Physicochemical, Pharmacokinetic, and Toxicity Evaluation of Methoxy Poly(ethylene glycol)- b-Poly(d,l-Lactide) Polymeric Micelles Encapsulating Alpinumisoflavone Extracted from Unripe Cudrania tricuspidata Fruit

Abstract

Alpinumisoflavone, a major compound in unripe Cudrania tricuspidata fruit is reported to exhibit numerous beneficial pharmacological activities, such as osteoprotective, antibacterial, estrogenic, anti-metastatic, atheroprotective, antioxidant, and anticancer effects. Despite its medicinal value, alpinumisoflavone is poorly soluble in water, which makes it difficult to formulate and administer intravenously (i.v.). To overcome these limitations, we used methoxy poly(ethylene glycol)-b-poly(d,l-lactide) (mPEG-b-PLA) polymeric micelles to solubilize alpinumisoflavone and increase its bioavailability, and evaluated their toxicity in vivo. Alpinumisoflavone-loaded polymeric micelles were prepared using thin-film hydration method, and their physicochemical properties were characterized for drug release, particle size, drug-loading (DL, %), and encapsulation efficiency (EE, %). The in vitro drug release profile was determined and the release rate of alpinumisoflavone from mPEG-b-PLA micelles was slower than that from drug solution, and sustained. Pharmacokinetic studies showed decreased total clearance and volume of distribution of alpinumisoflavone, whereas area under the curve (AUC) and bioavailability were significantly increased by incorporation in mPEG-b-PLA micelles. In vivo toxicity assay revealed that alpinumisoflavone-loaded mPEG-b-PLA micelles had no severe toxicity. In conclusion, we prepared an intravenous (i.v.) injectable alpinumisoflavone formulation, which was solubilized using mPEG-b-PLA micelles, and determined their physicochemical properties, pharmacokinetics, and toxicity profiles.

Keywords: alpinumisoflavone; mPEG-b-PLA micelle; pharmacokinetics; solubilization; toxicity.

Figure 1

Representative chromatograms of alpinumisoflavone (AIF) and genistein (internal standard [IS]) in stock solution and biological sample.

Figure 2

Extraction of alpinumisoflavone (AIF) from unripe C. tricuspidata fruits and preparation of AIF-loaded polymeric micelles using thin-film hydration method.

Figure 3

Isolation and nuclear magnetic resonance (NMR) imaging analysis of alpinumisoflavone (AIF) extracted from unripe fruits of Cudrania tricuspidata.

Figure 4

Representative size distribution profiles of alpinumisoflavone (AIF)-loaded mPEG-b-PLA micelles, AIF-loaded Soluplus^® micelles, and AIF-loaded Pluronics^® F127 micelles.

Figure 5

In vitro release profile of alpinumisoflavone (AIF) from mPEG-b-PLA micelles and Cremophor EL^®/EtOH solution at 37 °C.

Figure 6

Alpinumisoflavone (AIF) plasma concentration time profile after intravenous (i.v.) administration of AIF-loaded mPEG-b-PLA micelles and AIF dissolved in 25% Cremophor EL^®/ethanol (EtOH) solution.

Figure 7

Mean concentration time profiles of alpinumisoflavone (AIF) in each tissue within 8 h after intravenous (i.v.) administration of AIF-loaded mPEG-b-PLA micelles and AIF dissolved in 25% Cremophor EL^®/ethanol (EtOH) solution to rats (* p > 0.05, ** p < 0.01).

Figure 8

Relative body weight change and survival rate of rats after multiple intravenous (i.v.) injections of DPBS control, alpinumisoflavone (AIF) dissolved in 100% Cremophor EL^®/ethanol (EtOH) solution, AIF dissolved in 50% Cremophor EL^®/EtOH solution, AIF dissolved in 25% Cremophor EL^®/EtOH solution, and AIF-loaded mPEG-b-PLA micelles on day 0, 4, and 8. (A) Relative daily body weight change. (B) Survival rate demonstrated using Kaplan–Meier plot [42]. Red arrows indicate intravenous injections of the formulations.