Development and Validation of an HPLC Method for the Quantification of Morin Flavonoid Encapsulated within PLGA Nanoparticles

Background: Morin flavonoid exerts neuroprotective effects with potential interest in neurodegenerative disorders. For this, the use of surface-modified polymeric nanoparticles loaded with morin is an interesting approach. Objective: To develop and validate an HPLC method for the quantification of morin released from a new delivery system consisting of poly lactic-co-glycolic (PLGA) nanoparticles functionalized with the dipeptide phe-phe (phenylalanine-phenylalanine) used to facilitate their access to the CNS. Methods: The HPLC procedure was developed and validated with morin hydrate dissolved either in methanol (method A) or in methanol: 0.1N HCl (50:50, v/v, method B). Two new nanoparticle formulations were developed and characterized: morin-loaded PLGA nanoparticles (formulation F1), and morin-loaded PLGA phe-phe nanoparticles (formulation F2). Results: Method A was linear within the concentration range of 5-30 μg.mL^-1 and, 1-30 μg mL^-1 for method B. LOD and LOQ with method A were 1.23 μg.mL^-1 and 3.90 μg.mL^-1, respectively, and 0.481 μg.mL^-1 and 1.458 μg.mL^-1, respectively for method B. The average amount of phe-phe bound to formulation F2 (50 mg of NPs) was 431.33 μg. The encapsulation efficiency of morin within PLGA nanoparticles was around 80%. After functionalization, this value decreased significantly. Conclusion: Method B showed better sensitivity, accuracy, and precision for the quantification of morin. The procedure used to functionalize the nanoparticles was adequate for linking the dipeptide to their surfaces, but this procedure is not adequate when encapsulating water-soluble compounds.