Hygrolidin is a macrocyclic lactone originally isolated from S. hygroscopicus. It inhibits proliferation of a variety of cancer cell lines, including DLD-1 colon cancer, LNCaP prostate cancer, and K562 leukemia cells (IC50s = 2.9, 5.2, and 33 ng/ml, respectively). Hygrolidin induces the expression and levels of p21 in DLD-1 cells, but not WI-38 fibroblasts, and leads to cell accumulation in the G1 and S phases without inducing apoptosis. It has antiparasitic activity against T. cruzi, L. donovani, and T. b. brucei but also induces cytotoxicity in HepG2 cells (IC50s = 1.1, 72.5, 77, and 24.5 nM, respectively).