Phytochemicals in Fruits of Hawaiian Wild Cranberry Relatives.

BACKGROUND
Cranberries (Vaccinium macrocarpon Ait.) contain high levels of phytochemicals such as proanthocyanidins (PAC). These polymeric-condensations of flavan-3-ol monomers are associated with health benefits. Our objective was to evaluate phytochemicals in fruit from Hawaiian cranberry relatives, V. reticulatum Sm. and V. calycinum Sm. Normal-phase HPLC coupled with fluorescence and ESI-MS detected PAC; colorimetric DMAC assayed total PAC. Spectrophotometric tests and reverse-phase HPLC coupled to photodiode array and refractive index detectors evaluated phenolics, sugars, and organic acids. Antioxidant capacity was determined by ORAC and FRAP.

RESULTS
Antioxidant capacities of Hawaiian berries were high. The FRAP measurement for V. calycinum was 454.7 ± 90.2 µM Trolox equivalents/Kg for pressed fruit. Hawaiian berries had lower peonidin, quinic and citric acids amounts and invert (≈1) glucose/fructose ratio compared with cranberry. Both Hawaiian Vaccinium species were good PAC sources; they contained phenolics and PAC monomers, A and B-type trimers, tetramers, and larger polymers. Vaccinium reticulatum and V. calycinum showed comparable or higher PAC levels than in cranberry. Cranberries had higher percentage of A-type dimers than did V. reticulatum. A and B-type dimers were not differentiated in V. calycinum. The total PACs (as measured by DMAC) for V. calycinum (24.3 ± 0.10 mg catechin equiv/Kg) were about twice that in cranberry.

CONCLUSIONS
Berries of V. reticulatum and V. calycinum could serve as a rich dietary source of PAC's, comparable to or greater than cranberries. These finding suggest that Hawaiian Vaccinium berries could be a functional food. Additional examination of the phytochemicals in other wild Vaccinium species is warranted.