Rosmarinic acid is frequently found in the Boraginaceae and Lamiaceae families. It has also been identified in other families (Acanthaceae, Amaranthaceae, Apiaceae, Araceae, Araliaceae, Asteraceae, Boragina­ceae, Brassicaceae, Cannaceae, Celastraceae, Crassulaceae, Cucurbitaceae, Cyperaceae, Dipsacaceae, Fabaceae, Iridaceae, Lamiaceae, Linderniaceae, Malvaceae, Marantaceae, Melianthaceae, Moraceae, Myrtaceae, Onagraceae, Plantaginaceae, Poaceae, Polygonaceae, Portulacaceae, Potamogetonaceae, Rosaceae, Rubiaceae, Sapindaceae, Scrophulariaceae, Solanaceae, Zosteraceae etc.). For example, it has been found in ferns of the Blechnaceae family, in lower plants such as Anthocerotophyta, in marine plants, in monocotyledonous plants such as Potamogetonaceae and Cannaceae. Therefore, Rosmarinic acid is not a marker compound for chemotaxonomic studies. Before the structure of Rosmarinic acid was fully elucidated, the expression “Labiatengerbstoffe” (Lamiaceae tannin) was used for Rosmarinic acid and similar structures, meaning tannin-like structure in the Lamiaceae family. A short time later, in 1958, two Italian chemists isolated Rosmarinic acid from Rosmarinus officinalis for the first time and named Rosmarinic acid. The structure is discovered as the 3,4-dihydroxyphenyllactic acid ester of caffeic acid. Biogenetic studies with Rosmarinic acid began in the 1970s. It was found that how Rosmarinic acid was synthesized starting from phenylalanine and tyrosine by radioactive labeling of the amino acids of Mentha sp. The caffeic acid moiety consists only of phenylalanine and the 3,4-dihydroxyphenyllactic acid moiety consists only of tyrosine. The biosynthesis pathway has also been confirmed by plant cell culture studies with Coleus blumei (Petersen & Simmonds, 2003).