Content of phenolic acids and ferulic acid dehydrodimers in 17 rye (Secale cereale L.) varieties

The contents of pnenolic acids and ferulic acid dehydrodimers were quantified by HPLC analysis after alkaline hydrolysis in kernels of 17 rye (Secale cereale L.) varieties grown in one location in Denmark during 1997 and 1998. Significant variations (P < 0.05) with regard to the concentration of the analyzed components were observed among the different rye varieties and also between different harvest years. However, the content of phenolic acids in the analyzed rye varieties was narrow compared to cereals such as wheat and barley. The concentration of ferulic acid, the most abundant phenolic acid ranged from 900 to 1170 microgram g(-1) dry matter. The content in sinapic acid ranged from 70 to 140 microgram g(-1) dry matter, p-coumaric acid ranged from 40 to 70 microgram g(-1) dry matter, and caffeic, p-hydroxybenzoic, protocatechuic, and vanillic acids were all detected in concentrations less than 20 microgram g(-1) dry matter. The most abundant ferulic acid dehydrodimer 8-O-4 -DiFA was quantified in concentrations from 130 to 200 microgram g(-1) dry matter followed by 8,5 -DiFA benzofuran form (50-100 microgram g(-1) dry matter), 5,5 -DiFA (40-70 microgram g(-1) dry matter), and 8,5 -DiFA (20-40 microgram g(-1) dry matter).     

Structural identification of dehydrotriferulic and dehydrotetraferulic acids isolated from insoluble maize bran fiber

Two new dehydrotriferulic acids and two dehydrotetraferulic acids were isolated from saponified maize bran insoluble fiber using size exclusion chromatography on Bio-Beads S-X3 followed by Sephadex LH-20 chromatography and semipreparative phenyl-hexyl reversed phase high-performance liquid chromatography. On the basis of UV spectroscopy, mass spectrometry, and one- and two-dimensional NMR experiments, the structures were identified as 8-5(noncyclic)/5-5-dehydrotriferulic acid, 8-8(tetrahydrofuran)/5-5-dehydrotriferulic acid, and 4-O-8/5-5/8-O-4-dehydrotetraferulic acid. The second tetramer was tentatively identified as 4-O-8/5-5/8-5(noncyclic)-dehydrotetraferulic acid. Compounds containing an 8-5(noncyclic)-coupled dimeric unit probably do not exist in planta but are formed from their phenylcoumaran precursors containing an 8-5(cyclic)-coupled dimeric unit during saponification. The presented dehydrotrimers are the first dehydrotriferulates that do not contain an 8-O-4-coupled dimeric unit. The ferulate dehydrotetramers that are reported for the first time are presumed, like the dimers and trimers, to cross-link polysaccharides in the plant. Because both tetramers contain a 5-5/8-O-4-dehydrotriferulate moiety, the predominant dehydrotrimer in maize bran, it is not possible to deduce whether tetramers are formed by coupling of a fourth unit to a preformed dehydrotriferulate or by 5-5-coupling of preformed 8-O-4- and 8-5-dehydrodiferulates. Nevertheless, such compounds document expanded roles for ferulates in cross-linking polysaccharides in plant cell walls.     

Hydroxycinnamic acids and ferulic acid dehydrodimers in barley and processed barley

Hydroxycinnamic acid content and ferulic acid dehydrodimer content were determined in 11 barley varieties after alkaline hydrolysis. Ferulic acid (FA) was the most abundant hydroxycinnamate with concentrations ranging from 359 to 624 microg/g dry weight. p-Coumaric acid (PCA) levels ranged from 79 to 260 microg/g dry weight, and caffeic acid was present at concentrations of <19 microg/g dry weight. Among the ferulic acid dehydrodimers that were identified, 8-O-4'-diFA was the most abundant (73-118 microg/g dry weight), followed by 5,5'-diFA (26-47 microg/g dry weight), the 8,5'-diFA benzofuran form (22-45 microg/g dry weight), and the 8,5'-diFA open form (10-23 microg/g dry weight). Significant variations (p < 0.05) among the different barley varieties were observed for all the compounds that were quantified. Barley grains were mechanically fractionated into three fractions: F1, fraction consisting mainly of the husk and outer layers; F2, intermediate fraction; and F3, fraction consisting mainly of the endosperm. Fraction F1 contained the highest concentration for ferulic acid (from 77.7 to 82.3% of the total amount in barley grain), p-coumaric acid (from 78.0 to 86.3%), and ferulic acid dehydrodimers (from 79.2 to 86.8%). Lower contents were found in fraction F2, whereas fraction F3 exhibited the lowest percentages (from 1.2 to 1.9% for ferulic acid, from 0.9 to 1.7% for p-coumaric acid, and <0.02% for ferulic acid dehydrodimers). The solid barley residue from the brewing process (brewer's spent grain) was approximately 5-fold richer in ferulic acid, p-coumaric acid, and ferulic acid dehydrodimers than barley grains.     

Protective effects of 4-hydroxycinnamic ethyl ester derivatives and related dehydrodimers against oxidation of LDL: radical scavengers or metal chelators?

4-Hydroxycinnamate derivatives are known to be potent protectors against oxidation of low-density lipoproteins (LDL), via a combination of free radical scavenging and transition metal chelation. Through a series of 4-hydroxycinnamic ethyl ester derivatives and related 8-8 dehydrodimers, we have tried to bring out the structural requirements for radical scavenging and cupric ion chelation. We found that the monomeric compounds, except for highly lipophilic tert-butyl derivative 3, exhibited rather low radical scavenging properties. Furthermore, they did not chelate copper but, in contrast, reduced cupric ion to cuprous ion, affording the related 8-8 dehydrodimers, for which they could be considered as precursors in vitro. In the copper-dependent human LDL oxidation in vitro, the cyclic 8-8 dehydrodimer forms behaved essentially as efficient copper chelators, while related noncyclic 8-8 forms, which were found to be the best protectors, mainly acted as radical scavengers.     

Absorption of hydroxycinnamates in humans after high-bran cereal consumption

Hydroxycinnamic acids are a group of phenolic compounds that exhibit a wide range of in vitro chemoprotective and antioxidant properties. Cereals containing a high proportion of the bran layers are rich in ester-linked hydroxycinnamic acids, such as ferulic and diferulic acids. The present work investigated the absorption in humans of hydroxycinnamic acids from high-bran breakfast cereal (wheat). Plasma and urine samples from six volunteers were collected before and after cereal consumption and analyzed for total hydroxycinnamic acids content after beta-glucuronidase/sulfatase treatment both by HPLC-DAD and by LC-MS (SIM monitoring). High-bran cereal administration resulted in increased plasma ferulic and sinapic acid concentrations (maximum levels detected of approximately 200 and approximately 40 nM, respectively) with absorption peaks between 1 and 3 h. Increases of approximately 4-fold in ferulic acid and approximately 5-fold in feruloylglycine were detected in 24-h urine after consumption of the cereal. Most of the ferulic acid detected in urine and plasma was present as conjugates (feruloylglycine and/or glucuronides). Diferulic acids were undetectable. The data show that ferulic and sinapic acids are taken up in humans from dietary high bran wheat but that absorption is limited and may originate only from the free and soluble portions present in the cereal.     

Esterase activity able to hydrolyze dietary antioxidant hydroxycinnamates is distributed along the intestine of mammals.

Hydroxycinnamic acids are effective antioxidants and are abundant components of plant cell walls, especially in cereal bran. For example, wheat and rye brans are rich sources of the hydroxycinnamates ferulic acid, sinapic acid, and p-coumaric acid. These phenolics are part of human and animal diets and may contribute to the beneficial effects derived from consumption of cereal bran. However, these compounds are ester linked to the main polymers in the plant cell wall and cannot be absorbed in this complex form. The present work shows that esterases with activity toward esters of the major dietary hydroxycinnamates are distributed throughout the intestinal tract of mammals. In rats, the cinnamoyl esterase activity in the small intestine is derived mainly from the mucosa, whereas in the large intestine the esterase activity was found predominantly in the luminal microflora. Mucosa cell-free extracts obtained from human duodenum, jejunum, and ileum efficiently hydrolyzed various hydroxycinnamoyl esters, providing the first evidence of human cinnamoyl esterase(s). This study first demonstrates the release by human colonic esterase(s) (mostly of microbial origin) of sinapic acid and p-coumaric acid from rye and wheat brans. Hydrolysis by intestinal esterase(s) is very likely the major route for release of antioxidant hydroxycinnamic acids in vivo.     

Identification of 4-O-5'-coupled diferulic acid from insoluble cereal fiber

The extracts of saponified cereal fibers of whole grains of corn (Zea mays cv. microsperma KOERN.), wheat (Triticum aestivum L.), spelt (Triticum spelta L.), and rice (Oryza sativa L.) were investigated for dehydrodimers of ferulic acid using gas-liquid chromatography (GLC) with mass spectrometric detection (GLC-MS) and flame ionization detection (GLC-FID). In addition to the 8,5'-, 8, 8'-, 5,5'-, and 8-O-4'-coupled diferulic acids previously identified from other plant materials the 4-O-5'-coupled diferulic acid (E)-3-[4-[(E)-2-carboxyvinyl]-2-methoxyphenoxy]-4-hydroxy-5-methoxyci nnamic acid (4-O-5'-DFA) was identified in all fibers investigated. This new diferulate was authenticated by comparison of its mass spectrum and its relative GLC retention time with those of the synthesized compound. Semiquantitative determination of 4-O-5'-DFA showed that it is present at 8-30 microg/g, approximately 70-100 times lower concentrations than the sum of 8,5'-coupled diferulic acids, the major diferulic acids in the investigated fibers.     

Effect of storage on wall-bound phenolics in green asparagus

The cell walls of green asparagus spears have been analyzed for their phenolic and carbohydrate composition as modified by postharvest storage. Esterified phenolic components were released by sequential alkaline hydrolysis and identified and quantified by diode array HPLC. Significant quantities of ferulic acid (FA) and its derivatives were found to increase at least 3-fold during storage, particularly in walls from the lower parts of the stem, where accompanying changes in sugar composition were also observed. In fresh asparagus, >60% of the total FA was in the form of diferulic acid, and this increased to approximately 70% after 3 days of storage. The main FA dehydrodimers were 8-8-, 8-O-4-, and 8-5-diferulates. These have been detected in other monocotyledonous and dicotyledonous plants, but as a smaller proportion of the total FA. The possible roles phenolic esters might have in relation to the mechanical, textural, and wound-response properties of asparagus spears are discussed.     

Isolation and identification of DPPH radical scavenging compounds in Kurosu (Japanese unpolished rice vinegar)

Dihydroferulic acid (DFA) and dihydrosinapic acid (DSA) were isolated from Kurosu (unpolished rice vinegar) as the major constituents responsible for Kurosu's radical scavenging activity. The levels of antioxidative activity of DFA and DSA in DPPH radical scavenging were higher than those of their respective structurally related compounds, ferulic acid and sinapic acid. The concentrations of DFA and DSA were low in common rice vinegar (polished rice vinegar), suggesting that Kurosu is more advantageous than rice vinegars as an antioxidative food item. As the concentrations of DFA and DSA were low in unpolished rice, too, these acids are thought to be produced in Kurosu through the process of the fermentation from ferulic acid and sinapic acid, respectively.     

Biotransformation of sinapic acid catalyzed by Momordica charantia peroxidase

Biotransformation of sinapic acid (1) with H2O2/Momordica charantia peroxidase, which exists in the widely used food M. charantia, at pH 5.0, 43 degrees C, in the presence of acetone resulted in six compounds, including four new compounds. Compound 2 was the first isolation of a new unique sinapic acid tetrameric derivate, which is formed by peroxidase catalysis in vitro. Besides 2, three other new sinapic acid dimers, 3-5 have also been isolated. Their structures were established on the basis of spectroscopic data. Compound 5 showed a stronger antioxidative activity than the parent sinapic acid (1). Compounds 4 and 5 significantly inhibited the growth of HL-60 cell at the concentration of 10-5 microl/L.     

Oxidative Cross-Linking of Pentosans by a Fungal Laccase and Horseradish Peroxidase: Mechanism of Linkage Between Feruloylated Arabinoxylans

The potential of a laccase from the fungus Pycnoporus cinnabarinus to cross-link feruloylated soluble wheat arabinoxylans was investigated using capillary viscometry, size-exclusion HPLC, and reverse-phase HPLC of phenolic compounds. The laccase results were compared with those for a hydrogen peroxide/horseradish peroxidase system. The oxidants provoked an increase in viscosity of a 0.2% (w/v) arabinoxylan solution. A gel was formed after 30 min with laccase. Hydrogen peroxide was consumed rapidly before a gel could be formed. Free ferulic acid, methyl ferulate, and vanillic acid inhibited the gelation, whereas fumaric acid had no effect. This suggests that the aromatic ring, and not the propenoic chain of ferulic acid, was the initiating site for arabinoxylan cross-linking. Ferulic acid and its 8-O-4′, 8-5′, and 5-5′ dehydrodimers were present in nonoxidized arabinoxylans. Upon oxidation, the 8-8′ and 8-5′ benzofuran dehydrodimers appeared and the 8-O-4′ and 8-5′ dimers increased. The production of dimers was proportional to the consumption of ester-bound ferulic acid. In cross-linked arabinoxylans, the major dimers were 8-5′ benzofuran, 8-8′, and 8-O-4′, whereas the 5-5′ dehydrodimer remained at the same level as in the nonoxidized solution.     

Normal phase high-performance liquid chromatography method for the determination of tocopherols and tocotrienols in cereals

The eight vitamers of vitamin E (alpha-, beta-, gamma-, and delta-tocopherols and -tocotrienols) have different antioxidant and biological activities and have different distributions in foods. Some cereals, especially oat, rye, and barley, are good sources of tocotrienols. A fast procedure for the determination of tocopherols and tocotrienols (tocols) in cereal foods was developed. It involves sample saponification and extraction followed by normal phase high-performance liquid chromatography (HPLC). The results have been compared with those found by direct extraction without saponification. The method is sensitive and selective enough to be tested on a wide variety of cereal samples. The highest tocol levels were found in soft wheat and barley ( approximately 75 mg/kg of dry weight). beta-Tocotrienol is the main vitamer found in hulled and dehulled wheats (from 33 to 43 mg/kg of dry weight), gamma-tocopherol predominates in maize (45 mg/kg of dry weight) ), and alpha-tocotrienol predominates in oat and barley (56 and 40 mg/kg of dry weight, respectively).     

Simple Phenolic Acids in Flours Prepared from Canadian Wheat: Relationship to Ash Content,Color, and Polyphenol Oxidase Activity

Simple phenolic acid levels were determined on pooled millstreams of five different classes of Canadian wheat milled to ~75, 80, and 85% extraction. Pooled flours and whole grain were analyzed by reversed-phase high-performance liquid chromatography (RP-HPLC) to establish endogenous levels of insoluble bound, soluble esterified, and free phenolic acids. Only ferulic acid was detected in the insoluble bound category, which accounted for >80% of the total phenolic acids present in every flour. The soluble esterified phenolic acids accounted for up to 17% of the overall total phenolic acid content within a flour. The major constituents were sinapic, ferulic, and vanillic acids, with minor amounts of coumaric, caffeic, and syringic acids. Free phenolic acids accounted for a maximum of 6% of the total phenolic content of any prepared flour. Ferulic acid was the major free phenolic acid, while sinapic acid was not detected in any flour. Significant correlations (r = 0.64–0.97, P < 0.05) were observed between insoluble bound ferulic acid, individual soluble esterified acids, and most free acids with polyphenol oxidase activity, as well as color and ash content for each class.     

4-hydroxycinnamic ethyl ester derivatives and related dehydrodimers: Relationship between oxidation potential and protective effects against oxidation of low-density lipoproteins

The electrochemical oxidation potential of a series of monomeric and dimeric 4-hydroxycinnamic ethyl ester derivatives has been compared with their antioxidant activity toward copper-catalyzed human low-density lipoproteins (LDL) oxidation. Within the series of monomeric hydroxycinnamate derivatives, both oxidation potential and IC50 values decreased in the following order: sinapate > ferulate > p-coumarate. Among the 4-hydroxycinnamate dehydrodimer derivatives, noncyclized 8-8 diphenol dehydrodimers followed the same aforementioned sequence order and were found to be better antioxidants than their monomer counterparts. A good correlation between the inhibitory concentration and the oxidation potential was established among all these derivatives. However, a significantly deviating behavior was observed with the 8-5 dihydrobenzofuran and the 8-8 dihydronaphthol cyclic dehydrodimers, which showed lower activities toward copper-catalyzed human LDL, although their oxidation potentials remained very close to those of the noncyclized 8-8 dehydrodimers. Conversely, in the Trolox equivalent antioxidant capacity (TEAC) assay system, the 8-8 dihydronaphthol dehydrodimers were found to be the most efficient free-radical scavengers. Finally, in the series of dehydrodimers studied, it could be concluded that, whatever the in vitro test system used, (a) all dehydrodimer derivatives tested could contribute efficiently to the overall intake of antioxidants in the diet and (b) a low oxidation potential value was in favor of a satisfactory antioxidant activity.     

Regioselective dimerization of ferulic acid in a micellar solution.

Dehydrodimers of hydroxycinnamates play an important role in the cross-linking of plant cell walls. An aqueous solution of quaternary ammonium salts with a long aliphatic chain is known to spontaneously organize itself into micelles with the ionic part at the outer sphere. It is shown that regioisomeric ferulic acid dehydrodimers can be obtained in one step from trans-ferulic acid after attachment to these micelles and using the biomimetic peroxidase-H2O2 system. The surfactant hexadecyltrimethylammonium hydroxide yielded trans-4-(4-hydroxy-3-methoxybenzylidene)-2-(4-hydroxy-3-methoxyphenyl)-5-oxotetrahydrofuran-3-carboxylic acid (25%), (E,E)-4,4'-dihydroxy-5,5'-dimethoxy-3,3'-bicinnamic acid (21%), and trans-5-[(E)-2-carboxyvinyl]-2-(4-hydroxy-3-methoxyphenyl)-7-methoxy-2,3-dihydrobenzofuran-3-carboxylic acid (14%), whereas the surfactant tetradecyltrimethylammonium bromide gave 4-cis, 8-cis-bis(4-hydroxy-3-methoxyphenyl)-3,7-dioxabicyclo[3.3.0]octane-2,6-dione (18%) as the main product. The use of micelles appears to be not only a new way to synthesize regioisomeric ferulic acid dehydrodimers but may also help to understand the regiospecificity of dimeric hydroxycinnamate formation in vivo.     

Comparative Studies on Composition and Distribution of Phenolic Acids in Cereal Grain Botanical Fractions

The phenolic acid composition and concentration of four manually separated fractions (pericarp, aleurone layer, germ, and endosperm fractions) as well as whole grains of yellow corn, wheat, barley, and oats were analyzed by HPLC‐MS/MS following microwave‐assisted alkaline aqueous extraction. Phenolic acid compositions in whole grains and their fractions were similar, with minor differences among the grain fractions. Significant differences (P < 0.05), however, were observed in phenolic acid concentrations among cereal types, within cereal varieties, and among grain fractions, with yellow corn exhibiting the highest values. The concentrations of p‐coumaric and syringic acid in the pericarp were 10‐ to 15‐fold and 6‐ to 10‐fold higher, respectively, in yellow corn than in wheat, barley, and oats. In the aleurone layer, sinapic and vanillic acids in yellow corn were about 8‐ and 30‐fold more than in wheat. The germ fraction of wheat had 1.8 times more syringic acid than yellow corn germ. Grain fractions, excluding endosperm, had enhanced levels of phenolic acids compared with whole grain. Sinapic acid was more concentrated in the pericarp and germ of wheat, whereas isoferulic acid was concentrated in the germ of purple barley. Syringic and vanillic acids were concentrated in the pericarp and sinapic acid in the aleurone layer of yellow corn. These findings are important in understanding the composition and distribution of phenolic acids, and they act as a guide in identification of grain fractions for use as food ingredients. In addition, yellow corn fractions (aleurone and pericarp) may be potential alternative phenolic‐rich functional food ingredients in grain‐based food products.     

Peroxynitrite scavenging activity of sinapic acid (3,5-dimethoxy-4-hydroxycinnamic acid) isolated from Brassica juncea

Peroxynitrite (ONOO(-)), formed from a reaction of superoxide and nitric oxide, is one of the most potent cytotoxic species that are known to oxidize cellular constituents including essential proteins, lipids, and DNA. In this study, the ability of sinapic acid (3,5-dimethoxy-4-hydroxycinnamic acid), isolated from Brassica juncea, to scavenge ONOO(-) was investigated. The data obtained show that sinapic acid can efficiently scavenge native ONOO(-) as well as ONOO(-) derived from the peroxynitrite donor 3-morpholinosydnonimine hydrochloride (SIN-1). Spectrophotometric analyses revealed that sinapic acid suppressed the formation of ONOO(-)-mediated tyrosine nitration through an electron donation mechanism. In further studies, sinapic acid also showed a significant ability of inhibiting nitration of bovine serum albumin and low-density lipoprotein (LDL) in a dose-dependent manner. Sinapic acid decreased the LDL peroxidation induced by SIN-1-derived ONOO(-). The present study suggests that sinapic acid has an efficient ONOO(-) scavenging ability, which may well be a potent ONOO(-) oxidant scavenger for the protection of the cellular defense activity against the ONOO(-)-involved diseases.     

Near-infrared analysis of soluble and insoluble dietary fiber fractions of cereal food products

The use of near-infrared (NIR) reflectance spectroscopy for the rapid and accurate measurement of soluble and insoluble dietary fiber was explored in a diverse group of cereal products. Ground samples were analyzed for soluble and insoluble dietary fiber (AOAC Method 991.43) and scanned (NIRSystems 6500 monochromator) to obtain NIR spectra. Modified PLS models were developed to predict insoluble and soluble dietary fiber using data sets expanded to include products with high fat and high sugar contents. The models predicted insoluble dietary fiber accurately with an SECV of 1.54% and an R(2) of 0.98 (AOAC determined range of 0-48.77%) and soluble dietary fiber less accurately with an SECV of 1.15% and an R(2) of 0.82 (AOAC determined range of 0-13.84%). Prediction of independent validation samples by the soluble fiber model resulted in a bias that may be related to the way the reference method treats samples with different soluble fiber constituents. The insoluble fiber model can be used to rapidly monitor insoluble dietary fiber in cereal products for nutrition labeling.     

Wheat gluten phenolic acids: occurrence and fate upon mixing

Ferulic acid (FA, 4.9-17.7 microg/100 mg), sinapic acid (SA, 1.4-3.5 microg/100 mg), and traces of p-coumaric acid and vanillic acid were detected after saponification of six wheat glutens from industrial and pilot-scale origins. FA and SA occurred mostly as soluble-bound and insoluble-bound forms according to their extractability by acetone/methanol/water (7:7:6, v/v/v). The major part of FA (50-95%) was found in the unextractable fraction, whereas SA was mostly extractable (64-85%). The carbohydrate contents of the glutens were determined also after acid hydrolysis. The highest levels of glucose, arabinoxylan, and FA were obtained from the unextractable fractions of the pilot-scale extracted glutens, probably in relation with a lower efficiency of washing during extraction compared to industrial processes. On the other hand, SA compounds were in similar concentrations in all samples, suggesting their involvement in specific interactions during gluten protein agglomeration. Saponification of the soluble-bound phenolic acids released mainly glucose, whereas a beta-glucosidase treatment had no effect. FA and SA extractability, especially that of soluble-bound ones, decreased strongly in overmixed gluten/water doughs. These low molecular weight conjugates of phenolic acids could be involved in the dough breakdown phenomenon.     

Contents of phenolic acids, alkyl- and alkenylresorcinols, and avenanthramides in commercial grain products

The contents of free and total phenolic acids and alk(en)ylresorcinols were analyzed in commercial products of eight grains: oat (Avena sativa), wheat (Triticum spp.), rye (Secale cerale), barley (Hordeum vulgare), buckwheat (Fagopyrum esculentum), millet (Panicum miliaceum), rice (Oryza sativa), and corn (Zea mays). Avenanthramides were determined in three oat products. Free phenolic acids, alk(en)ylresorcinols, and avenanthramides were extracted with methanolic acetic acid, 100% methanol, and 80% methanol, respectively, and quantified by HPLC. The contents of total phenolic acids were quantified by HPLC analysis after alkaline and acid hydrolyses. The highest contents of total phenolic acids were in brans of wheat (4527 mg/kg) and rye (4190 mg/kg) and in whole-grain flours of these grains (1342 and 1366 mg/kg, respectively). In other products, the contents varied from 111 mg/kg (white wheat bread) to 765 mg/kg (whole-grain rye bread). Common phenolic acids found in the grain products were ferulic acid (most abundant), ferulic acid dehydrodimers, sinapic acid, and p-coumaric acid. The grain products were found to contain either none or only low amounts of free phenolic acids. The content of avenanthramides in oat flakes (26-27 mg/kg) was about double that found in oat bran (13 mg/kg). The highest contents of alk(en)ylresorcinols were observed in brans of rye (4108 mg/kg) and wheat (3225 mg/kg). In addition, whole-grain rye products (rye bread, rye flour, and whole-wheat flour) contained considerable levels of alk(en)ylresorcinols (524, 927, and 759 mg/kg, respectively).