FRIEDRICH, Jane E., LEE, C. Y *.

Phenolic compounds have been shown to exhibit protective effects reducing the risk of degenerative diseases such as cancer, atherosclerosis, and cardiovascular disease (Ames, 1983; Weisburger, 1992; Kinsella et al., 1993; Lin, 1994). Literature suggests that 60% of all cancers in women and more than 40% in men relate to diet (Doll and Peto, 1981). This link between diet and disease has spurred research interest focusing on foods that may possess these activities. In light of this, the non-anthocyanin phenolic compounds in several sweet cherry (Prunus avium) and sour cherry (Prunus cerasus) cultivars were isolated, identified and quantitatively analyzed.

Sweet and sour cherries were hand picked at the New York State Agriculture Experiment Station orchards in Geneva, New York. Six cultivars of sweet cherry and five cultivars of sour cherry were harvested. Phenolic compounds were extracted from cherries using 80% methanol and concentrated two-fold. Non-anthocyanin phenolic compounds were fractionated from all other phenolics using preconditioned C18 Sep-Pak cartridges for HPLC analysis. The phenolic compounds were further separated into neutral and acidic fractions by pH adjustment and C18 Sep-Pak separation for HPLC analysis. Individual phenolic compounds were isolated and analyzed using HPLC, column chromatography, thin layer chromatography, and mass-spectrometry.

High performance liquid chromatography (HPLC) analysis showed that chromatograms of sweet and sour cherries have the same basic pattern. However, sour cherries contain more phenolic compounds than sweet cherries mainly due to a large amount of phenolic acids. Of the compounds identified in this study, sweet and sour cherries were found to contain 130 to 450 mg/kg and 480 to 990 mg/kg fresh weight basis total non-anthocyanin phenolics, respectively. A wide range of phenolic constituents was observed between cultivars for both sweet and sour cherries. Of the compounds identified (-)-epicatechin, chlorogenic acid, caffeoyltartaric acid, and coumaroylquinic acid were found in sweet and sour varieties. (-)-Epicatechin was found to be the dominant flavan-3-ol in both sweet and sour cherries, as reported previously (Macheix et al., 1990).

Sweet cherries were characterized by two dominant compounds, caffeoyltartaric acid and 3’-p-coumaroylquinic acid as shown in the table below. The presence of quercetin glycoside was found exclusively in yellow sweet cherry cultivars and the concentration of quercetin glycoside was found to be dependent upon the intensity of the yellow color. Phenolic composition in sour cherries was more complex qualitatively and quantitatively. Among the acidic phenolic compounds in sour cherries 4’-p-coumaroylquinic acid and caffeoyltartaric acid were the major constituents. A significant amount of procyanidin B2 was found in sour cherries, which is absent in sweet cherries. This is the first time that procyanidin B2 has been identified in cherries. In addition, large amounts of (-)-epicatechin, rutin and one other unidentified compound were also found in sour cherries.

Table. Phenolic constituents in sweet and sour cherries (average concentration, mg/kg fresh weight basis).

n.d. = not detected.

AMES B. N., 1983. Dietary carcinogens and anticarcinogens. In Science 221, 1256-1264.

DOLL R. AND PETO R., 1981. The causes of cancer: Quantitative estimates of avoidable risks of cancer in the United States today. In Journal of the National Cancer Institute 66, 1192-1308.

KINSELLA J. E., FRANKEL E., GERMAN B. AND KANNER, J., 1993. Possible mechanisms for the protective role of antioxidants in wine and plant foods. In Food Technology 4, 85-89.

LIN R. I. S., 1994. Phytochemicals and antioxidants. In Functional Foods: Designer Food, Pharmafoods, Nutraceuticals. Goldberg, I. (ed.), New York: Chapman & Hall, 393-449.

MACHEIX J.-J., FLEURIET A. AND BILLOT J., 1990. Fruit Phenolics. Boca Raton, Florida: CRC Press.

WEISBURGER J. H., 1991. Nutritional approach to cancer prevention with emphasis on vitamins, antioxidants and carotenoids. In American Journal of Clinical Nutrition 53, 226s-237s.