Antileishmanial Activity and Immunomodulatory Effects of Tricin Isolated from Leaves of Casearia arborea (Salicaceae).  Bioactivity-guided fractionation of antileishmanial active extract from leaves of Casearia arborea led to isolation of three metabolites: tricin (1), 1'',6''-di-O-β-d-vanilloyl glucopyranoside (2) and vanillic acid (3). Compound 1 demonstrated the highest activity against the intracellular amastigotes of Leishmania infantum, with an IC50 value of 56 μm. Tricin (1) demonstrated selectivity in mammalian cells (SI > 7) and elicited immunomodulatory effect on host cells. The present work suggests that tricin modulated the respiratory burst of macrophages to a leishmanicidal state, contributing to the parasite elimination. Therefore, the natural compound tricin could be further explored in drug design studies for leishmaniasis treatment.