Phytochemicals in fruits of Hawaiian wild cranberry relatives

Abstract

Background: Cranberries (Vaccinium macrocarpon Ait.) contain high levels of phytochemicals such as proanthocyanidins (PACs). 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 PACs; the colorimetric 4-dimethylaminocinnamaldehyde (DMAC) assay was used to determine total PACs. 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 the ORAC and FRAP assays.

Results: Antioxidant capacities of Hawaiian berries were high. The FRAP measurement for V. calycinum was 454.7 ± 90.2 µmol L(-1) Trolox equivalents kg(-1) 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 sources of PACs; 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 equivalents kg(-1) ) were about twice that in cranberry.

Conclusion: Berries of V. reticulatum and V. calycinum could serve as a rich dietary source of PACs, 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.

Keywords: A-type linkage; FRAP; ORAC; PAC; Vaccinium calycinum; Vaccinium macrocarpon; Vaccinium reticulatum; anthocyanins; phenolics; proanthocyanidin; ‘ōhelo.