Daidzein-phospholipid complex loaded lipid nanocarriers improved oral absorption: in vitro characteristics and in vivo behavior in rats

A nano-based delivery system was developed to improve the oral absorption of daidzein, which has poor hydrophilicity and lipophilicity. A daidzein-phospholipid complex (DPC) was firstly prepared to improve its lipophilicity, and then encapsulated into lipid nanocarriers (DLNs) to verify the effectiveness of the strategy in enhancing the oral delivery of daidzein. DLNs were spherical nanosized particles with evidently increased dissolution. DLNs were mainly distributed in stomach and proximal intestine of mice after oral administration, and the intestinal permeability of DLNs in rats was significantly improved when compared with that of daidzein solution. The peak concentration of daidzein in rats after oral administration of DPC and DLNs was 6833 +/- 1112 ng mL(-1) and 14 512 +/- 2390 ng mL(-1), respectively, which was improved over 10-fold and 21-fold than that of free daidzein. Moreover, the areas under the concentration-time curve (AUC(0-t)) of DPC and DLNs were enhanced by 3.62-fold and 6.87-fold compared with that of free daidzein. These results suggested that DLNs could be an effective strategy to improve the oral absorption of poor hydrophilic and lipophilic drugs like daidzein.