Exploring para-thiophenols to expand the SAR of antimalarial 3-indolylethanones
- Authors: Chisango, Ruramai Lissa
- Date: 2018
- Subjects: Antimalarials , Malaria Chemotherapy , Thiols , Plasmodium falciparum , Blood-brain barrier
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/63515 , vital:28428
- Description: According to the WHO, malaria is responsible for over half a million deaths annually especially in populations from disadvantaged settings. Although there has been a documented improvement in the mortality rates, malaria has proved to be a global emergency. Mostly affecting the poor population, this disease is perpetuating a vicious cycle of poverty in the developing world as current preventive measures are not adequate unless adopted in addition to effective treatment. However, there has been a worldwide increase in resistance to available treatment which presents a need for novel, affordable treatment. A study conducted in our laboratory identified two hit thiophenol containing compounds 2.24 and 2.25. These molecules provided initial insight into the SAR and potential pharmacophore of this class of compounds. We decided to further explore these compounds by making bioisosteric replacements to optimize the structure as we monitor the effect of these modifications on the anti-plasmodial activity. The synthetic pathway to form the target compounds of our study comprised of three steps which were initiated by the Friedel-Crafts acetylation of the indoles resulting in compounds 3.5 - 3.7. A bromination step followed which yielded the -bromo ketones (3.8 - 3.11). Some of the thiophenols (3.14 and 3.16) were not readily available in our laboratory and so were synthesized for the final synthetic step. This step involved the nucleophilic displacement of the -bromine to generate the -aryl substituted 3-indolylethanones (3.17 - 3.27). The thioethers displayed improved antimalarial activity from 2.24 and 2.25 against the chloroquine sensitive 3D7 Plasmodium falciparum strain. In addition, these compounds were non-toxic against HeLa cells which indicated this potential novel class of antimalarials is selective for the malaria parasite as hypothesized in the previous study conducted in our laboratory. In an attempt to predict the bioavailability of some of our compounds, in silico studies were conducted revealing that these compounds could be passively absorbed by the gastrointestinal tract, a positive result for bioavailability purposes. However, results from these studies indicate that modifications of these compounds would be necessary to allow for permeation through the blood brain barrier (BBB) for instances when the patient has cerebral malaria. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2018
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- Date Issued: 2018
Expanding the SAR of Nontoxic Antiplasmodial Indolyl-3-ethanone Ethers and Thioethers.
- Authors: Lunga, Mayibongwe J , Chisango, Ruramai Lissa , Weyers, Carli , Isaacs, Michelle , Taylor, Dale , Edkins, Adrienne L , Khanye, Setshaba D , Hoppe, Heinrich C , Veale, Clinton G L
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/122908 , vital:35370 , https://doi.org/10.1002/cmdc.201800235
- Description: Despite major strides in reducing Plasmodium falciparum infections, this parasite still accounts for roughly half a million annual deaths. This problem is compounded by the decreased efficacy of artemisinin combination therapies. Therefore, the development and optimisation of novel antimalarial chemotypes is critical. In this study, we describe our strategic approach to optimise a class of previously reported antimalarials, resulting in the discovery of 1‐(5‐chloro‐1H‐indol‐3‐yl)‐2‐[(4‐cyanophenyl)thio]ethanone (13) and 1‐(5‐chloro‐1H‐indol‐3‐yl)‐2‐[(4‐nitrophenyl)thio]ethanone (14), whose activity was equipotent to that of chloroquine against the P. falciparum 3D7 strain. Furthermore, these compounds were found to be nontoxic to HeLa cells as well as being non‐haemolytic to uninfected red blood cells. Intriguingly, several of our most promising compounds were found to be less active against the isogenic NF54 strain, highlighting possible issues with long‐term dependability of malarial strains. Finally compound 14 displayed similar activity against both the NF54 and K1 strains, suggesting that it inhibits a pathway that is uncompromised by K1 resistance.
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