Rubiaceae, coumarins

The simple coumarin nucleus (Fig 7.3), which is derived by lactone formation of an ortho-hydroxy-czs cinnamic acid, is a common metabolite in higher plants and is often found in glycosidic form. Coumarins are common in Api-aceae, in certain genera of Fabaceae (e.g. Dipteryx odorata, Melilotus officinalis), Poaceae (e.g. Anthoxanthum odoratum) and Rubiaceae (e.g. Galium odoratum). However, proliferation of coumarins to the status of major chemical markers occurs in only a few cases, most notably, but not exclusively, in the Api-aceae (subfamily Apioideae) and in the Rutaceae (Gray and Waterman, 1978 Murray et al., 1982). In these cases, the coumarin nucleus has almost invariably been embellished by the addition of a prenyl unit leading to furocoumarin (Fig 7.3) and pyranocoumarin structures. 

The distribution of coumarins is widespread. Originally isolated from tonka beans, they are abundant in particular plant families, for example Rubiaceae—Asperula Poaceae—Avena Fabaceae—Medic-ago, Melilotus Rutaceae—Ruta, Citrus spp., Murraya Apiaceae— Angelica, Ammi. 

Farid HAR, Kunert O, Haslinger E, Seger C (2002) Isolation and structure elucidation of iridoid and coumarin derivatives from Xeromphis nilotica (Rubiaceae). Monatsh Chim 133 1453-1458... 

Origin of Some Central Trivial Names. Some names were chosen according to the discovery of the corresponding compounds such as cinnamic acid [Cinnamomum verum Presl., cinnamon tree (Lauraceae)], coumaric acids/ coumarin [Dipterix odorata (Aubl.) Wu-ld. sub nom. Coumarouna odorata Aubl. (Fabaceae)], caf-feic acid [Coffea arabica L., coffee tree (Rubiaceae)], and ferulic add (Ferula spp., Apiaceae). Quinic acid is named according to its discovery as a constituent of cinchona bark [Cinchona L. spp. (Rubiaceae)] this compound was named according to the German Chinarinde (cinchona bark) - corrupted from quina (Spanish... 

Coumarins are naturally found in many families of plants (Apiaceae, Asteraceae, Fabiaceae, Rosaceae, Rubiaceae, Rutaceae and Solanaceae) and microorganisms. 

---