Development of a High-Throughput Strategy for Functional Enhancement and Alteration of Antibacterial Natural Products

Abstract

Natural products have been valuable starting points for drug discovery. In this account, we describe a new high-throughput strategy for the functional enhancement and alteration of antibacterial, peptidic natural products. Our strategy integrates solid-phase peptide synthesis, a one-bead-one-compound approach for structural randomization, a microscale bioassay for the selection of hit compounds, and tandem mass spectrometry for structural determination. First, the antibacterial activity of the macrocyclic peptide lysocin E (1) was enhanced. A total of 2401 randomized analogues were synthesized and subjected to two assays to discover more active analogues 3-5. Second, the relative activities of gramicidin A (2) against bacteria and mammalian cells were altered. A total of 4096 randomized analogues were prepared, and their biological activities were evaluated by three assays, revealing that analogues B₀1 and B₁2 had comparable antibacterial activity but displayed significantly attenuated mammalian cytotoxicity. These results together demonstrated the efficiency of the newly designed strategy for the optimization of desirable features as pharmaceuticals in a short time frame.