Isolation of punicalagin from Punica granatum rind extract using mass-directed semi-preparative ESI-AP single quadrupole LC-MS

We are living in a era of alarming increases in microbial resistance to currently available antibiotics, and there is a growing need for new pharmaceutical products to treat infectious diseases. The pomegranate is an edible fruit that has virucidal and antimicrobial activities which is primarily attributable to the high concentration of hydrolysable tannins. Punicalagin, a high molecular weight tannin (1084.7), accounts for approximately 70% of the total and is concentrated in the fruit exocarp (rind). It is the focus of much research, although it is prohibitively expensive to purchase which presents an obstacle to further exploitation and development. Here we describe a method for the isolation of punicalagin from pomegranate rind extract and total pomegranate tannins using an Agilent preparative mass-directed LC–MS single quadrupole ESI-API system, where the ionization was set as negative and the mass signal acquired in Single Ion Monitoring. Thanks to the automatic fraction collector, the method can be used in automatic mode and is capable of producing punicalagin with >95% purity.