Inhibition of recombinant human histidine decarboxylase activity in different strawberry cultivars

Abstract

Strawberry fruit contains many constituents, some of which have the potential to inhibit histidine decarboxylase (HDC) activity. HDC converts l-histidine to histamine, which is associated with allergic and other biological reactions in the human body. The HDC inhibition levels were different and the component ratios varied by genotype in strawberry. Among the 11 cultivars collected locally in Japan, ‘Tokun’ had an approximately ten times higher inhibition ratio than the lowest cultivar. The reproducibility was confirmed using five cultivars under the same conditions in a glass greenhouse, suggesting that genotypic variation is a major factor of HDC inhibition. The potential inhibitors of HDC might be polyphenols because they showed moderate correlations with HDC inhibition rates. Among the polyphenols, the anthocyanin content possessed a moderate negative correlation. Ascorbic acid, which contributes to the overestimation of total polyphenol, did not independently inhibit HDC activity. These findings will support the identification of potential HDC inhibitors in strawberry and indicated that genotypic differences would make useful probes for inhibitor identification.