Free radical-mediated lipid peroxidation in cells: Oxidizability is a function of cell lipid vis-allylic hydrogen content

Abstract

This is the first study to employ a reaction flow (RF) HPLC column of a short 5 cm length to identify antioxidants in a variety of complex samples represented by tea, utilising simultaneous multiplexed detection techniques. The detection responses included: underivatised UV at 280 nm, underivatised fluorescence detection (FLD) and a post column derivatisation (PCD) colorimetric response for antioxidants via the ferric reducing antioxidant power (FRAP) assay. Both similarities and differences in the chromatograms obtained using the three detection modes highlight the power of multiplexed detection. The main findings from the bioactive profiling include: the Fruit of the Forest tea contains the lowest level of antioxidants and is clearly distinct from the other three teas which are based on Camellia sinensis. The antioxidants detected in the green tea and the two black teas are similar. The green tea contains a higher concentration of the two main antioxidants that eluted at 4.0 and 5.7 min.The simplicity of sample analysis and chemical profiling using RF columns and selective detection was the focus of this study via the analysis of antioxidants in tea using the FRAP reagent. The main advantage of RF-PCD is the ability to split flows for simultaneous detection with minimal post column dead volume contributions, making peak matching between detectors much easier. To date, few studies exploit the power of RF-PCD multiplexed detection to differentiate and identify bioactive compounds in various complex samples. Applications of the approach developed in this study may include antioxidant screening and profiling of natural products, foods and beverages.