Antifungal Activity of Cyclic D,L-alpha Peptides

DESCRIPTION (provided by applicant): Development of new antifungal agents is the long-term objective of this project. Systemic infections caused by fungi in humans have dramatically increased in the last two decades. Additionally, lack of fast and reliable diagnosis for some life-threatening fungal infections, current non-fungicidal and/or highly toxic therapeutics, and the emergence of new drug-resistant fungal strains require new effective therapies. A supramolecular approach is proposed to design, identify and select new antifungal agents based on cyclic D,L-alphapeptides. This novel class of compounds can self-assemble in tubular aggregates or peptide nanotubes with high activity against cellular membranes. High membrane selectivity is achieved by supramolecular self-sorting and self-organization, and access to a vast array of sequences and structures within the same superstructural motif and mode of action. The peptidic nature of these compounds and their common parent structure allows using combinatorial chemistry approaches in conjunction with high throughput techniques to rapidly screen and identify lead drug candidates for further study. In order to achieve the proposed objectives, the following aims will be performed: Aim 1: Design and synthesis of single compound per bead combinatorial six- and eight-residue cyclic D,L-alpha-peptide libraries. Aim 2: In vitro antifungal screening of cyclic peptide libraries, identification of desired active sequences using a novel high throughput MS-based sequencing algorithm, individual synthesis of identified active sequences, and establishment of preliminary SAR for use in for further lead optimization. Aim 3: Design and synthesis of small focused peptide libraries based on available SAR for use in further optimizing the potency and selectivity (versus mammalian cells) of the antifungal peptide sequences. Aim 4: Biophysical studies to gain further understanding of the mode of membrane action and its relationship to the observed fungistatic and/or fungicidal activities of selected sequences.