What is "phytoncide"

n. (context biochemistry English) Any volatile antimicrobial compound given off by a plant, especially one that prevents it from being eaten.

Phytoncides are antimicrobial allelochemic volatile organic compounds derived from plants. The word, which means "exterminated by the plant", was coined in 1928 by Dr. Boris P. Tokin, a Russian biochemist from Leningrad University. He found that some plants give off very active substances which prevent them from rotting or being eaten by some insects and animals.

Spices, onion, garlic, tea tree, oak, cedar, locust, pine, and many other plants give off phytoncides. Oak contains a substance called greenery alcohol. Garlic contains allicin and diallyl disulfide. Sophora flavescens contains sophoraflavanone G. Pine contains alpha- pinene, carene, myrcene, and other terpenes.

More than 5,000 volatile substances defend the surrounding plants from bacteria, fungi and insects. Phytoncides work by preventing the growth of the attacking organism.

They are widely used in Russian, Ukrainian, Chinese and Japanese medicine, including holistic medicine, aromatherapy, and veterinary medicine.