Lipid from polyketides

Lipids are natural products derived from polyketides which are originated from the acetate pathway. The term lipid has traditionally... 

Of the four major classes of biochemicals (carbohydrates, proteins, nucleic acids and lipids), experiments have shown that the first three classes could have arisen through prebiotic chemistry. Although the biosynthesis of many natural products can be traced back to acetate (e.g. fatty acids, terpenes and polyketide biosynthesis) or amino acids (e.g. alkaloid biosynthesis), there are many whose biosynthetic origins are either obscure or result from a complex combination of pathways (Fig. 2). 

As seen in figure 1, carbohydrates are degraded to pyruvic acid, which is oxidised to acetate in a form which can condense to form fatty acids and polyketides (includes aromatic benzenoid molecules). Fatty acids react with glycerol to give fats or lipids. A different biosynthetic pathway leads from acetate via the condensation product mevalonic acid to mono-, sesqui- and diterpenes which are ingredients... 

The squalestatins, e.g. 6.28, also known as the zaragozic adds, have attracted considerable interest as inhibitors of squalene synthase and hence of cholesterol biosynthesis and lipid deposition in the circulatory system. They are also inhibitors of farnesyl protein transferase and thus they may have other potentially useful biological applications. They are formed by Phoma spedes and also by Setosphaeria khartoumensis. The squalestatins are characterized by a dioxabicyclo-octane core bearing three carboxyl groups and two polyketide chains, one of which is attached as an ester. The biosynthetic incorporation of succinic acid into part of the bicyclo-octane, together with its oxygenation pattern, indicate that it may be derived via oxaloacetic acid. Both the polyketide chains have several pendant methyl groups attached to them, which arise from methionine, whilst benzoic add ads as a starter unit for one of the chains. These complex structures are thus the summation of several biosynthetic pathways. 

A number of applications of commercial lacs and of separated urushiol have been referred to (ref. 2). As with the phenolic lipids of Anacardium occidentale a great deal of work has been carried out particularly in Japan and China to diversify the uses of lacs from Rhus vemicifera. It is widely employed in artistic decoration, building materials, textile equipment and furniture. The industrial utilisation of polyketide natural products including the phenolic lipid urushiol has been reviewed (ref. 314). The great number of uses largely comprise polymerisation reactions and some non-polymeric processes, some of both of which are described in the next sections. 

R 475 G. Knothe, Quantitative Analysis of Mixtures of Fatty Compounds by H - NMR , Lipid Technol, 2003,15, 111 R 476 J. Kobayashi, K. Shimbo, T. Kubota and M. Tsuda, Bioactive Macro-lides and Polyketides from Marine Dinoflagellates , Pure Appl. Chem., 2003,75, 337... 

Asymmetric synthesis ch41 and protect sensitive functional groups How to make and manipulate sugars and their derivatives Lipids form the basis of membrane structures The main sorts of natural products are alkaloids, polyketides, terpenes, and steroids Alkaloids are amines made from amino acids Fatty acids are built up from acetyl CoA and malonyl CoA subunits ... 

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