The anti-tumour properties of novel gold compounds

Since the introduction of Auranofin in 1985 there has been no new clinically approved gold containing drugs introduced. Although promising results were achieved with a gold(I) phosphine complex [Au(dppe) 2]Cl (Hoke et al., 1991; Mckeage et al., 2002), this compound was never entered into clinical trials due to its toxicity to normal tissue such as the liver and heart (Smith et al.,1989). Six novel derivatives of [Au(dppe) 2]Cl were developed and synthesized to identify possible new candidates with improved tumour specificity compared to [Au(dppe) 2]Cl and cisplatin. Human cervical carcinoma cells (HeLa) were used for an initial toxicity screening. IC50’s obtained for [Au(dppe) 2]Cl and cisplatin were 0.661 and 0.710 µM respectively. Three mixed novel derivatives (MM4, MM5 and MM6) displayed IC50’s ranging between 0.026 and 0.103 µM. These compounds were then selected to be tested further for selectivity and cytotoxicity on various malignant and normal cell lines. MM4 showed selectivity for ovarian, prostate, cervical and breast cancer cells, while MM5 was the most effective against ovarian, colon, prostate, cervical and breast cancer cells. MM6 was most active against ovarian, colon, prostate, cervical and breast cancer cells. The experimental compounds had much higher IC50’s when tested on the normal cells, which indicates selectivity for cancer cells. The octanol/water partition coefficient (lipophilicity) of all the experimental compounds was measured to determine the lipophilicity of the compounds. [Au(dppe) 2]Cl was found to be strongly lipophilic; while the novel compounds had varying degrees of lipo- and hydrophilicity. The octanol/water partition coefficient (lipophilicity) was also used to establish whether there is a correlation between the lipophilicity, IC50 and tumour specificity. In this study no correlation was found between these parameters. [Au(dppe) 2]Cl is known to have an effect on the mitochondrial membrane potential of cells. MM4, MM5, MM6 and cisplatin were compared to [Au(dppe) 2]Cl for effects on mitochondrial membrane potential. PHA stimulated human lymphocytes and a human undifferentiated leukemia T-cell line (Jurkat cells) were used in these experiments. [Au(dppe) 2]Cl, MM4, MM5 and MM6 depolarized the mitochondrial membranes of PHA stimulated lymphocytes significantly, while only [Au(dppe) 2]Cl depolarized the mitochondrial membranes of the Jurkat cells significantly, indicating that a different mechanism of action might be operational. MM4, MM5, MM6 and cisplatin were compared to [Au(dppe) 2]Cl for effects on plasma membrane potential. PHA stimulated human lymphocytes and Jurkat cells were used in these experiments. [Au(dppe) 2]Cl and MM6 depolarized the plasma membranes of both PHA stimulated lymphocytes and the Jurkat cells significantly. In order to determine whether the depolarization of mitochondrial and plasma membranes was a precursor for apoptosis, experiments were done to determine whether MM4, MM5 and MM6 induce apoptosis in Jurkat cells. [Au(dppe) 2]Cl and cisplatin were added for comparison. [Au(dppe) 2]Cl, cisplatin, MM4 and MM6 did induce apoptosis in Jurkat cells, but MM5 did not. The effect of [Au(dppe) 2]Cl, cisplatin, MM4, MM5 and MM6 on the cell cycle of Jurkat cells was determined to establish whether the experimental compounds altered this process. [Au(dppe) 2]Cl, MM4, MM5 and MM6 arrested the cell cycle in the G1 phase and cisplatin did so in the S phase. In order to determine whether the inhibition of cell growth and partition coefficient of the experimental compounds is related to the uptake of the drug, radio labeled drug uptake experiments were carried out with 198Au labeled [Au(dppe) 2]Cl, MM5 and MM6. Two different types of ovarian cancer cells were used for these studies. One cell line was sensitive to cisplatin (A2780) and the other was resistant to cisplatin (A2780 cis). Results obtained from these experiments showed that the uptake of these experimental compounds was dependent on their octanol/water partition coefficient. However, the inhibition of cell growth did not correlate with the uptake of these compounds by the cells that were tested. To confirm the octanol/water partition coefficient and drug uptake results, 198Au labelled [Au(dppe) 2]Cl, MM5 and MM6 were testedin vivo for bio distribution in rats. [Au(dppe) 2]Cl (lipophilic) had higher bio distribution compared to MM5 and MM6 (hydrophilic). Conclusion The experimental compounds show low IC50’s combined with increased tumour specificity. This indicates that these compounds have great potential to target tumour cells selectively and should be investigated further as anti-cancer agents.Dissertation (MSc)--University of Pretoria, 2008.Pharmacologyunrestricte

Underlying mechanisms of cytotoxicity in HepG2 hepatocarcinoma cells exposed to arsenic, cadmium and mercury individually and in combination

BACKGROUND : Toxicity data regarding combinational exposure of humans to arsenic, cadmium and mercury is scarce. Although hepatotoxicity has been reported, limited information is available on their mechanistic underpinnings. The cytotoxic mechanisms of these metals were determined in HepG2 hepatocarcinoma cell lines after individual and combinational exposure. METHODS : HepG2 cells were exposed to heavy metals (sodium arsenite, cadmium chloride, and mercury chloride) individually or in combination for 24 h, after which cell density, mitochondrial membrane potential (ΔΨm), reactive oxygen species (ROS), reduced glutathione (GSH), adenosine triphosphate (ATP) and caspase-3/7 activity was assessed. RESULTS AND DISCUSSION : Cadmium (IC50 = 0.43 mg/L) and the combination (0.45 mg/L, arsenic reference) were most cytotoxic, followed by arsenic (6.71 mg/L) and mercury (28.23 mg/L). Depolarisation of the ΔΨm and reductions in ROS, GSH and ATP levels occurred. Arsenic, cadmium and the combination increased caspase-3/7 activity, while mercury reduced it. CONCLUSION : The combination produced a greater, albeit mechanistically similar, cytotoxicity compared to individual metals. Cytotoxicity was dependent on altered mitochondrial integrity, redox-status, and bioenergetics. Although the combination's cytotoxicity was associated with caspase-3/7 activity, this was not true for mercury. Heavy metal interactions should be assessed to elucidate molecular underpinnings of cytotoxicity.The Department of Pharmacology and NRF Rating grant.https://www.elsevier.com/locate/toxinvit2022-01-23hj2021Pharmacolog

A randomised clinical trail comparing the analgesic and anxiolytic efficacy and tolerability of Stilpane® and Tramacet® after third molar extraction

BACKGROUND : successful treatment of moderate to severe acute pain often necessitates several analgesics that target different sites of the nociceptive pathway. Fixed-dose combination analgesics facilitate a reduction in dose of individual components, increased compliance and strong-opioid sparing. The aim of this study was to compare the analgesic and anxiolytic efficacy and tolerability of two widely prescribed combination analgesics, Stilpane® (paracetamol/codeine/meprobamate) and Tramacet® (paracetamol/tramadol). METHODS : A prospective randomised parallel group phase IV clinical trial was conducted in 100 patients experiencing moderate to severe pain after third molar extraction at the Oral and Dental Hospital, University of Pretoria. Pain intensity and pain relief were assessed using Likert and visual analogue scales. Medication efficacy, time to perceptible pain relief and meaningful pain relief were also assessed. Primary variables included the Pain Intensity Difference (PID) between baseline and scheduled visits, and hourly pain relief (PAR). The Summed Pain Intensity Difference (SPID), Sum of hourly PAR, hourly PAR, hourly PIDs from baseline (SPRID) and Total Pain Relief (TOTPAR) were calculated according to standard methods. Beck Anxiety Questionnaire assessed anxiety. Tolerability was assessed chiefly by the reporting of adverse events. RESULTS : Stilpane® and Tramacet® were equally effective at relieving moderate to severe acute pain. No differences in anxiolytic efficacy were found between the two treatment arms and differences in tolerability failed to reach statistical significance. CONCLUSIONS : Despite their distinctive compositions and mechanisms of action, Stilpane® and Tramacet® are equally effective and well-tolerated combination analgesics in patients experiencing moderate to severe acute pain.Aspen Pharmacarehttp://www.tandfonline.com/ojfpam201

Self-isomerized−cyclometalated rhodium NHC complexes as active catalysts in the hydrosilylation of internal alkynes

ACCESSION CODES : CCDC 2065431–2065437 and 2081484 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.Please read abstract in the article.The National Research Foundation of South Africa and the University of Pretoria.https://pubs.acs.org/organometallicshj2023ChemistryPharmacolog

Cannabidiol-mediated green synthesis, characterization, and cytotoxicity of metal nanoparticles in human keratinocyte cells

This study investigated a unique one-pot microwave- assisted green synthesis method of gold (Au) and silver (Ag) nanoparticles (NPs) using cannabidiol (CBD) as a capping and reducing agent. Furthermore, Au and Ag NPs were also chemically synthesized using poly(vinyl pyrrolidone), which functioned as reference materials when comparing the size, shape, and cytotoxicity of NPs. Synthesis parameters such as reaction time, temperature, and precursor molar ratio were optimized to control the size and shape of the biosynthesized NPs. Various characterization techniques such as transmission electron microscopy, ultraviolet−visible spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction were used to confirm the formation and properties of Au and Ag NPs. Both biosynthesized metal NPs were spherical and monodispersed, with average particle sizes of 8.4 nm (Au-CBD) and 4.8 nm (Ag-CBD). This study also explored the potential cytotoxicity of CBD-capped NPs in human keratinocyte cells, which was observed to be of minimal concern. The novel synthesis approach presented in this study is free from harsh chemical reagents; therefore, these NPs can be used in a wide array of applications, including the pharmaceutical and biomedical fields.The Department of Science and Innovation and the Council for Scientific and Industrial Research.http://pubs.acs.org/journal/acsodfam2022PharmacologyPlant Production and Soil Scienc

One-step synthesis of metal oxide nanoparticles using cannabidiol: characterisation and cytotoxicity assessment in human keratinocyte cells

DATA AVAILABILITY STATEMENT : The data that support the findings of this study are available from the corresponding author upon reasonable request.Please read abstract in the article.The Department of Science and Innovation and the Council for Scientific and Industrial Research.https://chemistry-europe.onlinelibrary.wiley.com/journal/23656549hj2024PharmacologyPlant Production and Soil ScienceNon

A multi-centre, phase IV study to evaluate the steady-state plasma concentration and serum bactericidal activity of a generic teicoplanin preparation

INTRODUCTION : Teicoplanin is an effective treatment option against methicillin-resistant, Gram-positive bacteria, like Staphylococcus aureus. It is a glycopeptide antibiotic, produced through microbial fermentation, a process resulting in variations in the N-acyl side chain. Concerns that these variations may affect the pharmacokinetic profile and the clinical efficacy of generic teicoplanin preparations have been raised. METHOD : To address this issue, a multi-centre observational study was conducted to evaluate steady-state peak and trough serum concentrations, and the serum bactericidal activity (SBA) and safety of a generic teicoplanin preparation in critically ill patients. Additionally, the composition of the generic teicoplanin was compared to that of the innovator drug to assess differences in the composition. RESULTS: Following pre-determined loading and maintenance dose schedules, the mean peak and trough teicoplanin serum concentrations were 20.98 mg/l and 10.38 mg/l, respectively. A statistically significant association was observed between teicoplanin pharmacotherapy and increased ex vivo SBA. It was found using independent analysis that the composition of the generic teicoplanin preparation was similar to that of the innovator drug, and that both formulations met the European Pharmacopoeia specifications. CONCLUSION : The loading and maintenance schedules employed in this study were effective in establishing therapeutic serum teicoplanin concentrations in critically ill patients. Evidence of bactericidal activity measured in patients’ ex vivo serum samples, following treatment with the generic preparation, supports this finding.http://creativecommons.org/licenses/by-nc-nd/4.0am201

Design of oleanolic acid-based hybrid compounds as potential pharmaceutical scaffolds

BACKGROUND : Infectious diseases, as well as cancer, are the leading causes of death worldwide. Drug resistance usually results in their treatment requiring a combination of two or more drugs. OBJECTIVE : Oleanolic-based hybrid compounds were prepared via esterification and characterized using FTIR, NMR and LC-MS. In vitro antibacterial and in vitro cytotoxicity studies were performed. METHODS : Oleanolic acid was hybridized with selected known pharmaceutical scaffolds via the carboxylic acid functionality in order to develop therapeutics with increased biological activity. Antibacterial activity was determined using the micro-dilution assay against selected Gram-positive and Gram-negative bacteria and cytotoxicity using the sulforhodamine B assay. RESULTS : Compound 8 displayed potent antibacterial effect against five strains of bacteria, such as Bacillus subtilis, Staphylococcus aureus, Proteus vulgaris, Klebsiella oxytoca, and Escherichia coli, with MIC values of 1.25, 0.078, 0.078, 1.25, 1.25 mg/mL when compared to the control, oleanolic acid (MIC = 2.5 mg/mL). Furthermore, in vitro cytotoxicity, as determined using the SRB assay, against selected cancer cells revealed that compound 7 was the most cytotoxic on MDA, DU145, and MCF-7 cell lines with IC50 values of 69.87 ± 1.04, 73.2 ± 1.08, and 85.27 ± 1.02 μg/mL, respectively, compared to oleanolic acid with an IC50 > 200 μg/mL. CONCLUSION : Hybridization of oleanolic acid was successful, and further development of these potential antibacterial compounds with reduced cytotoxicity is therefore warranted.The South African Medical Research Council (Self-Initiated Research), National Research Foundation South African and Govan Mbeki Research and Development Centre (GMRDC), University of Fort Hare.https://benthamscience.com/journals/letters-in-drug-design-and-discoveryhj2023Pharmacolog

Binding pose analysis of hydroxyethylamine based β-secretase inhibitors and application thereof to the design and synthesis of novel indeno[1,2-b]indole based inhibitors

β-Secretase (BACE1) is recognised as a target for the treatment of Alzheimer’s disease, and transition-state isosteres such as hydroxyethylamines have shown promise when incorporated into BACE1 inhibitors. A computational investigation of previously reported carbazole-based hydroxylethylamines with contradictory binding poses was undertaken using molecular dynamic simulations to rationalise the ligands preferred binding preference. Visual inspection of the confirmed binding pocket showed unoccupied space surrounding the carbazole moiety which was probed through the synthesis of seventeen ligands wherein the carbazole ring system was replaced with an indeno[1,2-b]indole ring system. The most active compound, rac-1- [benzyl(methyl)amino]-3-(indeno[1,2-b]indol-5(10H)-yl)propan-2-ol, indicated an inhibition of 91% at 10 µM against β-secretase with a cytotoxicity IC50 value of 10.51 ± 1.11 µM against the SH-SY5Y cell line.This work was supported by the National Research Foundation (NRF) of South Africa (Thuthuka grant number 106959), the University of Pretoria (Research and Development Program) and the Council for Scientific and Industrial Research (CSIR), South Africa.The National Research Foundation (NRF) of South Africa, the University of Pretoria (Research and Development Program) and the Council for Scientific and Industrial Research (CSIR), South Africa.http://www.arkat-usa.orgpm2021ChemistryPharmacologyPhysiolog

The ability of three African herbal remedies to offer protection against an in vitro model of Parkinson’s disease

Parkinson’s disease, characterised by loss of dopaminergic neurons in the substantia nigra of the brain, is attributed to oxidative stress and mitochondrial dysfunction. As no cure is available, and dopamine-replacement therapy only offers symptomatic relief, other avenues of treatment are sought. Acokanthera oppositifolia, Boophone disticha and Xysmalobium undulatum are used ethnomedicinally for the treatment of neurological disorders, however, these plants have not been assessed in vitro for cytoprotective activity. The aim of the study was to assess the cytoprotective activity of these three plants in an in vitro SH-SY5Y cellular model of Parkinson’s disease induced by 6-hydroxydopamine (6-OHDA). Plant material was extracted using acetone and methanol ultrasonic maceration. Cytotoxicity was induced by exposing cells to 33.3 μM 6-OHDA for 2 h, followed by 24 h incubation with the crude extracts. Ultra-performance liquid chromatography high definition mass spectrometry was used for tentative identification of phytochemicals. Cytoprotection was initially assessed using the sulforhodamine B staining assay to determine concentration ranges. Mitochondrial membrane potential (MMP), reactive oxygen species (ROS) levels, reduced glutathione (GSH) content, intracellular Ca2+ flux and ATP levels were assessed using the JC-1 ratiometric, dihydrodichlorofluorescein cleavage, monochlorobamine adduct formation, Fura-2AM and bioluminescence assays, respectively. Cell morphology was visualized using polarisation-optical transmitted light differential interference contrast microscopy. Several phytochemicals were tentatively identified that are known markers in the plant species, however, little difference was noted between the acetone and methanol extracts qualitatively. Extracts reduced cell density by 91%, increased ROS (217.7%) and GSH (102.1%) levels. Mitochondrial depolarisation (54.2%) was evident. Crude extracts attenuated cytotoxicity by reducing ROS and sustaining ATP production, however, no alteration to MMP was observed. Furthermore, Ca2+ effects were maintained by B. disticha and X. undulatum, but reduced by A. oppositifolia. Morphological changes, characteristic of cytotoxicity, was observed when exposed to 6-OHDA-in the micrographs. Intermediate-polarity extracts reduced the detrimental effects associated with 6-OHDA-induced cytotoxicity. Xysmalobium undulatum (5 μg/mL) displayed the greatest level of cytoprotection, however, the inherent cytotoxicity may limit the usefulness of extracts during treatment of disease. Although none of the plant extracts showed potential to reverse in vitro characteristics of Parkinson’s disease completely, concomitant use with dopamine replacement therapy should be investigated as a possible treatment modality. Adjunct use of the crude extracts with traditional dopamine replacement therapy may offer an alternative approach, however, future studies are required to elucidate the feasibility of such a combination.The University of Pretoria Research Committee of the School of Medicine, Faculty of Health Sciences.http://www.elsevier.com/locate/sajb2020-11-01hj2019Pharmacolog