Terpenes

Terpenes are a large and diverse class of organic compounds, produced by a variety of plants, particularly conifers, though also by some insects. They are often strong-smelling. They may protect the plants that produce them by deterring parasites. The difference between terpenes and terpenoids is that terpenes are hydrocarbons, whereas terpenoids contain additional functional groups. When terpenes are modified chemically, such as by oxidation or rearrangement of the carbon skeleton, the resulting compounds are generally referred to as terpenoids. Some authors will use the term terpene to include all terpenoids. Terpenoids are also known as isoprenoids. Terpenes and terpenoids are the primary constituents of the essential oils of many types of plants and flowers. Essential oils are used widely as natural flavor additives for food, as fragrances in perfumery, and in medicine and alternative medicines such as aromatherapy. Synthetic variations and derivatives of natural terpenes and terpenoids also greatly expand the variety of aromas used in perfumery and flavors used in food additives. Vitamin A is a terpene

Isoprene structure

Terpenes General Structure More than terpenes are known at present in the literature. Their basic structure follows a general principle: 2-Methylbutane residues, less precisely but usually also referred to as isoprene units, (C5)n, build up the carbon skeleton of terpenes; this is the isoprene rule found by RUZICKA and WALLACH. Therefore, terpenes are also denoted as isoprenoids. In nature, terpenes occur predominantly as hydrocarbons, alcohols and their glycosides, ethers, aldehydes, ketones, carboxylic acids and esters.

Depending on the number of 2-methylbutane (isoprene) subunits one differentiates between hemi- (C5), mono- (C10), sesqui- (C15), di- (C20), sester- (C25), tri- (C30), tetraterpenes (C40) and polyterpenes (C5)n with n > 8. The isopropyl part of 2-methylbutane is defined as the head, and the ethyl residues the tail. In mono-, sesqui-, di- and sesterterpenes the isoprene units are linked to each other from head-to-tail; tri- and tetraterpenes contain one tail-to- tail connection in the center.

1-Hemiterpenes consist of a single isoprene unit. Isoprene itself is considered the only hemiterpene, but oxygen-containing derivatives such as prenol and isovaleric acid are hemiterpenoids. 2-Monoterpenes consist of two isoprene units and have the molecular formula C 10 H 16. Examples limonene, and myrcene, one of the main terpenes found in Cannabis Sativa plants. 3-Sesquiterpenes consist of three isoprene units and have the molecular formula C 15 H Diterpenes are composed of four isoprene units and have the molecular formula C 20 H Sesterterpenes, terpenes having 25 carbons and five isoprene units, are rare relative to the other sizes. (The sester- prefix means half to three, i.e. two and a half.) 6-Triterpenes consist of six isoprene units and have the molecular formula C 30 H 48. The linear triterpene squalene, the major constituent of shark liver oil. Squalene is then processed biosynthetically to generate either lanosterol or cycloartenol, the structural precursors to all the steroids. 7-Sesquarterpenes are composed of seven isoprene units and have the molecular formula C 35 H 56. Sesquarterpenes are typically microbial in their origin. Examples of sesquarterpenoids are ferrugicadiol and tetraprenylcurcumene. 8-Tetraterpenes contain eight isoprene units and have the molecular formula C 40 H 64. Biologically important tetraterpenes include the acyclic lycopene, the monocyclic gamma-carotene, and the bicyclic alpha- and beta-carotenes. 9-Polyterpenes consist of long chains of many isoprene units. Natural rubber consists of polyisoprene in which the double bonds are cis. Some plants produce a polyisoprene with trans double bonds, known as gutta-percha.

Biosynthesis

1-Hemiterpenes Cananga Tree (Cananga odorata)

Prenol, or 3-methyl-2-buten-1-ol, is a natural alcohol. It is one of the most simple terpenes. It is a clear colorless oil that is reasonably soluble in water and miscible with most common organic solvents. It has a fruity odor and is used occasionally in perfumery. Prenol occurs naturally in citrus fruits, cranberry, bilberry, currants(( الكشمش, grapes, raspberry, blackberry, tomato, white bread, hop oil, coffee, cloudberry and passion fruit. It is also manufactured industrially by BASF (in Ludwigshafen, Germany) and by Kuraray (in Asia) as an intermediate to pharmaceuticals and aroma compounds. Global production in 2001 was between 6000 and 13,000 tons.

2-Monoterpenes I) Acyclic monoterpens

Humulus lupulus جنجل

bitter orange(Citrus Vulgaris)

Basil الريحان أو الحبق

Pelargonium))Geraniaceae

Bay ورق الغار

Lavender Palmarosa Lemon Grass

Linalool is used as a scent in 60–80% of perfumed hygiene products and cleaning agents including soaps, detergents, shampoos, and lotions. It is also used as a chemical intermediate. One common downstream product of linalool is Vitamin E. In addition, linalool is used by pest professionals as a flea, fruit fly and cockroach insecticide. Linalool is used in some mosquito repellent products. Geraniol is a natural antioxidant. Geraniol has been suggested to help prevent cancer. Carnesecchi S. et al demonstrated in his study "Geraniol, a component of Plant Essential Oils, Inhibits Grwoth and Polyamine Biosyntehsis in Human Colon Cancer Cells", that geraniol caused a 50% increase of ornithine decarboxylase activity, which is enhances during cancer growth. Geraniol inhibits DNA synthesis. Burk YD concluded in his study "Inhibition of Pancreatic Cancer Growth by the dietary isoprenoids farnesol and geraniol" (that geraniol, farnesol and perilll alcohol suppress pancreatic tumor growth. Other animal studies have also demonstrated the anticancer effects of geraniol.

Orchid Flowers

Nardus Cymbopogon citronella

Tagetes Glandulifera