title: Antitumor agents XVII; Structure and stereochemistry of microhelenin-A, a new antitumor sesquiterpene lactone from Helenium microcephalum.
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000032:analysis*; D007783:Lactones / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D010946:Plants, Medicinal / Q000032:analysis*; D012717:Sesquiterpenes / Q000032:analysis*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D007783:Lactones; D012717:Sesquiterpenes