Biosynthesis of the necic acids of the pyrrolizidine alkaloids. Further investigations of the formation of senecic and isatinecic acids in Senecio species

Bale, Nicholas M.; Cahill, R.; Davies, Noel M.; Mitchell, Michael B.; Smith, Edward H.; Crout, David H. G.

doi:10.1039/p19780000101

Cited by 12 publications

(3 citation statements)

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“…Deprotonation would generate a mesomeric anion with a nucleophilic character at C-6 (numbering corresponding to that of l -isoleucine). This nucleophile might react with a suitable, yet unknown electrophile [111]. From the experiments with 3 H-labeled l -isoleucine and 2 H-labeled 2-aminobutanoic acid, it is clear that the electrophile cannot possess a carbonyl group at C-4 while an alkene would be in agreement with those results.…”

Section: Biosynthesis Of Pyrrolizidine Alkaloidssupporting

confidence: 52%

“…This observation suggested this compound as a possible intermediate (Figure 14A). Unfortunately, it could not be investigated whether the 14 C-label was incorporated in either or both halves of senecic acid [111].…”

Section: Biosynthesis Of Pyrrolizidine Alkaloidsmentioning

confidence: 99%

“…almost invariably present in necic acids of the senecic acid type. It must be emphasized that feeding experiments using ( S )-[ 14 C]-2-methylbutanoate, the precursor of tiglyl-CoA in the l -isoleucine degradation pathway, did not give conclusive results since high incorporation was observed, but the incorporation pattern was unspecific [111]. However, it might be worth reinvestigating a possible role of tiglyl-CoA in senecic acid biosynthesis by state of the art isotopologous NMR-based techniques.…”

Section: Biosynthesis Of Pyrrolizidine Alkaloidsmentioning

confidence: 99%

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Pyrrolizidine Alkaloids: Biosynthesis, Biological Activities and Occurrence in Crop Plants

2019

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Pyrrolizidine alkaloids (PAs) are heterocyclic secondary metabolites with a typical pyrrolizidine motif predominantly produced by plants as defense chemicals against herbivores. They display a wide structural diversity and occur in a vast number of species with novel structures and occurrences continuously being discovered. These alkaloids exhibit strong hepatotoxic, genotoxic, cytotoxic, tumorigenic, and neurotoxic activities, and thereby pose a serious threat to the health of humans since they are known contaminants of foods including grain, milk, honey, and eggs, as well as plant derived pharmaceuticals and food supplements. Livestock and fodder can be affected due to PA-containing plants on pastures and fields. Despite their importance as toxic contaminants of agricultural products, there is limited knowledge about their biosynthesis. While the intermediates were well defined by feeding experiments, only one enzyme involved in PA biosynthesis has been characterized so far, the homospermidine synthase catalyzing the first committed step in PA biosynthesis. This review gives an overview about structural diversity of PAs, biosynthetic pathways of necine base, and necic acid formation and how PA accumulation is regulated. Furthermore, we discuss their role in plant ecology and their modes of toxicity towards humans and animals. Finally, several examples of PA-producing crop plants are discussed.

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Section: Biosynthesis Of Pyrrolizidine Alkaloidssupporting

confidence: 52%

Section: Biosynthesis Of Pyrrolizidine Alkaloidsmentioning

confidence: 99%

Section: Biosynthesis Of Pyrrolizidine Alkaloidsmentioning

confidence: 99%

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