Over 20 Years of Health Research

Anthocyanins from tart cherries, Prunus cerasus L. (Rosaceae) cv. Balaton and Montmorency; sweet cherries, Prunus avium L. (Rosaceae); bilberries, Vaccinum myrtillus L. (Ericaceae); blackberries, Rubus sp. (Rosaceae); blueberries var. Jersey, Vaccinium corymbosum L. (Ericaceae); cranberries var. Early Black, Vaccinium macrocarpon Ait. (Ericaceae); elderberries, Sambucus canadensis (Caprifoliaceae); raspberries, Rubus idaeus (Rosaceae); and strawberries var. Honeoye, Fragaria x ananassa Duch. (Rosaceae), were investigated for cyclooxygenase inhibitory and antioxidant activities. The presence and levels of cyanidin-3-glucosylrutinoside 1 and cyanidin-3-rutinoside 2 were determined in the fruits using HPLC. The antioxidant activity of anthocyanins from cherries was comparable to the commercial antioxidants, tert-butylhydroquinone, butylated hydroxytoluene and butylated hydroxyanisole, and superior to vitamin E, at a test concentration of 125 microg/ml. Anthocyanins from raspberries and sweet cherries demonstrated 45% and 47% cyclooxygenase-I and cyclooxygenase-II inhibitory activities, respectively, when assayed at 125 microg/ml. The cyclooxygenase inhibitory activities of anthocyanins from these fruits were comparable to those of ibuprofen and naproxen at 10 microM concentrations. Anthocyanins 1 and 2 are present in both cherries and raspberry. The yields of pure anthocyanins 1 and 2 in 100 g Balaton and Montmorency tart cherries, sweet cherries and raspberries were 21, 16.5; 11, 5; 4.95, 21; and 4.65, 13.5 mg, respectively. Fresh blackberries and strawberries contained only anthocyanin 2 in yields of 24 and 22.5 mg/100 g, respectively. Anthocyanins 1 and 2 were not found in bilberries, blueberries, cranberries or elderberries.

Antioxidant capacity, as measured by oxygen radical absorbance capacity (ORAC), and total phenolic and total anthocyanin contents were evaluated in fruit tissues of 87 highbush blueberry (Vacciniumcorymbosum L.) and species-introgressed highbush blueberry cultivars. ORAC and phenolic levels were evaluated in leaf tissues of the same materials. Average values for ORAC, phenolics, and anthocyanins in fruit were 15.9 ORAC units, 1.79 mg/g (gallic acid equivalents), and 0.95 mg/g (cyanidin-3-glucoside equivalents), respectively. Cv. Rubel had the highest ORAC per gram of fresh weight values, at 31.1 units, and cv. Elliott had the highest values on the basis of ORAC per square centimeter of surface area. In leaf tissue, values for both ORAC and phenolics were significantly higher than in fruit tissue, with mean values of 490 ORAC units and 44.80 mg/g (gallic acid equivalents), respectively. Leaf ORAC had a low, but significant, correlation with fruit phenolics and anthocyanins, but not with fruit ORAC. An analysis of ORAC values versus calculated midparent values in 11 plants from the 87-cultivar group in which all parents were tested suggested that, across cultivars, ORAC inheritance is additive. An investigation of ORAC values in a family of 44 cv. Rubel x Duke seedlings showed negative epistasis for ORAC values, suggesting Rubel may have gene combinations contributing to ORAC that are broken up during hybridization.

The antioxidant activities against superoxide radicals (O(2)(*)(-)), hydrogen peroxide (H(2)O(2)), hydroxyl radicals (OH(*)), and singlet oxygen (‘O(2)) was evaluated in fruit juice from different cultivars of thornless blackberries (Rubus sp.), blueberries (Vaccinium spp.), cranberries (Vaccinium macrocarpon Aiton), raspberries (Rubus idaeus L. and Rubus occidentalis L.), and strawberries (Fragaria x ananassa Duch.). Among the different cultivars, juice of ‘Hull Thornless’ blackberry, ‘Earliglow’ strawberry, ‘Early Black’ cranberry, ‘Jewel’ raspberry, and ‘Elliot’ blueberry had the highest antioxidant capacity against superoxide radicals (O(2)(*)(-)), hydrogen peroxide (H(2)O(2)), hydroxyl radicals (OH(*)), and singlet oxygen (‘O(2)). In general, blackberries had the highest antioxidant capacity inhibition of O(2)(*)(-), H(2)O(2), and OH(*). Strawberry was second best in the antioxidant capacity assay for these same free radicals. With regard to ‘O(2) scavenging activity, strawberry had the highest value, while blackberry was second. Cranberries had the lowest inhibition of H(2)O(2) activity. Meanwhile, blueberries had the lowest antioxidant capacity against OH(*) and ‘O(2). There were interesting and marked differences among the different antioxidants in their abilities to scavenge different reactive oxygen species. beta-Carotene had by far the highest scavenging activity against ‘O(2) but had absolutely no effect on H(2)O(2). Ascorbic acid was the best at inhibiting H(2)O(2) free radical activity. For OH(*), there was a wide range of scavenging capacities from a high of 15.3% with alpha-tocopherol to a low of 0.88% with ascorbic acid. Glutathione had higher O(2)(*)(-) scavenging capacity compared to the other antioxidants.

Research indicates that vulnerability to oxidative stress (OSV) may increase in aging, suggesting that age-related neurodegenerative diseases such as Alzheimer’s disease (AD) or vascular dementia (VAD) may be superimposed upon a vulnerable neuronal environment. Determinations in cell models have suggested that the enhanced OSV may be the result of, (a) increases in membrane lipids, especially sphingomyelin and the sphingomyelin metabolite, sphingosine-1-phosphate, (b) decreases in glutathione, and (c) CNS distribution of OS-sensitive neuronal muscarinic receptor subtypes (e.g. M1, M2 and M4). These changes appear to enhance, (a) decrements in cellular calcium buffering following KCl-induced depolarization, and (b) cell death under OS conditions. Among the most effective agents that antagonized cellular OSV were the combination of polyphenolics found in fruits (e.g. blueberry extract) with high antioxidant activity. Subsequent experiments using dietary supplementation with fruit (strawberry) or vegetable (spinach) extracts have shown that such extracts are also effective in forestalling and reversing the deleterious effects of behavioral aging in F344 rats. Thus, it appears that the beneficial effects of the polyphenolics found in fruits and vegetables in neuronal aging and behavior may be similar to those seen with respect to carcinogenesis and cardiovascular disease.