Development and Validation of a Green Stability-Indicating UV–Spectrophotometric Method for Quantification of Fisetin in Bulk and Liposomal Nanoformulations

Abstract

Background: Fisetin is a bioactive flavonoid with potent antioxidant and anti-inflammatory properties. However, its poor aqueous solubility and low bioavailability limit clinical application, which has encouraged the development of nanoformulation. Reliable and environmentally sustainable analytical methods for fisetin quantification remain limited.
Objective: This study aimed to develop and validate a simple, stability-indicating, and environmentally sustainable UV–spectrophotometric method for the quantification of fisetin in bulk drug and liposomal nanoformulations.
Methods: Method development was performed using a methanol–phosphate buffer (pH 6.8) solvent system (1:1, v/v), with maximum absorbance observed at 363 nm. The method was validated according to ICH Q2(R1) guidelines. Forced degradation studies were performed to evaluate stability-indicating capability. Fisetin-loaded liposomes were prepared using the thin-film hydration technique and analysed using the developed method. Environmental sustainability was assessed using ComplexGAPI and BAGI metrices.
Results: The method demonstrated excellent linearity within 2–10 µg/mL (R² = 0.9962). The limits of detection and quantification were 0.085 µg/mL and 0.258 µg/mL, respectively. Accuracy ranged from 99.24% to 101.72%, while precision showed %RSD values below 2%. Forced degradation confirmed the stability-indicating nature of the method. The assay of fisetin in liposomal formulations was 99.5%. Greenness assessment indicated strong compliance with Green Analytical Chemistry (GAC) principles.
Conclusion: The proposed UV method is simple, accurate, stability-indicating, and environmentally sustainable, making it suitable for routine quality control of fisetin in bulk drug and nanoformulations.