| Tart cherry production and processing is an important industry in Michigan. Michigan's tart cherry industry produces 75% of the nation's tart cherry supply, which is about 250--300 million pounds annually. Anecdotal reports indicate that consumption of tart cherries could alleviate arthritic- and gout-related pain and reduce the incidence of cardiovascular diseases. These beneficial effects may be associated with the anthocyanins, phenolics and flavonoids present in tart cherries. In order to evaluate these claims, the bioactive components in tart cherries were isolated using antioxidant-bioassay-directed fractionation and purification.;The water extracts of Montmorency and BalatonTM tart cherries yielded three anthocyanins. Also, the results indicated that both cultivars contained identical anthocyanins. The hydrolysis of the total anthocyanins and subsequent gas chromatographic (GC) and nuclear magnetic resonance (NMR) spectral analyses suggested that the anthocyanins in Montmorency and Balaton TM cherries were anthocyanin 1 [cyanidin-3-(2 ″-O-beta-D-glucopyranosyl-6″ -O-alpha-L-rhamnopyranosyl-beta-D-glucopyranoside], anthocyanin 2 [cyanidin-3-(6″-O -alpha-L-rhamnopyranosyl-beta-D-glucopyranoside] and anthocyanin 3 [cyanidin-3-O-beta-D-glucopyranoside].;Antioxidant assays indicated that ethyl acetate and methanol extracts exhibited higher antioxidant activity than hexane extract. Further purification of the ethyl acetate extract yielded chlorogenic acid methyl ester and three novel compounds, 2-hydroxy-3-(o-hydroxyphenyl) propanoic acid, 1-(3',4'-dihydroxycinnamoyl)-cyclopenta-2,5-diol and 1-(3',4'-dihydroxycinnamoyl)-cyclopenta-2,3-diol. Similarly, the methanol extract yielded eight polyphenolic compounds, 5,7,4 '-trihydroxyflavanone, 5,7,4'-trihydroxyisoflavone, chlorogenic acid, 5,7,3',4-tetrahydroxyflavonol-3-rhamnoside, 5,7,4'-trihydroxyflavonol-3-rutinoside, 5,7,4 '-trihydroxy-3-methoxy-flavonol-3-rutinoside, 5,7,4' -trihydroxyisoflavone-7-glucoside and 6,7-dimethoxy-5,8,4' -trihydroxyflavone.;The antioxidant activities of the purified compounds were evaluated using the Fe2+-induced lipid peroxidation assay. Commercial antioxidants propyl gallate, butylated hydroxytoluene (BHT), tert-butylhydroquinone (TBHQ) and alpha-tocopherol were used as positive controls. The anthocyanins and their aglycones, cyanidin, 5,8,4'-trihydroxy-6,7-dimethoxyflavone and caffeic acid analogues from BalatonTM were the most active antioxidant compounds. The antioxidant activities of these compounds were greater than alpha-tocopherol and comparable to the activities of BHT and TBHQ.;In the anti-inflammatory assay, which measured inhibition of the cycloxygenase (COX) activities of the prostaglandin endoperoxide H synthase-1 and -2 isozymes (hPGHS-1 and -2), cyanidin showed significant inhibitory activities against COX-1 and COX-2 enzymes. The IC50 values of cyanidin against hPGH-1 and hPGH-2 were 90 and 60 muM, respectively. Similarly, the inhibitory activities on hPGHS-1 enzyme of the polyphenolics from BalatonTM tart cherries also were investigated. |
