Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2007
Publication Date: 1/23/2008
Citation: Hager, T., Howard, L.R., Liyanage, R., Lay, J.O., Prior, R.L. 2008. Ellagitannin composition of blackberry as determined by HPLC-ESI-MS and MALDI-TOF-MS. Journal of Agriculture and Food Chemistry. 56(3):661-669.
Interpretive Summary: Over the last decade, there have been numerous epidemiological studies that indicate that fruit and vegetable consumption may play a role in reducing the risks of various chronic diseases, including cardiovascular disease and cancer. These health benefits have been widely attributed to the phenolics content of plant foods. Tannins are one group of phenolics that has been considered a potential source of significant health benefits. Tannins are oligomeric and polymeric forms of phenolics. They are divided into two classes: condensed and hydrolysable tannins. Much research has been conducted on the structural classifications of condensed tannins or procyanidins in fruits, but there has been limited work on hydrolysable tannins, also known as gallotannins and ellagitannins. This study determined the presence of several isomeric forms of ellagitannins previously unidentified in fruit, while presenting a possible analytical High Pressure Liquid Chromatography method for the analysis of the major ellagitannins present in the fruit.
Technical Abstract: Apache blackberries (Rubus sp.) were evaluated by HPLC-MS and MALDI-TOF-MS to identify ellagitannins present in the flesh, torus (receptacle tissue), and seeds. Most ellagitannins were only present or detectable in seed tissues. Ellagitannins identified by HPLC-MS in the seeds included pedunculagin, casuarictin/potentillin, coralagin, lambertianin A/sanguiin H-6, lambertianin C, and lambertianin D. For several of the ellagitannins, isomeric separation was also obtained. The MALDI-TOF-MS analysis was primarily utilized to evaluate and identify high molecular weight (>1000 Da) ellagitannins. The MALDI analysis verified the presence of the ellagitannins identified by LC-MS, including lambertianin A/sanguiin H-6, lambertianin C, and lambertianin D, but the analysis also indicated the presence of several other compounds that are most likely ellagitannins based on the fragmentation patterns. In conclusion, this study determined the presence of several isomeric forms of ellagitannins previously unidentified in fruit, while presenting a possible analytical HPLC method for the analysis of the major ellagitannins present in the fruit.