The Antioxidant Activity of Vegetable Extracts I. Flavone Aglycones

A Review on Cistus sp.: Phytochemical and Antimicrobial Activities

Resistance to drugs is reaching alarming levels and is placing human health at risk. With the lack of new antimicrobials drugs, infectious diseases are becoming harder to treat. Hence, there is an increasing awareness of active phytochemicals with therapeutic functions. The tremendous research interest on the Cistus L. genus includes numerous plants used in traditional medicine by people living around the Mediterranean Sea, also resulted in some interesting discoveries and written literature. This review aimed at gathering scientific literature about Cistus species, describing phytochemical profiles and the various pharmacological activities. We also extensively reviewed the antimicrobial activities, including antiviral, antiparasitic, antifungal, and antibacterial potentials of Essential Oils (EO), raw extracts as well as isolated compounds. Mechanisms of action along with methods used are also investigated in this review. Considering the findings of the Cistus species extracts, this genus offers an adequate reserve of active phytochemicals since many have been used to create drugs. Therefore, this review work can serve society by providing a global view on Cistus L. sp. regarding pharmacological potentials and their chemical profiles.

Effect of Smoking Methods and Natural Spices on Quality and Consumer Acceptance of Smoked Silver Catfish (Chrysichthys nigrodigitatus)

AIMS AND BACKGROUND

Fish serves as a good source of dietary protein which is very inexpensive in relation to other animal protein foods and it is an excellent component of human diet. This study assessed the effects of smoking methods and natural spices on studied parameters and consumer acceptance of smoked silver catfish (Chrysichthys nigrodigitatus).

METHODS

One hundred samples of silver catfish were obtained by purposive sampling method. The fresh fish samples were smoked in two batches, the first batch was smoked with drum smoker and the second batch with oven smoker while the control was smoked without the natural spices. Rancidity indices (TVB-N, TMA-N, TBA and pH), microbiological analysis and sensory evaluation were carried out on smoked fish samples. The recent patents on edible fat blends (US20020031595A1), long chain fatty acids (WO2008085840A2) and esters of polyunsaturated fatty acids (US20090023808A1) helped in selecting the analytical methods.

RESULTS

The results showed that there was statistical significant difference (P≤0.05) between total volatile base-nitrogen, trimethylamine values and pH of the smoked silver catfish samples treated with different concentrations of clove, ginger and garlic paste and those samples which were not treated with clove, ginger and garlic. This study showed that smoking methods has effects on quality indices, microbial quality and consumer acceptance of smoked silver catfish. Clove, ginger and garlic have some anti-oxidative effects on rancidity indices of smoked silver catfish as there was inverse relationship between clove, ginger and garlic and values of peroxide, free fatty acid and thiobarbituric acid. This was also observed for the microbial quality of the smoked silver catfish. There was also inverse relationship between clove, ginger and garlic and all the sensory parameters except for texture and as the concentrations of the natural spices increase the values of the sensory parameters decrease.

CONCLUSION

In conclusion, this study showed that smoking methods affects the studied parameters, microbial quality and consumer acceptance of smoked silver catfish. Addition of clove, ginger and garlic had anti-microbial and anti-oxidative effects on quality parameters of smoked silver catfish. There was also a negative correlation between clove, ginger and garlic and all the sensory parameters except for texture.

Phytochemicals: Extraction, Isolation, and Identification of Bioactive Compounds from Plant Extracts

There are concerns about using synthetic phenolic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) as food additives because of the reported negative effects on human health. Thus, a replacement of these synthetics by antioxidant extractions from various foods has been proposed. More than 8000 different phenolic compounds have been characterized; fruits and vegetables are the prime sources of natural antioxidants. In order to extract, measure, and identify bioactive compounds from a wide variety of fruits and vegetables, researchers use multiple techniques and methods. This review includes a brief description of a wide range of different assays. The antioxidant, antimicrobial, and anticancer properties of phenolic natural products from fruits and vegetables are also discussed.

Calamintha nepeta (L.) Savi and its Main Essential Oil Constituent Pulegone: Biological Activities and Chemistry

Medicinal plants play an important role in the treatment of a wide range of diseases, even if their chemical constituents are not always completely recognized. Observations on their use and efficacy significantly contribute to the disclosure of their therapeutic properties. Calamintha nepeta (L.) Savi is an aromatic herb with a mint-oregano flavor, used in the Mediterranean areas as a traditional medicine. It has an extensive range of biological activities, including antimicrobial, antioxidant and anti-inflammatory, as well as anti-ulcer and insecticidal properties. This study aims to review the scientific findings and research reported to date on Calamintha nepeta (L.) Savi that prove many of the remarkable various biological actions, effects and some uses of this species as a source of bioactive natural compounds. On the other hand, pulegone, the major chemical constituent of Calamintha nepeta (L.) Savi essential oil, has been reported to exhibit numerous bioactivities in cells and animals. Thus, this integrated overview also surveys and interprets the present knowledge of chemistry and analysis of this oxygenated monoterpene, as well as its beneficial bioactivities. Areas for future research are suggested.

Ameliorative effect of quercetin against arsenic-induced sperm DNA damage and daily sperm production in adult male rats

In this study, the protective effect of quercetin was evaluated against arsenic induced reproductive ailments in male rats. For this purpose, male rats (n = 5/group) weighing 180-250 g were used. First group served as control, second group received arsenic (50 ppm) in drinking water. Third group was treated with quercetin (50 mg/kg) alone, while fourth group received arsenic + quercetin. All treatments were carried out for 49 days. After treatment, animals were killed by decapitation; testis and epididymis were dissected out. Right epididymis was minced immediately for comet assay, while left epididymis was processed for histology. Similarly, right testis was homogenized for estimation of daily sperm production (DSP) and detection of metal concentration. The results of our research revealed that arsenic treatment did not cause any significant change in body weight and testicular volume. Quercetin treatment significantly prevented tissue deposition of arsenic within the testis. Arsenic treatment caused a significant reduction in DSP, however, in the arsenic + quercetin-treated group and quercetin alone-treated group, DSP was significantly high as compared to the arsenic-treated group. Histological study of epididymis showed empty lumen in arsenic-treated group while in arsenic + quercetin-treated group and quercetin alone-treated group, lumen were filled with sperm and were comparable to control. Sperm DNA damage, induced by arsenic, was significantly reversed toward control levels by supplementation of quercetin. These results suggest that quercetin not only prevents deposition of arsenic in tissues, but can also protect the sperm DNA damage.

Simultaneous extraction, optimization, and analysis of flavonoids and polyphenols from peach and pumpkin extracts using a TLC-densitometric method

Background

The use of medicinal plants has been reported throughout human history. In the fight against illnesses, medicinal plants represent the primary health care system for 60 % of the world’s population. Flavonoids are polyphenolic compounds with active anti-microbial properties; they are produced in plants as pigments. Quercetin, myricetin, and rutin are among the most well-known and prevalent flavonoids in plants, with an antioxidant activity capable of decreasing the oxidation of low density lipoproteins [LDLs]. To date, this research is the first of its kind to employ a coupled thin-layer chromatography (TLC) and a densitometric quantification method with a Box-Behnken design (BBD) response surface methodology (RSM) for optimization of ultrasonic-assisted extraction and determination of rutin and quercetin from peach and ellagic acid and myricetin from pumpkin fruits.

Results

The effect of process variables (extraction temperature (°C), extraction power (%) and extraction time (min)) on ultrasound-assisted extraction (UAE) were examined by using BBD and RSM. TLC followed by Quantity-One™ (BioRad) image analysis as a simple and rapid method was used for identification and quantification of the compounds in complex mixtures. The results were consistent under optimal conditions among the experimental values and their predicted values. A mass spectrometry (MALDI-TOF MS) technique was also used to confirm the identity of the natural products in the TLC spots resolved.

Conclusion

The results show that the coupled TLC-densitometric methods & BBD can be a very powerful approach to qualitative and quantitative analysis of; rutin and quercetin from peach extracts; and ellagic acid and myricetin contents from pumpkin extracts.

Effects of ultrasonic treatments on the polyphenol and antioxidant content of spinach extracts

The objective was to test ultrasound treatments on spinach leaves during extraction, and conventional extraction was used as a control. The effects of different combinations of the ultrasonic water bath factors tested on phenolic compound yields included frequency (37 and 80 kHz), exposure time (5, 10, 15, 20, 25, and 30 min), temperature (30, 40, and 50°C), and ultrasonic power (30%, 50%, and 70%). The best conditions for extraction yields were ultrasonic frequency of 37 kHz, extraction time of 30 min, reaction temperature of 40°C, and ultrasonic power of 50%. The mean yield (mg/100g), total phenol (mg gallic acid/g DW), flavonoids (mg/g DW), % DPPH free-radical scavenging activity, and % ferric reducing antioxidant power were all high (64.88 ± 21.84, 33.96 ± 11.30, 27.37 ± 11.85, 64.18 ± 16.69 and 70.25 ± 9.68). Treatments were significantly different. The interaction among the ultrasonic parameters was significant. Temperature and power had significant effects on all other dependent variables.

Employing response surface methodology for the optimization of ultrasound assisted extraction of lutein and β-carotene from spinach

The extraction of lutein and β-carotene from spinach (Spinacia oleracea L.) leaves is important to the dietary supplement industry. A Box-Behnken design and response surface methodology (RSM) were used to investigate the effect of process variables on the ultrasound-assisted extraction (UAE) of lutein and β-carotene from spinach. Three independent variables, extraction temperature (°C), extraction power (%) and extraction time (min) were studied. Thin-layer chromatography (TLC) followed by UV visualization and densitometry was used as a simple and rapid method for both identification and quantification of lutein and β-carotene during UAE. Methanol extracts of leaves from spinach and authentic standards of lutein and β-carotene were separated by normal-phase TLC with ethyl acetate-acetone (5:4 (v/v)) as the mobile phase. In this study, the combination of TLC, densitometry, and Box–Behnken with RSM methods were effective for the quantitative analysis of lutein and β-carotene from spinach extracts. The resulting quadratic polynomial models for optimizing lutein and β-carotene from spinach had high coefficients of determination of 0.96 and 0.94, respectively. The optimal UAE settings for output of lutein and β-carotene simultaneously from spinach extracts were an extraction temperature of 40 °C, extraction power of 40% (28 W/cm³) and extraction time of 16 min. The identity and purity of each TLC spot was measured using time-of-flight mass spectrometry. Therefore, UAE assisted extraction of carotenes from spinach can provide a source of lutein and β-carotene for the dietary supplement industry.

Influence of different solvents in extraction of phenolic compounds from vegetable residues and their evaluation as natural sources of antioxidants

Dried residues from four different vegetables, viz. pea pod (pp), cauliflower waste (CW), potato peel (PP) and tomato peel (TP) were extracted using four solvents i.e., hexane, chloroform, ethyl acetate and methanol. Among the four solvents, methanolic extracts showed the highest total phenolic content (TPC) for all the four vegetable residues. Methanolic extracts were evaluated for antioxidant activities using diphenylpicryl-hydrazyl (DPPH) and reducing power assay. Tomato peel extract showed highest phenolic content of 21.0 mg GAE/g-dw and 80.8 % DPPH free radical scavenging ability, whereas potato peel extract had a low phenolic content, and it also showed the least antioxidant activity among the residues examined in this study. Total phenolic content and DPPH free radical scavenging activity in pea pods and cauliflower waste were 13.6 mg GAE/g-dw and 72 % and 9.2 mg GAE/g-dw and 70.7 %, respectively. The coefficient of determination (r(2)) for correlation between TPC and reducing power, DPPH and TPC, DPPH and reducing power for all extracts was 0.85, 0.91and 0.87, respectively, suggesting an important role of phenolics in imparting antioxidant ability. Extracts from vegetables residues therefore represent a significant source of phenolic antioxidants for use as nutraceuticals or biopreservatives.

Disposition of the flavonoid quercetin in rats after single intravenous and oral doses

The pharmacokinetic and mean time tissue distribution parameters, after a single 50-mg/kg dose of quercetin administered as intravenous bolus, oral solution, and oral suspension, were determined using rat as an animal model. Following intravenous administration, the elimination rate constant and the elimination half-life were found to be 0.0062 min(-1) and 111 min, respectively. Examining the mean time tissue distribution parameters reflected a strong binding affinity of the drug molecules to both plasma and tissue proteins. In addition, the low permeability rate of drug molecules in the peripheral system was demonstrated. Following the oral administration of the drug, the extent of absorption was greater from solution than from suspension. Moreover, the solution showed a shorter Tmax and a higher Cmax than suspension. The absolute bioavailability for the solution was 0.275 and that for suspension was 0.162. The mean residence time (MRT) and the mean absorption time (MAT) were higher for suspension, reflecting the need for dissolving the drug in order to be absorbed. The mean (in-vivo) dissolution time (MDT(in-vivo)) was 34.5 min. Thus, an oral quercetin formulation that can readily form a drug solution in the gastrointestinal tract may enhance the absorption of the drug.

Pre- and post-mortem use of grape seed extract in dark poultry meat to inhibit development of thiobarbituric acid reactive substances

Diets containing grape seed extract (GSE)-control, GSE [low GSE, low GSE + methionine, high GSE, and high GSE + methionine], or alpha-tocopherol-were fed to broiler chicks to estimate the antioxidative activity of GSE in processed meat. GSE was detrimental to the growth of chicks, and methionine did not reverse the detrimental effect. GSE with 85.4 g of gallic acid equiv/100 g (GAE 85.4) was added to ground dark turkey meat to obtain treatments with no GSE, 1.0% GSE, and 2.0% GSE and then processed as unsalted or salted and unheated or heated. Processed treatments were analyzed for thiobarbituric acid reactive substances (TBARS) and percent expressible moisture (%EM). GSE at 1.0 and 2.0% decreased TBARS values nearly 10-fold as compared to the control. GSE (1.0%) had a %EM value significantly greater than that of the control. GAE 85.4 decreased TBARS values more than GAE 88.9.

The biochemistry and medical significance of the flavonoids

Flavonoids are plant pigments that are synthesised from phenylalanine, generally display marvelous colors known from flower petals, mostly emit brilliant fluorescence when they are excited by UV light, and are ubiquitous to green plant cells. The flavonoids are used by botanists for taxonomical classification. They regulate plant growth by inhibition of the exocytosis of the auxin indolyl acetic acid, as well as by induction of gene expression, and they influence other biological cells in numerous ways. Flavonoids inhibit or kill many bacterial strains, inhibit important viral enzymes, such as reverse transcriptase and protease, and destroy some pathogenic protozoans. Yet, their toxicity to animal cells is low. Flavonoids are major functional components of many herbal and insect preparations for medical use, e.g., propolis (bee's glue) and honey, which have been used since ancient times. The daily intake of flavonoids with normal food, especially fruit and vegetables, is 1-2 g. Modern authorised physicians are increasing their use of pure flavonoids to treat many important common diseases, due to their proven ability to inhibit specific enzymes, to simulate some hormones and neurotransmitters, and to scavenge free radicals.

Flavonoids and antioxidant capacity of Georgia-grown Vidalia onions

Vidalia onion varieties Nirvana, DPS 1032, Yellow 2025, King-Midas, and SBO 133 grown at Vidalia, Georgia, were analyzed for flavonoid content. A high-performance liquid chromatographic (HPLC) method with photodiode array detection was used for quantification. Compounds were analyzed as aglycons after acid hydrolysis with 1.2 M HCl. Identification of each compound was based on comparison of its retention time and UV spectra with those of pure commercial standards. Three major flavonoids, kaempferol, myricetin, and quercetin, were identified and quantified. Quercetin was the major flavonoid (7.70-46.32 mg/100 g fresh weight, FW) present in all varieties, followed by myricetin (2.77-4.13 mg/100 g FW). Minor quantities of kaempferol (1.10-1.98 mg/100 g FW) were also detected. The total polyphenols and Trolox equivalent antioxidant capacity (TEAC) ranged from 73.33 to 180.84 mg/100 g FW and 0.92-1.56 microM TEAC/g FW, respectively. A positive but weaker correlation was obtained for total polyphenols versus antioxidant capacity. Nevertheless, a stronger correlation (r(2) = 0.34) was obtained between flavonoid content versus antioxidant capacity. The data indicate that Vidalia onions are a rich source of quercetin, and they also contain myricetin and kaempferol.

Attenuation of luminol-amplified chemiluminescent intensity and lipid peroxidation in the livers of quercetin-fed mice

We assessed the antioxidative effects of quercetin-feeding on ddY strain male mice by measuring luminol-amplified chemiluminescence that was enhanced by a hydrophilic free radical initiator 2, 2'-azobis(2-amidinopropane) dihydrochloride. Quercetin suppressed chemiluminescent intensity in a dose-dependent manner in vitro with a half-inhibition concentration (IC(50)) of 3x10(-8) M, which was lower than the value of synthetic antioxidant 2, 6-di-tert-butyl-p-cresol (IC(50): 7x10(-7) M). Lysosomal (12000xg pellet) and supernatant fractions obtained from the livers of mice fed a diet containing 0.2% quercetin for 7 days showed more inhibition of chemiluminescent intensity than those from non-treated mice. Quercetin feeding also resulted in the inhibition of lipid peroxidation as determined by a thiobarbituric acid reactive substance test which detected suppression of the release of lysosomal enzymes induced by lipophilic free radical initiator 2, 2'-azobis(2,4-dimethylvaleronitrile). These results probably reflect radical quenching activity of quercetin, indicating that the measurement of chemiluminescence is a useful tool for the assessment of total antioxidant activity in biological systems.

Dietary rutin has limited synergistic effects on vitamin C nutrition of fingerling channel catfish (Ictalurus punctatus)

A study was conducted to determine the possible synergistic effects between dietary rutin (a bioflavonoid) and vitamin C, and to evaluate their antioxidant effects in fingerling channel catfish. Purified casein/gelatin diets containing two levels of rutin (0 and 1000 mg/kg diet) and three levels of L-ascorbic acid (0, 1500 and 3000 mg/kg diet) in a factorial arrangement were fed to fingerling channel catfish for 16 weeks. Fish fed the diets without supplemental vitamin C showed deformed spinal columns, external hemorrhages and fin erosion after 10 to 12 weeks. Also these fish had significantly (p < 0.05) depressed body weight gain, feed efficiency, hematocrit, hepatosomatic index (% liver weight), as well as reduced liver, fillet and plasma vitamin concentrations after 16 weeks. Liver, fillet and plasma vitamin C concentrations were correlated with dietary vitamin C levels. Forced oxidation of fillet samples significantly (p < 0.05) increased 2-thiobarbituric acid (TBA) values of fillets from fish fed diets without vitamin C and rutin. However, results from the present study indicated only limited synergistic effects of dietary rutin on vitamin C nutrition of channel catfish.

[The antioxidant activity of citrus fruit peels]

The antioxidant properties of freeze-dried citrus fruit peels (orange, lemon, grapefruit) and methanolic extracts from the peel were studied. Freeze-dried orange peel showed the highest, lemon peel somewhat less and grapefruit peel the lowest but still remarkable antioxidant activity. This could be significantly improved by preparing methanolic extracts of the peels. Comparative examinations and autoxidation studies with the flavanon glycosides hesperidin and naringin as well as with their aglycones hesperetin and naringenin showed that the former are mainly responsible for the antioxidative activity of the citrus peel and extracts. In order to compare their antioxidative activity with that of the commercially available natural antioxidants alpha-tocopherol and ascorbylpalmitate, the freeze-dried citrus peels and their methanolic extracts should be used in higher concentrations, in consideration of their peculiar properties and complex natural composition. Furthermore, aspects of the correlation between antioxidant activity and molecular structure of the flavanones were discussed.

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.

Flavonoids, a class of natural products of high pharmacological potency

A review has been presented of the biochemistry and pharmacology of a class of natural products, the flavonoids. These substances which are widely distributed in the plant kingdom and present in considerable quantities in common food products, spices and beverages have in a concentrated form (Propolis) been used since ancient times by physicians and laymen to treat a great variety of human diseases but they have yet to pass the tests of modern, controlled, clinical experimentation. An attempt has been made to present the fundamental evidence from the basic biological sciences which is required to stimulate the interest of the clinicians in this new field. The few existing reports on the careful pharmacodynamic, pharmacokinetic and clinical studies which have been made have been summarized to provide a basis for a full-scale investigation of the therapeutic potential of flavonoids.

A review of the genetic effects of naturally occurring flavonoids, anthraquinones and related compounds

Two classes of common phenolic plant pigments, the anthraquinones and the flavonols, contain many members mutagenic in the Salmonella/mammalian microsome assay. Several reports on the mutagenicity or other genetic or "carcinogenic" effects of these compounds have appeared in the literature or have been presented at various scientific meetings. The object of this review paper is to assess the present state of knowledge with respect to the genetic toxicity of these agents and their dietary intake and metabolic fate in man. Such information is necessary for formulating an assessment of genetic or carcinogenic risk to man posed by these agents.