Biogenetic precursors of

Epinephrine itself does find some use in clinical medicine. The drug is used in order to increase blood pressure in cases of circulatory collapse, and to relax the bronchial muscle in acute asthma and in anaphylactic reactions. These activities follow directly from the agent s physiologic role. The biogenetic precursor of epinephrine, norepinephrine, has activity in its own right as a mediator of sympathetic nerve action. (An apocryphal story has it that the term nor is derived from a label seen on a bottle of a key primary amine in a laboratory in Germany N ohne... 

Didehydrogeissoschizine (147) has been proposed to be the biogenetic precursor of simple indolo[2,3-a]quinolizine alkaloids such as flavopereirine (148)... 

It is interesting to note that while vindoline and catharanthine are abundant in Catharan-thus roseus (L.) G. Don, a carbomethoxycleavamine (the initially presumed biogenetic precursor of the binary alkaloids), could not be detected or isolated. This suggested to Atta-ur-Rahman (45) that the VLB-type alkaloids are formed by union of Iboga and Aspidosperma alkaloids, an idea reinforced by biochemical studies (46-49). 

It is interesting to note that these experiments strongly suggested that anhydrovinblastine is the biogenetic precursor of the VLB-type alkaloids in the plant, a proposal recently substantiated (47,48,82-88). 

Pyoverdin-like siderophores with other chromophores have also been observed (see Fig. 1) (45). The 5,6-dihydropyoverdins (Chra without the 5,6-double bond) and the ferribactins (Chrc) are considered to be biogenetic precursors of the pyoverdins 318) (the term ferribactin was originally used for the Fe " complex 221) and later for the free ligand). An azotobactin chromophore (Chrd, see also below Sect. 2.2) is occasionally found in Pseudomonas isolates e.g. 146)). Siderophores produced by a specific Pseudomonas strain but differing in the chromophore always have identical peptide chains. 

Aromatic amino acids are biogenetic precursors of neuroamines (dopamine, serotonin, histamine, etc.). On the other hand, phenylalanine (Phe) is frequently present in peptide sequences, while tyrosine is an important site of phosphorylation of proteins. Aromatic amino acids and neuroamines fluorinated on the aromatic ring have been the focus of many investigations. Indeed, after incorporation in polypeptides and proteins, they can be used as probes in NMR and in PET. 

Loganin is the biogenetic precursor of secologanin, which is a key intermediate in the biosynthesis of a ... 

The halogenated acyclic marine monoterpenes are often considered to be the biogenetic precursors of the alicyclic monoterpenes that are presented in this section. Many of the preceding algae species also contain cyclic monoterpenes. As was the case in preceding sections only newly characterized compounds are numbered and the reader is referred to the first survey for structures of previously isolated compounds (7). 

Cueto M, Darias J, Rovirosa J, San-Martin A (1998) Pantoneurotriols Possible Biogenetic Precursors of Oxygenated Monoterpenes from Antarctic Pantoneura plocamioides. Tetrahedron 54 3575... 

Lindel T, Hochgiirtel M, Assmann M, Kock M (2000) Synthesis of the Marine Natural Product Wa-(4-Bromopyrrolyl-2-carbonyl)-L-homoarginine, a Putative Biogenetic Precursor of the Pyrrole-Imidazole Alkaloids. J Nat Prod 63 1566... 

From a Japanese sponge of the genus Haliclona two cytotoxic alkaloids, haliclamines A and B (252 and 253), were isolated (213). They are proposed to be biogenetic precursors of the petrosins or sarains. 

Lindheimerine occurs in extremely small quantity by comparison with ovatine. Since these two alkaloids are closely related chemically, we suggest that lindheimerine may be a biogenetic precursor of ovatine. These alkaloids did not exhibit any antitumor activity in vivo or in vitro. 

The authors were unable to carry out any transformation of staphinine and staphimine to staphisine and staphidine, respectively, because of the instability of these alkaloids toward various mild reducing agents (e.g., sodium borohydride, sodium cyanoborohydride). Staphimine and staphinine occur in extremely small amounts in the seeds of D. staphisagria. It has been suggested that the imine-containing alkaloids may be biogenetic precursors of staphisine and staphidine. 

Norlaudanosoline [166) R = H] has for a long time been regarded, in schematic terms, as the biogenetic precursor of the isoquinoline alkaloids, and since it is now known158 that noradrenaline [(167) R = OH] is incorporated into berberastine (168) in Hydrastis canadensis L., presumably via 4-hydroxynorlaudanosoline [(166) R = OH], it is possible159 that a series of alkaloids exists based on 166 (R = OH) as parent. It is significant in this context that the alkaloids imenine... 

In the plant, the unstable dihydrorhazinilam 25 is most certainly the direct biogenetic precursor of rhazinilam, which is an isolation artefact. Indeed, 25 was isolated together with 3 from the Apocynaceae Leuconotis eugenifolia and Leuconotis griffithii [58,59] and Kopsia singapurensis [60]. The question whether (+)-l,2-didehydroaspidospermidine 46 is the actual biogenetic precursor of 25 is still open. 

As possible biogenetic precursors of the streptovaricins, damavaricin C and D and the protostreptovaricins I-V have been isolated and characterized (Fig. 8)21,22. Streptovaricin C and D are the precursors of the other streptovaricins22. Figure 13 summarizes the various supposed routes of biosynthesis of the streptovaricins. 

Carotenoids are regarded as part of the aroma potential of grape, as they are the biogenetic precursors of C13-norisoprenoids, a chemical family with many powerful odorants, which are mainly found as glycoconjugates in grape (Baumes et al. 2002 Enzell 1985 Mathieu et al. 2005 Winterhalter 1993). Sunshine favors the biosynthesis of carotenoids in the berry, from the first stage of fruit formation... 

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