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.
Joseph K. Peterson, Howard F. Harrison, and Maurice E. Snook
Yuko Yoshizawa, Kenji Sakurai, Satoru Kawaii, Masayoshi Asari, Junichi Soejima, and Noboru Murofushi
Aqueous ethanol extracts prepared from 19 apple (Malus ×domestica Borkh.) cultivars were studied to explore their antiproliferative activity. Half of them showed strong inhibition on proliferation of human leukemic HL-60 cells, while the others were weak. Total polyphenols, 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, and total anthocyanins were measured and the results indicated that the antiproliferative activity was more strongly correlated to the polyphenols and radical scavenging activity than to the anthocyanin content. Several polyphenols in `Jonathan' were identified and quantified by high-performance liquid chromatography (HPLC) analysis. Among those compounds found during HPLC, catechin and epicatechin seemed partially responsible for HL-60 antiproliferation. A careful examination on parentage of the apple cultivars tested revealed that `Jonathan' and its progeny showed high antiproliferation toward HL-60. This is the first observation about the relationship between antiproliferative activity and parentage of apples, and the information would be useful to create new apple cultivars that posses more anticancer potential.
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.
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.
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.
Jane E. Lancaster, Julie Farrant, and Martin L. Shaw
1 Scientist; e-mail: email@example.com . 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
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
Vicky W. Lee, H.P. Vasantha Rupasinghe*, and Chung-Ja Jackson
Apples are excellent sources of dietary phenolics, in particular flavonoids and chlorogenic acid, which are potent antioxidants that may play important roles in the prevention of chronic diseases. This study investigated the major phenolics profiles of apple fruit in relation to (1) the distribution among 8 Ontario-grown cultivars, (2) the different fruit parts, and (3) the effect of processing of fresh-cuts. In addition, total antioxidant capacity (TAC) and total phenols content (TPC) were measured in apples by spectrophotometric assays. Flavonoids and chlorogenic acid were quantified using HPLC/PDA. Vitamin C was quantified using HPLC/Fluorescence. TAC, TPC and flavonoids levels were the highest in Honey Crisp and Delicious, moderate in Idared, Spartan, Granny Smith, and Cortland, and the lowest in Crispin and Empire. Apple peel contained 2 to 10-fold higher TAC, TPC and total of 10 major phenolics than that of core and flesh indicating peeling of apples during processing could reduced significantly the nutritional quality of fresh-cut apples. Dihydrochalcone (phloridzin) and chlorogenic acid levels were 2 to 21-fold higher in apple core than skin and flesh. TAC levels and vitamin C contents could be increased up to 3-fold and 14 to 20-fold, respectively by the post-cut dipping treatment with an ascorbic acid-based antioxidant formula. The phenolic profiles of sliced apples were stable up to 21 days at 4°C.
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.
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.