In vivo activity and atom pair fingerprint analysis of MMV665941 against the apicomplexan parasite Babesia microti, the causative agent of babesiosis in humans and rodents

Abstract

The effect of MMV665941 on the growth of Babesia microti (B. microti) in mice, was investigated in this study using a fluorescence-based SYBR Green I test. Using atom Pair signatures, we investigated the structural similarity between MMV665941 and the commonly used antibabesial medicines diminazene aceturate (DA), imidocarb dipropionate (ID), or atovaquone (AV). In vitro cultures of Babesia bovis (B. bovis) and, Theileria equi (T. equi) were utilized to determine the MMV665941 and AV interaction using combination ratios ranged from 0.75 IC₅₀ MMV665941:0.75 IC₅₀ AV to 0.50 IC₅₀ MMV665941:0.50 IC₅₀ AV. The used combinations were prepared depending on the IC₅₀ of each drug against the in vitro growth of the tested parasite. Every 96 h, the hemolytic anemia in the treated mice was monitored using a Celltac MEK-6450 computerized hematology analyzer. A single dose of 5 mg/kg MMV665941 exhibited inhibition in the B. microti growth from day 4 post-inoculation (p.i.) till day 12 p.i. MMV665941 caused 62.10%, 49.88%, and 74.23% inhibitions in parasite growth at days 4, 6 and 8 p.i., respectively. Of note, 5 mg/kg MMV665941 resulted in quick recovery of hemolytic anemia caused by babesiosis. The atom pair fingerprint (APfp) analysis revealed that MMV665941 and atovaquone (AV) showed maximum structural similarity. Of note, high concentrations (0.75 IC₅₀) of MMV665941 and AV caused synergistic inhibition on B. bovis growth. These findings suggest that MMV665941 might be a promising drug for babesiosis treatment, particularly when combined with the commonly used antibabesial drug, AV.

Keywords: Babesia microti; MMV665941; atovaquone; in vivo; structural similarity measurements.

Figure 1.

Chemotherapeutic efficacy of MMV665941 on the growth of Babesia microti. (a) Parasite growth as assessed by emitted fluorescence following staining of parasite DNA with SYBR Green. (b) Hemoglobin (HGB) levels in the blood. Mean ± SD for five mice per experimental group. Asterisks denote a statistically significant difference (P <0.05) between treated or infected mice and uninfected mice. Arrows indicate the dosing period for each drug (green arrow indicate the single oral dose of MMV compound at day 3 post-inoculation; red arrow indicate the five subcutaneous dose of diminazene aceturate (DA) from day 3 to day 7 post-inoculation).

Figure 2.

Structural similarities measurement between the MMV665941, diminazene aceturate, imidocarb dipropionate, and atovaquone. (a) Hierarchical clustering analysis. The hierarchical clustering analysis was performed using ChemmineR software. (b) A heatmap showing the molecular weight correlation. The single linkage method was used with Z-scores display values. Compound CID: 68050 = MMV665941, Compound CID: 5284544 = diminazene aceturate, Compound CID: 9983292 = imidocarb dipropionate, and Compound CID: 74989 = atovaquone.

Figure 3.

PubChem fingerprint for similarity workbench between MMV665941 and the commonly used antibabesial drugs.