The coumarin (benzopyran-2-one, or chromen-2-one) ring system, present in natural products such as tonka beans, warfarin, and clover leaf, displays interesting pharmacological properties. The parent molecule was first isolated by Vogel from tonka beans. The coumarin ring can be looked upon as arising out of a fusion of a pyrone ring with a benzene nucleus. The derivatives of coumarin usually occur as secondary metabolites present in seeds, roots, and leaves of many plant species. More than 300 coumarins have been identified from natural sources, especially from green plants. These varying substances have disparate pharmacological, biochemical, and therapeutic applications. As for physical properties, coumarin is a white crystalline, volatile compound. It smells like vanilla and has a melting point of 341-344 K.
Types of coumarin and examples
There are various ways to classify coumarins according to their chemical structure, occurrence, or synthesis, thus it creates several classes of coumarins. Here we mention roughly categorized coumarins on the basis of their structure:
a. Simple coumarins
d. Pyrone-substituted coumarin
Coumarin in disease biology
Coumarins display a remarkable array of biochemical and pharmacological activity. Certain members of this group of compounds may significantly affect the function of various mammalian cellular systems. Coumarin is an aromatic compound that has a bicyclic structure with lactone carbonyl groups. The presence of an electronegative atom is effective for hydrogen bond formation and for solubility, to some extent and aromatic ring is responsible for having hydrophobicity. These phenomena are the cause of better interaction of the molecule with a receptor site. The substitution of coumarins makes them more significant for effective bioactivity. Numerous types of coumarins have been synthesized and also are present in nature. With different structures due to the various types of substitutions or pharmacophore in their basic nuclei, they are significant in showing effective and diverse classes of biological activity.
Based on the substitution pattern, coumarins show anticancer, anti-HIV, anticoagulant, antimicrobial, antioxidant, hepatoprotective, antithrombotic, antituberculosis, antiviral, anticarcinigenic, and anti-inflammatory activities. The pharmacological and biochemical properties and therapeutic applications of simple coumarins depend on the pattern of substitution in basic coumarin moiety. Therefore, there is a need to conduct a careful study of the SAR of coumarins.
Penta, S. (Ed.). (2015). Advances in Structure and Activity Relationship of Coumarin Derivatives. Academic Press.