Sources and Health Effects of Dietary Ellagitannins - Chemistry and Biology of Ellagitannins - page 302

8.2.2 Fresh and processed berries
Daniel et al. (1989) determined the ellagic acid content of 21 fruits and 5
nuts after acid hydrolysis of the samples, and found measurable levels
only in strawberries, raspberries, blackberries, cranberries, walnuts and
pecans. The highest level was detected in berries of the genus Rubus
(raspberries and blackberries), intermediate levels in strawberries and
nuts, and a low level in cranberries (Table 8.1). High levels were also
detected in other Rubus berries, i.e ., in black raspberries, marionberries
and boysenberries (Wada and Ou, 2002). When 19 berries consumed in
Finland were screened for the presence of ellagic acid after acid
hydrolysis, high levels were detected in the Rubus berries (cloudberries,
arctic brambles, red raspberries) and strawberries, whereas in all other
berries only traces were detected (Häkkinen et al. , 1999). In a subsequent
study, Häkkinen et al. (2000) used an optimised method for
quantification of ellagic acid in strawberries and Rubus berries
(Table 8.1).
Free and glycosylated forms of ellagic acid, as well as ellagitannins,
have been identified and quantified in berries of Fragaria (strawberries)
and Rubus species (cultivated and wild, red and yellow raspberries,
cloudberries and arctic brambles) (Määttä-Riihinen et al. , 2004). In this
study, ellagitannins were quantified in their native forms as gallic acid
equivalents and after acid hydrolysis as ellagic acid equivalents (Table
8.1). Free ellagic acid was detected in all berries (the highest levels in
cloudberries and wild red raspberries), whereas ellagic acid glycosides
were detected only in raspberries (the highest level in wild red
raspberries). Two major ellagitannins were detected in all berries studied
at the following levels: arctic bramble > cloudberry > wild red raspberry
> cultivated yellow raspberry > cultivated red raspberry > strawberry.
The main ellagitannins were similar in all Fragaria and Rubus species,
and have been identified in raspberries and cloudberries as the dimer
sanguiin H-6 (Fig. 8.3) and the trimer lambertianin C (Mullen et al. ,
2003, Beekwilder et al. , 2005, Heinonen et al. , 2007). Sanguiin H-6 is
also present in strawberries (Cerdá et al ., 2005). Free ellagic acid and its
glycosides are minor constituents as compared to ellagitannins (Zafrilla
et al ., 2001, Määttä-Riihinen et al ., 2004). In strawberries, achenes have