Preparation of Nanoniosomes at different Cholesterol Concentrations Using the Thin-film Hydration Method for Nanoencapsulation of Pure Polyphenolic Compounds

IntroductionNowadays, the attention and desire of consumers to the role of food in health and nutrition has led the manufacturers to produce functional food and researchers to study this field. Polyphenols are secondary metabolites produced by many plants. They have anti-obesity, anti-inflammatory, anti-cancer and antioxidants activities. Despite all the mentioned benefits, due to the vulnerability of phenolic compounds to the environmental conditions and their low bioavailability in the digestive system, efforts have been made to encapsulate them with nanoniosomes. Encapsulation of polyphenolic compounds with nanoniosomes is an effective way to increase their stability and bioavailability as well ashinder their undesirable taste and smell. Niosomes are class of bi-layered structure formed by hydration of non-ionic surfactant, cholesterol or other amphiphilic molecules. This structure has two hydrophilic and hydrophobic properties, so it has the ability to be encapsulated with different solubility. Fortification food with polyphenols promotes community health. Therefore, the aim of this research was to produce nanoniosomes containing polyphenolic compounds, and to determine their important physical and chemical properties.Materials and MethodsIn this research, four polyphenol-loaded nanoniosomes were prepared using Span 60 and Tween 80 surfactants with a ratio of 3:1, and cholesterol with the concentration of 0, 10, 20 and 30 (mg/140 mg surfactant) as F1, F2, F3 and F4 treatments respectively. Physicochemical properties of the polyphenol-loaded niosomes (particle size, polydispersity index (PDI), zeta potential, encapsulation efficiency (EE)) were analyzed, and the formulation with the best characteristics was selected based on having the smallest size, less PDI and the highest EE. The selected formula was analyzed for morphology (scanning electron microscope (SEM)) and probably interactions (Fourier transforms infrared spectrometry (FTIR)). Additionally, the ability to preserve polyphenolic compounds as free or inside the nanonisomes during the storage period of 60 days was investigated. Further, the in vitro release of polyphenol from niosomes (gastric and intestinal simulated fluid) was also evaluated. The experiment was performed as completely randomized design (CRD) and the obtained data were analyzed with one-way analysis of variance (ANOVA).Results and DiscussionResults indicated that the effect of using different amounts of cholesterol on the average particle size (Z-average) of nanonisomes was significant (p<0.05). With increasing cholesterol up to 20 mg (F1 to F3), the Z-average decreased, but with further increase to 30 mg (F4), the Z-average increased. Different concentrations of cholesterol showed significant influence on the PDI of nanonisomes. The minimum value was observed for F3 (20 mg cholesterol) and the maximum for F4. The incorporation of cholesterol in the nanonisomes decreased the zeta potential (p<0.05), dedicated an increased electrostatical stability of the particle, and the values were in the range of -50.35 to -65.36 mV. The value of EE was in the range of 88-95%, and F3 treatment had the maximum EE. Based on particle size, PDI, zeta potential and EE, F3 was selected as the best nanoparticle for other assays. According to the FTIR results, there was no change in the spectrum of nanonisome (F3) containing polyphenol peaks, and the polyphenols were properly enclosed in the nanonisomal vesicles without changing its nature. SEM results also showed vesicles with a uniform and appropriate structure. Nanonisome (F3) containing polyphenol was more stable than the control sample (polyphenol) during 60 days of storage at ambient temperature, which indicated the higher potential of nanonisomes to preserve the polyphenolic compounds during storage. The release behavior in the simulated digestive system (gastric and small intestine media) indicated a diffusion-based release system, and the Kopcha model was the best model to describe the release behavior of polyphenol from the fabricated niosomes in the simulated digestive environment.ConclusionAccording to the results of this research, it is concluded that nanoencapsulation of polyphenols as a rich source of antioxidant properties inside the nanonisomes can be an effective strategy to maintain their nutritional value. These nanonisomes can be utilized to produce functional foods, and the effects of their addition on the physico-chemical properties of a model food can be investigated.