Phytoncide

Phytoncides are antimicrobial allelochemic volatile organic compounds derived from plants. The word, which means "exterminated by the plant", was coined in 1937 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. Various spices, onion, garlic, oak and pine trees, and many other plants give off phytoncides. Oak contains a substance called greenery alcohol; garlic contains allicin and diallyl disulfide; and pine contains alpha-pinene, carene, myrcene and other terpenes. More than 5000 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.

In Taiwan, South Korea and Japan, people commonly engage in so-called forest bathing to breathe in phytoncides emitted by plant and trees, in order to improve their health.