Peptide-drug conjugates (PDCs) have emerged as a promising modality in precision oncology, enabling targeted delivery of cytotoxic payloads while minimizing off-target toxicity. The integration of covalent warheads, such as those based on sulfur(VI) fluoride exchange (SuFEx) chemistry, enhances drug-target residence time and tumor accumulation. However, existing screening methods for covalent peptide (CP) libraries require post-translational warhead conjugation, limiting throughput. Here, we present an integrated mRNA display platform that incorporates covalent warheads during ribosomal synthesis, enabling efficient screening of ultra-diverse covalent macrocyclic peptide libraries (>10¹³ variants). This approach, using site-specific incorporation of N-chloroacetyl-d-phenylalanine and fluorosulfate-l-tyrosine, accelerated the discovery of irreversibly binding (K _i = 3.58 μmol/L) Nectin-4-targeting peptide CP-N1-N₃ via proximity-triggered SuFEx. The peptide was further conjugated to cytotoxic payloads, yielding the covalent PDC CP-N1-MMAE with potent cytotoxicity (IC₅₀ ≈ 43 nmol/L) against MDA-MB-468 cells. This platform establishes a new paradigm for precision covalent drug discovery.

Nine novel compounds, comprising seven tetrahydroanthraquinones (auxarthrolones A-G, 1-7), a γ-butenolide glycoside (malfilamentoside E, 26), and a γ-butenolide (auxarthrolide A, 27), together with eighteen known compounds (8-25) were isolated from rice-based solid culture of Auxarthron umbrinum (A. umbrinum) DSM3193 using the one strain many compounds (OSMAC) approach. The structural elucidation of these compounds was accomplished through nuclear magnetic resonance (NMR), mass spectrometry (MS), and NMR calculation combined with DP4+ analysis or MAEΔΔδ parameter, while the absolute configurations of new compounds were established through single-crystal X-ray diffraction, electronic circular dichroism (ECD) spectroscopic data analysis and/or chemical derivatization. Austrocortilutein (10) and auxarthrol H (14) demonstrated moderate cytotoxicity against U87 and U251 [half maximal inhibitory concentration (IC₅₀) 3.5-12.1 μmol·L^-1]. Additionally, auxarthrolone A (1), auxarthrol H (14), eupolyphagin B (15), and 7-hydroxy-2-(2-hydroxypropyl)-5-methylchromone (17) exhibited torsional effects on fibroblast proliferation challenges induced by oleic acid, thus demonstrating fibroblast proliferation-promoting activity.
4-Butyrolactone/pharmacology* ; Molecular Structure ; Anthraquinones/pharmacology* ; Humans ; Animals ; Mice ; Cell Line, Tumor ; Magnetic Resonance Spectroscopy