Anti-Parasitic Activity of ssDNA-Aptamers Targeting the Poly(A)-Binding Protein in Leishmania donovani Promastigotes

Haimn Abdulbassit Tawfiq; Ahmed Ali Mohammed; Yassir Mustafa Al Mulla Hummadi; Mohammed Abdaljabar Abdalqader

doi:10.32947/ajps.v26i3.1422

Authors

Haimn Abdulbassit Tawfiq Department of Pharmacology and Toxicology, College of Pharmacy, Mustansiriyah University, ‎Baghdad, Iraq
Ahmed Ali Mohammed Department of Clinical Laboratory Sciences, College of Pharmacy, Mustansiriyah University, Iraq
Yassir Mustafa Al Mulla Hummadi Department of Pharmacology and Toxicology, College of Pharmacy, Mustansiriyah University, Iraq
Mohammed Abdaljabar Abdalqader Faculty of Medicine, University of Cyberjaya, Persiaran Bestari, Cyber 11, 63000 Cyberjaya, Selangor Darul Ehsan, Malaysia

DOI:

https://doi.org/10.32947/ajps.v26i3.1422

Keywords:

Poly(A)-binding protein, ssDNA aptamers, Visceral leishmaniasis, promastigotes, Lipofectamine 2000

Abstract

Background: Visceral leishmaniasis caused by Leishmania donovani still depends on a small group of drugs whose value is diminished by toxicity, cost and resistance, so targets specific to the parasite remain attractive. The cytoplasmic poly(A)-binding protein (PABP) of Leishmania governs mRNA stability and translation, processes on which these parasites lean heavily because they lack conventional transcriptional control.

Aim: To evaluate the antiparasitic activity against L. ‎donovani promastigotes of two distinct PABP-targeting ssDNA aptamers complexed with Lipofectamine 2000, AP-7/LF and AP-11/LF.

Methods: Growth inhibition was measured by the MTT assay at 24 and 48 hours, and PABP protein abundance was quantified by Western blot densitometry against a GAPDH loading control.

Results: Both complexes inhibited promastigote growth in a concentration- and time-dependent manner, but AP-11/LF was the stronger agent throughout: its IC₅₀ values were 234 nM after 24 hours and 194 nM after 48 hours against 1810 nM and 1300 nM for AP-7/LF, a difference of roughly 7.7-fold and 6.7-fold, respectively. The Western blot results followed the same ranking, as AP-11/LF lowered PABP to 0.51 of the untreated control (a 48.6% reduction, p = 0.001), whereas AP-7/LF lowered it to 0.67 (a 32.9% reduction, p = 0.018). The lipofectamine alone and the carrier-free aptamers produced only small, non-significant changes.

Conclusion: The poly(A)-competitive aptamer (AP-11) outperformed the high-affinity, non-competitive aptamer (AP-7) at both the growth and the protein level, supporting PABP disruption as a workable starting point for antileishmanial drug development.

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