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Abstract:
The complexing behaviour of antamanide was studied with various mono- and bivalent cations in different solvents. Complexes of highest stability were found for Na, Ca and Tl(I). Polarity of solvent affects complex stability constants strongly, but the selectivity to a lesser degree. The antamanid-Na complex was isolated as a crystalline perchlorate. UV and CD spectral changes on addition of water indicate a transition between defined solvation states of antamanide, that were referred to a conformational change previously detected. The biological activity of some analogs of antamanide was related to Na complexation. From the analogs synthesized up to now it is evident, that Na complexation or at least an attribute of the molecule running parallel to this, is a prerequisite, but not the only one, for biological activity.
