Involvement of polyphenol compounds in histamine release suppression by pomegranate vinegar

Histamine release by granulocytes is a critical event in the induction of type I allergy. We investigated the effects of four different fruit vinegars made from yama-budo, haskap, blueberry and pomegranate on histamine release by the basophilic leukemia cell line RBL-2H3. Results clearly indicated that these fruit vinegars, especially pomegranate vinegar, have potent inhibitory effects on histamine release. We then performed adsorption chromatography with Diaion HP20 to estimate the bioactive components in pomegranate vinegar; the fraction eluted by 50% ethanol (EtOH) showed the most potent suppressive effect. Next, we subjected the 50% EtOHfraction to liquid-liquid division with ethyl acetate (AcOEt), and suppressive activity was observed in both the water and AcOEt layer fractions, indicating the existence of multiple bioactive components. Furthermore, suppression of histamine release by each fraction was almost completely abolished by treatment with polyphenol adsorbent polyvinylpolypyrrolidone. These results suggested that the pomegranate vinegar contains multiple polyphenol compounds involved in the suppression of histamine release by granulocytes.