Preliminary Evaluation of Artemisinin–Cholesterol Conjugates as Potential Drugs for the Treatment of Intractable Forms of Malaria and Tuberculosis |
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| Authors: | Mokhitli Morake Dr Dina Coertzen Dr Andile Ngwane Dr Johannes F Wentzel Dr Ho Ning Wong Dr Frans J Smit Prof Lyn‐Marie Birkholtz Ray‐Dean Pietersen Dr Bienyameen Baker Prof Ian Wiid Prof David D N'Da Prof Richard K Haynes |
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| Affiliation: | 1. Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, South Africa;2. Department of Biochemistry, Centre for Sustainable Malaria Control, University of Pretoria, Hatfield, South Africa;3. DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa |
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| Abstract: | To evaluate the feasibility of developing drugs that may be active against both malaria and tuberculosis (TB) by using in part putative cholesterol transporters in the causative pathogens and through enhancement of passive diffusion in granulomatous TB, artemisinin–cholesterol conjugates were synthesized by connecting the component molecules through various linkers. The compounds were screened in vitro against Plasmodium falciparum (Pf) and Mycobacterium tuberculosis (Mtb). Antimalarial activities (IC50) against Pf drug‐sensitive NF54, and drug‐resistant K1 and W2 strains ranged from 0.03–2.6, 0.03–1.9, and 0.02–1.7 μm . Although the compounds are less active than the precursor artemisinin derivatives, the cholesterol moiety renders the compounds relatively insoluble in the culture medium, and variation in solubilities among the different compounds may reflect in the range of efficacies observed. Activities against Mtb H37Rv were assessed using a standardized colony‐forming unit (CFU) assay after 24 h pretreatment of cultures with each of the compounds. Percentage inhibition ranged from 3–38 % and 18–52 % at 10 and 80 μm , respectively. Thus, in contrast to the comparator drug artemether, the conjugates display enhanced activities. The immediate aims include the preparation of conjugates with enhanced aqueous solubilities, assays against malaria and TB in vivo, and for TB, assays using an infected macrophage model and assessment of granuloma influx. |
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| Keywords: | artemisinins cholesterol conjugates malaria tuberculosis |
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