Coumarin is known as the parent organic chemical compound that belongs to a class of phytochemicals that occur naturally in several plant species. It is an oxygen heterocycle, which is better known for its aroma that has resemblance of vanilla or the scent of new-mown hay. Coumarin was identified for the first time way back in the 1820s and has been subsequently synthesized in laboratory from 1868 onwards. The synthesized or artificially prepared coumarin was mainly used in the manufacture of fragrances and essences. In addition, coumarin is used in the preparation of other chemicals, especially  rodent poison and anticoagulants.

Coumarin is present in an assortment of plants, including Tonka bean, licorice, lavender and sweet clover grass. In addition, coumarin is also found naturally in certain food plants, for instance, apricots, strawberries, cinnamon, cherries and dong quai. It is generally believed that coumarins function as a pesticide for the plants that produce this chemical compound.

Dicoumarol, a fermented produce of coumarin that occurs naturally in decomposed sweet clover, is a potent anticoagulant that ultimately causes hemorrhage or bleeding - this property of the substance forms the basis of warfarin rat poison. Over the years, numerous derivatives of coumarin have been used as anticoagulant agents in contemporary medicine. The derivatives of coumarin have resemblance to the structure of vitamin K and this has resulted in conjectures that they function by contending for the prothrombin - the substance in coumarin that is responsible for reasons behind the formation of clotting. In fact, this opinion has been strengthened following the discovery that the exploits of coumarins in this aspect are neutralized by vitamin K.

The presence of anti-clotting coumarins and also the haemolytic saponins actually averts safe injection of materials from plants directly into the bloodstream. Luckily enough, coumarins are counterbalanced to safe derivatives in the alimentary canal and, hence, generally do not create any problem when ingested. These are the main grounds for which coumarins are never used in the form of anti-coagulants in herbal medicine.

It may be noted that coumarins also possess a number of anti-bacterial attributes, for instance the ones like mouse eared hawkweed (botanical name, Pilosella officinal rum) has proved to be the prime active agent in the conventional as well as seemingly successful use of that plant in treating surging (rising and falling) fevers in goats.

Several other by-products of coumarin have been identified, for instance, the aglycone of the helpful vascular curative agent aesculin obtained from horse chestnut (botanical name, Aesculus hippocastanum); scopoletin  from the deadly nightshade family and umbelliferone, an anti-fungal present in the plants belonging to the parsley or Umbelliferae family as well as in several different individual medications, and also the strong vasodilators, such as visnagin and khellin from the Middle East plant Ammi visnaga. Bergapten is one more familiar coumarin. It is drawn from bergamot oil contentiously made use of in the form of a sun-screening agent in several contemporary suntan ointments.

In contemporary times, coumarins are considered to be an imperative cluster of organic compounds owing to their multifarious uses - they are extensively used in food and cosmetic production, as optical brightening agents, as dispersed incandescent as well as in the form of laser dyes.

While coumarins are only approved for a few remedial uses as pharmaceuticals, it may be noted that during a number of studies, they have also demonstrated some proof of numerous biological activities. The biological activities reported for coumarins comprise of anti-tumor, anti-HIV, anti-hypertension, anti-inflammatory, anti-arrhythmia (any substance that prevents and/ or slows down abnormal heartbeat), antiseptic, anti-osteoporosis and analgesic or palliative. In addition, coumarins are also used to treat asthma. Many physicians also recommend the use of coumarin in treating lymphedema (a condition wherein there is an accumulation of lymph in soft tissue, which is accompanied by swelling).

Coumarin has also been found to possess appetite-suppressing properties, which denotes that it has the ability to hold back hunger. This attribute of this organic chemical compound explains why it is naturally present in a large variety of plants, particularly clovers and grasses, and when animals graze on such fodder have a reduced appetite and, hence, the plants are saved from their onslaught. While this organic compound possesses a pleasurable sweet fragrance, sweet grass and sweet clover have derived their names from it, coumarin is not known to have a pleasant flavor. In fact, coumarin possesses a bitter flavor for which animals normally avoid it whenever it is possible.

A number of ordinary herbs enclose considerable amounts of coumarin. Some of these common herbs include:

  • Visnaga (Ammi visnaga)
  • Horse chestnut seed (Aesculus hippocastanum)
  • Sweet Woodruff (Asperula odorata)
  • Red Clover (Trifolium pratense)
  • Sweet Clover (Melilotus spp.)