Inhibitory effects of Syzygium aromaticum and Camellia sinensis methanolic extracts on the growth of Babesia and Theileria parasites

Abstract

Currently, chemotherapeutics against piroplasmosis are also associated with toxicity and the emergence of drug-resistant parasites. Therefore, the discovery of new drug compounds is necessary for the effective control of bovine and equine piroplasms. Syzygium aromaticum (clove) and Camellia sinensis (green tea) have several documented medicinal properties. In the present study, the growth-inhibiting effects of S. aromaticum and C. sinensis methanolic extracts were evaluated in vitro and in vivo. The half-maximal inhibitory concentration (IC₅₀) values for methanolic S. aromaticum against Babesia bovis, B. bigemina, B. divergens, B. caballi, and Theileria equi were 109.8 ± 3.8, 8.7 ± 0.09, 76.4 ± 4.5, 19.6 ± 2.2, and 60 ± 7.3 μg/ml, respectively. Methanolic C. sinensis exhibited IC₅₀ values of 114 ± 6.1, 71.3 ± 3.7, 35.9 ± 6.8, 32.7 ± 20.3, and 60.8 ± 7.9 μg/ml against B. bovis, B. bigemina, B. divergens, B. caballi, and T. equi, respectively. The toxicity assay on Madin-Darby bovine kidney (MDBK), mouse embryonic fibroblast (NIH/3T3), and human foreskin fibroblast (HFF) cell lines showed that methanolic S. aromaticum and methanolic C. sinensis affected only the viability of the MDBK cell line with half-maximal effective concentrations (EC₅₀) of 894.7 ± 4.9 and 473.7 ± 7.4 μg/ml, respectively, while the viability of NIH/3T3 and HFF cell lines was not affected even at 1000 μg/ml. In the in vivo experiment, methanolic S. aromaticum and methanolic C. sinensis oral treatments at 150 mg/kg inhibited the growth of Babesia microti in mice by 69.2% and 42.4%, respectively. These findings suggest that methanolic S. aromaticum and methanolic C. sinensis extracts have the potential as alternative remedies for treating piroplasmosis.

Keywords: Babesia; Camellia sinensis; In vitro; In vivo; Syzygium aromaticum; Theileria.