Abstract
Fifteen selected citrus flavonoids representing several different chemical classes
were studied for their effect on human basophil histamine release stimulated by three
secretogogues (antigen; the tumor promoter phorbol ester, tetradecanoyl phorbol acetate
(TPA); and the Ca2+ ionophore, A 23187). Each secretogogue stimulates histamine release by a different
mechanism. The effect of flavonoids on human neutrophil beta-glucuronidase release
stimulated by the chemoattractant peptide, f-methionyl-leucyl-phenylalanine (f-Met-LeuPhe)
was also examined. Several citrus flavonoids were very active inhibitors of basophil
histamine release and neutrophil beta-glucuronidase release. Compounds active against
all three basophil secretogogues tended to have activity against f-MetLeuPhe-induced
beta-glucuronidase release from neutrophils. A structure-activity relationship analysis
revealed that certain specific chemical structures appeared to be associated with
the capacity to inhibit basophil histamine release and neutrophil beta-glucuronidase
release. The data suggest indirectly that certain citrus flavonoids might possess
in vivo antiallergic and antiinflammatory activity.