Purification, proniosomal encapsulation and determination of bioactive properties of naringin from grapefruit peel wastes

In this thesis, naringin was purified from grapefruit peels, a significant by-product of the citrus industry. It was then encapsulated with proteasomes, a nanocarrier system, and its free and encapsulated forms were analyzed for their bioactive properties. The extraction conditions were optimized by considering the solvent ratio (60-80 %), the amount of sample (20-40 g), and the extraction time (70-120 hour). The optimized extraction condition was determined as 67,16 % solvent concentration, 38 g sample amount and 119 hour extraction time. This extraction condition resulted in 2,78 g of crystal formation, and the amount of naringin in the crystal structure was found to be 2,73 g, with a purity of 98,27%. Proniosomal formulations were prepared using varying amounts of naringin compound and different types of stabilizers (cholesterol, dodecanol). These formulations were then characterized in terms of their physicochemical properties and proniosomal formulation based on cholesterol and loaded with 50 mg naringin compound was selected for further analyses. The proniosomal powders produced in the selected formulation formed small vesicular structures (180 nm) with high encapsulation efficiency (70%). Additionally, it was determined that proniosomal powders had a stable structure with a high zeta potential value (-48 mV). FTIR analysis shows that there are no chemical changes in the structure of naringin within the proniosome, but it interacts with physical formulation changes. Physicochemical characterization confirmed the successful encapsulation of naringin within the niosomal structure, which is an important parameter for improving stability and sustained release properties. It was observed that the free form of naringin exhibited a higher level of antioxidant capacity and total phenolic substance content than proniosomal naringin. Naringin exhibited antimicrobial activity, with a low minimum inhibitory concentration (MIC), against the test microorganisms Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. In addition, the free form of naringin showed an observable protective effect on plasmid DNA aganist oxidative damage caused by the photolysis of H₂O₂. In vitro gastrointestinal digestive tract model revealed that proniosomal encapsulation was found to be capable of controlling the release of naringin without disturbing its structure.