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K R Price

Publications and source records attributed to K R Price.

At least 19 recordsLinked to original sources
PubMed2000

Effect of variety, processing, and storage on the flavonoid glycoside content and composition of lettuce and endive.

Eight varieties of lettuce (Lactuca sativum) and three varieties of endive (Cichorium endivia) were analyzed for flavonoid composition and content. Total flavonoid contents, expressed as units of aglycon for fresh material, were in the ranges of 0.3-229 microg/g for lettuce and 44-248 microg/g for endive. Five quercetin conjugates [quercetin 3-O-galactoside, quercetin 3-O-glucoside, quercetin 3-O-glucuronide, quercetin 3-O-(6-O-malonyl)glucoside, and quercetin 3-O-rhamnoside] and luteolin 7-O-glucuronide were measured in the green-leafed lettuce and an additional two cyanidin conjugates [cyanidin 3-O-glucoside and cyanidin 3-O-[(6-O-malonyl)glucoside]] in the red-leafed varieties. Three kaempferol conjugates [kaempferol 3-O-glucoside, kaempferol 3-O-glucuronide, and kaempferol 3-O-[6-O-malonyl)glucoside]] were measured in each of the endive varieties. The presence and identity of kaempferol 3-O-(6-O-malonyl)glucoside in endive was shown for the first time. Shredding of lettuce leaf followed by exposure to light produced significant losses of the flavonoid moiety in the green oak leaf (94%), red oak leaf (43%), iceberg (36%), green batavia (25%), lollo biondo (24%), and lollo rosso (6%) samples, whereas cos and green salad bowl samples did not show an overall loss. Shredding of endive also produced loss of the flavonoid moiety in escarole (32%), fine frisee (13%), and coarse frisee (8%). Significant demalonation was observed for both the quercetin and cyanidin glucosides in lettuce, whereas a similar degradation of the kaempferol analogue was found in endive tissue. Storage of whole heads of both lettuce and endive in the dark at 1 degrees C and 98% humidity for 7 days resulted in losses of total flavonol glycosides in the range of 7-46%. The identification of the amounts, position of substitution, and nature of the sugars is important for understanding the potential bioavailability and biological activities of flavonoids in salads.

Chromatography, High Pressure Liquid↗
PubMed1999

Antioxidant properties of flavonol glycosides from tea.

We have determined the antioxidant activity of the major flavonols found in tea: a monoglycoside, a diglycoside and two triglycosides of kaempferol and three monoglycosides, a diglycoside and two triglycosides of quercetin. The Trolox equivalent antioxidant capacity (TEAC) and inhibition of iron/ascorbate-induced lipid peroxidation of phosphatidyl choline vesicles were measured. In the aqueous phase TEAC assay, the quercetin monoglycosides and diglycoside were approximately half as effective as quercetin aglycone. The quercetin triglycosides were much less effective than the monoglycosides and the diglycoside. The kaempferol glycosides were 32-39% less effective in the aqueous phase antioxidant assay compared to the kaempferol aglycone. Quercetin monoglycosides and diglycoside were potent inhibitors of lipid peroxidation, in contrast to the triglycoside which was much less effective. All the kaempferol glycosides were significantly less potent inhibitors of lipid peroxidation compared to the kaempferol aglycone. The compounds described herein demonstrate the antioxidant activity of the major flavonols in tea and indicate the effect of substituting a range of sugar moieties in the phenolic C ring.

Antioxidants↗
PubMed1999

Antioxidant properties of flavonol glycosides from green beans.

We have examined the antioxidant activity of one class of polyphenolic compounds in green beans: two novel flavonol glycosides (quercetin 3-O-[xylosyl(1-->2)]-rhamnosyl (1-->6)-glucoside and the corresponding kaempferol analogue), quercetin 3-O-glucuronide, kaempferol 3-O-glucuronide, quercetin 3-O-rutinoside and kaempferol 3-O-rutinoside. The Trolox equivalent antioxidant capacity (TEAC) and inhibition of iron/ascorbate-induced lipid peroxidation of phosphatidyl choline vesicles were measured. In the aqueous phase TEAC assay, the glucuronide and rutinoside of quercetin were good antioxidants, but not as effective as the quercetin aglycone. TEAC values for the glucuronide and other glycosides of kaempferol were much lower than the corresponding quercetin species but similar to that of the kaempferol aglycone. Quercetin 3-O-glucuronide and quercetin 3-O-rutinoside were both potent inhibitors of lipid peroxidation, in contrast to the those of kaempferol. The compounds described herein demonstrate the antioxidant activity of the flavonols present in green beans and indicate the effect on antioxidant activity of sugar substitutions in the phenolic C ring.

Antioxidants↗
PubMed1997

Induction of the anticarcinogenic marker enzyme, quinone reductase, in murine hepatoma cells in vitro by flavonoids.

Some flavonoids induce phase II enzymes both in vivo and in vitro. We have determined the structural requirements for this activity by examining the ability of naturally-occurring flavonoids to induce the phase II enzyme, quinone reductase (NAD(P)H:quinone oxidoreductase; EC 1.6.99.2), in murine Hepalclc7 cells. Hydroxylation of the B ring is not essential for induction, since galangin and kaempferol (with 0 and 1 hydroxyl in the B ring, respectively) are better inducers than quercetin (2 B ring hydroxyls). A 2,3 double bond in the C ring is essential for induction, since taxifolin, which has the same substitution pattern as quercetin but lacks the 2,3 double bond, is not an inducer. This is supported by catechin and epicatechin, which do not possess the 2,3 double bond and are also not inducers. A 3-hydroxyl group increases the activity but is not essential for induction, since apigenin is an inducer but kaempferol (which has the same structure as apigenin but possesses a 3-hydroxyl group) is more effective. The data show that, of the flavonoids, the flavonols are the most effective inducers of quinone reductase activity in Hepa1c1c7 cells (kaempferol approximately galangin > quercetin > myricetin approximately apigenin (a flavone)) and that flavanols and flavans are ineffective.

Animals↗
PubMed1997

Identification and analysis of plant phenolic antioxidants.

Food plants contain a range of nutrient and non-nutrient compounds with antioxidant properties. Principal among these compounds are flavonols and the cinnamic acid derivatives. These two groups exist in plant foods largely as conjugates with sugars or with organic acids; and typically, plant foods contain complex mixtures of these glycosides and conjugates. The analysis of such mixtures in foods is an important outstanding problem. The present paper outlines methods for the extraction and purification of phenolic antioxidants as the conjugated forms that exist in plant foods.

Biological Availability↗
PubMed1997

Antioxidant properties of the major polyphenolic compounds in broccoli.

We have examined the antioxidant activity of the major phenolic compounds in Broccoli: two flavonol glycosides (quercetin 3-O-sophoroside and kaempferol 3-O-sophoroside) and four hydroxycinnamic acid esters (1,2'-disinapoyl-2-feruloyl gentiobiose, 1-sinapoyl-2-feruloyl gentiobiose, 1,2,2'-trisinapoyl gentiobiose and 1,2-disinapoyl gentiobiose). The Trolox C equivalent antioxidant capacity (TEAC) and inhibition of iron/ascorbate-induced lipid peroxidation of phosphatidyl choline vesicles were measured. In the aqueous phase TEAC assay, the two flavonol glycosides were less active than their respective aglycones. TEAC values for the hydroxycinnamic acid esters were less than the sum of their constituent hydroxycinnamic acids on a molar basis. Quercetin 3-O-sophoroside was a potent inhibitor of lipid peroxidation, in contrast to kaempferol 3-O-sophoroside. The hydroxycinnamic acid esters were highly effective at preventing lipid damage with the exception of 1,2,2'-trisinapoyl gentiobiose. The six compounds analysed herein demonstrate the antioxidant activity of the major phenolics in broccoli and indicate the effect on antioxidant activity of sugar substitutions in the phenolic B ring.

Antioxidants↗
PubMed1996

Improved method for the analysis of alpha-galactosides in pea seeds by capillary zone electrophoresis. Comparison with high-performance liquid chromatography-triple-pulsed amperometric detection.

A capillary zone electrophoretic (CZE) method is described for the analysis of the raffinose family of oligosaccharides (RFO) in pea seeds. Extraction of RFO was carried out in 80% ethanol and the extract was passed through a Sep-Pak C18 cartridge. This proved to be an improvement on the currently accepted purification technique. High-quality electrophoregrams were obtained which allowed the separation and quantitation of sucrose, raffinose, stachyose and verbascose The CZE results were compared with those obtained by anion-exchange high-performance liquid chromatography coupled to a triple-pulsed amperometric detection (HPAC-PAD). The samples were obtained from four pea strains which were near-isogenic except for genes at the r and rb loci. A high degree of precision and reproducibility was obtained for the RFO compositions of all the pea strains. No statistically significant differences (p < or equal to 0.05) were found between the two analytical techniques using paired Student-t tests.

Chromatography, High Pressure Liquid↗
PubMed1996

Dietary quercetin glycosides: antioxidant activity and induction of the anticarcinogenic phase II marker enzyme quinone reductase in Hepalclc7 cells.

It has recently been shown by Hollman et al. (Am. J. Clin. Nutr., 62, 1276-1282) that flavonoid glycosides are preferentially absorbed from dietary onions compared to the flavonoid aglycone. In the light of this, we have compared the bioactivities of the two most abundant flavonoid glycosides that we have purified from onions (quercetin-3,4'-diglucoside and quercetin-4'-glucoside) to the quercetin aglycone, and also to the more commonly studied commercially-available flavonoid glycosides, rutin (quercetin-3-rutinoside) and isoquercitrin (quercetin-3-glucoside). Quercetin aglycone was the most effective inducer of the anticarcinogenic phase II marker enzyme, quinone reductase (QR), in mouse Hepalclc7 cells. Of the glycosides, only quercetin-4'-glucoside was able to induce QR activity in this assay. Inhibition of NADPH/iron- and ascorbate/iron-induced lipid peroxidation of human liver microsomes, and the Trolox C-equivalent antioxidant capacity (TEAC), were also measured. The 4'-glycosylation dramatically decreased activity in the 'antioxidant' assays, whereas 3-substitutions produced much smaller changes. These results show that the preferentially-absorbed quercetin glycosides in onions have markedly different biological properties compared with the aglycone.

Animals↗
PubMed1994

Analysis of glycoalkaloids from potato shoots and tomatoes by four-sector tandem mass spectrometry with scanning-array detection: comparison of positive ion and negative ion methods.

A wide range of glycoalkaloids from potato shoots and tomatoes, including trisaccharide-containing glycoalkaloids (alpha-chaconine, alpha-solanine, and alpha-solasonine), tetrasaccharide-containing glycoalkaloids (alpha-tomatine and demissine), and disaccharide-containing glycoalkaloids (beta 1-chaconine, beta 2-chaconine, and beta-solamargine), have been studied by both positive and negative ion liquid secondary ion and four-sector tandem mass spectrometry with scanning-array detection. In positive ion mode, collisionally induced dissociation tandem mass spectra of the [M + H]+ ions induce three major fragmentation processes, Z cleavage, Y cleavage, and 1,5X cleavage, which are structurally informative. Signals resulting from Z0, Y0, and 1,5X0 cleavages provide information on the nature of various aglycone moieties in all glycoalkaloids. Linkages and positions of the sugars in trisaccharide- and tetrasaccharide-containing glycoalkaloids are indicated by the presence or absence of the ions corresponding to Z alpha/beta and Y alpha/beta cleavages and intensity differences of the peaks due to 1,5X alpha and 1,5X beta cleavages, respectively. In negative ion mode, collisionally induced dissociation tandem mass spectra of the [M - H]- ions induce Y cleavage as the major fragmentation process. The location of the terminal sugars in branched trisaccharide and tetrasaccharide glycoalkaloids is indicated by the difference in intensity of the ions due to Y alpha cleavage and Y beta cleavage. Isomeric structures cannot, however, be differentiated unambiguously; complete structural assignment is only possible by NMR of purified components. Both positive and negative ion tandem mass spectrometry are considered to be suitable for the characterisation of glycoalkaloids in mixtures. The positive ion method has the advantage of (i) a lower detection limit than in conventional mass spectrometry; (ii) numerous and intense fragment ions which are structurally informative; and (iii) the capability of analyzing minor components in crude extracts. Comparable analysis by other analytical means would not have provided the amount of structural information on the components in the glycoalkaloid mixtures.

Alkaloids↗
PubMed1994

Intravenous access in the critically ill trauma patient: a multicentered, prospective, randomized trial of saphenous cutdown and percutaneous femoral access.

STUDY OBJECTIVE: To compare the speed of IV access and the rate of infusion for saphenous venous cutdown and percutaneous femoral catheterization. DESIGN: Prospective, randomized, multicentered trial. Patient enrollment occurred from September 1990 through September 1991. SETTING: Patients were enrolled at three urban Level I trauma centers. TYPE OF PARTICIPANTS: Seventy-eight critically ill trauma patients. INTERVENTIONS: Participants were randomized to one of two groups: saphenous cutdown or percutaneous femoral line. After successful cannulation of the vein, 1 L of crystalloid was infused by gravity. RESULTS: The mean procedure time for the cutdown group was 5.63 +/- 2.58 minutes compared with 3.18 +/- 1.19 minutes for the femoral line group (P < .0001). The mean infusion time for the cutdown group was 6.65 +/- 4.29 minutes compared with 4.56 +/- 2.47 minutes for the femoral line group (P < .03). The mean overall time for the cutdown group was 11.76 +/- 4.81 minutes compared with 7.67 +/- 2.78 minutes for the femoral line group (P < .0002). CONCLUSION: Percutaneous femoral catheterization can be performed more rapidly than saphenous cutdown in the critically ill trauma patient with a palpable femoral pulse and allows for more rapid fluid administration. We support the use of a percutaneous femoral line as an acceptable alternative to saphenous venous cutdown in the initial resuscitation of trauma patients.

Adult↗
PubMed1994

The frequency of occurrence and severity of side-effects of immersion virtual reality.

Virtual reality (VR) has become increasingly well-known over the last few years. However, little is known about the side-effects of prolonged immersion in VR. This study set out to investigate the frequency of occurrence and severity of side-effects of using an immersion VR system. Out of 146 subjects, 61% reported symptoms of malaise at some point during a 20-min immersion and 10-min post-immersion period. These ranged from symptoms such as dizziness, stomach awareness, headaches, eyestrain and lightheadedness to severe nausea. These symptoms caused 5% of the subjects to withdraw from the experiment before completing their 20-min immersion period. Further research needs to be conducted that attempts to identify those factors that play a causative role in the side-effects of the VR system, and that looks for methods of reducing these side-effects.

Aerospace Medicine↗
PubMed1992

Adjuvanticity and ISCOM formation by structurally diverse saponins.

Adjuvant activity and immunostimulating complex (ISCOM) formation by a series of saponins and glycoalkaloids differing in the structures of their aglycones and sugar chains were examined. The only two saponins apart from Quillaia that were adjuvant-active were Gypsophila and Saponaria, which resemble Quillaia in that they contain saponins with branched sugar chains attached to positions 3 and 28 of the aglycone. Glycoalkaloids with a branched sugar chain lacked adjuvant activity. Saponaria saponins formed irregular ISCOM-like structures, and Gypsophila produced a sheet of joined pore-like structures. The alfalfa hederagenin saponin and Quinoa also formed pore-sheets, despite lacking adjuvanticity.

Adjuvants, Immunologic↗
PubMed1990

Treatment of caffeine toxicity with esmolol.

We present the case of a 58-year-old woman who ingested more than 35 g of caffeine in a suicide attempt. She manifested all the clinical symptoms and signs of caffeine toxicity. Esmolol, an ultrashort-acting beta 1-selective antagonist, controlled her multiple dysrhythmias and symptoms of sympathetic nervous system hyperstimulation. We suggest the use of esmolol for treatment of dysrhythmias secondary to caffeine toxicity; to the best of our knowledge, the use of esmolol has not been reported for this purpose.

Adrenergic beta-Antagonists↗
PubMed1988

Flatulence--causes, relation to diet and remedies.

In addition to causing embarrassment and unease, flatulence is linked to a variety of symptoms, some of which may be distressing. This review describes the origins of intestinal gas, its composition and methods which have been developed for its analysis. Emphasis is placed upon the effects of legumes in the diet in producing excessive intestinal gas and, particularly, on the role of raffinose-type oligosaccharides, containing alpha-galactosidic groupings. Suggestions for overcoming the problem are presented, including drug treatment, enzyme treatment, food processing and plant breeding. It is emphasised that removal of all raffinose-oligosaccharides from beans does not remove the problem of flatulence in animals and man; the compounds responsible--though assumed to be polysaccharides (or polysaccharide-derived oligomers formed by processing or cooking)--have yet to be characterised.

Animals↗
PubMed1988

The effect of Gypsophila saponins in the diet on mineral status and plasma cholesterol concentration in the rat.

1. Immature, male Wistar rats were allocated to one of six groups and caged individually. The first group was given a semi-synthetic diet containing 38 mg iron and 55 mg zinc/kg (basal group). The second and third groups were given a diet containing 10 mg Zn and 12 mg Fe/kg respectively (low-Zn and low-Fe groups). Groups four, five and six were given similar diets containing 20 g Gypsophila saponins/kg. After 21 d the Fe and Zn status of the rats was estimated and plasma cholesterol concentration determined. 2. Measurements of whole blood haemoglobin concentration, packed cell volume and liver Fe stores indicated that rats in the basal + saponin and low-Fe + saponin groups had a significantly reduced Fe status when compared with their controls. Rats in the low-Zn + saponin group also showed a trend toward reduced Fe stores. 3. Zn status, as judged by femur Zn concentration, was not adversely affected by the inclusion of Gypsophila saponins in the diet. 4. Consumption of the saponins resulted in a significant reduction in blood cholesterol concentration, with rats in both the low-Fe groups having significantly lower concentrations than their basal and low-Zn counterparts. 5. In view of suggestions that the consumption of saponins should be encouraged because of their ability to lower blood cholesterol, possible effects on Fe metabolism should be investigated further, particularly with respect to the levels and sources of saponin in the human diet.

Animals↗