Timothy Egan

Prof. Timothy Egan


Research Focus & Metrics

Academic Career Length

36Years (1991-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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8 October 2012 in ACS Chemical Biology
Verified
Journal Article
Closed access
JCJill M. Combrinck
Jill M. Combrinck
TMTebogo E. Mabotha
Tebogo E. Mabotha
KNKanyile K. Ncokazi
Kanyile K. Ncokazi
Melvin Anyasi AmbeleMelvin Anyasi Ambele
Melvin Anyasi Ambele
DTDale Taylor
Dale Taylor
TETimothy Egan
Timothy Egan

1 February 2008 in Molecular and Biochemical Parasitology
Verified
Journal Article
Closed access
TETimothy Egan
Timothy Egan

1 May 2008 in Journal of Inorganic Biochemistry
Verified
Journal Article
Closed access
TETimothy Egan
Timothy Egan

13 May 2021 in Accounts of Chemical Research
Verified
Journal Article
Closed access
KVKatherine A. de Villiers
Katherine A. de Villiers
TETimothy Egan
Timothy Egan

24 June 2015 in Malaria Journal
Verified
Journal Article
Open access
PDF file
JCJill M. Combrinck
Jill M. Combrinck
KFKim Y. Fong
Kim Y. Fong
LGLiezl Gibhard
Liezl Gibhard
PSPeter J. Smith
Peter J. Smith
David W. WrightDavid W. Wright
David W. Wright
TETimothy Egan
Timothy Egan
The activity of several well-known anti-malarials, including chloroquine (CQ), is attributed to their ability to inhibit the formation of haemozoin (Hz) in the malaria parasite. The formation of inert Hz, or malaria pigment, from toxic haem acquired from the host red blood cell of the parasite during haemoglobin digestion represents a pathway essential for parasite survival. Inhibition of this critical pathway therefore remains a desirable target for novel anti-malarials. A recent publication described the results of a haem fractionation assay used to directly determine haemoglobin, free haem and Hz in Plasmodium falciparum inoculated with CQ. CQ was shown to cause a dose-dependent increase in cellular-free haem that was correlated with decreased parasite survival. The method provided valuable information but was limited due to its low throughput and high demand on parasite starting material. Here, this haem fractionation assay has been successfully adapted to a higher throughput method in 24-well plates, significantly reducing lead times and starting material volumes. All major haem species in P. falciparum trophozoites, isolated through a series of cellular fractionation steps were determined spectrophotometrically in aqueous pyridine (5 % v/v, pH 7.5) as a low spin complex with haematin. Cell counts were determined using a haemocytometer and a rapid novel fluorescent flow cytometry method. A higher throughput haem fractionation assay in 24-well plates, containing at most ten million trophozoites was validated against the original published method using CQ and its robustness was confirmed. It provided a minimum six-fold improvement in productivity and 24-fold reduction in starting material volume. The assay was successfully applied to amodiaquine (AQ), which was shown to inhibit Hz formation, while the antifolate pyrimethamine (PYR) and the mitochondrial electron transporter inhibitor atovaquone (Atov) demonstrated no increase in toxic cellular free haem. This higher throughput cellular haem fractionation assay can easily be applied to novel anti-malarials with a significantly decreased lead time, providing a valuable tool with which to probe the mechanisms of action of both new and established anti-malarials.

1 May 2014 in Bioorganic & Medicinal Chemistry
Verified
Journal Article
Closed access
NWNing Wang
Ning Wang
KWKathryn J. Wicht
Kathryn J. Wicht
KIKento Imai
Kento Imai
MWMing-Qi Wang
Ming-Qi Wang
TNTran Anh Ngoc
Tran Anh Ngoc
TITsutomu Inokuchi
Tsutomu Inokuchi