Variability of the allergen pattern in different pomegranate cultivars

Introduction:Pomegranate, Punica granatum L., is one of the old-est cultivated fruit trees. The fruit contains the arils, which are seedscovered by a red pulp, that is a juice sac. The arils are surroundedby the white and fleshy mesocarp. Pomegranate can trigger allergicreactions, but the allergenic pattern of this fruit is still poorly charac-terized and only one allergen, the LTP Pun g 1, was reported.Objectives:The aim of this study was the investigation of theallergen pattern in pomegranate tissues and cultivars.Results:Seven different pomegranate types were selected for thisstudy: 2 cultivars, Dente di Cavallo and Zanna Bianca; 3 accessions,CREA-FRC4, CREA-PR1 and CREA-PR2; 1 commercial sampleimported from Israel. Protein extracts, prepared from the mesocarp,juice and seeds, were analyzed by SDS-PAGE and RP-HPLC. Someprotein components were purified, identified by protein sequencingand their IgE binding capacity was investigated by dot blotting,immunoblotting and FABER®test. A variable amount of proteinswas measured in the juice of the different cultivars/accessions,whereas the mesocarp was devoid of detectable amounts of them.SDS-PAGE and RP-HPLC separations highlighted a different proteinprofile for each cultivar. Four proteins were purified from pomegra-nate juice, namely chitinase, punein (homologous to Bra r 2), pom-maclein (homologous to Pru p 7) and the 9k-LTP Pun g 1. All the 4isolated proteins displayed positive signals in IgE dot blotting andimmunoblotting. Specific IgE towards chitinase, pommaclein and Pung 1 were recorded in 5 (0.31%), 6 (0.37%) and 44 (2.74%) patientsout of 1606, using the FABER nanotech test. In addition, 20 patients(1.25%) were positive to the seed extract.Conclusions:Three new IgE binding proteins were identified inpomegranate juice. It was observed that seed proteins provide a sig-nificant contribution to the pomegranate allergenicity, whereas themesocarp could represent a rich and safe source of nutraceuticalsalso for allergic subjects.