Terpenoids triterpene

Alisma platago (Alismataceae) Terpenoids Triterpenes (GC and HPLC) (61)... 

Steroids are plant and animal lipids with a characteristic tetracyclic carbon skeleton. Like the eicosanoids, steroids occur widely in body tissues and have a large variety of physiological activities. Steroids are closely related to terpenoids and arise biosynthetically from the triterpene lanosterol. Lanosterol, in turn, arises from cationic cyclization of the acyclic hydrocarbon squalene. 

From a chemical point of view, vegetable resins are a complex mixture of mono-, sesqui-, di- and triterpenes, which have, respectively, 10, 15, 20 and 30 carbon atoms per molecule. The mono- and sesquiterpenes are both present in most resins. The di- and triterpenes are rarely found together in the same resin, which means that terpenic resins can be divided into two main classes. Table 1.5 lists the botanical origin and the kind of terpenoid compounds of some natural resins. 

J. Karliner and C. Djerassi, Terpenoids. LVII. Mass spectral and nuclear magnetic resonance studies of pentacyclic triterpene hydrocarbons, J. Org. Chem., 31, 1945 1956 (1966). 

FIGURE 11.5 Terpenoids, (a) The basic five-carbon units isopentane and isoprene. (b) The monoterpenes borneol and a-pinene. (c) A monoterpene lactone, nepetalactone. (d) A sesquiterpene, germacrone. (e) A triterpene, papyriferic acid, from paper birch. 

The biological activity and toxicity of terpenoids to herbivores has been discussed (56,84) and representatives of each major type of terpene are known to be active. Well known examples are sesquiterpene lactones, pyrethrins, and several classes of diter-penes and triterpenes. 

The diverse, widespread and exceedingly numerous class of natural products that are derived from a common biosynthetic pathway based on mevalonate as parent, are synonymously named terpenoids, terpenes or isoprenoids, with the important subgroup of steroids, sometimes singled out as a class in its own right. Monoterpenes, sesquiterpenes, diterpenes and triterpenes are ubiquitous in terrestrial organisms and play an essential role in life, as we know it. Although the study of terrestrial terpenes dates back to the last century, marine terpenes were not discovered until 1955. 

The terpenoids form a large and structurally diverse family of natural products derived from C5 isoprene units (Figure 5.1) joined in a head-to-tail fashion. Typical structures contain carbon skeletons represented by (Cs) , and are classified as hemiterpenes (C5), monoterpenes (C10), sesquiterpenes (C15), diterpenes (C2o), sesterterpenes (C25), triterpenes (C30) and tetraterpenes (C40) (Figure 5.2). Higher polymers are encountered in materials such as rubber. Isoprene itself (Figure 5.1) had been characterized as a decomposition product from various natural cyclic hydrocarbons, and was suggested as the fundamental building block for these compounds, also referred to as isoprenoids . Isoprene is produced naturally but is not involved in the formation of... 

Cl 0 monoterpenes Cl 5 sesquiterpenes C20 diterpenes C30 triterpenes C27 steroids C40 tetraterpenes C(n) polyterpenes Saponins Cucurbitacins Terpenoid alkaloids... 

Steroid and Triterpene Biosynthesis Terpenes, Biosynthesis of Terpenoids in Plants ... 

Terpenoids, which are also known as isoprenoids, constitute the most abundant and structurally diverse group of plant secondary metabolites, consisting of more than 40,000 different chemical structures. The isoprenoid biosynthetic pathway generates both primary and secondary metabolites that are of great importance to plant growth and survival. Among the primary metabolites produced by this pathway are phytohormones, such as gibberellic acid (GA), abscisic acid (ABA), and cytokinins the carotenoids, such as chlorophylls and plastoquinones involved in photosynthesis the ubiquinones required for respiration and the sterols that influence membrane stmcture (see also Steroid and Triterpene Biosynthesis) (Fig. 1). Monoterpenoids (CIO), sesquiterpenoids (Cl5), diterpenoids (C20), and... 

Terpenoids are derived from the cytosolic mevalonate pathway or from the plastidial 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway (see also Terpenoid Biosynthesis). Both pathways lead to the formation of the C5 units isopentenyl diphosphate and its allylic isomer dimethylallyl diphosphate, which are the basic terpenoid biosynthesis building blocks (Fig. 1). Although increasing evidence suggests that exchange of intermediates occurs between these compartments, the cytoplasmic mevalonate pathway is generally considered to supply the precursors for the production of sesquiterpenes and triterpenes (including sterols) and to provide precursors for protein prenylation and for ubiquinone and heme-A production in mitochondria. In the plastids, the MEP pathway supplies the precursors for the production of isoprene, monoterpenes, diterpenes (e.g., GAs), and tetraterpenes (e.g., carotenoids). 

Chemistry of Cytochrome P450 Monooxygenases, Glycosyl Transferases and Methyl Transferases Metabolic Engineering Steroid and Triterpene Biosynthesis Terpenoid Biosynthesis... 

Triterpenols and sterols are present as free or esterified with fatty acids (oleic acid and linoleic acid as the most relevant). Total content of triterpens is between 100-300 mg/100 g of oil. 24-Methylen-cycloartanol and cycloartenol are dominant. Erythrodiol, uvaol and triterpenic acids (ursolic, oleanolic acids etc) have been described in the imsaponifiable fraction of olive oil. The terpenoid fraction is complex and many constituents are still imdefined. 

Mentha piperita subsp. citrata Briq. -horteia Tranquilizer Branch (infusion, ingested) Caboclos [57] Essential oils [138,139] flavonoid glycosides [140,141] menthol [142] menthofurolactone [143,144] pyridine-derivatives [145] mintlactone [146] flavones [147] triterpenes [148] terpenoids [149] sesquiterpenic hydrocarbons [150] menthofuran [151,152], Antimicrobial and antioxidant activities [138,265] antiallergic effect [140] anti-nociceptive and anti-inflammatory effects [266]... 

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