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MSc (Pharmaceutical Sciences), North-West University, Potchefstroom Campus Antimicrobial resistance is a major concern as existing antimicrobials are becoming less effective due to misuse and overuse (WHO, 2018b). Identifying novel compounds or treatments with a possible antimicrobial activity could facilitate the development of novel treatments, such as a Pheroid® plant extract delivery system. This Agapanthus africanus plant extract has proven in vitro and in vivo activity against fungi affecting crops in South Africa, however, activity against human pathogens have not been determined. In this study, the plant extract’s in vitro antimicrobial activity was tested against eleven human pathogens, namely Escherichia coli, Staphylococcus epidermidis, Staphylococcus aureus, Klebsiella pneumoniae, Salmonella enterica, Enterobacter aerogenes, Pseudomonas aeruginosa, Trichosporon dermatis, Cryptococcus neoformans, Saccharomyces cerevisiae, and Candida albicans. The plant extract was formulated and entrapped into the Pheroid® drug delivery system, containing different concentrations of the oil phase, i.e. 4%, 8%, 10%, 13% and 50%. The in vitro antimicrobial activity of these test formulations (Pheroid®-plant extract) was compared to the activity of the plant extract and control formulation (only Pheroid®), to determine if Pheroid® technology influenced the plant extract's activity. The formulations were subjected to accelerated stability testing, after which the minimum bactericidal/fungicidal concentration was determined at month 0, 1, 2, and 3. Improvements were made to this method by adding resazurin to also determine the minimum inhibitory concentration. The formulations were characterised by Malvern Mastersizer (particle size), Malvern Nanosizer (zeta potential) and confocal laser scanning microscopy (morphology) before and during accelerated stability testing. The characterisation tests showed that optimisation of the test formulations by adjusting the percentage oil phase was possible. Most of the formulations were stable i.e. no aggregation, flocculation or creaming was observed during accelerated stability testing. Test formulation PPE 4% proved to be the most promising formulation with the largest initial particle size and remained stable during accelerated stability testing. The A. africanus plant extract was identified to have moderate antimicrobial activity against three human pathogens, namely C. albicans, S. cerevisiae, and T. dermatis with a minimum inhibitory concentration of 1725 μg/ml, 54 μg/ml, and 108 μg/ml, respectively. In conclusion, the addition of Pheroid® drug delivery system increased the inhibitory activity in most cases (excluding S. cerevisiae), however, did not seem to have an effect on the fungicidal concentration. The formulation that showed the best initial antimicrobial activity against C. albicans was Pro-PPE 50%, however, after accelerated stability testing both Pro-PPE 50% and PPE 4% had the highest antimicrobial activity. Formulation PPE 13% had the highest initial fungicidal activity against both S. cerevisiae and S. epidermidis, while PPE 8% had the highest fungicidal activity after accelerated stability testing against S. cerevisiae. Masters

It has been shown that methylene blue has antimicrobial properties although few studies have determined its minimum inhibitory concentration (MIC), which is the gold standard used to measure antimicrobial activity. The exact antimicrobial mode of action of methylene blue is still unclear and to our knowledge no pharmacophore model has yet been created to investigate methylene blue's mode of action. The aim of this study was to determine the MIC of methylene blue and a number of its analogous against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, Salmonella enterica and Candida albicans, and to use these data to develop and validate a common feature pharmacophore model. Three statistical metrics, i.e. the enrichment factor (EF), hit rate (HR) and the area under the curve of a receiver operator characteristic (ROC-AUC), were used to determine the pharmacophore model's ability to differentiate between active/decoy compounds. The validated pharmacophore model was used to map similar antibacterial compounds in an attempt to elucidate methylene blue's antimicrobial mode of action. Most test compounds only had activity against S. aureus, S. epidermidis and K. pneumoniae. Dimethyl methylene blue, new methylene blue and acriflavine proved to be the most active compounds against S. aureus [1 µg/ml (dimethyl methylene blue); 4 µg/ml (new methylene blue); 8 µg/ml (acriflavine)], S. epidermidis [1 µg/ml (dimethyl methylene blue); 4 µg/ml (new methylene blue); 2 µg/ml (acriflavine)] and K. pneumoniae [8 µg/ml (dimethyl methylene blue); 0.5 µg/ml (new methylene blue); 2 µg/ml (acriflavine)]. A common feature pharmacophore model was created (rank score: 26.664, max. fit value: 4), which was able to accurately identify active methylene blue analogous out of the test set (EF2%: 51, HR2%: 100%, ROC-AUC: 1.00 ± 0.00). Six phenothiazine derivatives with known antibacterial activity had high fit values when mapped with the validated pharmacophore model, i.e. >3.4. Dimethyl methylene blue, new methylene blue and acriflavine had potent antibacterial activity against S. aureus, S. epidermidis and K. pneumoniae. The MIC data will allow other researchers to compare the activity across different laboratories. The common feature pharmacophore model was able to identify methylene blue analogous with known in vitro antibacterial activity out of a database containing active/decoy compounds and highlighted the importance of two hydrophobic features, an aromatic feature and a hydrogen bond acceptor. The validated pharmacophore model also correctly mapped six phenothiazine derivatives with known antibacterial activity suggesting that they may share a common antibacterial mechanism of action.

This review describes the usefulness of in silico design approaches in the design of new radiopharmaceuticals, especially peptide-based radiotracers (including peptidomimetics). Although not part of the standard arsenal utilized during radiopharmaceutical design, the use of in silico strategies is steadily increasing in the field of radiochemistry as it contributes to a more rational and scientific approach. The development of new peptide-based radiopharmaceuticals as well as a short introduction to suitable computational approaches are provided in this review. The first section comprises a concise overview of the three most useful computeraided drug design strategies used, namely i) a Ligand-based Approach (LBDD) using pharmacophore modelling, ii) a Structure-based Design Approach (SBDD) using molecular docking strategies and iii) Absorption-Distribution-Metabolism-Excretion-Toxicity (ADMET) predictions. The second section summarizes the challenges connected to these computer-aided techniques and discusses successful applications of in silico radiopharmaceutical design in peptide-based radiopharmaceutical development, thereby improving the clinical procedure in Nuclear Medicine. Finally, the advances and future potential of in silico modelling as a design strategy is highlighted.

Resistance against the current TB treatment regimens is spreading. A combination of the current TB regime with a novel drug delivery system, might lead to reduced resistance, shorter treatment durations and increased patient compliance. A delivery system is used to facilitate the delivery of specific therapeutically active ingredients to a targeted area in an organism (Vonarbourg et al., 2006). An ideal delivery system ought to be biodegradable, stable, pharmaceutically acceptable and suitable for targeted delivery (Buszello & Müller, 2000). The Pheroid® drug delivery system is such a system. It is an intricate polydisperse technology that is based on different colloidal emulsion systems (Grobler, 2009). In this study a novel Pheroid® drug delivery system was used with the addition of the mycobactericidal eicosapentaenoic fatty acid (EPA) and a targeting ligand Mycolic acid (MA). The in vivo anti-TB activity of the novel formulation alone, and in combination with the current treatment regime was determined against the H37Rv Mtb strain in the Kramnik mouse model. After inoculation, three groups of mice (n = 56) each received a different treatment formulation. Group 1 received the first line treatment API's (positive control), group 2 novel Pheroid® formulation and group 3 novel Pheroid® formulation in combination with the first line treatment API's. One group, group 4 (negative control), was infected but received no treatment. Six animals per treatment group were euthanised at different time intervals, i.e. at week 1, 2, 3, 4, 8 and lastly at week 12 and four animals in group 4 at different time intervals, i.e. at week 1, 8 and 12. Lungs were harvested for bacteriological examination in order to provide information regarding disease progression. Inflammation in the lungs indicates the presence of the Mtb infection, a direct correlation can be made between the mass of the lungs and the severity of the infection. Preliminary results obtained from the average mass of the lungs, showed that both group 1 and 3 suppressed the Mtb infection to a similar degree. Mice in these groups recovered quicker than those in groups 2 and 4. Some of the mice in group 2 and 4 reached the humane endpoint before the predetermined euthanasia dates, indicating an aggressive progression of the disease in these two groups. The preliminary results showed that the Mtb infection was suppressed in both treatment groups, group 1 and 3, while the carrier control (group 2) and the negative control (group 4) had no effect on the disease progression. Next the colony-forming units in the lung samples will be determined to give a more accurate quantitative measurement of the bacteriological infection. Further research will determine the relapse rate in the different study groups

This plant extract (PE) has proven activity against fungi affecting crops in South Africa. However, there is currently insufficient data on the activity of the PE against human pathogens. The general aim of this study is to determine whether the PE has in vitro antimicrobial properties against 11 human pathogens. Identification of compounds or treatments, which could have possible antimicrobial activity, will facilitate the development of novel treatments, such as a Pheroid® PE delivery system, and contribute to the indigenous knowledge of SA's plant. The PE was formulated and entrapped into the Pheroid® drug delivery system, containing different concentrations of the oil phase, i.e. 4%, 8%, 10%, 13% and 50%. The in vitro antimicrobial activity of these test formulations were compared to the activity of the PE and control formulation, i.e. Pheroid® without the PE, to determine if Pheroid® technology influenced the PE's activity. The formulations were subjected to accelerated stability testing (AST), after which the minimum bactericidal/fungicidal concentration (MBC/MFC) was determined at month 0, 1, 2, and 3. Improvements were made to this method by adding resazurin to determine the minimum inhibitory concentration (MIC) and MFC [1]. The formulations were subjected to characterization by Malvern Mastersizer, Malvern Nanosizer and confocal laser scanning microscopy (CLSM). The particle size, obtained from Malvern Mastersizer, for test formulations (4% and 8%) stayed relatively constant, while test formulations 10%, 13% and Pro-Pheroid® increased in size. There was statistically no difference in mean particle sizes for the control formulations. The zeta potential, obtained from Malvern Nanosizer, for both test- and control formulations generally decreased during the AST, resulting in more stable formulations. In general, after AST, test formulation (8%, 10%, and 13%) and PE tested against C. albicans had a 50% decrease in MFC, while the 4% test formulation's MFC stayed constant. All the control formulations had a N 90% decrease in MFC. The PE was found to have moderate activity against C. albicans, S. cerevisiae, and T. dermatis with a MIC of 1725 μg/mL, 54 μg/mL, and 108 μg/mL respectively. The test formulations had a general MIC of 108 μg/mL, 54 μg/mL, and 27 μg/mL against C. albicans S. cerevisiae, and T. dermatis respectively. Discussion Characterization showed that optimisation of the formulations was possible and that most of the formulations were stable i.e. no aggregation, flocculation or creaming was observed during AST. In conclusion, the addition of Pheroid® increased the MIC in all cases, however, did not seem to have an effect on the MFCs in general. This excludes S. cerevisiae where the PE had no MFC on its own, but by adding Pheroid® there were MFCs. Generally, adding the PE to Pheroid® resulted in more stable vesicles

A series of artemisininetriazine hybrids and hybrid-dimers were synthesized and their in vitro antimalarial activity against the chloroquine sensitive (CQS), the gametocytocidal (NF54) and the choroquine resistant (CQR) Dd2 strains of Plasmodium falciparum determined, while their toxicity against CHO cells were also established. These compounds were prepared by linking artemisinin and triazine pharmacophores through nucleophilic substitution, using conventional and microwave assisted methods. These hybrids and hybrid-dimers were all found to be active against all three Plasmodium strains, with the panisidino- substituted triazine hybrid-dimer 22 being the most active of all. It showed good antigametocytocidal activity against the NF54 strain, with a 50% inhibitory concentration value in the nanomolar range, while having a potency comparable to that of artesunate against the Dd2 strain. This hybrid-dimer further demonstrated selective toxicity towards the parasitic cells. This dimer hence showed the necessary potential as candidate for further investigation in the search for malaria transmission blocking drugs so desperately needed http://dx.doi.org/10.1016/j.ejmech.2014.01.040 http://www.journals.elsevier.com/european-journal-of-medicinal-chemistry/ Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.ejmech.2014.01.040 National Research Foundation (NRF) of South Africa; North-West University, Potchefstroom Campus; German Academic Exchange Service

A series of n-alkyl/aryl esters were synthesized and their in vitro antiplasmodial activity was measured alongside that of previously synthesized aminoethylethers of artemisinin ozonides against various strains of Plasmodium falciparum. The cytotoxicity against human cell lines was also assessed. The esters were synthesized in a one-step reaction by derivatization on carbon C-10 of dihydroartemisinin. Both classes were active against both the 3D7 and K1 strains of P. falciparum, with all compounds being significantly more potent than artemether against both strains. The majority of compounds possessed potency either comparable or more than artesunate with a high degree of selectivity towards the parasitic cells. The 10a-n-propyl 11 and 10a-benzyl 18 esters were the most potent of all synthesized ozonides, possessing a moderate ( 3-fold) and significant (22- and 12-fold, respectively) potency increases against the 3D7 and K1 strains, respectively, in comparison with artesunate. http://www.journals.elsevier.com/bioorganic-chemistry/

Series of bisquinolines 4e15 and bispyrrolo[1,2a]quinoxalines 16e20 containing various polyamine linkers were synthesized. The aqueous solubility and distribution coefficient were experimentally determined. The compounds were screened for antimalarial activity alongside chloroquine against D10 and Dd2 strains of Plasmodium falciparum. The growth inhibitory effects of biscompounds 4e9 were assessed against various cancer cell lines. The aqueous solubility was found to increase with an increase in potential proton.ation sites. Bisquinolines 8 and 9 featuring triethylenetetramine and N,N0-bis(3- aminopropyl)ethylene-diamine linkers, respectively, were the most active of all synthesized compounds. They were found as potent as chloroquine against D10 but significantly more potent against the Dd2 strain, with good selectivity towards parasitic cells. Compound 4 containing a diethylenetriamine bridge displayed the most important anticancer activity of the series, and was a more effective antiproliferative inhibitor than etoposide against all three TK10, UACC62 and MCF7 cancer cell lines National Research Foundation (NRF) and the North-West University (NWU)

In this study, a series of 11 10-aminoethylether derivatives of artemisinin were synthesised and their antimalarial activity against both the chloroquine sensitive (D10) and resistant (Dd2) strains of Plasmodium falciparum was determined. The compounds were prepared by introducing aliphatic, alicyclic and aromatic amine groups with linkers of various chain lengths through an ethyl ether bridge at C-10 of artemisinin using conventional and microwave assisted syntheses, and their structures were confirmed by NMR and HRMS. All derivatives proved to be active against both strains of the parasite. The highest overall activity was displayed by the short chain aromatic derivative 8 (IC50 = 1.44 nM), containing only one nitrogen atom, while long chain polyamine derivatives were found to have the lowest activity against both strains. An interesting correlation between the IC50, pKa values and resistance index (RI) was found National Research Foundation (NRF), the North- West University (NWU)

The aim of this study was to synthesize a series of mono-, di- and trisubstituted derivatives of the human African trypanosomiasis drug eflornithine (alpha-difluoromethylornithine, DMFO, CAS 70052-12-9) to determine their partition coefficients, and to assess whether they deliver the parent drug in the plasma. If increased plasma concentrations of eflornithine could be achieved in this way, an oral dosage form would be possible. The derivatives, nine in total, were successfully synthesized by multi-step derivatisation of eflornithine on either its alpha-carboxylic or/and alpha-amino or/and delta-amino groups by either esterification or/and amidation or/and carbamylation, and their structures confirmed by NMR and MS spectroscopy. The majority of derivatives were more lipophilic than eflornithine with log D values in phosphate buffer solution (pH 7.4) ranging from -1.34 to 1.59 (vs. -0.98 for eflornithine). The in vivo absorption after oral administration to Sprague-Dawley rats showed that no derivative delivered eflornithine in the plasma, indicating that the derivatives were either not absorbed from the gastrointestinal tract or not metabolized to the parent drug. Two of the monosubstituted activities were toxic for T. brucei blood stream forms.