Nanoencapsulation of Curcumin Using Biopolymers Derived from Nigerian Yam (Dioscorea rotundata) for Enhanced Oral Bioavailability

Curcumin, the principal bioactive polyphenol of turmeric, possesses well-documented anti-inflammatory, antioxidant, and anticancer properties. Its clinical utility is, however, severely constrained by poor aqueous solubility and low oral bioavailability. Biopolymer-based nanoencapsulation represents a promising strategy to overcome these limitations using locally available and renewable excipient materials. This study developed and characterised nanoparticles loaded with curcumin using starch isolated from Nigerian white yam (Dioscorea rotundata) varieties cultivated in Taraba State, North East Nigeria. Yam starch was extracted and chemically modified by octenyl succinic anhydride esterification to confer amphiphilic properties. Curcumin nanoparticles were prepared by the nanoprecipitation method. Nanoparticles were characterised for hydrodynamic diameter, polydispersity index, zeta potential, encapsulation efficiency, and drug loading by dynamic light scattering and HPLC. In vitro release was studied in simulated gastric and intestinal fluids. Optimised nanoparticles had a mean diameter of 186 nm, polydispersity index of 0.19, and zeta potential of negative 28 mV, indicative of physical stability. Encapsulation efficiency reached 84.6%, and in vitro release showed sustained curcumin delivery over 24 hours compared to immediate release of free curcumin. Compared to free curcumin suspension, nanoencapsulation significantly enhanced apparent solubility by approximately 18-fold. These findings demonstrate that modified Nigerian yam starch is a viable biopolymer matrix for curcumin nanoencapsulation with potential to improve oral bioavailability. Keywords: curcumin nanoparticles, yam starch, nanoencapsulation, oral bioavailability, Dioscorea rotundata.