Evaluation of Antioxidant Ability In Vitro and Bioavailability of trans-Cinnamic Acid Nanoparticle by Liquid Antisolvent Precipitate

TCD is a kind of organic acid that is isolated from cinnamon bark or benzoin. TCD has significant antioxidant activity and is widely used in pharmaceutical, cosmetic, and food additives. But TCD has shortcomings of low bioavailability due to poor water solubility. Therefore, we use ethanol as a solvent, deionized water as antisolvent, and hydroxypropyl methylcellulose HPMC as the surfactant to prepare TCD nanoparticle powder. The optimum preparation conditions were determined as follows: TCD-ethanol solution concentration was 170 mg/mL, the volume ratio of antisolvent was 4 times that of solvent, and the amount of the surfactant was 0.3% stirred for 10 min by 2500 rpm; TCD nanoparticle with a mean particle size MPS of 130±12.5 nm is obtained under the optimum conditions. SEM, FT-IR, LC-MS/MS, XRD, and DSC were used to characterize the TCD nanoparticle. The results showed that the chemical structure of TCD nanoparticle was not changed, but the crystallization was significantly reduced. Solubility, dissolution rate, antioxidant activity, the in vitro transdermal penetration, and bioavailability of TCD nanoparticles were all much better than these of the raw TCD. These results suggested that TCD nanoparticle might have potential value to become a new oral or transdermal TCD formulation with high bioavailability.