Development and validation of a rapid reversed-phase liquid chromatography method for CnAMP1 peptide quantification in human intestinal cell lines

Plant foods are rich sources of biologically active peptides that may have a role in the prevention of diseases. Coconut water is a valuable beverage due to its nutrient composition and the presence of bioactive compounds, such as the peptide CnAMP1. It is unknown if CnAMP1 can be absorbed into intestinal cells. We, therefore, aimed to develop and validate a simple reversed-phase liquid chromatographic method to quantify the peptide in Caco-2 and LS180 cell lysates. CnAMP1 standards (1-200 mu mol/L) and spiked cell lysates were injected onto a Reprosil-Pur 120 C18-AQ column (4.6x250mm) using acetonitrile:water:trifluoroacetic acid (14.0:85.9:0.1, by volume) as mobile phase in isocratic mode at flow rate of 1mL/min. The method achieved rapid separation (total run time of 6min), with linear response, good sensitivity (limit of detection, 8.2ng; lower limit of quantification, 30.6ng) and no interfering peaks. Best recoveries (84-96%), accuracies (7.6-14.8%) and precision (1.5-8%) were found for LS180 cell lysates spiked with medium (50 mu mol/L) and high (100 mu mol/L) amounts of the peptide. Uptake assays detected no peptides in the cell lysates; however, after the first 15-min incubation CnAMP1 underwent partial hydrolysis upon incubation with LS180 cells (29%) and extensive hydrolysis with Caco-2 cells (93%).