A new cucurbitacin D analogue, 2-deoxycucurbitacin D (1), as well as cucurbitacin D (2) and 25-acetylcucurbitacin F (3) were isolated from Sloanea zuliaensis. Compound 1 was found only in the young leaves of the plant and not in the mature leaves, and its structure was established using spectroscopic means. Compounds 1-3 demonstrated potent cytotoxic activity against breast (MCF-7), lung (H-460), and central nervous system (SF-268) human cancer cell lines.