In ergot alkaloids

Ergot Alkaloids.—4-(yy-Dimethylallyl)tryptophan (122) is the first intermediate beyond tryptophan in ergot alkaloid biosynthesis. Chanoclavine-I (127) is the first tricyclic base (cf. Vol. 10, p. 26, and ref. 2). Recently, (124 labels as shown) has been found to be a very efficient and intact precursor for elymoclavine (128).45 The high level of incorporation indicates that (123) is a probable intermediate situated between (122) and (127). The decarboxylation product (125) was not utilized for biosynthesis, so, although decarboxylation of (123) is required for the conversion of (123) into (127), either it is intimately associated with ring-closure or an imine that is related to (126) is involved. 

Ergot Alkaloids.—The enzyme which catalyses the first step in ergot alkaloid biosynthesis, namely the conversion of tryptophan into dimethylallyltryptophan (126),110 has been isolated from a Claviceps species and characterized.111 The biosynthesis of clavicipitic acid (127) may be a major alternative to the synthesis of other ergot metabolites, and further results in a study112 of an enzyme from C. purpurea which catalyses the formation of clavicipitic acid (127) from (126) have been published.113... 

Experiments have been carried out with elymoclavine (73) in whole cells and protoplasts of Claviceps strain SD 58 levels of dimethylallyltryptophan synthetase, the first enzyme in ergot alkaloid biosynthesis, were measured.64 The results that were obtained provide strong evidence that there is end-product regulation of the synthesis of alkaloids in vivo and that it involves feedback inhibition end-product repression of the synthesis of enzymes appears to be of lesser importance. 

Shibuya, M., Chou, H.-M., Fountoulakis, M., Hassam, S., Kim, S.-U., Kobayashi, K., Otsuka, H., Rogalska, E., Cassady, J.M. and Floss, H.G. (1990) Stereochemistry of the isoprenylation of tryptophan catalysed by 4-( Y, Y-dimethylallyl)tryptophan synthase from Claviceps, the first pathway-specific enzyme in ergot alkaloid biosynthesis. /. Am. Chem. Soc., 112, 297-304. 

Wang J. dmaW encoding tryptophan dimethylallyltransferase in ergot alkaloid biosynthesis from Clavicipitaceous fungi. PhD dissertation, University of Kentucky, Lexington, KY, 2000. 

Figure 1 Key intermediate and enzymes from the first committed step in ergot alkaloid biosynthesis through the synthesis of lysergic acid. Simple amides of lysergic acid and ergopeptines are covered in Figs 2 and 3, respectively. Abbreviations DMAPP = dimethylallyl pyrophosphate DMAT = dimethylallyl tryptophan AdoMet = S-adenosyl-methionine.

GENES ENCODING ENZYMES INVOLVED IN ERGOT ALKALOID BIOSYNTHESIS... 

In ergot alkaloid synthesis does not become appreciable until the sphacelial stage gives rise to sclerotia. Unpublished experiments in the author s laboratory (Groger) indicate that there is no change in the ratio of the alkaloids as the ergot matures. 

Dimethylallyltryptophan (139) has been identified as the first intermediate after tryptophan in ergot alkaloid biosynthesis.In experiments with a Claviceps species, clavicipitic acid (140) was identified as a major product formed from (139).(The enzyme catalysing this transformation was identified in both the supernatant and microsonal fractions oxygen is necessary for the reaction but cytochrome P-450 does not appear to be involved.) But radioactive clavicipitic acid was found to be a much less efficient precursor than (139) for elymoclavine and thus is in all probability not an intermediate in ergot alkaloid biosynthesis. 

The cyclization 334 - 335 in ergot alkaloid biosynthesis has been shown to involve loss of the 3-pro-S hydrogen of tryptophan in the process, casting light on the stereochemistry of the ring closure step (336). 

To probe the possibility of diastereomeric amino adds being intermediates in ergot alkaloid biosynthesis... 

A very detailed review of the HPLC methods has been carried out [7]. The author has described the stationary phase, the mobile phase, flow rate, and detector system used by researchers since 1973. We would like to describe the other analytical methods such as the capillary electrophoresis, flow injection analysis and two-dimensional fluorescence spectroscopy which have foimd applications in ergot alkaloid research. 

J. Wang, IF Encoding Tryptophan Dimethylallyltransferase in Ergot Alkaloid Biosynthesis from Clavicipitaceous Fungi. Ph.D. thesis. University of Kentucky, Lexington, 2000. 

A regular structure that for several years attracted more attention was formulated by Dorothy Wrinch in 1937 [7]. Her cyclol hypothesis postulates that, in proteins, secondary cyclic structures are present, similar to the crosslinks revealed later in ergot alkaloids, by the addition of amide, —NH-groups to opposite carbonyl groups forming an —N—C(OH)— bond and so preferably 6-membered rings (Fig. 1). Later it was shown in several instances that cyclols indeed occur in small cyclic peptides, but they were never found in proteins. 

Qavicipitic Acids were Isolated as an Isomcnic Mixture, and the Melting Point of the Mixture has been Reported Robbers JE, Otsuka H, Floss HG, Arnold EV, Clardy J (1980) Qavicipitic Acid Its Structure, Biosynthesis, and Role in Ergot Alkaloid FramatiOTt. J Org Qiem 45 1117... 

Cheng JZ, Coyle CM, Panaccione DG, O Connor SE (2010) A role for old yellow enzyme in ergot alkaloid biosynthesis. J Am Chem Soc 132 1776-1777... 

The ionization mode most effective in ergot alkaloid analysis is positive electrospray ionization, which produces more intense protonated molecular ions than the deprotonated molecular ions that result from negative ionization, and this has become the preferred ionization method. When ergot alkaloids are ionized in positive electrospray mode the ions formed are predominantly the protonated molecular ions [M -i- H] -i- ions, with little evidence of adduct formation with ions of sodium, potassium, or ammonia, despite the ubiquitous presence of sodium in aqueous mobile phase solvents and the addition of comparatively high levels of ammonium salts. 

Malinka, Z., Harazim, P., Bfemek, J. and Valik, J. (1987) Influence of aminoacids in ergot alkaloid biosynthesis. Bulletin Cs. spol. biochem. pfi CSAV, 15, 107 (In Czech). 

RehaSek, Z. (1983a) New trends in ergot alkaloid biosynthesis. Process Biochem., 18, 22-29, 33. 

RehaSek, Z. and Malik, K.A. (1971) Cell-pool tryptophan phases in ergot alkaloid fermentation. Folia Microbiol, 16, 359-363. 

This chapter contains information abont all the therapentically used ergot alkaloids and their mannfactnre. Not all snch information can be found in the literature and snpported by references. The technology used for manufacture can be traced in the patent literatnre bnt not all the patented processes are actnally used in the prodnction and, on the other hand, not all the technologies used have been patented. So at least a part of this information is based on personal commnnication only or is dednced from some indirect cues—for instance the profile of impnrities. Fnrther information, not usually published is the amount of individnal mannfactnred prodncts. These estimations are based on a long-term experience in ergot alkaloid business. Even if all such estimations can be inaccurate, I believe that in a book published in a series Industrial profiles they cannot be omitted. 

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