Lipids terpenoids

ARCHAEOMETRIC DATA FROM MASS SPECTROMETRIC ANALYSIS OF ORGANIC MATERIALS PROTEINS, LIPIDS, TERPENOID RESINS, LIGNOCELLULOSIC POLYMERS, AND DYESTUFF... 

Lipids are naturally occurring organic molecules that have limited solubility in water and can be isolated from organisms by extraction with nonpolar organic solvents. Fats, oils, waxes, many vitamins and hormones, and most nonprotein cell-meznbrane components are examples. Note that this definition differs from the sort used for carbohydrates and proteins in that lipids are defined by a physical property (solubility) rather than by structure. Of the many kinds of lipids, we ll be concerned in this chapter only with a few triacvlglycerols, eicosanoids, terpenoids, and steroids. 

In the Chapter 6 Focus On, "Terpenes Naturally Occurring Alkenes," we looked briefly at terpenoids, a vast and diverse group of lipids found in all living organisms. Despite their apparent structural differences, all terpenoids are related. All contain a multiple of five carbons and are derived biosynthetically from the five-carbon precursor isopentenyl diphosphate (Figure 27.6). Note that formally, a... 

Eicosanoids and terpenoids are still other classes of lipids. Eicosanoids, of which prostaglandins are the most abundant kind, are derived biosynthetically from arachidonic acid, are found in all body tissues, and have a wide range of physiological activity. Terpenoids are often isolated from the essential oils of plants, have an immense diversity of structure, and are produced biosynthetically from the five-carbon precursor isopentenyl diphosphate (IPP). lsopentenyl diphosphate is itself biosynthesized from 3 equivalents of acetate in the mevalonate pathway. 

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. 

Terpenoid (Chapter 6 Focus On. Section 27.5) A lipid that is formally derived by head-to-tail polymerization of iso-prene units. 

Chapter 27, Biomolecules Lipids—The chapter has been extensively revised, with increased detail on prostaglandins (Section 27.4), terpenoid biosynthesis (Section 27.5), and steroid biosynthesis, (Section 27.7). 

Lipids have been dehned on the basis of their stmctnre and solnbility. Lipids are natnrally occnrring componnds consisting of fatty acids and their derivatives, bile acids, pigments, vitamins, and steroids, as well as terpenoids, which are usually soluble in organic solvents such as benzene, chloroform, ether, and alcohol, etc., with variable solubility depending on the stmctnre of the lipid compound. 

Plant resins are lipid-soluble mixtures of volatile and nonvolatile terpenoid and/or phenolic secondary compounds that are usually secreted in specialized structures located either internally or on the surface of the plant. Although terpenoid resins constitute the majority of the resins produced and used, some other important resins are phenolic. Phenolic resin components, which occur on the surfaces of plant organs, have been used particularly in medicines [86]. 

THRELFALL, D.R., WHITEHEAD, I.M., Redirection of terpenoid biosynthesis in elicitor-treated plant cell suspension cultures. In Plant Lipid Biochemistry (P.J. Quinn and J.L. Harwood, eds,), Portland Press, London. 1990, pp. 344-346. 

The terpenes are simple lipids whose base unit is isoprene. Oxygen-containing ter-penes are called terpenoids, and terpenes with hydroxyl groups are called terpenols. Terpenes are further classified based on the number of isoprene imits in the molecule as shown in Table 22.6. Examples of terpene molecular structures are presented in Figure 22.18. 

Carotenoids are lipid-soluble terpenoids derived from the isoprenoid pathway and are located in hydrophobic areas of cells. All have a 40-carbon isoprene backbone with a variety of ring structures at one or both ends (Fig. 8.2) [25]. The carbon skeleton is derived from five-carbon isoprenoid groups and contains alternating conjugated double bonds. There are two kinds of carotenoids (Fig. 8.2) carotenes composed of carbon and hydrogen and xanthophylls composed of carbon, hydrogen, and oxygen. 

Lipids is a broad term that includes all oil-soluble, water-insoluble organic substances such as fats, waxes, fatty acids, sterols, pigments and terpenoids synthesized by contemporary biota. 

Many natural products, i.e. homologous aliphatic (lipids), polar (sugars, amino acids), and cyclic (terpenoids) compounds can be utilized as biomarkers. The following is a brief overview of the classical biomarkers commonly used, namely lipids and terpenoids. 

Arrendale. Isolation and quantitation of terpenoid and lipid constituents of tobacco. Lloydia 1978 41(6) 647-648. 

ThrelfaU DR, Whitehead IM (1990) Redirection of terpenoid biosynthesis in eUcitor-treated plant cell suspension cultines. In Qninn PJ, Harwood JL (eds) Plant lipid biochemistry. Portland Press, London, p 344... 

VolatUe Compounds fkom Heated Beef Fat. Um et aL (30) studied the volatile lipids in fraction FI from extractions at 207 bar/Sfr C and 345 bar/S0°C using the qualitative GLC/MS method of Suzuki and Bailey (25). They identified 71 compounds in fraction FI of the extracts and quantified 66 compounds including 17 hydrocarbons, 4 terpenoids, 15 aldehydes, 3 ketones, 4 phenols, 10 carboj lic acid 6 esters and 7 lactones. 

Volatile compounds formed by anabolic or catabolic pathways include fatty acid derivatives, terpenes and phenolics. In contrast, volatile compounds formed during tissue damage are typically formed through enzymatic degradation and/ or autoxidation reactions of primary and/or secondary metabolites and includes lipids, amino acids, glucosinolates, terpenoids and phenolics. 

Gershenzon, J. and Croteau, R. (1993). Terpenoid biosynthesis the basic pathway and formation of monoterpenes, sesquiterpenes and diterpenes. In Lipid Metabolism in Plants, ed. T. S. Moore Jr, pp. 339-388. Boca Raton, FL CRC Press. 

The aliphatic alicyclic hydrocarbon precursor is not well recognized as the major aliphatic component in dissolved humic substances, although it was previously postulated to occur (II). This precursor might arise from terpenoid hydrocarbon lipids, but the data presented in this chapter favor polyunsaturated lipid precursors that are oxidatively coupled and cyclized by free-radical mechanisms (20). Degradative studies have not identified this aliphatic component in recognizable fragments. The quantitative, structural-model approach presented here combines the results of 13C NMR, NMR,... 

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