THIN-LAYER CHROMATOGRAPHY OF ERGOT ALKALOIDS

Ergot alkaloids--sources, structures and analytical methods

Natural sources, i.e. fungal strains and species producing ergot alkaloids (EA), are surveyed together with the chemical structures of EA and a list of new natural EA discovered in the last three decades. Other topics include new efficient chromatographic methods (HPLC) for the separation and isolation of new natural EA and also immunological methods of EA detection.

Occurrence of mycotoxins in cereals and animal feedstuffs in Natal, South Africa 1994

During the year of 1994, 417 samples of agricultural commodities, comprising: maize, compound animal feeds, oil seeds, soya bean, fish meal and forage were examined for fungi and over 20 mycotoxins using a multi-screen augmented with individual assays. Trichothecenes had the highest incidence of over 19% in all samples received, followed by aflatoxin at 6% and then zearalenone at 3%. Selected samples (73) were analyzed for fumonisin B1 and of these, 69 (94%) were found to be positive. Because of this result and high incidence of Fusarium spp. (over 70%) in maize and maize containing feeds, which was higher than either Aspergillus spp. (19%) or Penicillium spp. (33%), attention is drawn to the actual and potential presence of fumonisin in the food chain.

An HPLC method for the detection of ergot in ground and pelleted feeds

A high performance liquid chromatography (HPLC) method is described for detecting ergot in ground or pelleted forages and grains. Samples were extracted with alkaline chloroform, filtered, and applied to silica gel/organic binder cleanup columns. Following elution of pigments with acetone: chloroform, ergopeptine alkaloids were eluted with methanol and analyzed by HPLC with fluorescence detection. Average recovery of ergotamine, the major ergopeptine alkaloid produced by Claviceps, was 93%, with a relative standard deviation of 4.9%. The detection limit of ergotamine was approximately 50 ppb in all feedstuffs. Confirmation of ergopeptine alkaloids was accomplished by treating the parent ergopeptine alkaloids with 0.2% acetic acid to produce their -inine isomers and reexamining by HPLC with fluorescence detection or silica gel/organic binder column cleanup in combination with tandem mass spectroscopy. The method described is a valid alternative to microscopic inspection for detecting ergot contamination in ground or pelleted feedstuffs.

Genetics of the ergot fungus Claviceps purpurea : I. Proof of a monoecious life cycle and segregation patterns for mycelial morphology and alkaloid production

The morphological and physiological evaluation of single ascorspore lines (F1) obtained from 4 production strains of Claviceps purpurea and the subsequent production and evaluation of an F2 from two of these strains has shown: 1. The breeding system responsible for the sexual cycle of C. purpurea is characterized by monoecism and self-compatibility. 2. Heterokaryosis is neither required for the completion of the life cycle nor for alkaloid synthesis. 3. The huge variability in both mycelial morphology and alkaloid spectra makes it evident that all production strains are highly heterogeneous. 4. A correlation between morphology and an alkaloid pattern was not found. 5. Alkaloid production is, however, correlated with distinct genotypes. 6. In some cases an increase in the total alkaloid content and in the formation of specific alkaloids was also found, showing that the genetic control of these metabolites may be accessible. Taken together these results open up the way to concerted breeding with Claviceps purpurea with the object of improving alkaloid production.

Biosynthesis of ergotamine by Claviceps purpurea (Fr.) Tul

High-yielding strains of Claviceps purpurea (Fr.) Tul, grown on a defined medium, have been used for a study of the biosynthesis of the peptide ergot alkaloid, ergotamine. l-[U-(14)C]tryptophan, dl-[2-(14)C]mevalonic acid lactone, sodium [2-(14)C]acetate, sodium [(14)C]formate and the methyl group of l-[methyl-(14)C]methionine were efficiently incorporated into the peptide alkaloids and specifically labelled the ergoline moiety of ergotamine. These results are the same as previously found for the biosynthesis of other ergot alkaloids. Time-course incubation experiments demonstrated that l-[U-(14)C]phenylalanine, l-[U-(14)C]proline and l-[U-(14)C]alanine were incorporated into the peptide ergot alkaloids. Chemical degradation of the radioactive alkaloid derived from additional precursor incubation experiments showed that phenylalanine and proline function as the most efficient precursors, and specifically label the constitutive side-chain phenylalanyl and prolyl moieties of the alkaloid. The evidence obtained from l-[U-(14)C]alanine-incorporation experiments was inconclusive. However, degradation of ergotamine isolated after incubation with dl-[1-(14)C]alanine, showed that the carboxyl group of the labelled amino acid was specifically incorporated into the alpha-hydroxy-alpha-amino acid residue of the alkaloid. This, in conjunction with the l-[U-(14)C]alanine-incorporation results, showed conclusively that all three carbon atoms of alanine were incorporated as a biosynthetic unit into the alpha-hydroxy-alpha-amino acid moiety of ergotamine.

Production of peptide ergot alkaloids in submerged culture by three isolates of Claviceps purpurea

Three strains of Claviceps purpurea (Fr.) Tul., isolated from sclerotia grown on rye, produce under submerged conditions ergocryptine and ergotamine, ergocornine and ergosine, and ergocristine, respectively. All of the strains either lacked the ability to produce conidia or formed them sparingly, but they accumulated large quantities of lipids and sterols. The fermentations are typically divided into two phases. The first is characterized by the rapid utilization and exhaustion of the phosphate contained in the medium, rapid uptake of ammonium nitrogen and of citric acid, rapid growth, and low alkaloid production; the second phase is characterized by slower growth and by a marked accumulation of lipids, sterols, and alkaloids.

Role of glycols and tweens in the production of ergot alkaloids by Claviceps paspali

Several glycols and Tweens markedly stimulated the production of ergot alkaloids in submerged cultures of Claviceps paspali. The role of these compounds was investigated in shake flasks and bench-scale fermentors. 2,3-Butanediol was not utilized by the fungus, and 1,2-propanediol-1-(14)C was not incorporated into the alkaloids. Glycols and Tweens lowered the surface tension of the basal medium and promoted the utilization of metabolites. In the presence of glycols and Tweens, an increased uptake of labeled sorbitol and succinic acid took place, whereas the specific radioactivity of the alkaloids was not affected. These results indicated that glycols and Tweens are not involved directly in the biosynthetic process; they apparently acted as surface-active agents, facilitating transport of metabolites into the cells.

Inhibition of lactation in mice following feeding with ergot sclerotia [Claviceps fusiformis (Loveless)] from the bulrush millet [Pennisetum typhoides (Staph and Hubbard)] and an alkaloid component

Female mice fed during the latter part of pregnancy on a diet containing sclerotia of Claviceps fusiformis a t 2 to 3% failed to raise their litters. The active principle of these sclerotia in inducing the pup mortality has been shown to be the alkaloid agroclavine which was found to inhibit normal mammary hypertrophy when administered in the food a t 5 to 7 mg %. Where the alkaloid treatment continued after parturition the litters died of malnutrition. When the alkaloidal diet was discontinued on the day before parturition there was a rapid recovery from the effect of agroclavine resulting in a normal pup growth rate. Agroclavine was also found to suppress well established lactation. This inhibition of mammary hypertrophy in mice by agroclavine administered orally at a non-toxic dosage is a new pharmacological action for the clavine alkaloids.