Bioavailability Enhancement of Curcumin Isolated from Curcuma longa Cultivated in North Central Nigeria Through Self-Nanoemulsifying Drug Delivery Systems

Curcumin, the principal bioactive polyphenol of Curcuma longa, exhibits documented anti-inflammatory, antioxidant, and anticancer activities but suffers from extremely poor oral bioavailability due to rapid metabolism and low aqueous solubility, severely limiting its clinical development potential. Curcuma longa is increasingly cultivated in North Central Nigeria, particularly in Kwara and Nassarawa States, creating a domestic raw material supply opportunity. This study develops and comprehensively characterises self-nanoemulsifying drug delivery systems (SNEDDS) for curcumin isolated from Nigerian-grown Curcuma longa, with in vitro and in vivo bioavailability evaluation. Curcumin was extracted and purified from Kwara State rhizomes by column chromatography and characterised by HPLC, UV, and NMR. Excipient screening identified optimal oil (castor oil), surfactant (Cremophor RH40), and co-surfactant (PEG 400) components for SNEDDS formulation. Optimisation was performed by D-optimal mixture design. The optimised formulation was characterised for droplet size, polydispersity index, zeta potential, self-emulsification time, drug release, and thermodynamic stability. In vivo pharmacokinetic evaluation in Wistar rats compared the SNEDDS formulation to curcumin suspension. The optimised SNEDDS produced a mean droplet size of 78.4 nm and encapsulation efficiency of 94.2%. In vivo Cmax increased 8.3-fold and AUC by 9.1-fold compared to plain curcumin suspension. The SNEDDS formulation represents a promising platform for clinical development of Nigerian curcumin as an oral phytomedicine. Keywords: curcumin, Curcuma longa, SNEDDS, bioavailability, North Central Nigeria