Monoterpenes: Compounds with a core of 10 carbons generally formed via the mevalonate pathway from the combination of 3,3-dimethylallyl pyrophosphate and isopentenyl pyrophosphate. They are cyclized and oxidized in a variety of ways. Due to the low molecular weight many of them exist in the form of essential oils (OILS, VOLATILE).Terpenes: A class of compounds composed of repeating 5-carbon units of HEMITERPENES.Cyclohexenes: Six-carbon alicyclic hydrocarbons which contain one or more double bonds in the ring. The cyclohexadienes are not aromatic, in contrast to BENZOQUINONES which are sometimes called 2,5-cyclohexadiene-1,4-diones.Oils, Volatile: Oils which evaporate readily. The volatile oils occur in aromatic plants, to which they give odor and other characteristics. Most volatile oils consist of a mixture of two or more TERPENES or of a mixture of an eleoptene (the more volatile constituent of a volatile oil) with a stearopten (the more solid constituent). The synonym essential oils refers to the essence of a plant, as its perfume or scent, and not to its indispensability.Intramolecular Lyases: Enzymes of the isomerase class that catalyze reactions in which a group can be regarded as eliminated from one part of a molecule, leaving a double bond, while remaining covalently attached to the molecule. (From Enzyme Nomenclature, 1992) EC 5.5.Lavandula: A plant genus of the LAMIACEAE family.Thuja: A plant genus of the family CUPRESSACEAE.Polyisoprenyl Phosphates: Phosphoric or pyrophosphoric acid esters of polyisoprenoids.Hemiterpenes: The five-carbon building blocks of TERPENES that derive from MEVALONIC ACID or deoxyxylulose phosphate.Bicyclo CompoundsPentanes: Five-carbon saturated hydrocarbon group of the methane series. Include isomers and derivatives.Sesquiterpenes, Germacrane: SESQUITERPENES cyclized to one 10-carbon ring.Volatilization: A phase transition from liquid state to gas state, which is affected by Raoult's law. It can be accomplished by fractional distillation.Clarkia: A plant genus, of the family ONAGRACEAE, which is the subject of genetic studies. The floral aroma is attributed to benzenoid esters and benzyl acetate.Lamiaceae: The mint plant family. They are characteristically aromatic, and many of them are cultivated for their oils. Most have square stems, opposite leaves, and two-lipped, open-mouthed, tubular corollas (united petals), with five-lobed, bell-like calyxes (united sepals).Alkyl and Aryl Transferases: A somewhat heterogeneous class of enzymes that catalyze the transfer of alkyl or related groups (excluding methyl groups). EC 2.5.Mentha piperita: A plant genus of the family LAMIACEAE that is the source of peppermint oil.Thymol: A phenol obtained from thyme oil or other volatile oils used as a stabilizer in pharmaceutical preparations, and as an antiseptic (antibacterial or antifungal) agent. It was formerly used as a vermifuge.NorbornanesSesquiterpenesResins, Plant: Flammable, amorphous, vegetable products of secretion or disintegration, usually formed in special cavities of plants. They are generally insoluble in water and soluble in alcohol, carbon tetrachloride, ether, or volatile oils. They are fusible and have a conchoidal fracture. They are the oxidation or polymerization products of the terpenes, and are mixtures of aromatic acids and esters. Most are soft and sticky, but harden after exposure to cold. (From Grant & Hackh's Chemical Dictionary, 5th ed & Dorland, 28th ed)Wood: A product of hard secondary xylem composed of CELLULOSE, hemicellulose, and LIGNANS, that is under the bark of trees and shrubs. It is used in construction and as a source of CHARCOAL and many other products.Menthol: An alcohol produced from mint oils or prepared synthetically.Pinus sylvestris: A plant species of the genus PINUS which is the source of pinosylvin. It is sometimes called Scotch pine or Scots pine, which is also a common name for other species of this genus.Nitric Acid: Nitric acid (HNO3). A colorless liquid that is used in the manufacture of inorganic and organic nitrates and nitro compounds for fertilizers, dye intermediates, explosives, and many different organic chemicals. Continued exposure to vapor may cause chronic bronchitis; chemical pneumonitis may occur. (From Merck Index, 11th ed)Acaridae: Family of MITES, in the superfamily Acaroidea, order Astigmata. They are frequently found in cereal-based foodstuffs including GRAIN and FLOUR.Myrtus: A plant genus of the family MYRTACEAE. Members contain PHYTOHEMAGGLUTININS.Pinus: A plant genus in the family PINACEAE, order Pinales, class Pinopsida, division Coniferophyta. They are evergreen trees mainly in temperate climates.Illicium: A plant genus of the family Illiciaceae, order Illiciales, subclass Magnoliidae, class Magnoliopsida. They have evergreen, aromatic leaves and bisexual flowers. The female portion of the flower consists of 7 to 15 carpels.Gas Chromatography-Mass Spectrometry: A microanalytical technique combining mass spectrometry and gas chromatography for the qualitative as well as quantitative determinations of compounds.Camphor: A bicyclic monoterpene ketone found widely in plants, especially CINNAMOMUM CAMPHORA. It is used topically as a skin antipruritic and as an anti-infective agent.Dimethylallyltranstransferase: An enzyme that, in the pathway of cholesterol biosynthesis, catalyzes the condensation of isopentenyl pyrophosphate and dimethylallylpyrophosphate to yield pyrophosphate and geranylpyrophosphate. The enzyme then catalyzes the condensation of the latter compound with another molecule of isopentenyl pyrophosphate to yield pyrophosphate and farnesylpyrophosphate. EC 2.5.1.1.Beetles: INSECTS of the order Coleoptera, containing over 350,000 species in 150 families. They possess hard bodies and their mouthparts are adapted for chewing.Isomerases: A class of enzymes that catalyze geometric or structural changes within a molecule to form a single product. The reactions do not involve a net change in the concentrations of compounds other than the substrate and the product.(from Dorland, 28th ed) EC 5.Mevalonic AcidPlant Oils: Oils derived from plants or plant products.Diphosphates: Inorganic salts of phosphoric acid that contain two phosphate groups.Asteraceae: A large plant family of the order Asterales, subclass Asteridae, class Magnoliopsida. The family is also known as Compositae. Flower petals are joined near the base and stamens alternate with the corolla lobes. The common name of "daisy" refers to several genera of this family including Aster; CHRYSANTHEMUM; RUDBECKIA; TANACETUM.Plant Leaves: Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)Diterpenes: Twenty-carbon compounds derived from MEVALONIC ACID or deoxyxylulose phosphate.Stereoisomerism: The phenomenon whereby compounds whose molecules have the same number and kind of atoms and the same atomic arrangement, but differ in their spatial relationships. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Lovastatin: A fungal metabolite isolated from cultures of Aspergillus terreus. The compound is a potent anticholesteremic agent. It inhibits 3-hydroxy-3-methylglutaryl coenzyme A reductase (HYDROXYMETHYLGLUTARYL COA REDUCTASES), which is the rate-limiting enzyme in cholesterol biosynthesis. It also stimulates the production of low-density lipoprotein receptors in the liver.Plant Extracts: Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.Chromatography, Gas: Fractionation of a vaporized sample as a consequence of partition between a mobile gaseous phase and a stationary phase held in a column. Two types are gas-solid chromatography, where the fixed phase is a solid, and gas-liquid, in which the stationary phase is a nonvolatile liquid supported on an inert solid matrix.