A membrane permeable dihydroquinolinyloxo-isoindolinedione compound that acts as a potent and selective agonist of lysosomal mucolipin transient receptor potential (TRP) channel 1,2,3 (TRPML) in all mammalian cells. Does not appear to affect six other related TRP channels. Shown to rapidly activate whole-endolysosome TRPML-like current and induce lysosomal Ca2+ release (~10uM). Its activating action on whole-endolysosome is comparable to that of PI(3,5)P2 (1uM) with which it shows a synergistic effect. ML-SA1-induced Ca2+ responses are reportedly abolished by glycyl-L-phenylalanine 2-naphthylamide, induces osmotic lysis of lysosomes, and Bafilomycin A1, a V-ATPase inhibitor. Also reduces lactosylceramide and cholesterol accumulation and corrects trafficking defects in Niemann-Pick (NP) disease cells.