Screening for Inhibitory Activity of Citrus Fruit Extracts against Platelet Cyclooxygenase and Lipoxygenase

Abstract

Inhibitory activities of the albedo extracts of 42 species and cultivars of the genus Citrus and those of two Fortunella and one Poncirus species against rat platelet cyclooxygenase and lipoxygenase were screened. Among the species investigated, the extract of Lumie (Citrus lumia) was shown to possess the highest inhibitory activity against cyclooxygenase (IC50 = 24 μg/mL), and that of Shuto (Citrus aurantium) was the highest against lipoxygenase (IC50 = 56 μg/mL). The albedo extracts of citrus from the same taxonomic group appeared to have similar inhibitory tendencies toward these enzymes. The flavedo extract of ripe lumie inhibited cyclooxygenase to the same degree as the albedo, more than the pulp extract. The flavedo, pulp, and juice extracts of ripe Ponkan (C. reticulata) also inhibited lipoxygenase in addition to the albedo extract. Both the flavedo and albedo tissues were shown to be effective sources of inhibitory compounds against cyclooxygenase and lipoxygenase. Keywords: Citrus; platelet cyclo...