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Updated: Jun 25, 2026

A Fluorescence-based Protocol for Preliminary Screening of Protein Synthesis Inhibitors from Natural Sources
Published on: January 27, 2026
Quassinoid inhibition of AP-1 function does not correlate with cytotoxicity or protein synthesis inhibition
John A Beutler1, Moon-Il Kang, Francis Robert
1Molecular Targets Development Program and Laboratory of Cancer Prevention, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, USA. beutlerj@mail.nih.gov
Abstract:
Several quassinoids were identified in a high-throughput screening assay as inhibitors of the transcription factor AP-1. Further biological characterization revealed that while their effect was not specific to AP-1, protein synthesis inhibition and cell growth assays were inconsistent with a mechanism of simple protein synthesis inhibition. Numerous plant extracts from the plant family Simaroubaceae were also identified in the same screen; bioassay-guided fractionation of one extract (Ailanthus triphylla) yielded two known quassinoids, ailanthinone (3) and glaucarubinone (4), which were also identified in the pure compound screening procedure.
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