A novel UV-spectrophotometric method as a reliable alternative for the spectrofluorimetric analysis of lucifer yellow

Abstract

Background Human colon adenocarcinoma cell-line (Caco-2) monolayer is a well-established ex vivo model used for estimation of drug-apparent permeability through the human intestinal barrier. Lucifer yellow (LY) is a paracellular permeability marker used generally for examining the integrity of Caco-2 monolayer using spectrofluorimetric detection. No other spectroscopic methods were reported for analysis of LY. Objective To introduce a novel validated simple ultraviolet (UV)-spectrophotometric method, for LY determination, as an alternative to the commonly used spectrofluorimetry, as well as to apply the developed UV method to confirm the monolayer integrity of Caco-2 cell line compared with the spectrofluorimetric detection. Materials and methods The measurement was carried out at a wavelength of 277 nm. The linearity range was 1.0–12.5 μg/ml with the regression coefficient (R 2)=0.9992. Validation of the method was carried out following the ICH guidelines concerning linearity, precision, accuracy, robustness, and stability and statistically compared with the conventional spectrofluorimetric one. Measurement of cultured Caco-2 cell monolayer integrity was carried out using LY employing spectrofluorimetric and UV-spectrophotometric methods. Results and conclusion The calculated t test and F values indicated that no significant difference existed between both methods regarding precision and accuracy. The developed method has been successfully applied for checking the monolayer integrity of Caco-2 cell line. Comparing permeability percentage results of LY, both methods resulted in LY-permissible values of 2.354 and 2.303% using spectrofluorimetric and UV-spectrophotometric methods, respectively, indicating Caco-2 cell-line monolayer integrity.