Review: Anti-infectives Echinocandin lipopeptide antifungal agents: New agents and recent chemical modification studies

The search for new and effective antifungal agents has been intensified by the increase in the incidence of opportunistic infections due to immunological diseases and aggressive immunosuppressive chemotherapy. Natural products have provided several novel leads in this field. Of these the echinocandin lipopeptides are of special interest due to their fungicidal properties and low toxicity. Their mode of action uniquely targets fungal cell wall biosynthesis by inhibiting the production of β-(1,3)-D-glucan, an essential cell wall component. Echinocandin B (ECB) consists of a cyclic hexapeptide whose N-terminus is acylated with linoleic acid. Other natural products of this class have closely related structures with some modification of the cyclic peptide and/or the N-acyl fatty acid chain. Although these natural products share excellent antifungal activity, especially against Candida albicans, and low toxicity, further improvements in therapeutic and solubility properties were sought through chemical modifica...