EFFECTS OF SOME LIPOXYGENASE AND CYCLOOXYGENASE INHIBITORS ON THE LUMINOL-ENHANCED CHEMILUMINESCENCE OF PHAGOCYTES

Effects of the lipoxygenase (nordihydroguaiaretic acid - NDGA, esculet in) and the cyclooxygenase (diclofenac, piroxicam and acetylsalicylic acid) inhibitors (concentration range 10(-7)-10(-4) M) On the producti on of reactive oxygen species during the respiratory burst of phagocyt es were investigated. Piroxicam and acetylsalicylic acid failed to sup press luminol-enhanced chemiluminescence of both isolated human polymo rphonuclear leukocytes and murine bone marrow cells. Neither piroxicam and acetylsalicylic acid showed direct oxygen radical trapping proppe rties when the xanthine-xanthine oxidase system was used to generate r eactive oxygen species. Diclofenac significantly reduced the level of chemiluminescence in phagocytic cells only at the highest concentratio n used (10(-4) M). However, it was unable to scavenge reactive oxygen species in the xanthine-xanthine oxidase system. In contrast, NDGA and esculetin strongly inhibited luminol-enhanced chemiluminescence both in phagocytic cells and in a cell-free system of xanthine-xanthine oxi dase in a dose dependent manner. Direct oxygen radical scavenging seem s to be responsible for these effects of lipoxygenase inhibitors on lu minol-enhanced chemiluminescence of phagocytes.