Professor Juan David Valencia-Hernandez (Armenia / CO), Dr. Diego Molina (Armenia / CO), Professor Juan Carlos Sepulveda-Arias (Pereira / CO), Professor Angela Veloza (Pereira / CO), Professor Jorge Enrique Gómez Marin (Armenia / CO)
Tabebuia is a large flowering tree genus widely used in traditional medicine in Colombia. We obtained methanol, n-hexane, chloroform, ethyl acetate, n-butanol, and water extracts from the leaves and stems of Tabebuia rosea and Tabebuia chrysantha collected on the Campus of the Universidad Tecnológica de Pereira in May 2021, under permission number 1133/2014, issued by the National Environmental Licensing Authority 431 (Autoridad Nacional de Licencias Ambientales - ANLA) in Colombia. The in vitro anti-Toxoplasma activity of triplicates of increasing concentrations (6.25, 12.5, 25, 50 and 100 mg/ml) from 17 extracts was evaluated using the β-galactosidase colorimetric assay to obtain half-maximal inhibitory concentration (IC50). The cytotoxicity for human cells was assayed by an Alamar Blue assay with 0.5 mM resazurin in non-cancer human foreskin fibroblast cell culture –HFF (ATCC SCRC-1041) in T-25 flasks until 100% of cell confluence. Host cell viability was determined by comparing treatments with no compound treatment at 100% viability. The median toxicity dose (TD50) on HFF cells was obtained, therapeutic index (TI) was calculated by TD50/IC50. We found four extracts that showed significant inhibitory effects on the proliferation of T. gondii: one from the leaves of T. rosea (IC50:6,8, TI: 7,3) and three from T. chrysantha, two from the inner bark, one extracted with chloroform (IC50:3,4; TI: 41,7) and one with hexane (IC50:74,8; TI: 54), and one from leaves after extraction with chloroform (IC50:5,6; TI: 4,4). Our study successfully identified components from native Tabebuia species with promising anti-Toxoplasma activity. Funding: Sistema General de Regalías de Colombia (BPIN 2020000100077).