Modulation of luminol-dependent chemiluminescence of murine macrophages by flavone and its synthetic derivatives.

The effect of flavone (CAS 525-82-6, 2-phenylbenzopyran-4-one, 1), flavone-8-acetic acid (CSA 87626-55-9, FAA, 2) and 10 substituted flavones on the luminol-dependent chemiluminescence of murine macrophages was studied in vitro. The synthetic derivatives were variously substituted with halo, nitro, amino, hydroxy and methoxy substituents in the 3' and 4' positions. Chemiluminescence was used in this study as an indicator for the production of reactive oxygen species by macrophages, stimulated in vitro by phorbol myristate acetate (PMA). All flavones except FAA (2) showed more than 20% inhibition at 10 mumol/l or 100 mumol/l. 3'-Amino-4'-hydroxyflavone (8) was the most potent inhibitor. The IC50s for inhibition of chemiluminescence were 4.2 +/- 1.1 mumol/l, 5.0 +/- 1.0 mumol/l and 3.3 +/- 1.4 mumol/l for resident, elicited and LPS-Poly I:C-primed macrophages, respectively. Small but statistically significant enhancements of chemiluminescence were caused by low concentrations of flavone (1), FAA (2) and 4'-methoxyflavone (6). These results suggest that modulation of the chemiluminescent capacity of macrophages depends on the nature of the substituents and the concentration of the flavones.