Verbenone is a natural

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

classified as a

terpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ar ...

that is found naturally in a variety of plants. The chemical has a pleasant characteristic odor. Besides being a natural constituent of plants, it and its analogs are insect pheromones. In particular, verbenone when formulated in a long-lasting matrix has an important role in the control of bark beetles such as the

mountain pine beetle The mountain pine beetle (''Dendroctonus ponderosae'') is a species of bark beetle native to the forests of western North America from Mexico to central British Columbia. It has a hard black exoskeleton, and measures approximately , about the siz ...

and the Southern pine bark beetle.

Chemistry

Verbenone is a monoterpene, to be specific a bicyclic

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...

terpene. It is the primary constituent of the oil of Spanish verbena, hence its name; it is also found in the oil of

rosemary ''Salvia rosmarinus'' (), commonly known as rosemary, is a shrub with fragrant, evergreen, needle-like leaves and white, pink, purple, or blue flowers, native plant, native to the Mediterranean Region, Mediterranean region. Until 2017, it was kn ...

. It is nearly insoluble in water, but miscible with most organic solvents. Verbenone can be readily prepared synthetically by the

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

of the more common terpene

α-pinene α-Pinene is an organic compound of the terpene class, one of two isomers of pinene. It is an alkene and it contains a reactive four-membered ring. It is found in the oils of many species of many coniferous trees, notably the pine. It is also ...

: : Verbenone can then be converted into

chrysanthenone Chrysanthenone (C10H14O) is a terpenoid. It can be produced from its isomer verbenone in a photochemical Photochemistry is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemic ...

through a

photochemical Photochemistry is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemical reaction caused by absorption of ultraviolet (wavelength from 100 to 400 nm), visible light (400–7 ...

rearrangement reaction In organic chemistry, a rearrangement reaction is a broad class of organic reactions where the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. Often a substituent moves from one atom to another ...

: :

Use for insect control

The southern pine beetle (''

Dendroctonus frontalis ''Dendroctonus frontalis'', the Southern Pine Beetle (also known as SPB), is a species of bark beetle native to the forests of southern United States, Mexico and Central America. The Southern Pine Beetle reddish brown to black exoskeleton and me ...

''), a

bark beetle A bark beetle is the common name for the subfamily of beetles Scolytinae. Previously, this was considered a distinct family (Scolytidae), but is now understood to be a specialized clade of the "true weevil" family (Curculionidae). Although the ...

, is a major threat to pine trees in the southeastern United States. Its reproductive cycle is controlled by varying ratios of certain natural chemicals, including verbenone. To reproduce, pine bark beetles aggregate in large numbers in their host pine trees. At the beginning of an attack, various chemicals produced by infested trees and by the beetles attract additional beetles of the same species. When the numbers of adults and larvae approach the maximum that the tree can support, antiaggregation signal chemicals, i.e., verbenone, are produced, reducing the likelihood that additional beetles will land and attack the tree. Forest managers frequently try to control infestations of the Southern pine bark beetle by cutting down and sometimes burning infested trees and nearby healthy trees. They then place verbenone formulations on nearby susceptible healthy trees to repel and confuse the beetles. Verbenone is also used to manage

(''Dendroctonus ponderosae'') infestations. Verbenone is recognized by the mountain pine beetle, ''Dendroctonus ponderosae'' Hopkins, a notable forest insect capable of causing extensive levels of tree mortality in western North America. Several formulations of verbenone have been registered with the U.S. Environmental Protection Agency for tree protection. Failures in tree protection efficacy can be seen in situations where there is an excessive population of infesting insects, for example an area which contains more than 50 percent infested trees. Loss of response to verbenone as a repellent is not due to any particular failure of the verbenone devices but is instead a response innate to the biology of the beetles which allows populations to continue flourishing even in situations of extreme environmental stress. Verbenone is also used to manage

redbay ambrosia beetle ''Xyleborus glabratus'', the redbay ambrosia beetle, is a type of ambrosia beetle invasive species, invasive in the United States. It has been documented as the primary Vector (epidemiology), vector of ''Raffaelea lauricola'', the fungus that ca ...

(''Xyleborus glabratus'') the vector of the fungus that causes

laurel wilt Laurel wilt, also called laurel wilt disease, is a vascular disease that is caused by the fungus ''Raffaelea lauricola'', which is transmitted by the invasive redbay ambrosia beetle, ''Xyleborus glabratus''. The disease affects and kills membe ...

. A 9-month trial in forest demonstrated a reduction in the number of beetles landing on redbay and a reduction in redbay mortality

Other uses

Because of its pleasant aroma, verbenone (or

essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the o ...

s high in verbenone content) are used in

perfume Perfume (, ; french: parfum) is a mixture of fragrant essential oils or aroma compounds (fragrances), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agreeable scent. Th ...

ry,

aromatherapy Aromatherapy is based on the usage of aromatic materials including essential oils and other aroma compounds, with claims for improving psychological and physical well-being. It is offered as a complementary therapy or as a form of alternative m ...

herbal tea Herbal teas, also known as herbal infusions and less commonly called tisanes (UK and US , US also ), are beverages made from the infusion or decoction of herbs, spices, or other plant material in hot water. Oftentimes herb tea, or the plain term ...

spice A spice is a seed, fruit, root, bark, or other plant substance primarily used for flavoring or coloring food. Spices are distinguished from herbs, which are the leaves, flowers, or stems of plants used for flavoring or as a garnish. Spices a ...

s, and

herbal remedies Herbal medicine (also herbalism) is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. With worldwide research into pharmacology, some herbal medicines have been translated into modern remedie ...

. The L-

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

is used as a

cough suppressant Cold medicines are a group of medicinal, medications taken individually or in Combination drug, combination as a Symptomatic treatment, treatment for the symptoms of the common cold and similar conditions of the upper respiratory tract. The t ...

under the name

levoverbenone Levoverbenone is an expectorant. It is the L-isomer of verbenone Verbenone is a natural organic compound classified as a terpene that is found naturally in a variety of plants. The chemical has a pleasant characteristic odor. Besides being a ...

. Verbenone may also have antimicrobial properties.{{cite journal , pmid = 15830672 , year = 2005 , last1 = Santoyo , first1 = S , last2 = Cavero , first2 = S , last3 = Jaime , first3 = L , last4 = Ibañez , first4 = E , last5 = Señoráns , first5 = FJ , last6 = Reglero , first6 = G , title = Chemical composition and antimicrobial activity of Rosmarinus officinalis L. Essential oil obtained via supercritical fluid extraction , volume = 68 , issue = 4 , pages = 790–5 , journal = Journal of Food Protection, doi = 10.4315/0362-028x-68.4.790

References

External links

U.S. Environmental Protection Agency
Fact sheet for verbenone. Insect pheromones Monoterpenes Cyclic ketones Bicyclic compounds Enones