Biogenetic origin

In keeping with its biogenetic origin m three molecules of acetic acid mevalonic acid has six carbon atoms The conversion of mevalonate to isopentenyl pyrophosphate involves loss of the extra carbon as carbon dioxide First the alcohol hydroxyl groups of mevalonate are converted to phosphate ester functions—they are enzymatically phosphorylated with introduction of a simple phosphate at the tertiary site and a pyrophosphate at the primary site Decarboxylation m concert with loss of the terti ary phosphate introduces a carbon-carbon double bond and gives isopentenyl pyrophos phate the fundamental building block for formation of isoprenoid natural products... 

Biosynthetic studies using acetate (Ac), propionate (Pr), and butyrate (Bu) revealed the polyketide nature of aurodox which has the composition Pr(Ac)g for the goldinamine skeleton C-7 to C-25 and the composition Bu(Ac) for the C-27 to C-39 carbon chain of goldinonic acid. In contrast to the methyl branch at C-8, those at C-19 and C-21 are methionine-derived as are all remaining methyl groups (52,53). The biogenetic origin of the pyridone moiety is not clear. 

A similar reaction sequence starting from tryptophan yields 1-methyl-3,4-dihydro-)3-carbohne-3-carboxylic acid (465). This compound has been shown to undergo photochemical oxidation to l-methyl-)3-carbohne-3-carboxyhc acid (466). Such a sequence of events may account for the biogenetic origin of the amino acid 466. 

The molecular frameworks of the endiandric acids were unprecedented at the time of their discovery. Intrigued by these unique structures and Black s hypothesis for their biogenetic origin, the... 

It is immediately clear that Acanthomyops need not rely on dietary sources of terpenes but can synthesize citronellal and citral from either acetate or mevalonate. The higher total activity of the citronellal as compared with the citral probably reflects the natural preponderance of citronellal (ca. 90%) in the ant secretion. As the specific activities show, these results are consistent with a common biogenetic origin of both terpenes. In the mevalonic acid pathway as described from other organisms (13), the radioactive carbon of l-C14-mevalonate is lost upon formation of isopentenyl pyrophosphate. 

Marine sponges are a source of an array of polycyclic diamine alkaloids of common biogenetic origin. This class of secondary metabolites has been the subject of four previous reviews [4-7]. Therefore, the present review will include literature reports previously not discussed, dealing with the isolation, structure determination, biological activities, and total synthesis of polycycUc diamine alkaloids isolated from marine sponges. This review will not include guanidine alkaloids [8,9] or the manzamine alkaloids [10,11], since these compounds have been recently reviewed elsewhere. Only polycycUc... 

In the subfamily Chilocorinae, only three species of one tribe (the Chilocorini) have been chemically studied. This has led to the isolation and structure determination of several alkaloids made up of the familiar 2-methylperhydro-9b-azaphenalene skeleton linked to an azaacenaphthylene ring system, which probably has a biogenetic origin similar to that of the former, but a different cyclization pattern (Fig. 3). 

A quantitive, spontaneous cyclization of the 16-carbomethoxy C-20-C-21 unsaturated cleavamine to coronaridine (HO) and the general failure of dehydrosecodine to serve as a synthetic precursor of catharanthine (see Ref. HI for literature review) suggest, however, that the Iboga alkaloids may be preferably assigned a biogenetic origin based on cleavamine cyclizations rather than on a dehydrosecodine. 

The structures of six new geranyl-hydroquinone-derived compounds, from Cordia alliodora, provide additional support for proposed biogenesis in Cordia species (see Vol. 4, p. 69). The isolation of ethuliacoumarin (260) and cycloethuliacoumarin (261) from Ethulia conyzoides suggests an ocimenone (54) biogenetic origin, ... 

Aromatic monoterpenes which contain a benzene ring like p-cymene 9, car-vacrol 12, thymol 13 and phenylethyl alcohol 14 (Structure 4.4) are common constituents of many essential oils, e.g. oregano (Origanum sp.), thyme (Thymus sp.), savory (Satureja sp.) and rose (Rosa sp.) oils. Another important constituent class of essential oils is phenypropanoids [36]. They are not considered as terpenoids owing to their different biogenetic origins, which will be mentioned later. 

Grechkin AN (1995) Clavulones and Related tert-Hydroxycyclopentenone Fatty Acids Occurrence, Physiological Activity and Problem of Biogenetic Origin. J Lipid Mediators Cell Signal 11 205... 

There are several approaches that can be taken to supply material for pharmaceutical evaluation. Two of these, invertebrate cell culture and fermentation of associated microorganisms, begin with determining the biogenetic origin of the compound. There are numerous reports of metabolite localization, primarily in sponges, in which production of a bioactive metabolite has been inferred or demonstrated to be localized either in a host invertebrate cell or in microbial associates which include cyanobacteria and heterotrophic bacteria and fungi.72-73... 

The numbering system used for lactonic Lythraceae alkaloids is that introduced by Spenser (10) and originally employed by Schopf et at. (11). The system closely corresponds to the that introduced by Fujita et al. (12, 13) for metacyclophane alkaloids (B and C). The new system is attractive since the carbon atoms that correspond in biogenetic origin to the three types (A, B, C) maintain corresponding numbers. 

The biogenetic origin of the Guatteria bisbenzylisoquinolines with three linkages between the monomeric units can be traced to the cooccurring oxyacanthine-... 

The six optically active alkaloids ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine, and the N-methylated N-methylephedrine and N-methylpseudoephedrine are described in detail in Reti s review (2). Two new alkaloids of related structure have since been identified in Ephedra species, namely, (9-benzoylpseudoephedrine (271) and the oxazolidine derivative ephe-droxane (272). The 4-quinolone derivative ephedralone, recently isolated from Ephedra alata (273), may be of similar biogenetic origin as the ephedrines. Ephedra species also contain macrocyclic alkaloids of more complex structure (275). The two major Ephedra alkaloids (—)-ephedrine and (+)-pseudoephedrine are diastereomers. (—)-Ephedrine has the erythro and (+)-pseudoephedrine has the threo configuration. 

Numerous studies have been conducted with cultures of the marine dinoflagellate Protoceratium reticulatum not only to confirm the biogenetic origin of yessotoxin 17 and 45,46,47-trinoryessotoxin 20 <1997MI164, 1999MI147>, but also to isolate and assign the structure of known and new YTX analogues, such as 27 (a l-en-3-one isomer of... 

The authors hypothesized the following biogenetic origin for palau amines (Scheme 10.2). 

Scheme 10.2 Postulated biogenetic origin of palau amines.

Scheme 10.3 The biogenetic origin of stevensine from the sponge T. morchella.

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