Bivalent Metal-Chelating Properties of Harzianic Acid Produced by <i>Trichoderma pleuroticola</i> Associated to the Gastropod <i>Melarhaphe neritoides</i>

Abstract

Harzianic acid is a secondary metabolite of Trichoderma, structurally belonging to the dienyltetramic acid subgroup of the tetramic acids. Biological activities of harzianic acid are of great interest for its antimicrobial and plant growth-promoting activities, which might be related to its chelating properties. In the present work harzianic acid, isolated from cultures of a strain of Trichoderma pleuroticola associated to the gastropod Melarhaphe neritoides, was studied as a complexant agent of a number of biologically relevant transition metals (i.e., Zn2+, Fe2+, Cu2+, and Mn2+), using UV-VIS, potentiometry, MS and NMR techniques. Our findings show the coordination capacity of harzianic acid toward the above cations through the formation of neutral or charged complexes in a variable ratio depending on the metal and pH conditions.

Keywords

• <i>Trichoderma</i> secondary metabolites
• bioactive products
• chelating metal
• tetramic acids
• harzianic acid complexes