Punicalagins are tannins, large polyphenol compound which are isomers of 2,3-(S)-hexahydroxydiphenoyl-4,6-(S,S)-gallagyl-D-glucose, hydrolysable tannins with a molecular weight of 1084. They are found in forms alpha and beta in pomegranite. Punicalagins are the largest molecule found intact in rat plasma after oral ingestion^[1] and were found to show no toxic effects in rats who were given a 6% diet of punicalagins for 37 days^[2]. Punicalagins are also found to be the major component responsible for pomegranate juice's antioxidant and health benefits^[3].

Punicalagins are water soluble and have high bioavailability. They are known to hydrolyze into smaller polyphenols such as ellagic acid in vivo where one potential mechanism is hydrolysis across the mitochondrial membrane of cultured human colon cells.^[4].^[5]

A study in Taiwan showed that punicalagin alpha (1-alpha-O-galloylpunicalagin) induced nitric oxide production in a dose-dependent manner in endothelial cells.^[6] as well as inhibited ERK, JNK and Akt, all of which play roles in cancer growth, so their inhibition is points to punicalagins' potential as strong cancer suppressors.

Extract

A few dietary supplements and nutritional ingredients are available that contain extracts of whole pomegranate and/or are standardized to punicalagins, the marker compound of pomegranate. Extracts of pomegranate are also 'Generally Recognized As Safe' (GRAS) by the United States. It has been recommended to look for pomegranate ingredients that mimic the polyphenol ratio of the fruit, as potent synergistic effects have been observed in 'natural spectrum' extracts, especially pomegranate concentrate normalized to punicalagins^[7].

A pomegranate extract standardized to punicalagins marketed under the name [Pomella] was found to absorb into the bloodstream after consumption in humans. A maximum 32% increase in plasma antioxidant status measured by ORAC was also noted in this study^[8].

Plants

As the chemistry of punicalagins became known, however, it was found to be not unique to pomegranate, but is also present in other plants, such as numerous species of the genus Terminalia, species chebula Retz. (?Fructus Chebulae?), myriocarpa, catappa and citrina (tropical flowering trees historically used in African traditional medicine for antiobiotic and antifungal purposes). Punicalagins have also been isolated from Cistus salvifolius (Mediterranean shrub) and Combretum molle (African shrub).

References

1. ↑ Cerda et al. Eur J Nutr. 2003 Jan;42(1):18-28.
2. ↑ Cerda et al. J. Agric. Food Chem. 2003, 51, 3493-3501
3. ↑ Gil et al. J Agric Food Chem 2000 48 (10) 4581-89
4. ↑ Seeram et al. Clin Chim Acta. 2004 Oct;348(1-2):63-8.
5. ↑ Larrosa et al. J Nutr Biochem. 2006 Sep;17(9):611-25.
6. ↑ http://www.ncbi.nlm.nih.gov/pubmed/18435486
7. ↑ Seeram et al. J Nutr Biochemistry 2005 (16) 360-367.
8. ↑ Mertens-Talcott et al. J Agric Food Chem. 2006 Nov 15;54(23):8956-8961

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