A novel 16, 23-epoxy-5β-cholestane triglycoside (1) was isolated from the bulbs of Ornithogalum saundersiae (Lilaceae). The structure was determined by extensive spectroscopic analysis. The conformation of the E-ring part of 1 was studied through molecular mechanics and molecular dynamics calculation methods. Compound 1 potently inhibited proliferation of peripheral blood lymphocytes provided from a chronic renal failure patient without causing any cytotoxicity in the lymphocytes and HL-60 human leukemia cells.