D-Valyl-L-tryptophan anhydride

Mould Metabolites.—The presence of pre-echinulin [L-alanyl-2 (l, 1-dimethyl-allyl)-L-tryptophan anhydride] in Aspergillus chevalieri has been confirmed,26 and two new metabolites, L-alanyl-L-tryptophan anhydride27" and D-valyl-L-tryptophan anhydride (30),276 have been isolated it is interesting to note that (30), unlike the other metabolites of this micro-organism, contains an amino-acid of the D series. 

Few fungal metabolites consist of a diketopiperazine ring derived from tryptophan and an amino acid other than alanine and proline. Those known in Aspergillus species include ditryptophenaline and D-valyl-L-tryptophan anhydride. 

D-Valyl-L-tryptophan anhydride (57) was isolated by Stipanovic et al. (106) from cultures of Asp. chevalieri (Margin) Thom and Church together with pre-echinulin (MICAT). The rhombic crystals change to long needles between 235 and 255°C, and 57 melts at 277-279°C. High-resolution mass measurement... 

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