Lys05, or Lys01 trihydrochloride, is a potent, water soluble lysosomal autophagy inhibitor. Lys05 is a previously undescribed dimeric chloroquine which more potently accumulates in the lysosome and blocks autophagy compared with HCQ. Lys05 produced more p

HT29 cells:7.9 μM, LN229:6μM, 1205Lu:3.6μM, C8161 cells:3.8μM

Lys01 is an autophagy inhibitor significantly (10-fold) more potent than hydroxychloroquine (HCQ). Its water-soluble derivative, Lys05, demonstrates enhanced potency by more effectively accumulating in and deacidifying lysosomes compared to HCQ. Both Lys01 and its trihydrochloride version induce similar dose-dependent effects, such as an increase in the LC3II/LC3I ratio, p62 protein accumulation, and identical half-maximal inhibitory concentrations (IC50) in the MTT assay[1].

In a study utilizing high-dose, short-term administration of lys01 trihydrochloride at 76 mg/kg intraperitoneally (i.p.), no mortality was observed in mice. However, symptoms such as arched backs and lethargy became apparent after two days of treatment. Electron microscopy (EM) revealed that in lys01 trihydrochloride-treated tumors, cells maintained intact nuclear and cytoplasmic membranes but demonstrated a significant presence of large autophagic vacuoles (AVs). This treatment markedly inhibited tumor growth, showing a substantial 53% decrease in the average daily tumor growth rate compared to tumors in vehicle-treated control mice. Furthermore, a pronounced increase in AV accumulation was noted in treated tumors—three-fold in HCQ-treated and six-fold in lys01 trihydrochloride-treated tumors—after 14 days of treatment, when compared to control-treated tumors.

1205Lu, c8161, LN229 and HT-29 cells are treated with lys01 trihydrochloride (0, 0.01, 0.1, 1, and 10 μM) or Lys01 (0, 0.01, 0.1, 1, and 10 μM) in five replicates for 72 h. The Acid Phsophatase Assay kit is used for the MTT assay[1].