Combination with anticoagulant drugs, particularly coumarin derivatives, also increases the risk of bleeding. Coniferyl alcohol is an intermediate in biosynthesis of eugenol and of stilbenoids and coumarin. Other coumarin glycosides are obtained from dried leaves of "Psoralea corylifolia". These oral anticoagulants are derived from coumarin, which is found in many plants. Other historically common fluorophores are derivatives of rhodamine (TRITC), coumarin, and cyanine. The biosynthesis of coumarin in plants is via hydroxylation, glycolysis, and cyclization of cinnamic acid. "Gerbera" contains naturally occurring coumarin derivatives. The chemical structure of furanocoumarins consists of a furan ring fused with a coumarin. Coumestrol, an isoflavone coumarin derivative, is the only coumestan in foods. They consist of coumarin annulated with furan. Coumarin and its derivatives are all considered phenylpropanoids. Osthol is a chemical compound which is a derivative of coumarin. Two chemicals found in sweetgrass, phytol and coumarin, repel mosquitoes. Its report specifically states that Ceylon cinnamon ("Cinnamomum verum") contains "hardly any" coumarin. Here, the aglycone is coumarin or a derivative.