Chemical structure of the terpenoid isopentenyl pyrophosphate.

The terpenoids, sometimes referred to as isoprenoids, are a large and diverse class of naturally-occurring organic chemicals similar to terpenes, derived from five-carbon isoprene units assembled and modified in thousands of ways. An organic compound is any member of a large class of Chemical compounds whose Molecules contain Carbon. Terpenes are a large and varied class of Hydrocarbons, produced primarily by a wide variety of plants particularly Conifers though also by some insects such Isoprene is a common synonym for the chemical compound 2-methylbuta-13-diene Most are multicyclic structures that differ from one another not only in functional groups but also in their basic carbon skeletons. In Organic chemistry, functional groups are specific groups of Atoms within Molecules that are responsible for the characteristic Chemical reactions These lipids can be found in all classes of living things, and are the largest group of natural products. Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble

Plant terpenoids are used extensively for their aromatic qualities. They play a role in traditional herbal remedies and are under investigation for antibacterial, antineoplastic, and other pharmaceutical functions. Antiseptics (from Greek αντί - anti, '"against" + σηπτικός - septikos, "putrefactive" are antimicrobial Antineoplastics (or "antitumor antibiotics" or "noncovalent DNA-binding drugs" or " Cytotoxic antibiotics" see also Neoplastics are Terpenoids contribute to the scent of eucalyptus, the flavors of cinnamon, cloves, and ginger, and the color of yellow flowers. Eucalyptus (From Greek ευκάλυπτος meaning "well covered" is a diverse Genus of Trees (and a few shrubs the members of which Cinnamon ( Cinnamomum verum, synonym C zeylanicum) is a small Evergreen Tree 10–15 metres (32 This article is about the Spice; for other meanings see Clove (disambiguation. Ginger is commonly used as a cooking spice throughout the world Well-known terpenoids include citral, menthol, camphor, Salvinorin A in the plant Salvia divinorum, and the cannabinoids found in Cannabis. Citral, or 37-dimethyl-26-octadienal or lemonal, is either of a pair of Terpenoids with the molecular formula C 10 H 16 Menthol is an Organic compound made synthetically or obtained from Peppermint or other mint oils } Camphor is a waxy white or transparent solid with a strong aromatic odor Salvinorin A is the main active Psychotropic molecule in Salvia divinorum, a Mexican plant which has a long history of use as an Entheogen by Salvia divinorum, also known as Diviner’s Sage, ska María Pastora, Sage of the Seers, or simply by the genus name Cannabinoids ( are a group of terpeno[[phenol]]ic compounds present in Cannabis ( Cannabis sativa L Cannabis ( Cán-na-bis) is a Genus of Flowering plants that includes three putative species Cannabis sativa subsp

The steroids and sterols in animals are biologically produced from terpenoid precursors. A steroid is a Terpenoid Lipid characterized by a Carbon skeleton with four fused rings generally arranged in a 6-6-6-5 fashion Sterols, or steroid alcohols are a subgroup of Steroids with a Hydroxyl group at the 3-position of the A-ring Sometimes terpenoids are added to proteins, e. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl g. , to enhance their attachment to the cell membrane; this is known as isoprenylation. The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer Prenylation or isoprenylation or lipidation is the addition of Hydrophobic molecules to a Protein.

Many of these are substrates for plant Cytochrome P450. Cytochrome P450 (abbreviated CYP, P450, infrequently CYP450) is a very large and diverse superfamily of Hemoproteins found in all Domains

Structure and classification

Terpenes are hydrocarbons resulting from the combination of several isoprene units. Terpenes are a large and varied class of Hydrocarbons, produced primarily by a wide variety of plants particularly Conifers though also by some insects such In Organic chemistry, a hydrocarbon is an Organic compound consisting entirely of Hydrogen and Carbon. Isoprene is a common synonym for the chemical compound 2-methylbuta-13-diene Terpenoids can be thought of as modified terpenes, wherein methyl groups have been moved or removed, or oxygen atoms added. In Chemistry, a methyl group is a Hydrophobic Alkyl Functional group named after Methane (4 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the (Some authors use the term "terpene" more broadly, to include the terpenoids. ) Just like terpenes, the terpenoids can be classified according to the number of isoprene units used:

• Monoterpenoids, 2 isoprene units
• Sesquiterpenoids, 3 isoprene units
• Diterpenoids, 4 isoprene units
• Sesterterpenoids, 5 isoprene units
• Triterpenoids, 6 isoprene units
• Tetraterpenoids, 8 isoprene units
• Polyterpenoids with a larger number of isoprene units

Terpenoids can also be classified according to the number of cyclic structures they contain.

Biosynthesis

Simplified version of the steroid synthesis pathway with the terpenoid intermediates isopentenyl pyrophosphate (IPP), dimethylallyl pyrophosphate (DMAPP), geranyl pyrophosphate (GPP), and squalene shown. Isopentenyl pyrophosphate (IPP is an intermediate in the classical HMG-CoA reductase pathway used by organisms in the biosynthesis of Terpenes and Terpenoids Dimethylallyl pyrophosphate (or -diphosphate (DMAPP is an intermediate product of both Mevalonic acid (MVA pathway and DOXP/ MEP pathway Geranyl pyrophosphate is an intermediate in the HMG-CoA reductase pathway used by organisms in the biosynthesis of Farnesyl pyrophosphate, Geranylgeranyl pyrophosphate Squalene is a natural Organic compound originally obtained for commercial purposes primarily from Shark liver oil, though there are botanic sources as well including Some intermediates are omitted for clarity.

There are two metabolic pathways of creating terpenoids:

Mevalonic acid pathway

Many organisms manufacture terpenoids through the HMG-CoA reductase pathway, the pathway that also produces cholesterol. In Biochemistry, a metabolic pathway is a series of chemical reactions occurring within a cell. The mevalonate pathway or HMG-CoA reductase pathway or mevalonate-dependent (MAD route, is an important cellular Metabolic pathway present Cholesterol is a Lipid found in the Cell membranes and transported in the Blood plasma of all Animals It is an essential component of mammalian The reactions take place in the cytosol. The cytosol or intracellular fluid (or cytoplasmic matrix) is the liquid found inside cells. The pathway was discovered in the 1950s. The 1950s Decade refers to the years of 1950 to 1959 inclusive

MEP/DOXP pathway

The 2-C-methyl-D-erythritol 4-phosphate/1-deoxy-D-xylulose 5-phosphate pathway (MEP/DOXP pathway), also known as non-mevalonate pathway or mevalonic acid independent pathway, takes place in the plastids of plants and apicomplexan protozoa, as well as in many bacteria. The non-mevalonate pathway or 2- C -methyl-D-erythritol 4-phosphate/1-deoxy-D-xylulose 5-phosphate pathway ( MEP/DOXP pathway) of isoprenoid biosynthesis is an alternative The non-mevalonate pathway or 2- C -methyl-D-erythritol 4-phosphate/1-deoxy-D-xylulose 5-phosphate pathway ( MEP/DOXP pathway) of isoprenoid biosynthesis is an alternative Mevalonic acid is a key Organic compound in biochemistry It is a precursor in the biosynthetic pathway known as the HMG-CoA reductase pathway, that produces Plastids are major Organelles found in plants and algae Plastids often contain pigments used in photosynthesis and the types of pigments present can change The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have It was discovered in the late 1980s.

Pyruvate and glyceraldehyde 3-phosphate are converted by DOXP synthase (Dxs) to 1-deoxy-D-xylulose 5-phosphate, and by DOXP reductase (Dxr, IspC) to 2-C-methyl-D-erythritol 4-phosphate (MEP). Pyruvic acid (CH3COCO2H is an alpha-keto acid. The Carboxylate Anion of pyruvic acid is known as pyruvate. Glyceraldehyde 3-phosphate, also known as triose phosphate or 3-phosphoglyceraldehyde and abbreviated as G3P, GADP, GAP or PGAL The subsequent three reaction steps catalyzed by 4-diphosphocytidyl-2-C-methyl-D-erythritol synthase (YgbP, IspD), 4-diphosphocytidyl-2-C-methyl-D-erythritol kinase (YchB, IspE), and 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase (YgbB, IspF) mediate the formation of 2-C-methyl-D-erythritol 2,4-cyclopyrophosphate (MEcPP). Finally, MEcPP is converted to (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMB-PP) by HMB-PP synthase (GcpE, IspG), and HMB-PP is converted to isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) by HMB-PP reductase (LytB, IspH). Isopentenyl pyrophosphate (IPP is an intermediate in the classical HMG-CoA reductase pathway used by organisms in the biosynthesis of Terpenes and Terpenoids Dimethylallyl pyrophosphate (or -diphosphate (DMAPP is an intermediate product of both Mevalonic acid (MVA pathway and DOXP/ MEP pathway

IPP and DMAPP are the end-products in either pathway, and are the precursors of isoprene, monoterpenoids (10-carbon), diterpenoids (20-carbon), carotenoids (40-carbon), chlorophylls, and plastoquinone-9 (45-carbon). Isoprene is a common synonym for the chemical compound 2-methylbuta-13-diene Carotenoids are organic Pigments that are naturally occurring in Chromoplasts of plants and some other photosynthetic Organisms Chlorophyll is a green Pigment found in most Plants Algae and Cyanobacteria. Plastoquinone, (often abbreviated PQ) is a Quinone molecule involved in the electron transport chain in the Light-dependent reactions of photosynthesis Synthesis of all higher terpenoids proceeds via formation of geranyl pyrophosphate (GPP), farnesyl pyrophosphate (FPP), and geranylgeranyl pyrophosphate (GGPP). The terpenoids, sometimes referred to as isoprenoids, are a large and diverse class of naturally-occurring organic chemicals similar to Terpenes derived Geranyl pyrophosphate is an intermediate in the HMG-CoA reductase pathway used by organisms in the biosynthesis of Farnesyl pyrophosphate, Geranylgeranyl pyrophosphate Farnesyl pyrophosphate (FPP is an intermediate in the HMG-CoA reductase pathway used by organisms in the biosynthesis of Terpenes and Terpenoids It Geranylgeranyl pyrophosphate is an intermediate in the HMG-CoA reductase pathway used by organisms in the biosynthesis of Terpenes and Terpenoids In plants

Although both pathways, MVA and MEP, are mutually exclusive in most organisms, interactions between them have been reported in plants and few bacteria species. Plants are living Organisms belonging to the kingdom Plantae. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have

See also

• Pharmacology

External links

• IUPAC nomenclature of terpenoids