Acute oral toxicity of zein nanoparticles with encapsulated gamma oryzanol in Sprague Dawley rats

Gamma oryzanol (GO) is well known for its antioxidant activity and health-promoting benefits. The gamma oryzanol-loaded zein nanoparticles (GOZNs) were successfully prepared in our previous study. In the present work, the acute oral toxicity of GOZNs was evaluated based on OECD guideline 420. GOZNs were fabricated by the liquid-liquid dispersion and lyophilized. The samples displayed a mean diameter of 311.20±3.01 nm and high loading capacity of 311.22±7.97 to 322.69±5.67 mg-GO/g-powder after 42-day storage at -18oC. Healthy female Sprague Dawley rats (8 weeks of age) were used for the experiments. Five female rats were administered a single dose of 2,000 mg GO/kg body weight via the oral route. Observations of toxicity signs were recorded for the first 24 hours, and the changes in the general physical conditions were monitored for 14 days before the gross necropsy on day 15. The results show that Sprague Dawley rats exhibited normal growth, and neither mortality nor acute toxicity signs were observed throughout the study period. The findings revealed that GOZNs did not have acute toxicity and were safe when administered orally in Sprague Dawley rats for short periods with LD50 > 2,000 mg/kg

Preparation and characterization of gamma oryzanol loaded zein nanoparticles and its improved stability

Gamma oryzanol (GO), a bioactive ingredient found in rice bran oil, performs a variety of biological effects such as antioxidant activity, reduction of total cholesterol, anti-inflammation, and antidiabetes. However, GO is water-insoluble and normally degrades through oxidation. Thus a nano-encapsulation technique was investigated to improve its stability and quality. In this research, gamma oryzanol was successfully encapsulated into zein nanoparticles. The fabrication parameters including pH, zein concentration (0.3, 0.4, and 0.5% w/v), and % GO loading (30, 40, and 50% by weight) were investigated. Particle size, zeta potential, yield, encapsulation efficiency and the stability or GO retention during the storage were determined. The morphology of gamma oryzanol loaded zein nanoparticles (GOZNs) was observed by scanning electron micrographs and transmission electron microscope. The increase of zein concentration and % GO loading resulted to an increase of yield, encapsulation efficiency, and particle size. The particle size of the GOZNs ranged from 93.24–350.93, and 144.13–833.27, and 145.27–993.13 nm for each zein concentration with 3 loading levels, respectively. Nano-encapsulation exhibited higher % GO retention compared with nonencapsulated GO during 60 days storage both at 4°C and −18°C. In vitro study indicated the sustained release of GO in the simulated gastric fluid followed by simulated intestinal fluid. This finding indicated a high potential for the application of insoluble GO with improved stability by encapsulation with the hydrophobic zein protein