Chalcones: Compounds based on CHALCONE. They are important intermediates in the formation of FLAVONOIDS.ChalconeAngelica: A plant genus of the family Apiaceae.Salix: A plant genus of the family SALICACEAE. Members contain salicin, which yields SALICYLIC ACID.Millettia: A plant genus of the family FABACEAE. Members contain ISOFLAVONES, some of which show molluscicidal and schistosomicidal activity. Some species of Pongamia have been reclassified to this genus and some to DERRIS.Flavanones: A group of FLAVONOIDS characterized with a 4-ketone.Plant Bark: The outer layer of the woody parts of plants.Luciferases, Renilla: Luciferases from RENILLA that oxidizes certain LUMINESCENT AGENTS to cause emission of PHOTONS.Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.Structure-Activity Relationship: The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.Antiprotozoal Agents: Substances that are destructive to protozoans.Flavonoids: A group of phenyl benzopyrans named for having structures like FLAVONES.