Physical and chemical properties of β-sitosterol containing nanoliposomes

Introduction: Natural sterols and stanolols in plant cell membranes are known as phytosterols. In recent years, interest in the use of phytosterols in dietary compounds to reduce cholesterol has increased. Diet provides a daily amount of phytoestrol 500-180 mg, which is not enough to lower blood cholesterol. The main mechanism of action of phytosterol in reducing cholesterol is interfering with the dissolution of cholesterol in the intestinal micelles which leads to a decrease in cholesterol absorption. These compounds also reduce the risk of gastric cancer, prevent tumor growth, improve inflammatory diseases, and prevent atherosclerosis. Taking two to three grams of phytosterol per day can lead to approximately a 10% decrease in blood cholesterol levels and a 15% decrease in low density lipoproteins. Phytosterol is a white, water-insoluble, high-melting powder that is difficult to dissolve in fats and oils, which makes it difficult to add phytosterol to foods.
Phospholipids are cell membrane constituents with a hydrophilic end and one or more hydrophobic tails; they also have antioxidant activity. These compounds are used to make carriers called nanoliposomes that have in recent years been an important carrier in the pharmaceutical and food industries for the coating and release of hydrophilic or lipophilic active compounds such as vitamin A, Vitamin E and vitamin C, ascorbic acid, micronutrients, omega-3 essential fatty acids, medium chain fatty acids - vitamin C, cinnamon oil, polyphenols including catechin, curcumin and other active ingredients. Nanoliposomes are colloidal structures formed from one or more spheres consisting of two lipid layers that surround the aquatic environment. This structure of liposomes provides special properties, such as spontaneous sealing in the aqueous medium, which makes them suitable carriers for active compounds in the field of medicine, immunology, diagnosis, substances Manufactures cosmetics, cleaning and food industries. Nanoliposomes provide greater surface area than liposomes, and improve bioavailability and targeted targeting of embedded materials. In the design of nanoliposomes used in the food industry, two important parameters must be taken into account; the first parameter, the stability of nanoliposomes, in order to increase the shelf life and storage of the food and the second parameter, the composition of their structure should not be compromised. Make a difference in the texture and taste of the food.
Reducing the size of liposomes to nanosize can reduce their stability. For this reason, the addition of stabilizers can extend the life and stability of these nanocarriers.
Adding Cholesterol to Phospholipids Increases Stability of Nanoliposomes by reducing lipid membrane permeability and membrane stiffness. Nanoliposomes have shown good potential to encapsulate and stabilize molecules against a wide range of environmental conditions and to protect them from degradation.
The main purpose of this study was to incorporate phytosterol into nanoliposomal formulations in order to improve its dispersion in aqueous and aqueous media, to select the optimal formulation from soybean-cholesterol formulation. Different concentrations of cholesterol were used as stabilizers. Mean particle volume diameter, dispersion index, zeta potential, physical stability and pH were studied as important parameters. The use of edible grade compounds in the preparation of nanoliposomes and the overlay of the beneficial phytoestrol compound is the most important advantage of this study over other studies. According to studies done, no research into the intrinsic phytosterol content of edible materials was found. In this study, ultrasonic homogenizer was used to reduce particle size and more efficient loading of phytosterol into nanoliposomes.
Material and methods: In this study, β-sitosterol containing nanoliposomes were prepared from different concentrations of soy-lecithin and cholesterol by thin layer hydration method. The ultrasonic homogenizer was used to reduce the particle size. Fourier-transform infrared spectroscopy (FTIR) was performed to investigate the possible interaction between beta-cytosterol and the prepared nanoliposomal carriers. Particle size, polydispersity index and zeta potential of nanoliposomes were analyzed according to cholesterol content of samples. Also, pH and stability of nanoliposomes in different temperatures were analyzed according to cholesterol content.
Results and discussion: The results demonstrated that the interaction between β-sitosterol and nanoliposomes is a hydrogen bond type. The tension created in the area of the OH bond stretch proved to be a hydrogen bond between lecithin, cholesterol and β-sitosterol. The mean particle diameter, polydispersity index, zeta potential, physical stability and pH of the nanoliposomes were investigated. The size of nanoliposomes can vary depending on the physical conditions such as temperature, chemical conditions such as pH as well as the type of phospholipid, the type of carrier and the type of stabilizer. The mean particle diameter was between 90 and 100 nm. Although the addition of cholesterol to the samples slightly increased the mean particle diameter of nanoliposomes (P<0.05), it reduced the zeta potential (P<0.05) and increased the stability of the samples at different temperatures. Cholesterol addition, although it has led to an increase in the particle size and dispersion index of nanoliposomes, these effects are negligible. Increasing the cholesterol level decreased the pH in the range of 6.88 to 6.51; the proximity of pH to neutral range in these samples is an advantage. The pH of the samples was close to the neutral range, which proves that the use of these nanoliposomes does not affect the pH of the food stuffs. Statistical analysis of physical stability test showed that samples with higher cholesterol percentage showed longer stability at different temperatures.
Conclusion: The use of thin layer hydration and ultrasonic homogenizer resulted in the formation of particles with an average volume diameter of about 100 nm and lower which, however, increased cholesterol and had a mild and slight effect on increasing particle size and distribution; In the prepared samples, it reduced the zeta potential and consequently increased the stability of the samples. It is also a measure of the stability of the specimens at different temperatures predicted for optimal storage and use. The best results for a sample containing 0.06 g cholesterol were obtained. Although the size of the particle was slightly larger than other samples, zeta potential, physical stability and pH were more favorable than other ones.