Validated RP-HPLC Method for Estimation of Chrysin in Bulk Form and Nanostructured Lipid Carriers for Topical Application

Background: Chrysin, a flavonoid, occurs naturally in plants and possesses many pharmacological actions, but there is a lack of suitable analytical methods for its estimation. Objective: To develop a simple analytical method and validate it for the estimation of Chrysin using reverse phase high-performance liquid chromatography (RP-HPLC). Methods: Isocratic elution was carried out in methanol and 0.1% v/v formic acid in a 70:30 ratio using a C-18 reverse-phase column. The flow rate was set to 1 mL min^-1 and the detection wavelength at 268 nm. As per ICH Q2 (R1) guidelines, the developed method was validated in terms of accuracy, precision, system suitability, and robustness. Results: The retention time of Chrysin was found at 10.269 min. In the concentration range of 2-10 μg/mL, the developed method was linear with a regression coefficient (R²) value of 0.998. The mean percentage recovery of Chrysin was found within 95-105% at all three levels, which confirms that the developed method was accurate. Moreover, the % RSD was found to be less than 2% confirming that the developed method was precise. The limit of detection and limit of quantification were found to be 0.071 and 0.217 μg/mL. Moreover, the validated method was robust with no significant changes in response to variation in flow rate, mobile phase composition, wavelength, and different lots of columns. Conclusion: It was concluded that the developed method has passed all validation tests and was successfully applied to estimate the presence of Chrysin in bulk as well as in pharmaceutical formulations.