Fig. 4: Effect of liposomes encapsulation on metabolism and excretion of Dox.

a Metabolic kinetics of Dox to Doxol in zonated hepatocytes from sLip/Dox treated mice. The bile distribution of Dox (b) and Doxol (c) at 4, 12, and 24 h post injection. The feces distribution of Dox (d) and 7-Deo (e) at 12 and 24 h post injection. The urine distribution of Dox (f), Doxol (g), and 7-Deo (h) 12 and 24 h post injection. The sLip/Dox or free Dox was intravenously injected into C57BL/6J mice at a dose of 5 mg/kg Dox. The statistical significance was analyzed by two-way ANOVA multiple comparisons corrected by Sidak’s test. P values are provided when there are statistical significances (P < 0.05). Data were means ± SDs for a–h (n = 3 mice). i Injected sLip/Dox or free Dox would excrete through hepatobiliary or renal elimination pathway. For hepatobiliary elimination (liver → bile → intestine → feces), sLip/Dox exhibited a zonated metabolism behavior in the liver as Doxol concentration decreased from cHC to pHC, adapting to both Dox and CYP3A in zonated distribution. As for excretion into bile, Dox encapsulated in liposomes was slower and constant compared to free Dox, and also was less metabolized before entering bile. In the intestine, Dox would be metabolized into 7-Deo by reductive deglycosylation with the aid of gut microbiome, for example, R. planticola. For excretion in feces, compared to free Dox treated mice, sLip/Dox treated mice displayed slower Dox excretion and metabolism to 7-Deo, and from 12 to 24 h, Dox from sLip/Dox excretion into feces and metabolizing into 7-Deo displayed an increasing trend while reversed for free Dox. For renal elimination, sLip/Dox could be degraded and excreted into the urine. Compared to free Dox treated mice, both Dox and two metabolites was much less in the urine from sLip/Dox treated mice except for 24 h, that 7-Deo excretion was higher than the free Dox group. Source data are provided as a Source Data file.