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Robert C. Hansen, Kenneth D. Cochran, Harold M. Keener, and Edward M. Croom Jr.

Ohio Agricultural Research and Development Center, in cooperation with the Univ. of Mississippi. Project support provided in part by OARDC, National Cancer Inst., USDA/CSRS, and Zelenka Nursery Inc., Grand Haven, Mich. Manuscript no. 78-94.

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Shiow Wang, Kimberly Lewers, Linda Bowman, and Min Ding

Representatives of three species of strawberries (Fragaria virginiana, F. chiloensis and F. ×ananassa) were evaluated for antioxidant capacity, scavenging capacity for reactive oxygen species (ROO·, ·OH, 1O2 and O2 .-), and inhibitory effect on proliferation of A549 human lung epithelial cancer cells. Differences among the strawberry genotypes were observed for all three qualities. High antioxidant and scavenging capacities were found in `CFRA 0982', `JP 95-1-1', NC 95-19-1 and RH 30. Lowest antioxidant and scavenging capacities were found in `Allstar'. There was also a relationship between scavenging capacity and the inhibition of cancer cell proliferation. The correlations (R 2) between the scavenging capacities for the reactive oxygen species and the inhibition of cancer cell proliferation were 0.8074, 0.8279, 0.7862 and 0.7761 for ROO·, ·OH, 1O2 and O2 .-, respectively. These results suggest that antioxidants, specifically their scavenging capacities, may play an important role in the antiproliferative activity of strawberries. This study also identified strawberry germplasm of value in developing cultivars useful for cancer prevention.

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Jed W. Fahey and Katherine K. Stephenson

Foundation, the American Institute for Cancer Research and the National Cancer Institute (PO1 CA44530). The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked

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Napaporn Sae-Lee, Orapin Kerdchoechuen, Natta Laohakunjit, Benjawan Thumthanaruk, Dipayan Sarkar, and Kalidas Shetty

anticancer properties; however, no published study has previously explored anticancer activity of cultured grape cells. There are also no existing reports on enhanced phenolic-linked antioxidant activity and associated cancer cell cytotoxicity in cell culture

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John A. Juvik

Extensive epidemiological evidence suggests that carotenoids (including vitamin A), ascorbate (vitamin C), tocols (including vitamin E), and glucosinolate breakdown products exert anticarcinogenic effects in a range of human tissues. Consumption of fresh and processed vegetables with enhanced levels of these phytochemicals could reduce human risk of cancer. The vitamins play a major role as antioxidants, offering protection against cancer by preventing or reversing oxidative damage to DNA and other cellular components. Cruciferous vegetables contain glucosinolates (GSs), which, during mastication, are hydrolyzed by the enzyme myrosinase into bioactive breakdown products (BBPs), including sulforaphane. BBPs appear to induce synthesis of drug metabolism enzymes resulting in increased detoxification rates of carcinogens. This paper describes an interdisciplinary investigation designed to develop vegetable cultivars that offer chemoprotection from cancer at doses commensurate with a normal American diet. Initial work has focused on surveying sweet corn and Brassicae oleraceae germplasm for variation in vitamin and glucosinolate content in conjunction with in vitro and in vivo bioassays to determine which compounds and concentrations optimize chemoprotectant activity. Segregating populations from crosses between sweet corn and Brassica lines that vary in vitamin and GS concentrations will be assayed for chemical content and chemoprotectant activity, and genetically characterized using DNA marker technology to identify and map genes controlling these traits. This information will improve selection methodology in a breeding program aimed to develop brassica and sweet corn germplasm with enhanced cancer chemoprevention.

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Shibu M. Poulose, Edward D. Harris, and Bhimanagouda S. Patil

Limonoids are triterpinoids unique to citrus and neem trees with potential cancer-preventing properties in animals and human cell lines. Antioxidant activity and apoptotic induction are thought to be the principal effects of citrus limonoids in the antiproliferative properties, but this postulate lacks firm experimental evidence. In this study four highly purified 17 β-D glucopyranosides of citrus, limonin glucoside (LG), obacunone glucoside (OG), nomilinic acid glucoside (NAG), and deacetylnomilinic acid glucoside (DNAG), were tested for their effects against human SH-SY5Y neuroblastoma cells. Neuroblastomas account for 10% of childhood cancers, and in our study the cultured cells were treated with different concentrations and different time intervals. Micromolar levels of LG and OG significantly (P ≤ 0.001) stopped cell growth and induced cell death in 24 hours, but had no adverse effect over Chinese hamster ovary (CHO) cells at the highest toxic level tested. The viability studies were based on trypanblue exclusion and dimethylthiazol diphenyltetrazolium (MTT) reduction assays. The limonoids significantly increased the downstream caspases 3/7 activity (P ≤ 0.005) within 12 hours of treatment, suggesting an explicit role of apoptotic induction, which was confirmed by flow cytometry and DNA fragmentation assays. Highest S phase cell number was reduced by LG, followed by OG, NAG, and DNAG as compared to the known inhibitor camptothecin. Structural variations of limonoids could be ascribed to antioxidant activity. This study strongly supports apoptosis induction as an anticancer mechanism of citrus limonoids. Funded by USDA 2001-52102-11257 and 2004-34402-14768.

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Allan F. Brown, Gad G. Yousef, Elizabeth H. Jeffery, Barbara P. Klein, Mathew A. Wallig, Mosbah M. Kushad, and John A. Juvik

Ten broccoli [Brassica oleracea L. (Botrytis Group)] accessions were grown in several environments to estimate glucosinolate (GS) variability associated with genotype, environment, and genotype × environment interaction and to identify differences in the stability of GSs in broccoli florets. Significant differences in genetic variability were identified for aliphatic GSs but not for indolyl GSs. The percentage of GS variability attributable to genotype for individual aliphatic compounds ranged from 54.2% for glucoraphanin to 71.0% for progoitrin. For total indolyl GSs, the percentage of variability attributable to genotype was only 12%. Both qualitative and quantitative differences in GSs were detected among the genotypes. Ten-fold differences in progoitrin, glucoraphanin, and total aliphatic GS levels were observed between the highest and lowest genotypes. Only two lines, Eu8-1 and VI-158, produced aliphatic GSs other than glucoraphanin in appreciable amounts. Differences in stability of these compounds among the cultivars were also observed between fall and spring plantings. Results suggest that genetic factors necessary for altering the qualitative and quantitative aliphatic GS profiles are present within existing broccoli germplasm, which makes breeding for enhanced cancer chemoprotectant activity feasible.

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Faith J. Wyzgoski, A. Raymond Miller, Joseph C. Scheerens, Peter L. Rinaldi, Bert L. Bishop, R. Neil Reese, Mustafa Ozgen, Artemio Z. Tulio Jr., M. Monica Giusti, and Joshua A. Bomser

We have developed a Nuclear Magnetic Resonance (NMR)-based approach to metabolomics research that enables the identification of bioactive compounds in crude plant extracts. For this work, we used black raspberries, which are known to contain compounds that exhibit chemopreventive activity toward oral, esophageal, and colon cancers. To ascertain bioactive components and their interrelationships, NMR results for black raspberry samples from four cultivars grown on commercial farms in Ohio were examined using principal component analysis. Multivariate analysis that included anthocyanin content (HPLC), antioxidant activity (DPPH, ABTS, FRAP), total phenolics (Folin-Ciocalteau assay), and bioactivity as measured by inhibition of colon cancer HT-29 cell line proliferation showed correlations with specific regions of NMR spectra at 400 MHz. Correlations were also observed for major and minor groupings of the black raspberry samples. Replicate black raspberry samples were examined with a 750 MHz NMR spectrometer equipped with a cryoprobe that provided a 4- to 5-fold improvement in sensitivity. In this manner, even minor bioactive components in black raspberries could be examined to determine additive and synergistic effects.

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J.K. Collins, P. Perkins-Veazie, and W. Roberts

Lycopene is a pigment that imparts a red or red–orange color to some fruits and vegetables. This carotenoid has been extensively studied over the last 10 years because of its potent antioxidant activity and medical evidence that dietary intake can reduce the incidence of cardiovascular disease and some cancers. The purpose of this review is to provide researchers in the areas of horticulture and food science a current summary of available information on lycopene in plants, stabilization and extraction, and potential health benefits as delineated in current medical studies.

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Jed W. Fahey and Paul Talalay

High fruit and vegetable consumption is associated with a striking reduction in susceptibility to malignancy. In addition to other health benefits (e.g., high levels of vitamin C, carotenoids, and dietary fiber), cruciferous vegetables contribute significantly to this chemoprotective effect. Cruciferous vegetables (e.g. Brassica sp.), contain glucosinolates, water-soluble secondary metabolites that are converted to highly reactive isothiocyanates as a defense response to predation or injury. When fed to mammals, isothiocyanates induce Phase 2 enzymes such as glutathione-S-transferase and quinone reductase, that detoxify xenobiotics. Phase 2 enzyme induction potential was assessed for fruits and vegetables from a wide variety of plant families and the Brassica vegetables were particularly rich in such activity. Tremendous variability in glucosinolate content and Phase 2 enzyme induction potential was found between commercial broccoli cultivars (n = 12) and between sites (n = 7) growing transplants produced at the same time, from the same seedlot. Broccoli (B. oleracea var. italica) cvs. Green Comet and Excelsior had an almost identical spatial distribution of Phase 2 enzyme induction potential that varied by position on market-stage plants. Fertilization regime also affected Phase 2 enzyme induction by these two cultivars. Additionally, induction of detoxication enzymes and glucosinolate profiles have been evaluated in primary and axillary shoots of two greenhouse-grown broccoli cultivars (Broccolo Natalino and a proprietary hybrid), harvested over the duration of a 2-month period of side-shoot production. This approach to evaluating the germplasm, positional, temporal, and cultural effects on levels of inducers of mammalian detoxication enzymes should lead to development of cultivation strategies to enhance the chemoprotective effect of Cruciferous vegetables.