Isoprenoid quinones

Fluorescein paraffin derivatives, waxes, hydrocarbons [140,141] aliphatic acids [142] hydroquinone and chlorinated derivatives [143] isoprenoids, quinones [111,144] oxathizine fungicides [145] barbiturates, phenothiazines [146]... 

Rhodamine 6G long-chain hydrocarbons [169] squalene, a-amyrin [170] methyl esters of fatty acids [171] glycerides [91] sterols [172, 173] isoprenoids, quinones [HI] lipoproteins [174] glycosphingolipids [175] phenolic lipids [176] phosphonolipids [177] increasing the sensitivity after exposure to iodine vapor [178,179]... 

Solanesol and other prenyl alcohols are important as metabolites in mulberry and tobacco leaves and in the synthesis of isoprenoid quinones. Hence, Sato and collaborators107 have developed a stereoselective synthesis of all-trans-polyprenol alcohols up to C50. Construction of the requisite skeletons was accomplished by the alkylation of a p-toluenesulphonyl-stabilized carbanion, followed by reductive desulphonylation of the resulting allylic sulphonyl group. This was achieved most efficiently by the use of a large excess of lithium metal in ethylamine (equation (43)), although all reaction conditions led to mixtures. The minor product results from double bond rearrangement. 

Collins, M. D. Isoprenoid quinone analyses in bacterial classification and identification. Soc. Appl. Bacteriol. Techn. Ser. 1985,20,267-287. 

Suzuki, K. Application of mass spectrometry to bacterial taxonomy. Cellular fatty acids and isoprenoid quinones. Iyo Masu Kenkyukai Koenshu 1987,12,45-53. 

Male sperm cells of the alga Chlamydomonas allen-sworthii (Fig. 1-11) are attracted to female gametes by a pentosylated isoprenoid quinone.330... 

Collins, M.D. and Jones, D. (1 981) Distribution of isoprenoid quinone structural types in bacteria and their taxonomic implication. Microbiological Reviews 45, 31 6-354. 

Simple, direct and regioselective allylation of 1,4-benzoquinones is an important objective in the synthesis of many isoprenoid quinones such as plastoquinone-1 and vitamin Ki, which play important roles in cellular metabolism and photosynthesis. In a new procedure where the use of a strongly coordinating solvent was found to play an important role, it was shown that reaction of 3 equivalents of (3-methyl-2-butenyl)trifluorosilane with one equivalent of 2,3-dimethyl-l,4-benzoquinone in formamide in the presence of 5 equivalents of FeCl3.6H20 for 23 hours at 40°C gave plastoquinone-1 1, in 90% yield. 

LPDE solution also catalyzes the conjugate allylation of quinones. This is an important reaction in the preparation of biologically active isoprenoid quinones such as vitamin E, vitamin K, coenzyme Qi, and plastoquinones. If 123 is reacted with the allylsi-lane in 5.0 m LPDE for 15 h at 40 °C, allylhydroquinone 124 is obtained in 73 % yield, together with non-allylated hydroquinone 125 (Sch. 63) [113]. 

Meganathan R (1996) Biosynthesis of the isoprenoid quinones menaquinone (vitamin K2) and ubiquinone (coenzyme Q). In Neidhardt FC, Curtiss III R, Ingraham JL, Lin ECC, Low KB, Magasanik B, Reznikoff WS, Riley M, Schaechter M, Umbarger HE (eds) Escherichia coli and Salmonella typhimurium Cellular and Molecular Biology. Vol 1. ASM, Washington DC, p 642... 

Figure 1 Structures of major isoprenoid quinones found in E. coli. (1) Q-8, ubiquinone (2) MK-8, menaquinone (3) DMK-8, demethylmenaquinone. in the structure of MK, the A ring and B ring of the naphthoquinone are shown.

R. Bentley R. Meganathan, The Biosynthesis ot Isoprenoid Quinones Ubiquinone and Menaquinone. In Escherichia coll and Salmonella Typhimurium Cellular and Molecular Biology F. C. Neidhardt, J. Ingraham, K. B. Low, B. Magasanik, M. Schaechter,... 

R. Meganathan, Biosynthesis ot the Isoprenoid Quinones Menaquinone (Vitamin K2) and Ubiquinone (Coenzyme Q). In Escherichia coli and Salmonella Cellular and Molecular Biology E. C. Neidhardt, R. Curtiss III, J. L. Ingraham, E. C. C. Lin,... 

Interest in enzyme stereospecificity and the stereochemistry of prochiral centres, such as the methylene groups of mevalonic acid, has necessitated more precise definitions of the stereochemistry of the various molecules involved and of the enzymological consequences. The use of multiply labelled mevalonic acid in terpenoid and steroid biosynthesis has been reviewed by Hanson. The Proceedings of the 1970 Phytochemical Society symposium have been published. They include a general discussion of terpenoid pathways of biosynthesis by Clayton and specific chapters on monoterpenoids, diterpenoids, eedysones, carotenoids, isoprenoid quinones, and chromanols. Other reviews concerning biosynthesis have appeared on furanocoumarins, indole alkaloids, monoterpenoids, and diterpenoids. ... 

Reaction of Tc-allylnickel bromide complexes mth quinones (4, 354-355). Complete details are available for this method of synthesis of isoprenoid quinones. Yields in general are moderate to high. The reaction is sensitive to both substrate and conditions, and each case requires individual attention. In some cases, unusual enediones are obtained (example I). 

Isopentenylhydroquinone, 397, 398 Isopentyl nitrite, 48 Isophorone, 287 oxide, 282, 283, 394 Isoprene dimers, 4-5 Isoprene epoxide, 79 isoprenoid quinones, 250 Isoprenylation, 397-398 N-Isopropylideneanilines, 3 Isopropylidenecarbene. 358 Isup ropy I idenecy do propanes, 358... 

Fig. 2 (1)]. A key intermediate in the pathway is chorismate from which branched pathways lead to tryptophan, phenylalanine, tyrosine, 4-amino benzoate, isoprenoid quinones, and metacarboxyphenylalanine. A secondary branch also occurs at prephenate leading to phenylalanine and tyrosine. A representative number of non amino acid compounds in relation to their shikimic acid pathway precursors are shown in Fig. 1. One side branch leads to quinate which participates in the formation of depsides. 

From chorismic acid, four major pathways lead to essential metabolites tryptophan, phenylalanine and tyrosine, p-aminobenzoic acid and the folate group of coenzymes, and the isoprenoid quinones (Fig. 7.2). Numerous secondary compounds in plants and other organisms are formed from products and intermediates of these pathways. 

The flesh of Chroogomphus helveticus contains considerable quantities of a second isoprenoid quinone, helveticone (221) 606). In the mass spectrum helveticone exhibited characteristic ions arising by fragmentation of a farnesyl side chain and the structure (221) was corroborated by comparison of this and other spectroscopic data with those of the isoprenologue (222). 

Threlfall, D. R. Polyprenols and terpenoid quinones and chromanols. In Encyclopedia of Plant Physiology, New Series, Vol. 8 Secondary Plant Products (E. A. Bell, B. V. Charlwood, eds.), pp. 288-308. Springer, Berlin-Heidelberg-New York 1980 Threlfall, D. R., Whistance, G. R. Biosynthesis of isoprenoid quinones and chromanols. In Aspects of Terpenoid Chemistry and Biochemistry (T. W. Goodwin, ed.), pp. 357-404. Academic Press, London 1971... 

The isoprenoid quinones, e.g. the ubiquinones 5.36), are essential metabolites, being involved in electron transport in living systems. In the ubiquinones a particular chain length is favoured from n = 6 in certain micro-organisms to w = 10 in most mammals. Mevalonic acid (5.55) is well established as the source of polyprenyl side-chains in these metabolites. It is probable that the side-chain is assembled as a polyprenyl pyrophosphate which then couples with the aromatic fragment. The evidence is that polyprenyl pyrophosphate synthetases and 4-hydroxybenzoate polyprenyltransferases have been isolated from living systems and ubiquinones co-occur with polyprenyl alcohols [as (5.57)] [26, 27]. 

Threlfall D R, Whistance G R 1971 Biosynthesis of isoprenoid quinones and chromanols. In Goodwin T W (ed) Aspects of terpenoid chemistry and biochemistry. Academic Press New York, 357-404... 

CW Moss, MA Lambert-Fair, MA Nicholson, GO Guerrant. Isoprenoid quinones of Campylobacter cryaerophila, C. cinaedi, C. fennelliae, C. hyointestinalis, C. pylori, and C. ups aliens isJ Clin Microbiol 28(2) 395-397, 1990. 

Several metabolites of the shikimate pathway such as the various isoprenoid quinones and the catecholamines have clearly defined biochemical roles in the life of the organism. However, for a great many aromatic metabolites, particularly those from higher plants, their physiological function, if any, is poorly understood. This represents a problem of considerable magnitude for future work in this area and it is one to which attention should now be given. 

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