Osteogenic efficacy enhancement of kaempferol through an engineered layer-by-layer matrix: a study in ovariectomized rats

Aim: A layer-by-layer matrix (LBL) comprising kaempferol (LBL-KEM) was prepared for improved osteogenic action. Materials & methods: The LBL-KEM consisted of alternate layers of sodium alginate and protamine sulfate, which were sequentially deposited on the preformed kaempferol (KEM)-loaded CaCO3 core (CaCO3-KEM) by LBL self-assembly. The LBL matrix developed was evaluated for layer growth by z-potential and size alterations after self-assembly of each layer. Its physicochemical properties and intestinal absorption pattern were characterized and its pharmacokinetic behavior, mineralization of bone marrow cells, bone mineral density, bone strength, microcrack formation and estrogenicity were evaluated after oral administration. Results: The entrapment efficiency of KEM was 94 +/- 2% and the cumulative % KEM released from LBL-KEM was 19.2 and 63.5% at pH 1.4 and 7.4, respectively, after 24 h. Stepwise polyelectrolyte assembly onto initially positively charged particles (+21.2 mV) resulted in alterations between -28.5 and +10.9 mV. A final z-potential of -8.9 mV was obtained after terminal surface modification with sodium deoxycholate. Fluorescein isothiocyanate-labeled LBL matrix was diffused into the basolateral lacteal region upon oral administration to rats. The area under the KEM serum concentration curve following oral administration of LBL-KEM to rats was 2479 +/- 682 ng.h/ml, nearly twofold higher than free KEM. The concentration-time profile in bone marrow indicated improved penetration and retention of KEM on administration of LBL-KEM. Treatment with LBL-KEM restored bone mineralization, bone mineral density, microcrack formation and empty osteocyte lacunae density in ovariectomized (OVx) rats, which was significantly (p < 0.05) improved in femoral diaphysea, tibial head and vertebrae compared with free KEM treatment. Administration of LBL-KEM to growing female rats for 4 weeks resulted in no estrogenicity when compared with OVx rats. Conclusion: The data suggests that LBL matrix enhanced drug delivery, improved pharmacokinetics and maintained better bone quality under OVx conditions.