Synthesis, biological, and photophysical studies of molecular rotor-based fluorescent inhibitors of the Trypanosome Alternative Oxidase

Cueto-Díaz, E. J. et al. (2021) Synthesis, biological, and photophysical studies of molecular rotor-based fluorescent inhibitors of the Trypanosome Alternative Oxidase. European Journal of Medicinal Chemistry, 2020, 113470. (doi: 10.1016/j.ejmech.2021.113470) (PMID:33940464)

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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.

Item Type:Articles
Additional Information:This work was supported by the Spanish Ministerio de Economia y Competitividad (grant SAF2015-66690-R), the Spanish Ministerio de Ciencia, Innovacion y Universidades (MCIU/AEI/FEDER, UE; grants RTI2018-093940-B-I00 to CD, and CTQ2017-85658-R to AO) and the Japan Society for the promotion of Science (JSPS grant-17F17420 to GUE). MAU is funded through a studentship from the Petroleum Technology Development Fund (PTDF), Abuja, Nigeria. IAA was funded through a Ph.D. studentship from the Ministry of Health of Saudi Arabia.
Glasgow Author(s) Enlighten ID:ALFAYEZ, IBRAHIM ABDULLAH M and Ebiloma, Mr Godwin and Ungogo, Mr Marzuq and De Koning, Professor Harry and Lemgruber Soares, Dr Leandro
Authors: Cueto-Díaz, E. J., Ebiloma, G. U., Alfayez, I. A., Ungogo, M. A., Lemgruber, L., González-García, M. C., Giron, M. D., Salto, R., Fueyo-González, F. J., Shiba, T., González-Vera, J. A., Ruedas Rama, M. J., Orte, A., De Koning, H. P., and Dardonville, C.
College/School:College of Medical Veterinary and Life Sciences
College of Medical Veterinary and Life Sciences > School of Infection & Immunity
Journal Name:European Journal of Medicinal Chemistry
ISSN (Online):1768-3254
Published Online:16 April 2021
Copyright Holders:Copyright © 2021 The Authors
First Published:First published in European Journal of Medicinal Chemistry 220:113470
Publisher Policy:Reproduced under a Creative Commons License

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