Biogenetic relationships

Goutarel, Janot, Prelog, and Taylor have suggested that the structure of cinchonamine provides an important clew to the nature of the processes by which the cinchona alkaloids are produced in the plant (248). 

It will be noted that in a formal sense, cinchonamine (CCXXV at CCX) may be converted to a substance having the normal cinchona skeleton (CCXXVI) through cleavage of the N.1-C.2 bond, followed by formation of a new link between N.l and C.2, after rotation of the benzenoid ring. This relationship indicates that cinchonamine repre- 

The origin of the quinuclidine moiety of the cinchona alkaloids is suggested by the close structural relationship between the skeleton of cinchonamine (OCX s CCXXIX) and that present in yohimbine 

Finally, analogy for the cleavage of ring C of the yohimbine skeleton at 

4 may be found in processes which relate the berberine (CCXXXIl) and the benzophenanthridine (CCXXXIII) groups. 

Evidence regarding the biosynthetic routes leading to coloured carotenoids in higher plants, algae and certain microorganisms was thoroughly reviewed by Goodwin in 1971 (80) and has been updated in symposium reviews in 1975 (30, 61) and 1978 (60, 147). 

When biosynthetic data are lacking mere knowledge of chirality may provide indirect information about possible biogenetic relationships, as illustrated by examples in the discussion below. In other cases established chirality may render reexamination of presumed biosynthetic pathways 

Eschscholtzxanthin (27) produced in Californian poppies from (4R)-[2- C, 4- H] mevalonate showed the same ratio (8 6) as P,P- 

In the bicyclic Cso-series recent biosynthetic evidence from a cell-free system has defined the origin of the H-2,6,10,14,2, 6, 10, 14 and the olelinic proton of the two isopropylidene groups of decaprenoxanthin (8) as the 4-pro(R) hydrogen of mevalonic acid. The 2-pro(R) and 5-pro(S) hydrogens were also retained in the polyene chain in the same 

It is generally assumed that animals do not have the capability to carry out de novo carotenoid synthesis. However, they occassionally have the ability to modify structurally carotenoids obtained through their diet. The absolute configuration of the carotenoids involved may throw light on such metabolic transformations. 

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The nine skeletal types mentioned above are biosynthetically related, or conceivable proposals for their formation in vivo are accepted. A discussion on biogenetic relationships among indole alkaloids is outside the scope of this review and summaries on this subject can be consulted (7, 8, 13). 

Although l,2-methylenedioxy-4-allylbenzene and 1,2-methylenedioxy-4-prope-nylbenzene are really heterocyclic compounds, they are discussed here because of their close biogenetic relationship to the 2-methoxy-4-alkenylphenols. 

The plentiful occurrence of these galactomannans in certain members of the legume family, and the widespread (perhaps universal) distribution of the raffinose oligosaccharides in legumes, make it tempting to suggest that there may be a close biogenetic relationship between these two types of saccharide. 

Obviously a substructure search within the >15000 alkaloids [23] known will uncover many compounds with a 1,4-relationship between a nitrogen atom and a carboxylic acid functionality, a carboxamide, or a carboxylic acid ester ( 1100 examples) [23]. Also anthranilic acid might be regarded as a 2,3-dehydro /1-amino-acid. However, these formal /1-amino acids [139] will not be discussed further, because we do not see a general biogenetic relationship with the real /1-amino acids (vide infra). 

The nature and position of the carbon-nitrogen linkage in the 2-amino sugars endows them with unique properties and biological function that differ widely for example, from those of the nucleotide and nucleoside type of molecule. These substances are theoretically derived by condensation of an amine with carbon atom 1 of a hexose. Although no biogenetic relationship between these two groups has yet been discovered such a possibility cannot be discounted. 

The biogenetic relationship between cleistopholine (154) and annopholine (155) is trivial. Dielsiquinone (134), on the other hand, raises the question of... 

Extracts from Aspergillus amstelodami catalysed the formation of cyc/o-L-prolyl-2-(l,l-dimethylallyl)-L-tryptophanyl (122) from [1-3H]DMAPP and cyc/o-L-prolyl-L-tryptophanyl (123).389 The same enzyme could isoprenylate cyclo-L-alanyl-L-tryptophanyl, but cyc/o-pentylidene-ethyl pyrophosphate did not function as a substrate. The conclusion that echinulin (124) is derived from the prenylation of a pre-formed cyc/o-analyltryptophanyl system is further supported by the isolation of (125) from the mycelium of A. amstelodami,390 whilst the co-occurrence and biogenetic relationship between (125), (12b), (127), and (128) has led to speculation concerning the route to neoechinulin. 

The numbering system for the alkaloids in this chapter is based on biogenetic relationships, i.e., an atom is assigned the same number as its supposed equivalent in yohimban,... 

Lancini, G.C., Gallo, G.G., Sartori, G., Sensi, P. Isolation and structure of rifamycin L its biogenetic relationship with other rifamycines. J. Antibiotics 22, 369 (1969)... 

The close biogenetic relationship of the ipecac and monoterpenoid indole alkaloids has already been reviewed in several places (3,5,117,287). In the case of the ipecac alkaloids, tracer experiments (288) have shown that labeled geraniol (146) and loganin (148) are incorporated by Cephaelis ipecacuanha into radioactive cephaeline (149) and ipecoside (150). Thus, the C9-C,0 units of the ipecac alkaloid and ipecoside, represented by thickened lines in formulas 149 and 150, are of monoterpenoid origin from geraniol (145), and loganin (147) acts as a precursor for both alkaloids. The incorporation of glycine into the C9 unit of cephaeline (2) in Cephaelis plants has also been reported (289). 

Based on the consideration that there are some plausible biogenetic relationships among three major compositions 1, 20, and 10 in qinghao, Huang et al. and Wang et al. succeeded in the incorporation of MVA into 20 in qinghao and then realized the biotransformation of 20 into 1 and 10 in the homogenate. 

The biogenesis of solerone 1 and related compounds was successfully rationalized by biomimetic model reactions. As key step we established the pyruvate decarboxylase catalyzed acyloin condensation of pyruvic acid with ethyl 4-oxobutanoate 4 or ethyl 2-oxoglutarate 3 with acetaldehyde. The importance of the ethyl ester function in 3 and 4 serving as substrates for the enzymatic formation of a-hydroxy ketones 5 and 6 was demonstrated. The identification of six yet unknown sherry compounds including acyloins 5 and 6, which have been synthesized for the first time, confirmed the relevance of the biosynthetic pathway. Application of MDGC-MS allowed the enantiodifferentiation of a-ketols and related lactones in complex sherry samples and disclosed details of their biogenetic relationship. 

The dextrorotatory antipode of the widely distributed (-)-centrolobol (2) was first discovered by Sasaya in A. hirsuta (21) in the company of an interesting tetrahydronaphthopyrone derivative (17), being in evident biogenetic relationship to open chain diarylheptanoids. 

Pentanortriterpenoids.—Recently a fascinating group of highly cleaved C25 terpenoids has been isolated from the Cneoraceae (for a review see ref. 55). Initially these compounds, e.g. cneorin C (76), were considered to be sesterterpenoids, but with the structural elucidation of cneorin B the biogenetic relationship with tetranortriterpenoids became more apparent. The carbon framework (78) helps to emphasize this relationship. It has now been proposed that the cneorins and related compounds are pentanortriterpenoids with the same biogenetic origins as tetranortriterpenoids with which they co-occur. 

Scheme 2 Biogenetic relationship between the skeleta of Taxus alkaloids Numbering refers to the structural formula and not to the biogenesis.

Because of their close biogenetic relationship, earlier reviews (1-3) treated the ajmaline alkaloids together with the sarpagine alkaloids. The number of known structures in the two series has grown markedly, however, and to do this now would require a long and time consuming editorial process, which would diminish the relevance of the information udien published. For this reason, we prefer to treat the... 

Fig. 13. Putative biogenetic relationships of the sponge quinolizidine alkaloids.

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