Non-toxic, pH-sensitive fluorescent dye (blue-green range) for live imaging of pH alteration in acidic organelles, vesicles, cells, tissue and even small whole animals over several days without side effects. Stronger fluorescent intensity under acidic conditions and barely detectable in alkaline solutions (wide range from pH 4 to pH 8). Highly cell/membrane permeable. Trapped within the cells and acidic organelles through hydrophobic interactions with the inner side of the membranes. Barely metabolized and long-term stable, thus slow photobleaching. Angiogenesis inhibitor. Inhibitor of matrix metalloproteinases MMP-1,-2,-8,-9,-12,-13. TYK2, DYRK2,Dyrk1A, YSK4 and RPS6KA1/2 inhibitor.