Pyronin Y

Pyronin Y (CAS No.: 92-32-0) is a cationic fluorescent dye widely employed in biomedical research as a nucleic acid–intercalating probe with strong affinity for RNA, enabling selective staining and semi-quantitative analysis of cellular RNA in both live and fixed cells. By forming stable fluorescent complexes with double-stranded nucleic acids, particularly RNA, it facilitates the visualization and differentiation of RNA-rich cellular compartments, ribonucleoprotein complexes, and specific RNA subspecies, thereby supporting investigations into RNA dynamics, gene expression, and cell signaling pathways. Pyronin Y is also capable of labeling DNA and certain organelles, broadening its utility in cell biology studies, including the assessment of cell cycle status, especially in stem cell populations, and compatibility with flow cytometry-based analyses. Its fluorescence properties, with excitation and emission maxima in the green-orange spectral range, make it suitable for multiplex imaging applications. Mechanistically, its activity is driven by electrostatic interactions and intercalation into nucleic acid structures rather than direct modulation of enzymatic targets, and thus it is primarily categorized as a research probe rather than a therapeutic agent. In vitro applications typically involve micromolar concentrations, with experimental conditions adjusted according to cell type and assay design, and in live-cell systems it is often used in combination with efflux inhibitors to enhance intracellular retention. Pyronin Y remains a valuable tool in drug discovery and functional genomics workflows where monitoring RNA content and distribution is critical.