UCLA Center for Human Nutrition

Pomegranate (Punica granatum L.) fruits are widely consumed fresh and in the forms of juice, concentrate, wine and jam. Pomegranate fruit husk is a rich source of hydrolyzable tannins called ellagitannins (ETs). During processing methods in the commercial pomegranate juice (PJ) industry, ETs are extracted from the fruit husk in significant quantities into the juice. Pomegranate husk, a by-product of the PJindustry, is therefore an inexpensive and abundant source of ETs which are present in PJ. Previous methods to isolate pomegranate ETs included labor intensive and time-consuming solid phase extractions by column chromatography (C-18, polyamides, cellulose, Sephadex Lipophilic LH-20, Diaion HP20) and/or use of specialized instruments such as preparative-high performance liquid chromatography (HPLC). We have used an Amberlite XAD-16 resin vacuum-aspirated column to rapidly purify an aqueous extract of pomegranate husk to afford total pomegranate tannins (TPT) in substantial yields (58-60 g TPT/Kg husk; time <1h). Using analytical HPLC, NMR and tandem LC-ES/MS, evaluation of TPT showed that it contains the major fruit husk ET, punicalagin (85% w/w), and ellagic acid (EA; 1.3% w/w) as well as unquantified amounts of punicalin and EA glycosides (hexoside, rhamnoside and pentoside). Since ETs are reported to show potent antioxidant, antiatherosclerotic and anticancer activities, this method can be used for the large-scale production of TPT for future in vitro and in vivo biological studies. This method is practical for industrial applications and could provide a low-cost means to use a currently underutilized food by-product to develop phytoceuticals with potential health benefits or to develop products for use in the cosmetic and food biopreservative industries.