Furocoumarin

Part of speech: noun

Definitions

1. A naturally occurring organic compound found in certain plants that makes skin more reactive and susceptible to burning when exposed to ultraviolet light
2. A phototoxic chemical present in plants like citrus and parsley that enhances the skin's response to sun exposure and can cause severe burns
3. A plant-derived substance that increases photosensitivity in human skin, causing exaggerated reactions to sunlight exposure

Etymology: Furocoumarin is a chemical coinage built from parts that were named in the 19th and early 20th centuries. "Coumarin" comes from "coumarou," the Tupi-Guarani name for the tonka bean, from which the compound was first isolated. The "furo-" prefix comes from "furan," the name of a five-membered oxygen-containing ring, which itself derives from Latin "furfur," meaning bran, because furfural was first obtained from bran. Chemists combined these pieces to describe a coumarin molecule with a furan ring fused onto it. The name therefore describes structure rather than effect. The compounds it covers, such as psoralens, are concentrated in plants like figs, celery, and parsnips, and their photosensitizing action, which is the reason the term matters to dermatologists and to people handling those plants, comes from how they absorb ultraviolet light once they reach the skin. The word itself says nothing about that property; it simply records the molecular architecture that chemists identified.