Research background: Gallic acid is a polyphenol with antioxidant and antitumor activities; however, its use as a nutraceutical or drug is hindered by its low bioavailability. Zein is a natural protein found in corn and has been applied as nanoparticle drug carrier. In this study, zein nanoparticles were obtained and stabilized with polyethylene glycol (PEG) as gallic acid carriers.
Experimental approach: Nanoparticles were obtained by the liquid-liquid method and characterized in terms of mean size, polydispersity index, zeta potential, morphology, solid-state interactions and encapsulation efficiency/drug loading. The stability of nanoparticles was evaluated in simulated gastrointestinal fluids and food simulants, and the antioxidant activity was determined by the scavenging of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical.
Results and conclusions: Zein nanoparticles containing gallic acid were obtained and stabilized only in the presence of PEG. Under optimal conditions, nanoparticles with mean size <200 nm, low polydispersity index (<0.25) and negative zeta potential (-20 mV) were obtained. The gallic acid encapsulation efficiency was about 40%, loading about 5%, and it was encapsulated in an amorphous state. Fourier transform infrared spectroscopy (FTIR) did not identify chemical interactions after gallic acid nanoencapsulation. Zein nanoparticles were more prone to release the gallic acid in gastric than intestinal simulated medium; however, more than 50% of drug content was protected from premature release. In food simulants, the gallic acid release from nanoparticles was prolonged and sustained. Moreover, the nanoencapsulation did not reduce the antioxidant activity of gallic acid.
Novelty and scientific contribution: The results show the importance of PEG in the formation and its effect on the properties of zein nanoparticles obtained by the liquid-liquid dispersion method. This study indicates that PEG-stabilized zein nanoparticles are potential carriers for oral intake of gallic acid, preserving its antioxidant properties and enabling its use in the pharmaceutical and food industries.
Keywords: DPPH scavenging; food simulants; gallic acid release; polyethylene glycol; zein nanoparticles.