Stability indicating UV spectrophotometric method development and validation of quercetin and apigenin simultaneously by quality by design approach

The purpose of this study was to develop and test a reliable method for simultaneously determining apigenin and quercetin, two bioactive flavonoids known for their antioxidant, anti-inflammatory, and skin-health properties. Despite its significance, limitations in existing UV spectroscopic methods, such as low sensitivity and limited applicability, necessitate the development of an improved analytical approach. The researchers used Quality by Design approach to develop a cost effective and reliable UV spectrophotometric method. The method was optimized using design expert software, with a sonication period of 10 min and a medium scanning speed proving to be the ideal conditions for analyzing Apigenin and Quercetin concurrently. The UV spectrophotometric approach used methanol as a solvent where Apigenin was detected at 260 nm, and quercetin at 353 nm. The study completely assessed the developed approach by measuring the absorbance of both drugs under optimal conditions. The developed approach was validated using the International Council for Harmonization (ICH) Q2 R1 criteria. Calibration curves for Apigenin and Quercetin showed linearity at concentrations of 3–15 µg/mL, with correlation coefficients of 0.999 each. The approach demonstrated good precision, accuracy, robustness, and ruggedness, with % RSD values below 2%, meeting ICH standards. This work is innovative in that it developed a stable and accurate UV spectrophotometric approach for simultaneously quantifying apigenin and quercetin, which can be employed in pharmacological studies, skin-health research, and nutraceuticals. Additionally Forced degradation study was also performed under acidic, basic, oxidative, photolytic and thermal conditions to check for their stability.