From natural templates to precision tools: Alkaloid-derived probes in elucidating signaling and disease biology.

Alkaloids are a class of plant secondary metabolites with diverse structures and broad biological activities, serving as a crucial source for drug discovery. Currently, the research paradigm in this field is shifting from traditional structure-activity relationship (SAR) analysis to the development of systematic chemical probes. This review systematically elaborates on the core strategies and application progress of designing alkaloid analogs as high-performance chemical probes: it focuses on methods such as structure-based rational design, activity-guided probe derivation, and modular introduction of fluorescent, biotin, and photo-crosslinking groups to construct probe tools with high potency, excellent selectivity, and favorable modifiability; summarizes the multifunctional applications of such probes in decoding core physiological processes including cytoskeletal dynamics, cell cycle, ion channels and neurotransmission, as well as epigenetic regulation; and further discusses their successful cases in uncovering pathways associated with cancer, neurodegenerative diseases, and infection-immune related disorders, along with the discovery of novel targets. Despite the current challenges faced by these probes in terms of selectivity, cell permeability, and fluorescent performance, future integration with cutting-edge technologies such as CRISPR, super-resolution imaging, and chemical proteomics, coupled with the development of activatable smart probes, subcellular organelle-targeted probes, and multimodal probes for in vivo imaging, will greatly promote their pivotal role in deciphering life mechanisms and advancing drug discovery.