Plant Coumarins: Myths and Realities

Abstract

Plant coumarins are structurally distinct, nonanticoagulant compounds that have significant medical activity. They can be fermented by various fungi to metabolites, which then dimerize to vitamin K—antagonist anticoagulants, but these are not inherently found in any known plants. Plant coumarins are often described as being anticoagulant and as interacting with drug anticoagulants, despite all evidence to the contrary. Coumarin itself does have potential to cause hepatotoxicity, perhaps in the tiny subset of people who take enough and have insufficient CYP2A6 activity to break coumarin down into safe catabolites. The particular concern over Cinnamomum aromaticum (cassia) versus Cinnamomum zeylanicum (true cinnamon) is discussed. Plant coumarins and plants rich in these compounds, including Melilotus spp. (sweet clover), Angelica keiskei (ashitaba), Angelica pubescens (pubescent angelica), Artemisia scoparia (yin-chen wormwood), Citrus spp. (orange), Glycyrrhiza uralensis (licorice), Justicia pectoralis (c...