Detection of chemiluminescence in lipid peroxidation of biological systems and its application to HPLC

A combined system of chemiluminescence detection and high performance liquid chromatography (CL-HPLC) was developed to determine primary peroxidation products in biological tissues, such as phosphatidylcholine hydroperoxide (PCOOH). The CL-HPLC assay consists of separation of lipid classes with HPLC and detection of hydroperoxide-specific chemiluminescence. Hydroperoxides react with heme compounds to produce oxidants as suggested by our early studies on tissue low-level chemiluminescence in which singlet molecular oxygen is generated as one of the excited species in several biological systems involving free radical events. In the CL-HPLC method, a cytochrome c-luminol mixture was used as a hydroperoxide-specific luminescent reagent, and the quantification of hydroperoxide was performed by detecting chemiluminescence due to the luminol oxidation caused by the oxidant produced during the lipid hydroperoxides with heme. The detection limit of PCOOH was 10 pmole hydroperoxide-O2. PCOOH in normal human blood was found to be 10-500 pmol/ml plasma and significantly higher levels of PCOOH were observed in some hospitalized patients.