Induction of the anti-carcinogenic enzyme quinone reductase by food extracts using murine hepatoma cells.

Over 145 extracts of vegetables, fruits, herbs, spices and beverages which are consumed regularly in the European diet have been surveyed for potential anti-carcinogenic activity using an assay which measures the induction of NAD(P)H: (quinone acceptor) menadione oxidoreductase (quinone reductase, QR) activity in murine cells challenged with solutions of potential inducers. When appropriate the study has included extracts prepared from cooked and autolysed material. The results indicate that extracts of some brassicas, legumes (peas), lettuces, red pepper, grapefruit and some herbs including basil, tarragon and rosemary are inducers of QR activity. Inducing activity is strongly dependent on processing and on variety.

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.

Effects of some purified saponins on transmural potential difference in mammalian small intestine.

The effect of a range of saponins, commonly present in foods or dietary supplements, on the potential difference (PD) across the mucosa of the rat small intestine in vitro has been examined. Saponins from Gypsophila, guar, alfalfa, Quillaja, clover and liquorice together with glycoalkaloids from the potato and tomato were examined. The typical response was an immediate reduction in PD, although there was considerable variation in the response to particular compounds. Amongst the factors affecting the nature and magnitude of the de-polarizing effect were pH, solubility and the chemical form of the saponin. In agreement with the findings of others, glycyrrhizic acid, isolated from liquorice root, was found to exhibit a protective effect against the activity of a more potent saponin. The observations are discussed in the light of the known physiological activities of plant saponins and the regular, or excessive, consumption of certain foods or dietary supplements.

Differential induction of mixed-function oxidase (MFO) activity in rat liver and intestine by diets containing processed cabbage: correlation with cabbage levels of glucosinolates and glucosinolate hydrolysis products.

Both white and Savoy-type cabbage added to a semi-purified diet at 25% dry weight and fed to rats ad lib. for 5 days significantly induced ethoxyresorufin (ERR) deethylation in the small and large intestine. Savoy cabbage also induced hepatic activity and, in general, exhibited a greater inducing effect than white cabbage. These enzyme-inducing effects were altered when the cabbage had been processed. The content of intact glucosinolate was greater in Savoy than in white cabbage. The indole glucosinolate (glucobrassicin) content of both types of cabbage was approximately halved by cooking but was unaffected by fermentation, whilst homogenization of Savoy cabbage led to the total disappearance of intact glucosinolates. Levels of the indole glucosinolate breakdown products ascorbigen and indole-3-carbinol were highest in homogenized cabbage, and ascorbigen levels were also higher in cooked than in fresh cabbage of either type. When added to the semi-purified diet and fed ad lib. to rats for 5 days, indole-3-carbinol was a potent inducer of hepatic ERR deethylation and cytochrome P-450 activity, but had much less effect in the intestine. Other glucobrassicin metabolites, diindolylmethane and indole-3-acetonitrile, also had some inducing effect in the liver but no effect in the intestine, while ascorbigen significantly induced ERR deethylation in the small and large intestine but had no effect on hepatic MFO activity.

Chemical and biological properties of indole glucosinolates (glucobrassicins): a review.

Glucosinolates are a group of secondary products commonly, but not exclusively, found in plants of the family Cruciferae. They give rise, upon enzymic hydrolysis, to a range of volatile, pungent and physiologically active compounds. Recently, particular attention has been focused upon those that are trytophan-derived--the indole glucosinolates (glucobrassicins). When chemically or enzymically hydrolysed these compounds give rise to a range of involatile indole compounds which have been implicated in the anti-carcinogenic and mixed-function-oxidase stimulatory activities of brassica vegetables. This review details the chemical and physiological properties of indole glucosinolates and their products and suggests possible areas for future research.

The effect of feeding brassica vegetables and intact glucosinolates on mixed-function-oxidase activity in the livers and intestines of rats.

Significant induction of mixed-function-oxidase (MFO) activity was observed in the small intestines of rats within 4-6 hr of ingestion of a single meal containing a Brassica vegetable (cabbage). Intact Brussels sprouts and a fractionated methanol-water extract of Brussels sprouts induced similar degrees of MFO activity in the livers, and small and large intestines of rats. However, the residue left after extraction of the polar compounds did not induce MFO activity. Different amounts of the various naturally-occurring thioglycosides and glucosinolates were found in the intact Brussels sprouts and in the extract, but virtually none were found in the extracted residue. When glucusinolates that were found in Brussels sprouts (sinigrin, progoitrin, glucobrassicin and glucotropaeolin) were fed separately to rats, only the indole glucosinolate, glucobrassicin, induced MFO activity (causing induction in the small intestines of the rats). This is consistent with the inducing activity of the various hydrolysis products of this glucosinolate. This is the first study in which an attempt has been made to define the inducing compounds in Brassica vegetables by feeding the individual purified glucosinolates.

Determination of indole and 3-methylindole in plasma and rumen fluid from cattle with fog fever or after L-tryptophan administration.

A modified gas liquid chromatography method has been developed to analyse the concentrations of indole and 3-methylindole in samples of plasma and rumen fluid from four cows with fog fever together with four control animals and from two cattle given L-tryptophan orally. Satisfactory recoveries of the metabolites were obtained in test samples examined by the gas liquid chromatography procedure and increased levels were found in rumen fluid after tryptophan administration. Absence of abnormal concentrations of the toxic metabolite 3-methylindole in samples from field cases of fog fever was not considered to rule out the metabolite as a possible cause of the disease in view of the rapid restoration of 3-methylindole to normal levels by the second day after loading with L-tryptophan.

Rapeseed induced liver haemorrhage, reticulolysis and biochemical changes in laying hens: the effects of feeding high and low glucosinolate meals.

Rapeseed meal hepatosis was produced by feeding high and low glucosinolate meals as a source of protein (about 200 g kg-1 diet) but could not be distinguished histologically from fatty liver-haemorrhagic syndrome which occurred in birds on the control diet. Both types of meal increased haemorrhage, reticulolysis and lymphoproliferation in the liver, reduced the packed cell volume and caused thyroid enlargement. Haemorrhages emanated from ruptured intrahepatic portal veins, capillaries and sinusoids and were associated with degenerative changes in vessel walls. Haemorrhage and reticulin scores were correlated. Parenchymal necrosis occurred only around large haematomas and caused increased aspartate transaminase activity in the plasma. Both meals also caused hyperglycaemia and reduced the plasma triglyceride content. Only the high glucosinolate meal decreased egg production, caused liver enlargement and reduced the plasma urate level. The addition of myrosinase enhanced its effects on egg production and packed cell volume but did not increase its hepatotoxicity.

Effects of rapeseed meal on laying hens (Gallus domesticus) in relation to fatty liver-haemorrhagic syndrome and egg taint.

Fatty liver-haemorrhagic syndrome (FLHS) occurred in the controls and was modified in hens that received a diet containing 10 per cent rapeseed meal. This diet increased the extent and severity of the hepatic haemorrhage without affecting the reticulin content of the liver but decreased the body weight and liver lipid levels and so weakened the correlation between these parameters and haemorrhage score found in FLHS. Plasma aspartate transaminase and beta-glucuronidase activities tended to increase with the score. The rapeseed meal diet also produced thyroid hypertrophy and since this was greater in the hens that produced tainted eggs and was positively correlated with the trimethylamine (TMA) content of the eggs it was postulated that rapeseed meal goitrogens may be involved as secondary factors in producing the disturbance in TMA metabolism that causes the egg taint. This abnormality was associated with a reduction in the soluble protein content of the liver, which reflected a decrease in TMA oxidase activity, but was not related to hepatic haemorrhage, steatosis or reticulolysis, or to lipid levels and the activities of lysosomal enzymes and transaminases in the plasma.

The identification of the goitrogen (-)5-vinyloxazolidine-2-thione (goitrin), as a bitter principle of cooked brussels sprouts (Brassica oleracea L. var. gemmifera).

(-)5-Vinyloxazolidine-2-thione (goitrin), a well-known goitrogen, has been identified as a bitter principle in cooked Brussels sprouts (Br. oleracea var. L. gemmifera). The identification was carried out by chemical analysis and sensory assessment.

Natural toxins and protective factors in brassica species, including rapeseed.

Many plant secondary metabolites exhibit a wide range of dose-related physiological properties when included in the diet of animals and man. Within the brassica family, the glucosinolates, a group of sulphur-containing glucosides have been the subject of a vast amount of study and the effects of dietary inclusion of such compounds or their metabolites on the health of animals and man are briefly reviewed. Although excessive amounts of glucosinolates in animal feed formulations may reduce growth and performance as well as affecting thyroid, liver, and kidney function, there is little evidence of such effects in man. On the contrary, compounds derived from glucosinolates as a consequence of enzymic breakdown or metabolism have been shown to activate mechanisms which moderate or reverse carcinogenic processes. Such effects may contribute to the net anti-carcinogenic benefit attributed to these vegetables in numerous epidemiological studies.

The genus Allium. Part 2.

Allium is a genus of some 500 species belonging to the family Liliaceae. However only a few of these are important as food plants, notably onion, garlic, chive, leek, and rakkyo. Such plants have been used for many centuries for the pungency and flavoring value, for their medicinal properties, and, in some parts of the world, their use also has religious connotations. The flavors of members of the genus Alliums, in addition to having certain characteristics, are also complex, being derived enzymically from a number of involatile precursors. In addition to there being variation of flavor between different alliums, there are also considerable changes that occur as a result of cooking and processing. Of course, these are of importance to the consumer and food technologist-processor. The review will introduce the subject by an historical perspective and will set this against data on the present cultivation and usage of commercially cultivated alliums. The chemical composition of these plants will be discussed, emphasis being given to nonvolatile constituents which are, perhaps, less often considered. Discussion of the volatile constituents, which will include mention of the methods currently used for their analysis and for the determination of "flavor strength", will be mainly concerned with literature taken from the last 5 years. In considering the extent and nature of allium cultivation and processing, factors affecting the nutritional value and quality will be highlighted. The medicinal properties of garlic and onion oils have been much studied over the last decade and the review will include critical assessment of this area and also will touch on the more general properties (antimicrobial, antifungal, antibacterial, and insecticidal) of these oils. Finally mention will be made of the antinutritional, toxic, or otherwise undesirable effects of alliums, for example, as inadvertent components of animal diets, tainting of milk and other food products. It is our intention to review the literature up to mid-1984.

The genus Allium--Part 1.

Alliums have been grown for many centuries for their characteristic, pungent flavor and medicinal properties. The present review, which includes references published up to the middle of 1984, is primarily concerned with the chemical composition, flavor, and physiological properties of these crops, their extracts, and processed products. Special emphasis is placed upon the relationship between the organoleptically and biologically active components of onion and garlic. Following a brief historical introduction, current production of commercially important alliums is described and their botanical origins and interrelationships are explained. Following consideration of the major economic diseases and pests of alliums, the agronomic, husbandry, and practices associated with their cultivation are described, particular emphasis being placed upon the storage and processing of onion and garlic. The detailed, overall chemical composition and nutritional value of members of the genus Allium are presented in Section 7; after an outline of the origin and nature of flavor components and precursors, the flavor volatiles of individual members are presented. The effects of agronomic, environmental, and processing practices on chemical and flavor content and quality are considered in Section 9. The following section deals critically with the human and animal studies which have been conducted into the medical and therapeutic properties of alliums, emphasis being placed upon the studies into the antiatherosclerotic effect of onion and garlic and their essential oils. After a study of antimicrobial properties of alliums and their effects on insects and animals, an overview is presented which highlights unexplored or inadequately studied areas and suggests rewarding areas for future research.

The genus Allium--Part 3.

Allium is a genus of some 500 species belonging to the family Liliaceae. However, only a few of these are important as food plants, notably onion, garlic, chive, leek, and rakkyo. Such plants have been used for many centuries for their pungency and flavoring value, for their medicinal properties, and in some parts of the world, their use also has religious connotations. The flavors of members of alliums, in addition to being characteristic, are also complex, being derived enzymically from a number of involatile precursors. As well as there being variation of flavor between different alliums there are also considerable changes that occur as a result of cooking and processing. These are, of course, of importance to the consumer and food technologist/processor. The review will introduce the subject by an historical perspective and will set against this data on the present cultivation and usage of commercially cultivated alliums. The chemical composition of these plants will be discussed, emphasis being given to nonvolatile constituents which are, perhaps, less often considered. Discussion of the volatile constituents, which will include mention of the methods currently used for their analysis and for the determination of "flavor strength," will be mainly concerned with literature taken from the last 5 years. In considering the extent and nature of allium cultivation and processing, factors affecting the nutritional value and quality will be highlighted. The medicinal properties of garlic and onion oils have been extensively studied over the last decade and the review will include critical assessment of this area; it will also touch on the more general properties (antimicrobial, antifungal, antibacterial, and insecticidal) of these oils. Finally, mention will be made of the antinutritional, toxic, or otherwise undesirable effects of alliums, for example, as inadvertant components of animal diets, tainting of milk, and other food products. It is our intention to review the literature up to mid-1984.