The toxic peptides from Amanita mushrooms

The results of 50 years of effort in the chemistry of Amanita toxins are reviewed. The phallotoxins, fast acting components, but not responsible for fatal intoxications after ingestion, are bicyclic heptapeptides. They combine with F-actin, stabilizing this protein against several destabilizing influences. The virotoxins likewise fast acting are monocyclic heptapeptides. The amatoxins which are the real toxins lead to death within several days by inhibiting the enzymatic synthesis of m-RNA. They are bicyclic octapeptides. The structures of all of these compounds are described, as well as conformations, chemical reactions and modification, syntheses and correlations between structures and biological activities.

Preparative merits of the mixed anhydride (MA) method in the excess use of DDZ-amino acids in the peptide synthesis of biologically active new antamanide analogues

The mixed anhydride (MA) method of peptide synthesis is further simplified by the repetitive excess use of Ddz-amino acids. In six comparative preparations of decapeptides this is demonstrated by the ease and speed of the synthetic manipulations, the efficiency of the monitoring of the reactions and purifications, and by the complete recycling of excess amino acid derivatives. In using of Ddz-amino acyl isobutylformate mixed anhydrides, side reactions are effectively suppressed, as proved by good coupling of Ddz-proline on to prolyl-peptides. Hydrophilic, crystalline and biological active antamanide analogues are obtained containg various functional side groups. The known cis-conformation of the antamanide prolyl-prolyl bonds is also established in the analogues by 13C-n.m.r. measurements. All new compounds are characterized by molecular peaks in the mass spectra.

Syntheses of monocyclic and bicyclic peptides of tryptathionine and glycine

L-3a-Hydroxy-1.2.3.3a.8.8a-hexahydropyrrolo [2,3-b-]-indole-2-carboxylic acid (Hpi), obtained from L-tryptophan by oxidation with peroxyacetic acid (Savige, 1975), after introduction of the Boc-residue at N-1, is coupled with various glycine peptides of S-trityl-L-cysteine to give the Hpi-peptides 6(a-f). By treatment with absolute trifluoroacetic acid these peptides are converted by an intramolecular thiolysis to the monocyclic thioethers 7(a-f). Two of them, 7e and 7f, can be subjected to a second cyclization by the mixed anhydride method thus yielding the bicyclic tryptathionine heptapeptide 8e and octapeptide 8f. In their structures the bicyclic molecules resemble the mushroom phallotoxins and amatoxins, respectively. They show CD spectra closely related to the naturally occurring bicyclic peptides thus indicating conformational similarities. The CD spectra of the other cyclic peptides synthesized are also presented and discussed.