In vitro inhibitory effects of puberulic acid on the growth of Babesia and Theileria parasites

: Puberulic acid, a tropolone compound, has antibacterial and antimalarial activities. In this study, we investigated the in vitro inhibitory effects of puberulic acid on three Babesia species and Theileria equi . Puberulic acid inhibited the growth of Babesia bovis , Babesia bigemina , Babesia caballi , and Theileria equi with IC 50 values of 1.79 ± 0.3, 1.58 ± 0.2, 2.6 ± 0.3, and 3.83 ± 0.4 µM, respectively, starting from an initial parasitemia of 1%. At 5 M, puberulic acid completely inhibited growth in B. caballi , 10 µM in B. bovis , and 25 µM in B. bigemina and T. equi cultures. Parasite growth was inhibited in the viability test at concentrations of 5 µM for B. bigemina and B. caballi , 10 µM for B. bovis , and 100 µM for T. equi . Puberulic acid had higher IC 50 values than diminazene aceturate. At the concentrations used, the DMSO solvent did not influence the growth of the parasites. According to the in vitro results, puberulic acid may be a promising candidate for developing a new antibabesial drug. More research, including extensive in vivo assessment, is urgently needed.