Enhancement of oral bioavailability and hypoglycemic activity of liquiritin-loaded precursor liposome.

The purpose of this study was to develop a precursor liposome nano-delivery system for liquiritin (LT) to improve its solubility, oral bioavailability, and efficacy. The characterizations of the particle diameter, zeta potential, polydispersity index (PDI), droplet morphology, drug release in vitro, and oral bioavailability of the prepared LT precursor liposomes (LTMs) were carried out. In addition, streptozotocin intraperitoneal injection successfully induced diabetic mouse model, while the LT hypoglycemic effect, oral glucose tolerance, biochemical parameters and pathological sections were studied. The prepared LTMs were diluted to obtain a clear and transparent solution with a diameter of 91.84 ± 1.85 nm, zeta potential of -38.59 ± 2.65 mV and PDI of 0.215 ± 0.016. The in vitro release of the LTMs was superior to that of the free LT suspension, which may be related to the increased solubility of LT, as well as the small diameter and increased surface area. The obtained pharmacokinetic parameters indicated that the relative oral bioavailability of LTMs was increased by 8.8 times compared with the free LT suspension. Pharmacodynamic studies showed that LTMs effectively improved LT's hypoglycemic effect and diabetes-related organ repair, simultaneously confirmed its antioxidant activity. These results implied that the LTMs was an effective method to improve the solubility, oral bioavailability, and hypoglycemic activity of LT.