Growth inhibitory effect of selected quinones from Indian medicinal plants against Theileria annulata

Tropical Bovine Theileriosis, caused by the protozoan parasite Theileria annulata, poses a significant threat to cattle populations. Currently, Buparvaquone is the sole effective naphthoquinone drug commercially available for its treatment. In our research, we delved into the potential of naturally occurring quinones as alternative treatments. We isolated two quinones, emodin and chrysophanol, from Rheum emodi Wall, and two more, embelin and lawsone, from Embelia ribes Burm.f. and Lawsonia inermis L. respectively. We assessed the anti-Theileria efficacy of these quinones in vitro using MTT and flow cytometric assays on T. annulata-infected bovine lymphocytes. Additionally, we evaluated their safety on uninfected bovine Peripheral Blood Mononuclear Cells (PBMC) and Vero cells. Emodin emerged as a promising candidate, exhibiting an IC50 value of 4 μM, surpassing that of buparvaquone. Emodin also displayed relatively low LD50 values of 1.74 mM against uninfected PBMC and 0.87 mM against Vero cells, suggesting potential safety. Remarkably, emodin demonstrated a high cell absorption rate of 71.32%. While emodin's efficacy and bioavailability are encouraging, further research is imperative to validate its safety and effectiveness for treating Tropical Bovine Theileriosis. [Display omitted] •Isolated and characterized four naturally occurring quinones from Rheum emodi, Embelia ribes, and Lawsonia inermis.•Conducted a structural similarity analysis between these quinones and the existing anti-theilerial drug, Buparvaquone.•Investigated dose-dependent drug response of quinones against Tropical Bovine Theileriosis caused by Theileria annulata using MTT assay.•Determined IC50 and IC99 values for each quinone, comparing their efficacy to buparvaquone.•Evaluated the rate of quinone uptake by the cells and determined the the LD50 values of the quinones against uninfected PBMC and Vero cell line.