@misc{10481/69941,
year = {2021},
month = {4},
url = {http://hdl.handle.net/10481/69941},
abstract = {We have recently reported on the development and trypanocidal activity of a class of inhibitors of
Trypanosome Alternative Oxidase (TAO) that are targeted to the mitochondrial matrix by coupling to
lipophilic cations via C14 linkers to enable optimal interaction with the enzyme’s active site. This strategy
resulted in a much-enhanced anti-parasite effect, which we ascribed to the greater accumulation of the
compound at the location of the target protein, i.e. the mitochondrion, but to date this localization has
not been formally established. We therefore synthesized a series of fluorescent analogues to visualize
accumulation and distribution within the cell. The fluorophore chosen, julolidine, has the remarkable
extra feature of being able to function as a viscosity sensor and might thus additionally act as a probe of
the cellular glycerol that is expected to be produced when TAO is inhibited. Two series of fluorescent
inhibitor conjugates incorporating a cationic julolidine-based viscosity sensor were synthesized and
their photophysical and biological properties were studied. These probes display a red emission, with a
high signal-to-noise ratio (SNR), using both single- and two-photon excitation. Upon incubation with
T. brucei and mammalian cells, the fluorescent inhibitors 1a and 2a were taken up selectively in the
mitochondria as shown by live-cell imaging. Efficient partition of 1a in functional isolated (rat liver)
mitochondria was estimated to 66 ± 20% of the total. The compounds inhibited recombinant TAO enzyme
in the submicromolar (1a, 2c, 2d) to low nanomolar range (2a) and were effective against WT and
multidrug-resistant trypanosome strains (B48, AQP1-3 KO) in the submicromolar range. Good selectivity
(SI > 29) over mammalian HEK cells was observed. However, no viscosity-related shift could be detected,
presumably because the glycerol was produced cytosolically, and released through aquaglyceroporins,
whereas the probe was located, virtually exclusively, in the trypanosome’s mitochondrion.},
organization = {Spanish Ministerio de Economia
y Competitividad (grant SAF2015-66690-R)},
organization = {Spanish Ministerio
de Ciencia, Innovación y Universidades (MCIU/AEI/FEDER,
UE; grants RTI2018-093940-B-I00 to CD, and CTQ2017-85658-R to AO)},
organization = {Japan Society for the promotion of Science (JSPS grant-
17F17420 to GUE)},
organization = {Petroleum Technology Development Fund (PTDF), Abuja, Nigeria},
organization = {Ph.D. studentship from the Ministry of
Health of Saudi Arabia},
publisher = {Elsevier},
keywords = {Trypanosome alternative oxidase (TAO)},
keywords = {Inhibitor},
keywords = {Trypanosoma brucei},
keywords = {Molecular rotor},
keywords = {Fluorescent probe},
keywords = {2,4-dihydroxybenzoic acid derivative},
keywords = {Julolidine},
title = {Synthesis, biological, and photophysical studies of molecular rotorbased fluorescent inhibitors of the trypanosome alternative oxidase},
doi = {10.1016/j.ejmech.2021.113470},
author = {Cueto Díaz, Eduardo J. and González García, María del Carmen and Girón González, María Dolores and Salto González, Rafael and González Vera, Juan Antonio and Ruedas Rama, María José and Orte Gutiérrez, Ángel},
}