Enhanced Stability and Dissolution of Curcumin Nanocrystals Stabilized by Octenyl Succinic Anhydride Modified Starch

Curcumin (CUR) has known to have poor oral bioavailability due to its poor aqueous solubility and stability in gastrointestinal fluid condition as well as its limited permeability which greatly limits its applications in food and medical fields. The present study reported the development of CUR nanocrystal suspension (CUR-NS) for enhanced bioavailability, stabilized with octenyl succinic anhydride modified starch (OSA-S), a naturally renewable and biocompatible biomolecule. This preparation was achieved via an antisolvent precipitation combined with ultrasonic dispersion method, following which the suspension was freeze-dried to form powder CUR nanocrystals (CUR-NCs). Physicochemical properties of the prepared CUR-NS and CUR-NCs powders were extensively characterized. The particle size of the nanocrystals was found to be around 322.8±15.7 nm with a small polydispersity index (PDI) of about 0.230±0.039. Rod like crystal shape was observed by the SEM. Results from powder X-ray diffraction (pXRD) and differential scanning calorimetry (DSC) indicated that the crystal form of CUR in CUR-NCs was a monoclinic polymorph Form 2. Stability results indicated that CUR-NCs possessed an excellent storage-, thermal-, and photo-stabilities. CUR-NCs had a significantly higher dissolution rate, a 68-fold increase in its solubility than that of raw CUR. The cytotoxicity assay demonstrated that CUR-NCs exhibited lower toxicity towards normal human kidney epithelial cells compared to raw CURs. Parallel artificial membrane permeability assay (PAMPA) characterization confirmed that the flux of CUR was significantly enhanced after forming nanocrystals with OSA-S, probably resulting from its increased solubility and dissolution rate. The study showed that OSA-S could effectively stabilize CUR-NCs, and CUR-NCs developed in the current work exhibited significant enhancement in the stability and dissolution rate leading to an improved bioavailability which might be helpful for further development of CUR based products.