Coumarin derivatives are derivatives of coumarin and are considered phenylpropanoids. [1] Among the most important derivatives are the 4-hydroxycoumarins, which exhibit anticoagulant properties, a characteristic not present for coumarin itself.
Some naturally occurring coumarin derivatives include umbelliferone (7-hydroxycoumarin), aesculetin (6,7-dihydroxycoumarin), herniarin (7-methoxycoumarin), psoralen and imperatorin.
4-Phenylcoumarin is the backbone of the neoflavones, a type of neoflavonoids.
Coumarin-pyrazole hybrids have been synthesized from hydrazones, carbazones and thiocarbazones via Vilsmeier Haack formylation reaction. Whereas, coumarin-pyridine hybrids have been prepared from the Knoevenagel condensation of pyridylacetontriles with substituted salicylaldehydes. [2]
Compounds derived from coumarin are also called coumarins or coumarinoids; this family includes:
Coumarin is transformed into the natural anticoagulant dicoumarol by a number of species of fungi. [8] This occurs as the result of the production of 4-hydroxycoumarin, then further (in the presence of naturally occurring formaldehyde) into the actual anticoagulant dicoumarol, a fermentation product and mycotoxin. Dicoumarol was responsible for the bleeding disease known historically as "sweet clover disease" in cattle eating moldy sweet clover silage. [8] [9] In basic research, preliminary evidence exists for coumarin having various biological activities, including anti-inflammatory, anti-tumor, antibacterial, and antifungal properties, among others. [8]
Warfarin – a coumarin – with brand name, Coumadin, is a prescription drug used as an anticoagulant to inhibit formation of blood clots, and so is a therapy for deep vein thrombosis and pulmonary embolism. [10] [11] [12] It may be used to prevent recurrent blood clot formation from atrial fibrillation, thrombotic stroke, and transient ischemic attacks. [12]
Coumarins have shown some evidence of biological activity and have limited approval for few medical uses as pharmaceuticals, such as in the treatment of lymphedema. [10] [13] Both coumarin and 1,3-indandione derivatives produce a uricosuric effect, presumably by interfering with the renal tubular reabsorption of urate. [14]
Arising from tunable intramolecular charge transfer (ICT) properties within the molecule, coumarins have found purpose as dyes and stains, particularly those featuring electron-donating substituents at the 7-position, which can be used to enhance this behavior. Coumarin dyes are extensively used as gain media in blue-green tunable organic dye lasers. [15] [16] [17] Among the various coumarin laser dyes are coumarins 480, 490, 504, 521, 504T, and 521T. [17] Coumarin tetramethyl laser dyes offer wide tunability and high laser gain, [18] [19] and they are also used as active medium in coherent OLED emitters. [20] [15] [16] [17] and as a sensitizer in older photovoltaic technologies. [21]