The Effects of Citrus Flavonoids on Human Basophil and Neutrophil Function

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.