Showing papers in "Journal of Medicinal Food in 1999"

Antioxidant capacity of edible plants: extraction protocol and direct evaluation by cyclic voltammetry

Abstract: Reactive oxygen-derived species are produced in cells under physiological conditions and in response to stress. Among the various antioxidant systems responsible for protection against these species, the low-molecular-weight antioxidants (LMWA), such as ascorbate, play an important role. Cyclic voltammetry (CV) has been proposed as a tool for quantitation of the total antioxidant capacity of plasma. It has also been shown that biological oxidation potentials, as determined from the anodic current waves of the CV tracings, are specific characteristics of the various LMWA components, and that the amplitude of each wave can be used for quantitation of the specific component. The adaptation of CV for evaluation of the total antioxidant capacity of edible plants is demonstrated here. The area under the anodic current wave is proposed as a better indicator for the content of LMWA, compared with the amplitude. This distinction could prove valuable when more than a single molecule contributes toward a specific anodic wave and when the identities of the components of a wave are not known. Vegetables and fruits that are commonly consumed in the U.S. diet were used. They were extracted with either water, aqueous acetic acid (30%), or a mixture of water, acetic acid, and acetonitrile (40:30:30). The LMWA contents were evaluated by CV. In three to five steps the LMWAs were completely extracted from the edible foods, and their amounts were translated into equivalents of ascorbate.

Liquid chromatography: mass spectrometry of isoflavones.

Abstract: High-performance liquid chromatography (HPLC) or capillary electrophoresis (CE) is particularly suited to the separation and analysis of a wide range of biological compounds. When investigating such compounds in complex matrices (e.g., blood, tissue, urine, foods), specificity of the detection method becomes an important issue. This can be overcome by extensive purification procedures before HPLC or CE analysis, but at the cost of a lot of effort and often unknown losses during the extraction and purification procedures. Such losses can be overcome by the addition of isotopically labeled internal standards, subject to their availability. The coupling of HPLC or CE with mass spectrometry provides a very specific method of detection. Compounds are transferred as ions to the gas phase by two types of spraying technologies, electrospray ionization (ESI) and heated nebulizer-atmospheric pressure chemical ionization. Although the mass-to-charge ratios of the molecular ions can be used to provisionally identify a compound, full confirmation of structure requires collision-induced dissociation and analysis of the resulting fragment ions. Combination of specific parent ion-daughter ion pairs allows for the quantitative measurement of isoflavones in the 1-5 pmol range with coefficients of variation for duplicate samples in the range of 5-9%. CE places greater demands on the mass spectrometer than does HPLC, because it generates narrow peak widths. A mass spectrometer with a scanning quadrupole analyzer does not enable full exploitation of the power of CE; in this context, an instrument with an ESI interface and a time-of-flight analyzer is ideal.

Marketing Functional Foods: What Have We Learned? An Examination of the Metamucil, Benefit, and Heartwise Introductions as Cholesterol-Reducing Ready-to-Eat Cereals

Abstract: Health claims, U.S. Food and Drug Administration regulatory actions, and marketing practices are examined in the environment precipitating the introduction of the Nutrition and Labeling Education Act (NLEA) in 1990. The introduction of three psyllium-based products in 1989 and 1990, Procter & Gamble's Metamucil wafers, General Mills' Benefit cereal, and Kellogg's Heartwise cereal, are examined for their use of health claims and marketing tactics in a changing regulatory environment. Inconsistent approval of psyllium-based health claims for drug and food products created a confusing environment in the pre- and early post-NLEA era. This was exacerbated by marketing issues regarding consumer communication and product positioning. Suggestions for marketing products with health positionings in the new NLEA environment are proposed.

Method for Measurement of Dietary Secoisolariciresinol Using HPLC with Multichannel Electrochemical Detection

Abstract: We describe a sensitive and specific assay for the determination of the plant lignan secoisolariciresinol, one of the main dietary precursors to the mammalian derived lignans, enterodiol and enterolactone. Quantification of secoisolariciresinol aglycone is achieved by reversephase high-performance liquid chromatography with multichannel electrochemical detection after hydrolysis of the glycoside moieties. This approach affords greater specificity than conventional ultraviolet detection and has a detection limit of 2.8 pmol. The method is ideally suited to the determination of secoisolariciresinol in processed flaxseed samples and can be used to assess the level of incorporation of flaxseed in fortified foods.

A Comparative Study of the Constituents of Aesculus hippocastanum and Aesculus indica.

Abstract: This work compared the phytochemical composition of two species, of Aesculus hippocastanum (horse chestnut) and Aesculus indica grown under comparable conditions. Thin-layer chromatography zone profiles of the constituents in methanol extracts from leaves, seeds, and husks indicated differences within and between the two species. Similar profiles were observed for seeds and leaves from the two species but not for the husks. Aesculin and its aglycone, aesculetin, were not detected in leaves, husks, or seeds of the two species. The content of aescin found in A. indica seeds (13.4% weight/weight) was higher than in A. hippocastanum (9.5%). Laurie acid, palmitic acid, myristic acid, stearic acid, arachidic acid, and oleic acid were detected, by capillary gas chromatography, in the saponified extracts of the seeds, leaves, and husks of the two species.

Determination of the Fatty Acid content of pumpkin seed, pygeum, and saw palmetto.

Abstract: Fatty acids are major components of many plants, foods and medicines, including pumpkin seeds (Cucubita pepo), pygeum bark (Prunus africana) and saw palmetto (Serenoa repens). With the gas chromatography methods reported here, free fatty acids of these species can be quantified as their trimethylsilyl derivatives. Because of their different fatty acid contents and composition, the gas chromatography method can distinguish which of three plant species was extracted, and, in the case of S. repens, the method of extraction. Although phytosterols can be separated by this method, their content is too low to be assigned directly. The total fatty acid content can be determined through formation of the methyl esters. This is helpful for estimation of the kind and percentage of fatty acids that are present as triglyceride esters in the plant material and for standardization of the products.

Lignans and isoflavonoid polyphenols in tea and coffee.

Abstract: Tea (camellia sinensis) has been revealed to contain numerous polyphenols (flavanols, catechins, flavonols, flavonediols, phenolic acids, bisflavonols, theaflavins, thearubigens, and other oligomers) and theophylline, which may have both beneficial and hazardous effects in humans. Consumption of tea has been advocated to play a role in prevention of cancer, coronary heart disease, and atherosclerosis (Imai and Nakachi, 1995; Kohlmeier et al., 1997; Jankun et al., 1997; Bushman, 1998; Ahmad and H, 1999; Weisburger, 1999). Simultaneously, recent international epidemiological comparisons have linked the semivegetarian diet of Asiatics with a reduced incidence of chronic diseases (i.e., hormone-dependent cancers and coronary heart disease), indicating that some nonnutrient compounds in that diet may contribute to homeostasis and thus have a role in the maintenance of health (Adlercreutz, 1984, 1990, 1995). High consumption of legumes, (mainly soy in different forms), teas (particularly green tea), and rice differentiate the Asian diet from theWestern diet. We reasoned, based

Antioxidant Intracellular Activity of Genistein and Equol

Abstract: Antioxidant effects of isoflavonoids have recently been described. To learn whether the isoflavonoids genistein and equol have actions on the intracellular free radicals, human neutrophils and J774 monocyte-macrophage cell line were used to measure the intracellular production of O(2) (superoxide anion) and H(2)O(2) (hydrogen peroxide) by flow cytometry. The results shown significatives decrease in O(2) and H(2)O(2) production after 1 hour of incubation with equol and genistein. The phagcytic oxidant production decreased owing to the effects of both isoflavonoids in a concentration-dependent manner.

Chemical Synthesis of [13C]Daidzein

Abstract: Pharmacokinetic and metabolic studies of phytoestrogens of the isoflavone class have been hampered by the lack of suitable stable-isotope-labeled analogs. A method for preparation of a [13C]-labele...

Natriuretic Effect of Equol

Abstract: A furosemide-sensitive Na-K-Cl cotransporter (NKCC2 isoform) accounts for almost all luminal NaCl reabsorption in the thick ascending limb of Henle's loop (TALH). The activity of this transport protein is regulated by humoral factors known as cotransport inhibitory factors. One family of these compounds is represented by the urinary phytoestrogens equol and genistein, which inhibit cotransport fluxes at concentrations similar to furosemide. Moreover, they possess salidiuretic potency similar to furosemide in the isolated perfused rat kidney, but are less potent than furosemide (in vivo). Thus, dietary phytoestrogens can be responsible, at least in part, for the low blood pressure of vegetarians.

Synthesis of Deuterated Plant Lignans for Gas Chromatography—Mass Spectrometry Analysis

Abstract: Stabile deuterated plant lignans D6-matairesinol, D8-secoisolariciresinol, and D8-anhydrosecoisolariciresinol are synthesized to be used as internal standards in isotope dilution technique of gas c...

Isoflavone-mediated inhibition of tyrosine kinase: a novel antiinflammatory approach.

Abstract: Tyrosine kinase (TK)-mediated phosphorylation regulates signal transduction pathways resulting in the expression of a variety of inflammatory genes. Inhibition of TK activity in vivo has been shown to increase survival in a lethal model of murine endotoxemia, suggesting a novel therapeutic approach to inflammation and circulatory shock. We examined the role of TK activity on the expression of the inducible nitric oxide (NO) synthase (iNOS). Under resting conditions, iNOS is not expressed in human cells. In response to various proinflammatory stimuli, however, iNOS expression is upregulated, resulting in high-output NO synthesis. iNOS-derived NO plays a critical role as a cytotoxic effector species and has been implicated in the pathogenesis of many clinical inflammatory conditions, including inflammatory bowel disease, arthritis, transplant rejection, diabetes, and sepsis. We examined the signaling pathways governing iNOS expression in monolayers of DLD-1 cells, a human epithelial cell line derived from a...

Application of topoisomerase assays in the evaluation of natural products as antitumor agents.

Abstract: Initially, DNA topoisomerase (topo) inhibitors found clinical applications as antibiotics and cancer chemotherapeutic agents. Recently, we demonstrated that plant flavonoids that inhibit mammalian topo I or topo II might be useful as cancer chemopreventive agents (Constantinou et al., 1995b). Phytochemicals can inhibit DNA topoisomerases in different ways; depending on the mode and the type of enzyme, these can be classified as topo I poisons, topo II poisons, topo I antagonists, or topo II antagonists. Correctly classifying topo inhibitors is critical because it provides an important lead as to whether the plant agent can be useful in chemoprevention or in chemotherapy. We outline below a strategy that was designed to identify and classify topo I and II inhibitors.

Pilot study on the effect of hyperimmune egg protein on elevated cholesterol levels and cardiovascular risk factors.

Abstract: Coronary heart disease is the leading cause of death in the United States, accounting for almost half of all deaths. Animal studies have suggested that the daily addition of "hyperimmune egg" to one's diet might reduce the risk of cardiovascular disease. Military personnel with initial total cholesterol levels higher than 180 mg/dl were randomly enrolled in a 26-week double-blind study of a drink containing a hyperimmune egg protein. Subjects were randomly assigned to three groups: control (no drink); placebo (drink without egg); and active (drink combined with hyperimmune egg). Throughout the study this physically fit group maintained a program of strenuous exercise and participated in a dietary education program intended to reduce fat and cholesterol intake. At the end of the trial, total cholesterol levels of the control and placebo groups had increased, whereas the group that consumed the drink with hyperimmune egg showed no significant change in total cholesterol. The ratio of total cholesterol to high-density lipoproteins and the apolipoprotein B level increased in both control and placebo groups but remained essentially unchanged in the group consuming hyperimmune egg. Triglyceride and apolipoprotein A-I values did not change significantly in any of the groups. These findings suggest that hyperimmune egg may beneficially modify the regulation of serum lipoprotein levels and thereby reduce the possibility of cardiovascular diseases.

Immunoassay of phytoestrogens in human plasma.

Abstract: Highly sensitive plasma immunoassay methods based on time-resolved fluorometry were developed for plasma enterolactone, genistein, and daidzein. For daidzein and genistein three types of methods and for enterolactone two different methods were developed and validated and the results compared with our gas chromatographic-mass spectrometric reference method. All three compounds may be determined in duplicate in a 2-300 μ plasma sample, even in subjects with low phytoestrogen values.

Chemical and Genetic Evaluation of Somaclonal Variants of Egyptian Garlic (Allium sativum L.).

Abstract: Garlic (Allium sativum L.) is used in the household and as an ingredient in many pharmaceutical products. Tissue culture technique provides an excellent source for induction of both chemical and genetic variation in garlic. A callus was induced on root meristem cultured on Murashige and Skoog (MS) medium in the presence of kinetin, indole acetic acid, and 2,4-dichlorophenoxyacetic acid. Shoots with a small bulb were produced on medium containing MS salts, B vitamins, and naphthalene acetic acid. Regenerated plants were transplanted into soil, and a nondivided bulb was formed in the first somaclonal generation (SCI). Plants were normal in their phenotypes in SC2. After four cycles of field cultivation, the selected somaclones (variants) in the fourth generation showed significant differences in bulb character compared with the original plants. Mitotic division and chromosomal abnormalities were investigated in meristimic root tip cells of regenerated plants for the first and fourth regeneration and for con...

Method for the detection of nucleosides, bases, and hydroxylated adducts using gradient HPLC with coulometric array and ultraviolet detection.

Abstract: Free radicals are compounds with an unpaired electron capable of independent existence. These highly reactive species have been implicated in many disease states and can react with cell membranes, lipids, proteins, and DNA. When an oxygen radical reacts with DNA, base damage, cross-linking (e.g., DNA-DNA or DNA-protein), or DNA backbone damage (e.g., single- or double-strand breaks) can occur and often result in cell death. The field of oxidative metabolism as it relates to DNA damage has grown tremendously, with more DNA adducts being identified as biomarkers. These biomarkers are indicative of DNA damage. Measurement of these biomarkers has proved to be a challenge because of their relatively low occurrence (1 per 10(5)-10(6) bases). Methodologies for the measurement of DNA damage include thin-layer chromatography, enzyme-linked immunosorbent assay, gas chromatography-mass spectrometry, DNA sequencing, high-performance liquid chromatography (HPLC)-ultraviolet, and HPLC-ECD. HPLC-ECD (electrochemical detection) is a powerful technique that is both sensitive and selective. However, HPLC-ECD is generally not amenable to gradient analyses, so its utility is restricted. In addition, many of the bases and nucleosides are not electrochemically active. Gradient HPLC separation coupled to both a coulometric electrochemical array detector and an ultraviolet detector overcomes these limitations. Presented here is a gradient HPLC method that measures a wide variety of nucleosides, bases, and hydroxylated adducts using the inherent stability, sensitivity, and wide dynamic range of a coulometric electrochemical array detector and the universal detection qualities of an ultraviolet detector. Linear ranges, limits of detection, and detailed methods development are presented.

Biosynthesis and distribution of phytoestrogens and their roles in plant defense, signal transduction, and cell-to-cell signaling.

Abstract: Phytoestrogens are natural products from plants that function as estrogen agonists. Here we briefly review the biochemistry, distribution, and proposed roles of phytoestrogens in plants. A primary role appears to be in host-microbe interactions. For example, results from our laboratory suggest that genistein plays multiple roles in soybean defense, including the initiation of hypersensitive (apoptotic) cell death and the activation or potentiation of the defense competency of soybean cells. Recent results from our laboratory suggest that mammalian estrogens and estrogen agonists (including other phytoestrogens and fungal estrogen agonists) and certain specific peroxisome proliferators can also potentiate defense competency in soybean. These findings suggest that some overlap in nuclear receptor or other lipid/steroid signaling pathways may exist between plants and animals.

Dietary Soy Protein and Soy Isoflavones: Histological Examination of Reproductive Tissues in Female Rats

Abstract: Soy products contain estrogenic compounds called phytoestrogens that have been shown to affect reproductive function in animals (Setchell et al., 1987; Whitten et al., 1994; Adams, 1995; Knight and Eden, 1996). The isoflavone genistein is the most common phytoestrogen in soybeans and remains in the meal after processing (Franke et al., 1995). Research has shown that there are multiple pathways by which phytoestrogens elicit their effects. In addition to engaging an estrogen receptor mechanism, the soy isoflavones act as potent tyrosine kinase inhibitors and antioxidants (Knight and Eden, 1996). It is apparent that the effects of phytoestrogens are both tissue and pathway specific. Our objectives were to determine the effects of phytoestrogens on the reproduction of animals fed these soy products. Specifically, in this study, we examine how ingestion of soy protein with and without the phytoestrogen genistein affects the histology of female reproductive tissues.

In vitro and in vivo estrogenic activity of dietary flavonoids: importance of bioavailability and metabolism.

Abstract: NATURALLY OCCURRING COMPOUNDS that exhibit estrogenic activity are widely distributed in the plant kingdom. Among these compounds are the isoflavonoids; they are closely related to the flavonoids, which occur ubiquitously in food plants. Unlike the flavonoids, the isoflavonoids have a limited taxinomie distribution and are largely confined to the Leguminosa family. Isoflavonoids are particularly rich in certain legumes, such as soya, lentils, and chick peas, which are components of traditional Asian and African diets. The isoflavonoids are of great interest to human health because they occur at substantial concentrations in human urine (Adlercreutz et al., 1982,1995; Bannwart et al., 1984). The high concentration of isoflavonoids found in the urine of Asian women, who are known to exhibit a low incidence of breast cancer, suggests that isoflavonoids might play a protective role in the pathogenesis of estrogen-dependent carcinoma. The central role estrogens play in sexual differentiation in mammals, however, may be taken to suggest that isoflavonoids might exert