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Joseph K. Peterson, Howard F. Harrison, and Maurice E. Snook

After removal of the periderm, cortex tissue of the sweetpotato cultivar Regal was collected. Polar extracts of this tissue strongly inhibited germination of proso-millet seed. C18 preparative, step-gradient chromatography (H2O → 100% methanol) gave some 50+ fractions, all of which were assayed for inhibitory properties. Analytical HPLC, using diode array detection and signal processing, showed the presence of chlorogenic, p-coumaric and caffeic acid, scopolin and some unknown phenolic acids. Most fractions were inhibitory to some degree; however, the least polar ones (in 90% and 100% methanol), containing unknown compounds, were most inhibitory. Semi-prep HPLC of these fractions produced eight major peaks (λmax at 210–213 nm, λ2 at 281–284 nm). In our bioassays, the compounds produced 50% inhibition of proso-millet seed germination at ≈60 ppm. It is likely that these compounds contribute significantly to the allelopathic properties of sweetpotato.

Open access

T. W. Starman, J. W. Kelly, and H. B. Pemberton

Abstract

Ancymidol foliar spray at 66 and 132 mg·liter−1 a.i. significantly decreased height, node number, leaf area, fresh weight, and dry weight of four sunflower cultivars. Ancymidol resulted in darker green leaves and increased chlorophyll content per unit area, as measured spectrophotometrically, when compared with controls. However, chlorophyll a, b, and total chlorophyll were increased in only two cultivars when measured on a weight basis using high-performance liquid chromatography (HPLC). Ancymidol increased three xanthophyll levels (neoxanthin, vio-laxanthin, and lutein) in the four cultivars, but had no effect on β-carotene when measured on a weight basis by HPLC. Chemical name used: a-cyclopropyl-a-(4-methoxyphenyl)-5-pyrimidine methanol (ancymidol).

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M.E. Garcia, C.R. Rom, J.B. Murphy, and G.W. Felton

The leaf phenolic content of 25 Malus species obtained from the National Germplasm Repository was evaluated. Two methods were utilized for determination of phenolic quantity and form. Total dihydroxy phenolic content was determined by spectrophotometric method using diphenlboric acid 2 aminoethyl ester as the reagent. These phenolics were quantified by using HPLC. Differences in phenolic quantity and type among the species were observed. This variation will be discussed in relation to apple–insect interactions.

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Lailiang Cheng and Fengwang Ma

Lisong Chen, Chris Watkins, and Sunita Kochhar for helpful discussions on antioxidant measurements and Rich Raba for technical assistance with HPLC.

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Jan E. Paul Debaene and Laren Robison

Tepary beans (Phaseolus acutifolius A. Gray) are considered drought and heat tolerant, desirable characteristics for arid regions. Knowing the genetic distances among tepary lines can indicate both compatibility for intraspecific crosses and potential for Interspecific P. acutifolius × P. vulgaris hybrids. Fifteen tepary lines, including cultivars and landraces, were compared to two pinto bean varieties using random amplified polymorphic DNA's (RAPDs). At the present time polymorphisms have been clearly identified between wild and cultivated teparies and the pinto bean. An ammo acid profile is also being determined using HPLC. More work needs to be completed before relationships among cultivated teparies can be established.

Open access

Gerald M. Sapers and Donna L. Hargrave

Abstract

Variation in the proportions of individual anthocyanins in cranberry (Vaccinium macrocarpon Ait.) fruit of different coloration was investigated. Light-, medium-, and dark-red subsamples of ‘Franklin’, ‘McFarlin’, and ‘Searles’ cranberries were analyzed to determine the soluble solids : acidity ratio (SS:A), total anthocyanin, and individual anthocyanins. Qualitative and quantitative differences in the pattern of individual anthocyanins among clones studied over three seasons were not significant. Proportions of individual anthocyanins in fruit subsamples of different coloration within cultivar samples also were similar, indicating constant biosynthetic rates for each anthocyanin during color development. Linear relationships between HPLC peak areas for individual anthocyanins and subsample total anthocyanin or SS:A values were observed.

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C.R. Brown, C.G. Edwards, C.-P. Yang, and B.B. Dean

and technical support for the HPLC analysis of these materials. 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 advertisement solely to

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Jane E. Lancaster, Julie Farrant, and Martin L. Shaw

1 Scientist; e-mail: jlancaster@xtra.co.nz . 2 Research assistant. Research funded by New Zealand Institute for Research Science and Technology. Statistical assistance of Fred Potter and Ruth Butler and HPLC analytical assistance of Kevin Sutton is

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Jose L. Perez, G.K. Jayaprakasha, and Bhimanagouda S. Patil

Grapefruit has potential health-promoting properties due to the presence of multitude bioactive compounds. Ongoing cell culture and animal studies in our lab using limonoids and flavonoids have provided strong evidence of their protective properties for preventing chronic diseases. Studies related to D-glucarate, a natural, nontoxic bioactive compound found in grapefruit, has not been explored. One of the derivatives, such as D-glucaro-1,4-lactone, is reported to be a potent ß-glucuronidase inhibitor. With the inhibition of ß-glucuronidase enzyme, glucuronidation will be favored. Glucuronidation is a conjugation process through which potentially carcinogenic environmental toxins can be neutralized. In this context, quantification of glucarate using HPLC was developed. Samples from grapefruits were prepared by heating fruit extract with distilled water. Further, the extract was homogenized and centrifuged. The supernatant was treated with petroleum ether to remove non-polar substances. Then the extract was subject to ion exchange chromatography. Fractions were collected and analyzed by analytical HPLC for the quantification of D-glucarate content and its lactone. This project was supported by the USDA-CSREES grant for Designing Foods for Health through the Vegetable and Fruit Improvement Center.

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Jose E. Villarreal, Leonardo Lombardini, and Luis Cisneros-Zevallos

Pecans nuts from `Kanza' and `Desirable' cultivars were irradiated with 0, 1.5, and 3.0 kGy using electron beam (E-beam) irradiation and stored under accelerated conditions (40 °C and 55% to 60% RH). Antioxidant capacity (AC), phenolic (TP) and condensed tannin (CT) content, HPLC phenolic profile, tocopherol content, peroxide value (PV), and fatty acid profile were evaluated in kernels after 0, 7, 21, 55, and 134 days of storage. Irradiation had no detrimental effects in AC and TP; however, variation was found throughout storage. Tocopherol content of 1.5 and 3.0 kGy kernels decreased after irradiation, but no further decrease was observed thereafter. Irradiated `Desirable' samples had greater PV than controls, while `Kanza' 1.5 kGy samples had increased PV only after 134 days of storage. No change in fatty acid composition was detected for any cultivar. Color modification induced by storage included a decrease in lightness and yellowness and an initial increase of redness followed by a decrease after 98 days of storage. No differences in phenolic profile were observed after irradiation. Compounds identified by HPLC in hydrolyzed extracts were gallic and ellagic acid, catechin, and epicatechin. In general, beside the decrease in tocopherol content, no detrimental effects were found in antioxidant composition caused by irradiation treatments. While a faster oxidation rate was seen in irradiated kernels for `Desirable' cultivar, no other quality attribute was affected by E-beam irradiation.