators have been found. By mapping the complex, heterogeneous literature, we aim to identify the key concepts that underpin a major public health issue in SSA. The central question that this review addresses is how to control hypertension in SSA.

Background Cardiovascular disease (CVD) is the leading cause of mortality in India. Social and behavioural factors are strongly interrelated in the prevention and control of CVD. The ability to make lifestyle changes to control hypertension and diabetes (major risk factors for CVD) is determined by factors such as education, gender, caste, poverty, and urbanicity. This study aimed to improve our understanding of the inter-relationship of social and behavioural factors in the management of elevated serum glucose and high blood pressure and co-morbid mental health conditions. Methods A population-based catchment area cross sectional survey was conducted in Kerala, India. Data were collected from residents aged over 30 years (n = 997) using standardized tools and clinical measures. We performed latent class analysis incrementally to extract homogeneous latent classes of individuals based on their responses to social and behavioural risk factors in the survey. Using structural equation models, we assessed the mediating effect of depression and anxiety, and social or behavioural risk factors, on management of high blood pressure and raised serum glucose levels. Results The prevalence of high blood pressure and blood glucose in the sample was 33 and 26% respectively. Latent class analysis found three clusters of risk factors. One had a predominance of behavioural characteristics, another of social risk factors and the third was a low risk group. Age, female sex, and marital status had an effect on high blood pressure and high glucose, though were mediated by mental health, social and behavioural risk factors. Conclusions Interventions to improve the management of risk factors for CVD need to address social risk factors and be sensitive to the needs of population sub-groups that may require additional support to access health services. An integration of social and health services may be required to achieve this.

A series of multi-target directed edaravone derivatives bearing N-benzyl pyridinium moieties were designed and synthesised. Edaravone is a potent antioxidant with significant neuroprotective effects and N-benzyl pyridinium has previously exhibited positive results as part of a dual-site binding, peripheral anionic site (PAS) and catalytic anionic site (CAS), acetylcholinesterase (AChE) inhibitor. The designed edaravone-N-benzyl pyridinium hybrid compounds were docked within the AChE active site. The results indicated interactions with conserved amino acids (Trp279 in PAS and Trp84 in CAS), suggesting good dual-site inhibitory activity. Significant in vitro AChE inhibitory activities were observed for selected compounds (IC50: 1.2–4.6 µM) with limited butyrylcholinesterase inhibitory activity (IC50’s >160 µM), indicating excellent selectivity towards AChE (SI: 46 – >278). The compounds also showed considerable antioxidant ability, similar to edaravone. In silico studies indicated that these compounds should cross the blood–brain barrier, making them promising lead molecules in the development of anti-Alzheimer’s agents.

This article belongs to the Special Issue Molecular Simulations Applications in Biochemistry and Molecular Biology., The solid-state structural analysis and docking studies of three adamantane-linked 1,2,4-triazole derivatives are presented. Crystal structure analyses revealed that compound 2 crystallizes in the triclinic P-1 space group, while compounds 1 and 3 crystallize in the same monoclinic P21/c space group. Since the only difference between them is the para substitution on the aryl group, the electronic nature of these NO2 and halogen groups seems to have no influence over the formation of the solid. However, a probable correlation with the size of the groups is not discarded due to the similar intermolecular disposition between the NO2/Cl substituted molecules. Despite the similarities, CE-B3LYP energy model calculations show that pairwise interaction energies vary between them, and therefore the total packing energy is affected. HOMO-LUMO calculated energies show that the NO2 group influences the reactivity properties characterizing the molecule as soft and with the best disposition to accept electrons. Further, in silico studies predicted that the compounds might be able to inhibit the 11β-HSD1 enzyme, which is implicated in obesity and diabetes. Self- and cross-docking experiments revealed that a number of non-native 11β-HSD1 inhibitors were able to accurately dock within the 11β-HSD1 X-ray structure 4C7J. The molecular docking of the adamantane-linked 1,2,4-triazoles have similar predicted binding affinity scores compared to the 4C7J native ligand 4YQ. However, they were unable to form interactions with key active site residues. Based on these docking results, a series of potentially improved compounds were designed using computer aided drug design tools. The docking results of the new compounds showed similar predicted 11β-HSD1 binding affinity scores as well as interactions to a known potent 11β-HSD1 inhibitor., This research was funded by the Deanship of Scientific Research at Princess Nourah bint Abdulrahman University through the Research Groups Program (Grant No. RGP-1442-0010-4).

Nineteen new thiazole-based derivatives were synthesized and their structures characterized with analytical and spectral data. The in vitro assessment of their acetylcholinesterase (AChE) inhibitory activity revealed that compounds 10 and 16 produced potent AChE inhibitory activities with IC50 values of 103.24 and 108.94 nM, respectively. Compounds 13, 17, 18, 21, 23, 31, and 33 displayed moderate activity with 25-50% relative potency compared to the known potent AChE inhibitor donepezil. Molecular docking studies of the active compounds docked within the active site cavity of AChE showed a binding orientation similar to that of donepezil, with good predicted binding affinities. These compounds could therefore be considered as potential lead compounds for the development of new and potentially improved AChE inhibitors.

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.

In India, cardiovascular disease (CVD), with hypertension as its foremost risk factor, has the highest prevalence rate of non-communicable diseases (NCDs) and a rising mortality. Previous research has found a clustering of behavioural and social risks pertaining to NCDs, though the latter are infrequently addressed in public health interventions in India. This paper reaches toward the development of a social intervention to address social determinants of NCD relating to hypertension and diabetes. We used Theory of Change (ToC) as a theoretical approach to programme design. Mixed methods were used, including qualitative interviews with community members (n = 20), Accredited Social Health Activists (n = 6) and health professionals (n = 8), and a stakeholder workshop (n = 5 participants). The recruitment of participants from one local area in Kerala enabled us to map service provision and gain a holistic understanding of how to utilise the existing workforce to target social risk factors. The findings suggest that social interventions need to focus on ensuring health behaviour information reaches all parts of the community, and that those with more social risk factors are identified and supported to engage with treatment. Further research is required to test the resulting intervention model.

The impact of excitotoxicity mediated by N-methyl-D-aspartate (NMDA) receptor overactivation and voltage gated calcium channel (VGCC) depolarization is prominent among the postulated processes involved in the development of neurodegenerative disorders. NGP1-01, a polycyclic amine, has been shown to be neuroprotective through modulation of the NMDA receptor and VGCC, and attenuation of MPP+-induced neurotoxicity. Recently, we reported on the calcium modulating effects of tricycloundecene derivatives, structurally similar to NGP1-01, on the NMDA receptor and VGCC of synaptoneurosomes. In the present study, we investigated novel 4-oxatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione derivatives for their cytotoxicity, neuroprotective effects via attenuation of MPP+-induced neurotoxicity and calcium influx inhibition abilities through the NMDA receptor and VGCC using neuroblastoma SH-SY5Y cells. All compounds, in general, showed low or no toxicity against neuroblastoma cells at 10&ndash, 50 &micro, M concentrations. At 10 &micro, M, all compounds significantly attenuated MPP+-induced neurotoxicity as evident by the enhancement in cell viability between 23.05 &plusmn, 3.45% to 53.56 &plusmn, 9.29%. In comparison to known active compounds, the derivatives demonstrated mono or dual calcium modulating effect on the NMDA receptor and/or VGCC. Molecular docking studies using the NMDA receptor protein structure indicated that the compounds are able to bind in a comparable manner to the crystallographic pose of MK-801 inside the NMDA ion channel. The biological characteristics, together with results from in silico studies, suggest that these compounds could act as neuroprotective agents for the purpose of halting or slowing down the degenerative processes in neuronal cells.

The impact of excitotoxicity mediated by N-methyl-D-aspartate (NMDA) receptor overactivation and voltage gated calcium channel (VGCC) depolarization is prominent among the postulated processes involved in the development of neurodegenerative disorders. NGP1-01, a polycyclic amine, has been shown to be neuroprotective through modulation of the NMDA receptor and VGCC, and attenuation of MPP+-induced neurotoxicity. Recently, we reported on the calcium modulating effects of tricycloundecene derivatives, structurally similar to NGP1-01, on the NMDA receptor and VGCC of synaptoneurosomes. In the present study, we investigated novel 4-oxatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione derivatives for their cytotoxicity, neuroprotective effects via attenuation of MPP+-induced neurotoxicity and calcium influx inhibition abilities through the NMDA receptor and VGCC using neuroblastoma SH-SY5Y cells. All compounds, in general, showed low or no toxicity against neuroblastoma cells at 10–50 µM concentrations. At 10 µM, all compounds significantly attenuated MPP+-induced neurotoxicity as evident by the enhancement in cell viability between 23.05 ± 3.45% to 53.56 ± 9.29%. In comparison to known active compounds, the derivatives demonstrated mono or dual calcium modulating effect on the NMDA receptor and/or VGCC. Molecular docking studies using the NMDA receptor protein structure indicated that the compounds are able to bind in a comparable manner to the crystallographic pose of MK-801 inside the NMDA ion channel. The biological characteristics, together with results from in silico studies, suggest that these compounds could act as neuroprotective agents for the purpose of halting or slowing down the degenerative processes in neuronal cells.

ObjectivesThe purpose of this study is to examine the existing literature of the major social risk factors which are associated with diabetes, hypertension and the comorbid conditions of depression and anxiety in India.DesignScoping review.Data sourcesScopus, Embase, CINAHL Plus, PsycINFO, Web of Science and MEDLINE were searched for through September 2019.Eligibility criteria for selecting studiesStudies reporting data on social risk factors for diabetes or hypertension and depression or anxiety in community-based samples of adults from India, published in English in the 10 years to 2019, were included. Studies that did not disaggregate pooled data from other countries were excluded.Data extraction and synthesisTwo independent reviewers extracted study aims; methods; sample size and description; demographic, social and behavioural risk factors and a summary of findings from each paper. Risk factors were synthesised into six emergent themes.ResultsTen studies were considered eligible and included in this review. Nine presented cross-sectional data and one was a qualitative case study. Six themes emerged, that is, demographic factors, economic aspects, social networks, life events, health barriers and health risk behaviours.ConclusionsLiterature relating to the major social risk factors associated with diabetes, hypertension and comorbid depression and anxiety in India is sparse. More research is required to better understand the interactions of social context and social risk factors with non-communicable diseases and comorbid mental health problems so as to better inform management of these in the Indian subcontinent.

Butyrylcholinesterase (BuChE) is considered a promising drug target as it plays an important role in the progression of late stage Alzheimer’s disease (AD). Two compound libraries were selected and 64 124 amine containing moieties were screened using a hierarchical virtual screening protocol to discover new selective BuChE inhibitors. From these and subsequent docking experiments, 9-phenylacridinedione (9-PAD) was identified as a promising scaffold for selective inhibition of BuChE. Selected top dock scored 9-PADs were assayed and compounds 3 and 6 exhibited 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 substantial toxicities, especially hepatotoxicity, and no significant in vitro cytotoxicity against SH-SY5Y neuroblastoma cells at concentrations up to 100 µM. These findings indicate that 9-PAD is a promising lead structure for the development of agents able to treat late stage AD.

A series of indole derivatives was designed and synthesised to improve on activity and circumvent pharmacokinetic limitations experienced with the structurally related compound, ladostigil. The compounds consisted of a propargylamine moiety (a known MAO inhibitor and neuroprotector) at the N1 position and a ChE inhibiting diethyl-carbamate/urea moiety at the 5 or 6 position of the indole ring. In order to prevent or slow down the in vivo hydrolysis and deactivation associated with the carbamate function of ladostigil, a urea moeity was incorporated into selected compounds to obtain more metabolically stable structures. The majority of the synthesised compounds showed improved MAO-A inhibitory activity compared to ladostigil. The compounds possessing the propargylamine moiety showed good MAO-B inhibitory activity with 6 and 8 portraying IC50 values between 14-20 fold better than ladostigil. The ChE assay results indicated that the compounds have non-selective inhibitory activities on eeAChE and eqBuChE regardless of the type or position of substitution (IC50: 2-5 μM). MAO-A and MAO-B docking results showed that the propargylamine moiety was positioned in close proximity to the FAD cofactor suggesting that the good inhibitory activity may be attributed to the propargylamine moiety and irreversible inhibition as confirmed in the reversibility studies. Docking results also indicated that the compounds have interactions with important amino acids in the AChE and BuChE catalytic sites. Compound 6 was the most potent multifunctional agent showing better inhibitory activity than ladostigil in vitro on all enzymes tested (hMAO-A IC50 = 4.31 μM, hMAO-B IC50 = 2.62 μM, eeAChE IC50 = 3.70 μM, eqBuChE IC50 = 2.82 μM). Chemical stability tests confirmed the diethyl-urea containing compound 6 to be more stable than its diethyl-carbamate containing counterpart compound 8. Compound 6 also exerted significant neuroprotection (52.62% at 1 μM) against MPP+ insult to SH-SY5Y neural cells and has good in silico predicted ADMET properties. The favourable neuronal enzyme inhibitory activity, likely improved pharmacokinetic properties in vivo and the potent neuroprotective ability of compound 6 make it a promising compound for further development.

C22H28N2O2S, monoclinic, P21/n (no. 14), a = 9.2516(7) Å, b = 10.5122(8) Å, c = 19.7782(15) Å, β = 98.9530(10)°, V = 1900.1(2) Å3, Z = 4, R gt(F) = 0.0356, wR ref(F 2) = 0.1004, T = 100(2) K.

The versatile biological activities of tacrine, trolox and β-carboline derivatives make them promising lead structures for the development of multifunctional Alzheimer’s disease (AD) agents. Based on the topology of the active site of cholinesterases and other target proteins involved in the pathogenesis of AD, we have designed and synthesized tacrine-trolox and tacrine-tryptoline hybrids with various linker chain lengths. The hybrids containing the trolox moiety (8a-8d) showed moderate to high TcAChE inhibition (IC50: 17.37 - 2200 nM), eqBuChE inhibition (IC50: 3.16 – 128.82 nM) and free radical scavenging activities (IC50: 11.48 – 49.23 µM). The hybrids with longer linker chain lengths in general showed better ChE inhibitory activity. As expected, free radical scavenging activities were not significantly affected by varying linker chain lengths. The hybrid compound containing the tryptoline moiety linked with a 7 carbon spacer to tacrine (14) displayed the best AChE and BuChE inhibitory activity (IC50 = 17.37 and 3.16 nM). Docking experiments exhibited that compounds 8d and 14 were able to bind to both the CAS and PAS of TcAChE and eqBuChE, suggesting that they will be able to inhibit ChE induced Aβ aggregation. Novel multi-target agents that exhibit good ChE inhibition (8d and 14) and anti-oxidant (8d) activity were identified as suitable candidates for further investigation.

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. 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 influence of the crystal field, density functional theory (DFT) calculations were conducted. Results indicated that the DFT optimized geometry of 4 produced a conformer (4a) that is significantly different from the crystal structure. Further experiments confirmed that the crystal structure is not the absolute minimum conformation. This indicated that the crystal packing forces has significantly influenced 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.

Excitotoxicity related to the dysfunction of the N-methyl-d-aspartate receptor (NMDAR) has been indicated to play an integral role in the pathophysiology of multiple disease states, including neurodegenerative disorders such as Parkinson&rsquo, s disease. There is a notable gap in the market for novel NMDAR antagonists, however current methods to analyse potential antagonists rely on indirect measurements of calcium flux and hazardous radioligand binding assays. Recently, a fluorescent NMDAR ligand, N-adamantan-1-yl-dimethylamino-1-naphthalenesulfonic acid, known as AM-DAN was developed by our group. Additional studies on this ligand is necessary to evaluate its potential as a biological tool in NMDAR research. Therefore, this study was aimed at conducting structural analyses, fluorescence experiments, high-accuracy NMDAR molecular modelling and NMDAR phencyclidine (PCP) site competition binding studies using AM-DAN. Results revealed that AM-DAN has appropriate structural properties, significant fluorescent ability in various solvents and is able to bind selectively and compete for the PCP-binding site of the NMDAR. Therefore, AM-DAN holds promise as a novel fluorescent ligand to measure the affinity of prospective drugs binding at the NMDAR PCP-site and may circumvent the use of radioligands.

Introduction: Recent research points to the Sigma Receptor (σR) as a possible neuromodulatory system with multi-functional action and σ1Rs have been suggested as a drug target for a number of CNS conditions. Hexacyclododecylamines have shown σ1R activity and provide an advantageous scaffold for drug design that can improve the blood-brain barrier permeability of privileged structures. Methods and Materials: A series of oxa- and aza- hexaxcyclododecylamines were synthesised and evaluated for sigma-1 receptor activity and voltage-gated calcium channel blocking ability to determine the effect of inclusion of amine containing heterocycles. Results & Discussion: The compounds had promising σ1R activities (Ki = 0.067 – 11.86 µM) with the aza-hexacyclododecylamines 12, 24 and 27 showing some of the highest affinities (Ki = 0.067 µM, 0.215 µM and 0.496 µM respectively). This confirms, as observed in previous studies, that the aza compounds are more favourable for σ1R binding than their oxa counterparts. The addition of the amine heterocycle showed affinities similar to that of related structures with only two lipophilic binding regions. This indicates that the inclusion of an amine heterocycle into these structures is a viable option in the design of new σ1R ligands. Significant voltage-gated calcium channel blocking ability was also observed for 12, 24 and 27, suggesting a link between σ1R activity and intracellular calcium levels. Conclusion: The σ1R activity and potential effect on other receptor classes and calcium channels could prove beneficial in pharmacological application.

In order to utilize the neuroprotective properties of polycyclic cage compounds, and explore the NO-donating ability of nitrophenyl groups, an array of compounds was synthesized where the different nitrophenyl groups were appended on oxa and aza-bridged cage derivatives. Biological evaluations of the compounds were done for cytotoxicity, neuroprotective abilities, the inhibition of N-methyl-d-aspartate (NMDA)-mediated Ca2+ influx, the inhibition of voltage-mediated Ca2+ influx, and S-nitrosylation abilities. All of the compounds showed low toxicity. With a few exceptions, most of the compounds displayed good neuroprotection and showed inhibitory activity for NMDA-mediated and voltage-gated calcium influx, ranging from high (>70%) to low (20–39%) inhibition. In the S-nitrosylation assay, the compounds with the nitro moiety as the NO-donating group exhibited low to good nitrosylation potency compared to the positive controls. From the biological evaluation of the tested compounds, it was not possible to obtain a simple correlation that could explain the results across all of the biological study domains. This can be ascribed to the independent processes evaluated in the different assays, which reiterate that neuroprotection is a result of multifactorial biochemical mechanisms and interactions. However, these results signify the important aspects of the pentacylcoundecylamine neuroprotectants across different biological study realms.

Drug resistance in Mycobacterium tuberculosis (M. tuberculosis) complicates management of tuberculosis. Efflux pumps contribute to low level resistance and acquisition of additional high level resistance mutations through sub-therapeutic concentrations of intracellular antimycobacterials. Various efflux pump inhibitors (EPIs) have been described for M. tuberculosis but little is known regarding the mechanism of efflux inhibition. As knowledge relating to the mechanism of action and drug target is central to the rational drug design of safe and sufficiently selective EPIs, this review aims to examine recent developments in the study of EPIs in M. tuberculosis from a rational drug development perspective and to provide an overview to facilitate systematic development of therapeutically effective EPIs. Review of literature points to a reduction in cellular energy or direct binding to the efflux pump as likely mechanisms for most EPIs described for M. tuberculosis. This review demonstrates that, where a direct interaction with efflux pumps is expected, both molecular structure and general physicochemical properties should be considered to accurately predict efflux pump substrates and inhibitors. Non-competitive EPIs do not necessarily demonstrate the same requirements as competitive inhibitors and it is therefore essential to differentiate between competitive and non-competitive inhibition to accurately determine structure activity relationships for efflux pump inhibition. It is also evident that there are various similarities between inhibitors of prokaryotic and eukaryotic efflux pumps but, depending on the specific chemical scaffolds under investigation, it may be possible to design EPIs that are less prone to inhibition of human P-glycoprotein, thereby reducing side effects and drug-drug interactions.

An in vitro medium-throughput screen using M. tuberculosis H37Rv was employed to screen an in-house library of structurally diverse compounds for antimycobacterial activity. From this initial screen, eleven 7-substituted coumarin derivatives with confirmed monoamine oxidase-B and cholinesterase inhibitory activities, demonstrated growth inhibition of more than 50% at a 50 µM concentration. This prompted further exploration of all the 7-substituted coumarins in our library, nineteen in total, as potential antimycobacterial agents. Four derivatives showed promising antimycobacterial activity with MIC99 values of 8.31 – 29.70 µM and 44.15 – 57.17 µM on M. tuberculosis H37Rv in independent assays using Gaste-Fe and 7H9 + OADC media, respectively. These compounds were found to bind to albumin which may explain the variations in MIC between the two assays. Preliminary antimycobacterial evaluation of moxifloxacin resistant M. tuberculosis show that these compounds are able to maintain their activity in fluoroquinolone resistant mycobacteria. Analysis of structure activity relationships for antimycobacterial versus neuronal enzyme inhibitory activity indicate that structural modification on position 4 and/or 7 of the coumarin scaffold may be utilized to improve selectivity towards either inhibition of neuronal enzymes or antimycobacterial effect. Cytotoxicity evaluations of the compounds indicate moderate cytotoxicity with slight selectivity towards mycobacteria. Further neuroprotective assays on SH-SY5Y human neuroblastoma cells indicate significant neuroprotection for selected compounds irrespective of their neuronal enzyme inhibitory properties. These coumarin molecules are thus interesting lead compounds that may provide insight into the design of new antimicrobacterial and/or neuroprotective agents.

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.

Neurodegenerative disorders are frequently associated with increased oxidative damage to the brain as a result of free radicals produced by cellular respiration. The onset and progression of neurodegeneration may therefore be curbed by exogenous hydrogen-donating antioxidant moieties such as the naturally occurring flavonoids. A series of 2-phenylquinolin-4(1H)-ones was synthesised and displayed moderate to high antioxidant activity when compared to structurally related flavones and quinolines. Activity of the hydroxy-2-phenylquinolin-4(1H)-ones (8–10) was established in reducing ferrous ions and diminishing hydrogen peroxide and hydroxyl radical production, in the FRAP (1.41–97.71% Trolox® equivalents), ORAC (9.18–15.27 μM Trolox® equivalents at 0.001 mM) and TBARS (0.05–0.72 nmol MDA/mg tissue) assays, respectively. The results indicated that the additional hydrogen donating groups on the synthesised 2-phenylquinolin-4(1H)-one series increased antioxidant activity. http://dx.doi.org/10.1016/j.bmc.2011.11.068

Dengue fever is a major public health concern in many tropical and sub-tropical regions. The development of agents that are able to inhibit the dengue virus (DENV) is therefore of utmost importance. This study focused on the synthesis of dual acting hybrids comprising structural features of known DENV inhibitors, amantadine (1) and benzsulfonamide derivatives. Hybrid compound 3, N-(adamantan-1-yl)-4-[(adamantan-1-yl)sulfamoyl]benzamide, was synthesized by reacting amantadine (1) with 4-(chlorosulfonyl)benzoic acid (2), after optimization, in a 2:1 ratio under microwave irradiation conditions in a one-pot reaction. Mono-adamantane derivatives 6 and 7 were synthesised via acyl halide formation of benzoic acid (4) and 4-sulfamoyl benzoic acid (5), respectively, followed by conjugation with amantadine (1) through a conventional or microwave irradiation assisted nucleophilic addition/substitution reaction. The use of microwave irradiation lead to significant increases in yields and a reduction in reaction times. Nuclear magnetic resonance, infra-red and mass spectral data confirmed the structures. Compound 3 and 7 showed significant anti-DENV serotype 2 activity (IC50 = 22.2 µM and 42.8 µM) and low cytotoxicity (CC50 < 100 µM). Possible mechanisms of action are also proposed, which are based on the biological results and molecular docking studies.

Much progress has been made in designing analogues that can potentially confer neuroprotection against debilitating neurodegenerative disorders, yet the multifactorial pathogenesis of this cluster of diseases remains a stumbling block for the successful design of an ‘ultimate’ drug. However, with the growing popularity of the “one drug, multiple targets” paradigm, many researchers have successfully synthesized and evaluated drug-like molecules incorporating a propargylamine function that shows potential to serve as multifunctional drugs or multitarget-directed ligands. It is the aim of this review to highlight the reported activities of these propargylamine derivatives and their prospect to serve as drug candidates for the treatment of neurodegenerative disorders.