Isolation and structure elucidation of anthocyanidin 3,7-β-O-diglucosides and caffeoyl-glucaric acids from calafate (Berberis mycrophylla G. Forst) berries

RUIZ , A.; MARDONES, C.; VERGARA, C.; VON BAER, D.; GÓMEZ-ALONSO, S.; GOMEZ, M.; HERMOSÍN-GUTIÉRREZ, I.:
Journal of Agricultural and Food Chemistry 62:29 (2014) 6918-6925.

DOI: 10.1021/jf5012825

Abstract

Calafate (Berberis microphylla G. Forst) is an edible wild berry growing in South Patagonia that is very rich in anthocyanins and hydroxycinnamic acid derivatives. Calafate contains unusual phenolic compounds compared to other berries, like anthocyanidin dihexosides, different to the common 3,5-diglucosides, and isomeric esters of caffeic acid with hexaric acids. After isolation, their structures have been elucidated by UV/Vis, MS/MS and NMR spectroscopies. The anthocyanidin dihexosides constitute the complete series of 3,7-β-O-diglucosides of the five anthocyanidins usually found in calafate, whose structures were completely elucidated in the cases of delphinidin, petunidin, and malvidin derivatives, and tentatively suggested in the cases of cyanidin and peonidin, and their occurrence seems to be characteristic of calafate among other wild berries from South Patagonia. With regards to caffeoyl hexaric acids, two of four isomers have been assigned as 3- and 4-trans-caffeoyl-glucaric acids, but the determination of the linkage position for each isomer was not possible. A third isomer was also isolated but it easily degraded and was suggested to be the 2- or 5-trans-caffeoyl-glucaric acid. The caffeoyl-glucaric acids account for around the half of the pool of hydroxycinnamic acid derivatives in calafate.

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