Thesis (Ph. D.)--Oregon State University, 2002. / Typescript (photocopy). Includes bibliographical references. Also available online.

The purpose of this study was to design and develop anti-hyperglycemic functional foods containing phenolic carbohydrate absorption modulator. Physical, chemical, structural and digestive aspects of the reactions of carbohydrates in the presence of phenolic extracts of traditional Chinese medicines were investigated. Water extracts of 14 traditional Chinese medicinal (TCM) plants with reputation of usefulness in treating diabetes were examined for total phenolic contents, antioxidant activities and α-amylase inhibitory activities through in vitro assays. A positive and significant linear relationship between total phenolic content and antioxidant capacity was found (R2=0.99), indicating that the phenolic compounds are the major antioxidant components in the tested materials. Extract of Chinese galls from Rhus chinensis exhibited highest total phenolic content, antioxidant capacity and α-amylase inhibitory activities. The results of this study demonstrate that the extract of Rhus chinensis would be the most effective carbohydrate modulator among the samples tested. Swelling, pasting and thermal properties of wheat and potato starch were studied in the presence of aqueous extract of Galla chinensis (GAC), also known as Chinese galls. The swelling factor was reduced in both starches after GAC extract addition. The extract increased peak viscosity and cold paste viscosity of wheat starch, but decreased those of potato starch. Increased breakdown has shown for wheat starch, but that for potato starch decreased. GAC extract also delayed gelatinization of both starches with higher onset temperature (To). The results of this study demonstrated that GAC extract supplementation can alter the physicochemical properties of wheat and potato starch. To examine the potential application of Galla chinensis (GAC) extract supplementation in Asian white salted noodles, the effects of various GAC extract addition levels on microstructure and in vitro starch digestibility of noodles were investigated. Scanning electron microscopy (SEM) indicated that the gluten protein network was improved (more compact and smooth) by GAC extract in both raw and cooked noodles. The estimated glycemic index (GI) was significantly decreased from 100 to 90.6 after 0.5% GAC extract was added. This indicated that GAC extract supplementation could reduce starch digestibility and blood glucose response. This feature might make GAC extract-enriched noodles sufficiently attractive to health-conscious consumers. / published_or_final_version / Biological Sciences / Master / Master of Philosophy

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Kinetic studies are reported of the reactions of 1,3,5-trinitrobenzene with aniline in dimethyl sulfoxide (DMSO). In the presence of buffers containing 1,4- diazabicyclo(2.2.2)octane, (Dabco), and its acid salt, DabcoH(^+), the anilide σ-adduct is formed. The reaction of ethyl 2,4,6-trinitrophenyI ether with aniline in DMSO containing Dabco occurs in two stages. The first gives σ-adduct intermediate on the substitution pathway, which has been identified spectroscopically. The second yields 2,4,6-trinitrodiphenyIamine, the substitution product. Kinetic studies show that proton transfer is rate-limiting both in the formation of the intermediate and in its subsequent acid-catalysed decomposition. Phenoxide is a considerably better leaving group than ethoxide and the substitution reactions of phenyl 2,4,6- trinitrophenyl ethers and phenyl 2,4-dinitronaphthyI ether with aniline in DMSO occur without the accumulation of intermediates. The kinetics indicate both uncatalysed and base catalysed pathways. Values have been determined for the pK(_a) in DMSO of several ammonium ions derived from amines which have previously been widely used as nucleophiles in nucleophilic aromatic substitution reactions; values are also given for four polynitrodiphenylamines used as indicators. Second order rate constants (K(_s)) are presented for the reaction of substituted phenyl 2,4,6-trinitrophenyl ethers with a series of phenolate ions having pK(_a) values both higher and lower than that of the respective leaving groups in aqueous solution. The rate constants for the reverse reaction (k(_-s)) have also been measured. The Brømsted diagram formed when plotting log k(_s) versus pK(_a) shows a change in slope when ΔpK(_a) = 0 (ΔpK(_a) being the difference in pK(_a) values of the leaving group and nucleophile). This is consistent with a two step process involving a discrete σ-adduct intermediate. From the measured β values effective charges have been determined and the overall effective charge map constructed. Kinetic studies have been made for the reactions of substituted phenyl 2,4,6- trinitrophenyl ethers with substituted phenolate ions in 74% DMSO-water (v/v). Two reactions are observed. The evidence suggests that the more rapid involves formation of a 1,1 σ-adduct between the substrate and the phenolate ions. The slower reaction is attributed to hydroxide attack at the 3-position of the substrate.

One of the many ways to address health, obesity and hunger issues is genetic bio-fortification, a strategy of breeding or transforming staple crops with micronutrients and vitamins. This dissertation details efforts to bio-fortify bioactive compounds (phenols, antioxidants, condensed tannins, flavonoids and anthocyanins) in Vigna unguiculata, a staple legume grain crop. Approaches included screening of genetic variation in polyphenolic compositions to identify potential varieties and phenotypes, evaluating the impact of environment (drought stress) on these compositions and elucidating the underlying genetics of their inheritance. Our screening showed significant diversity among genotypes for phenols (2.05 –15.48 mg GAE/g), condensed tannin (0.05 -15.29 mg CE/g) and antioxidant activity (4.0 -201.8 µM TE/g). The highest levels of phenols and antioxidant activity were observed in genotypes with light brown, black and red seed coat color, and those with smooth texture and medium maturity (70-90 days). Red and black phenotypes showed the highest content of flavan-3-ols, flavonols and phenolic acids among all color groups, with values of 169 µg CE/g, 26.17 µg QHE/g, 27.14 µg GAE/g for red and 281 µg CE/g, 23 µg QHE/g and 25 GAE/g for black phenotypes. When studying the impact of drought stress, genotypeXtreatment and treatmentXyear interactions for bioactive compounds were significant when tested under irrigated and drought stress conditions. Anthocyanins showed a 14 % decrease under drought stress. The genotypes that were stable to drought stress are favorable for breeding programs in preparation towards climate change. An FTNIR method was established for high-throughput, non-destructive quantification of bioactive compounds. This was used in inheritance studies of bioactive compounds. Phenols, condensed tannins and flavonoids showed heterosis in F1 and exhibit transgressive segregation in F2 populations. The information presented in this manuscript will be useful for nutritional improvement of cowpeas, where potential genotypes and phenotypes with health benefits offered by enhanced contents of bioactive compounds can be improved further upon.

Graduation date: 1971

Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Wine and Horticulture, 2004. / Bibliography: leaves 195-209.

Thesis (Ph. D.)--Oregon State University, 1992. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.