Background: Quercetin (QE) is one of the flavonoids with various biological functions
such as anti-oxidation, anti-inflammatory and antitumor. However, the low aqueous solubility and
short half-life in the body reduce its in vivo efficacy. Therefore, the appropriate delivery techniques
to solve those problems have drawn much attention. In the present study, methoxypolyethylene glycol-
poly-DL-lactic acid (MPEG-PLA) nanoparticles loaded with quercetin (QE), called NP, were
prepared, and their antitumor characteristics were investigated in vitro and in vivo.
Method: NPs were produced by evaporating organic solvent from the organic solvent-water mixture
in four formulations. The particle characteristics and in vitro release were examined for the obtained
preparations (NP1 – NP4). The antitumor features were investigated in vivo with different administration
schedules using mice inoculated subcutaneously with murine Sarcoma 180. In addition, the
efficacy of co-administration of NP with a strong antitumor chemotherapeutic agent, irinotecan hydrochloride
(CPT-11), was examined. Biodistribution studies were performed using the same animal
Result: The NP with the higher drug content (0.58 % (w/w)) and gradual release profile, Preparation
NP4, were chosen and used as NP in the in vivo studies. NP suppressed tumor growth better than QE
solution in various dosing schedules (total dose = 2 mg/kg). In the combination therapy with CPT-11,
NP exhibited antitumor efficacy in a nearly additive manner. No decrease in body weight observed
with any administration. NP markedly enhanced the systemic distribution and tumor localization.
Conclusion: These results indicated that the present NP should promote the efficacy of QE, and
might have useful therapeutic potential in the treatment of solid tumors.