Phytoncides are antimicrobial

Antimicrobial

An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...

 allelochemic volatile organic compounds derived from plant

Plant

Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s. The word, which means "exterminated by the plant", was coined in 1937 by Dr. Boris P. Tokin, a Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

n 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 spice

Spice

A spice is a dried seed, fruit, root, bark, or vegetative substance used in nutritionally insignificant quantities as a food additive for flavor, color, or as a preservative that kills harmful bacteria or prevents their growth. It may be used to flavour a dish or to hide other flavours...

s, onion

Onion

The onion , also known as the bulb onion, common onion and garden onion, is the most widely cultivated species of the genus Allium. The genus Allium also contains a number of other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion The onion...

, garlic

Garlic

Allium sativum, commonly known as garlic, is a species in the onion genus, Allium. Its close relatives include the onion, shallot, leek, chive, and rakkyo. Dating back over 6,000 years, garlic is native to central Asia, and has long been a staple in the Mediterranean region, as well as a frequent...

, tea tree

Tea tree oil

Tea tree oil, or melaleuca oil, is a pale yellow colour to nearly clear essential oil with a fresh camphoraceous odor. It is taken from the leaves of the Melaleuca alternifolia, which is native to the northeast coast of New South Wales, Australia...

, oak

Oak

An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...

 and pine

Pine

Pines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...

 trees, and many other plants give off phytoncides. Oak contains a substance called greenery alcohol; garlic contains allicin and diallyl disulfide

Diallyl disulfide

Diallyl disulfide is an organosulfur compound found in plants of the genus Allium. Along with diallyl trisulfide and diallyl tetrasulfide, it is one of the principal components of the distilled oil of garlic. It is a yellowish liquid which is insoluble in water and has a strong garlic odor...

; Sophora flavescens

Sophora flavescens

Sophora flavescens is a species of plant in the genus Sophora. Ku shen or kushenin is a typical traditional Chinese medicine that is found in this plant...

contains sophoraflavanone G

Sophoraflavanone G

Sophoraflavanone G is a volatile phytoncide, released in to the atmosphere, soil and ground water, by members of the Sophora genus. Due to an increase in the rates of antibiotic-resistant bacteria, scientific efforts have focused on finding either naturally-made or genetically modified compounds...

; and pine contains alpha-pinene

Pinene

Pinene is a bicyclic monoterpene chemical compound. There are two structural isomers of pinene found in nature: α-pinene and β-pinene. As the name suggests, both forms are important constituents of pine resin; they are also found in the resins of many other conifers, as well as in non-coniferous...

, carene

Carene

Carene, or delta-3-carene, is a bicyclic monoterpene which occurs naturally as a constituent of turpentine, with a content as high as 42% depending on the source. Carene has a sweet and pungent odor. It is not soluble in water, but miscible with fats and oils....

, myrcene and other terpene

Terpene

Terpenes are a large and diverse class of organic compounds, produced by a variety of plants, particularly conifers, though also by some insects such as termites or swallowtail butterflies, which emit terpenes from their osmeterium. They are often strong smelling and thus may have had a protective...

s. More than 5000 volatile substances defend the surrounding plants from bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

, 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

Alternative medicine

Alternative medicine is any healing practice, "that does not fall within the realm of conventional medicine." It is based on historical or cultural traditions, rather than on scientific evidence....

, aromatherapy

Aromatherapy

Aromatherapy is a form of alternative medicine that uses volatile plant materials, known as essential oils, and other aromatic compounds for the purpose of altering a person's mind, mood, cognitive function or health....

, and veterinary medicine

Veterinary medicine

Veterinary Medicine is the branch of science that deals with the prevention, diagnosis and treatment of disease, disorder and injury in non-human animals...

.

In Taiwan

Taiwan

Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

, South Korea

South Korea

The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...

 and Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, people commonly engage in so-called forest bathing

Forest bathing

In Japan, a forest bathing trip, called Shinrinyoku in Japanese, is a short, leisurely visit to a forest and is regarded as being similar to natural aromatherapy.-History:...

to breathe in phytoncides emitted by plant and trees, in order to improve their health.