Alkylresorcinol Content Research Articles

Alkylresorcinols in cereals and cereal products.

The alkylresorcinol (AR) content of 8 commonly consumed cereals, 125 Triticum cultivars, milling fractions of wheat and rye, bread, and other cereal products was analyzed. ARs were found in wheat (489-1429 microgram/g), rye (720-761 microgram/g), triticale (439-647 microgram/g), and barley (42-51 microgram/g), but not in rice, oats, maize, sorghum, or millet. One durum wheat variety was found to have an exceptionally low level of ARs (54 microgram/g) compared to other durum wheat varieties (589-751 microgram/g) and Triticumspecies analyzed. The AR content of milling fractions closely followed the ash content and could be used as a marker of the presence of bran in flour. Using hot 1-propanol extraction, all ARs could be extracted from bread, contrary to previous studies which suggested that ARs were destroyed during baking. Cereal products varied greatly in AR content, with those containing wheat bran or whole rye having the highest content.

Encystment and alkylresorcinol production by Azotobacter vinelandii strains impaired in poly-beta-hydroxybutyrate synthesis.

The lipids poly-beta-hydroxybutyrate (PHB) and alkylresorcinols are the major metabolic products of Azotobacter vinelandii cysts. Cysts are formed in less than 0.01% of late stationary phase cells grown on sucrose. Culturing vegetative cells in n-butanol or beta-hydroxybutyrate induces encystment. After induction of encystment, PHB rapidly accumulates in large granules. Then, the cells begin the synthesis of alkylresorcinols that replace the phospholipids in the membranes and are components of the exine, the outer layer of the cyst envelope. Vegetative cells do not synthesize alkylresorcinols. We report here the effect of mutations in the phbBAC operon, coding for the enzymes of the PHB biosynthetic pathway, on the synthesis of alkylresorcinols and cyst formation. The phb mutations did not impair the capacity to form mature cysts. However, the cysts formed by these strains posses a thicker exine layer and a higher content of alkylresorcinols than the cysts formed by the wild-type strain. A blockage of PHB synthesis caused by phb mutations resulted in the synthesis of alkylresorcinols and encystment even under non-inducing conditions. We propose that, as a consequence of the blockage in the PHB biosynthetic pathway, the acetyl-CoA and reducing power pools are increased causing the shift to lipid metabolism required for the synthesis of alkylresorcinols and cyst formation.

Gas chromatographic analysis of alkylresorcinols in rye (Secale cereale L) grains

AbstractA method was established for fast and easy analysis of 5‐n‐alkylresorcinols in rye grains, considering effects of milling (intact grains versus flour), extraction solvent (ethyl acetate, methanol and acetone), extraction volume per gram of sample (20 and 40 ml) and extraction time (3, 6, 18 and 24 h). For intact kernels, extraction of 1 g samples with ethyl acetate (40 ml, 24 h) is recommended. The ease of extraction is consistent with the presence of alkylresorcinols in the outer layers of the kernel and their absence in the endosperm. The extracts were analysed (without further purification or derivatisation) by gas chromatography using methyl behenate (C22:0, fatty acid methyl ester) as internal standard. Alkylresorcinols were identified by gas chromatography/mass spectrometry, and the major homologues were found to contain alkyl chains of C17:0, C19:0, C21:0, C23:0 and C25:0. The methodology was then applied to analyse the alkylresorcinol content in 15 rye cultivars grown at two locations in Sweden. Total alkylresorcinol contents varied within the range 549–1022 µg g−1, and the average percentages of the different alkylresorcinols were: 17:0, 23%; 19:0, 32%; 21:0, 26%; 23:0, 11%; and 25:0, 8%.© 2001 Society of Chemical Industry

Identification of chemical components of corn kernel pericarp wax associated with resistance to Aspergillus flavus infection and aflatoxin production.

Kernel pericarp wax of the corn breeding population GT-MAS:gk has been associated with resistance to Aspergillus flavus infection and aflatoxin production. GT-MAS:gk wax, previously compared to waxes of three susceptible genotypes, was presently compared to wax of a different, and more numerous, group of susceptible lines. Wax separation by TLC confirmed previous findings, demonstrating a unique GT-MAS:gk band and a unique "susceptible" band. Only GT-MAS:gk wax inhibited the growth of A. flavus; however, no association was established, as before, between kernel wax abundance and resistance. Gas chromatography-mass spectroscopy (GC-MS) analysis of kernel whole wax showed a higher percentage of phenol-like compounds in wax from GT-MAS:gk than in waxes from the susceptible lines. The GT-MAS:gk unique band contained phenol-like compounds and ethyl-hexadecanoate; butyl-hexadecanoate was preeminent in most of the "susceptible bands". Alkylresorcinol (phenolic compounds) content was dramatically higher in GT-MAS:gk wax than in the wax of susceptible lines. An alkylresorcinol, 5-methylresorcinol, also inhibited in vitro growth of A. flavus. These and other phenolic compounds may contribute to kernel wax inhibition of A. flavus infection/aflatoxin production. Further investigation is needed to confirm a role for them in GT-MAS:gk resistance.

Properties of mixed monolayers and bilayers of long-chain 5- n-alkylresorcinols and dipalmitoylphosphatidylcholine

5- n-Alkylresorcinols with different chain length are known to occur in different plants and procaryonts, for example in the cysts of the Azotobacter genus. To study the monolayer and bilayer behaviour of these amphiphilic compounds, we synthesized three analogues with different chain length, namely 5- n-octadecylresorcinol (18AR), 5- n-nonadecylresorcinol (19AR) and 5- n-heneicosylresorcinol (21AR). The pure alkylresorcinols form stable monolayers, 18AR and 19AR, show a phase transition from a liquid-condensed to a liquid-expanded state at temperatures between 20 and 40°C and at lateral pressures below 15 dyn/cm. In mixtures with dipalmitoylphosphatidylcholine (DPPC), monolayer isobars at higher lateral pressures (20–30 dyn/cm) show an increase in the transition temperature to values greater than 50°C for the liquid-condensed to liquid-expanded state of DPPC when the alkylresorcinol content is increased. Particularly in the liquid-expanded state, alkylresorcinols show a strong condensing effect on DPPC monolayers. 18AR/DPPC monolayers at a pressure of 5 dyn/cm show indications of an azeotropic behaviour. A similar increase in transition temperature is observed by differential scanning calorimetry (DSC) and differential scanning densitometry (DSD) in DPPC/alkylresorcinol bilayers. The transition enthalpy decreases with increasing alkylresorcinol content. All alkylresorcinols seem to be completely miscible with DPPC up to at least 50 mol%. The DSD data indicate a slight condensing effect of the alkylresorcinols on the liquid-crystalline phase of DPPC.

The effect of hydrothermic treatment on the physicochemical properties of rye grain

It is generally accepted that the hydrothermic treatment of cereal grain improve the nutritional value of foodstuffs. In this report, the changes induced in the processed rye grain by alkyl-resorcinols and pentosans as well as by modifications of starch and protein complexes are characterized. Also demonstrated are a minor effect of boiling and autoclaving the grain with respect to the alkylresorcinols content, a high increase of the soluble carbohydrates and a decrease of soluble pentosan contents. The incorporation of the pentosan fraction into the starch/pentosan and/or protein/starch/pentosan complexes of limited dispersibility and high molecular weights is reported, as well as the protective role of swelled starch during the process of thermic denaturation of proteins.

Analysis of alkyl‐ and alkenylresorcinols in triticale, wheat and rye

AbstractAlkyl‐ and alkenylresorcinols were extracted with acetone from whole kernels of wheat, rye and various triticales. The resorcinols were ethylated, analysed by GC on a capillary column and further identified by GC‐MS. Alkylresorcinols with chain lengths of C15, C17, C19, C21, C23 and C25 and pairs of isomeric C17, C19, C21, C23 and C25 alkenylresorcinols were quantified in all samples. The content of alk(en)ylresorcinols was highest in rye, intermediate in triticale and lowest in wheat. The relative composition of the resorcinols differed between grains, with a higher content of the C19 alkylresorcinol in rye and of the C21 alkylresorcinol in wheat.Wheat and three lines of triticale were harvested at three stages of maturity after the grain filling period was ended (water content ∼40,30 and 20%). During this period of time the gross chemical composition, water extract viscosity, and content and relative composition of the alk(en)ylresorcinols, were relatively constant.

Selfcompatibility in microspore-derived doubled-haploid rye lines and single grain selection for alkylresorcinol content

From a total of 138 green androgenetic rye lines, 25 were fertilized and examined in field tests: 7 were heterozygous and 18 were homozygous. Of the homozygotes, 4 turned out to be selfincompatible, while 14 set seed after selfing. Four characters were analyzed in detail: 100 kernel weight, plant height, ear length, and alkylresorcinol content. Here we present the first approach in prescreening selfcompatible androgenetic doubled-haploid rye plants with the single grain procedure. The usefulness of this method was confirmed by quantitative resorcinol determination in the following generation. Furthermore, it was demonstrated that all the homologues of the alkylresorcinol were equally reduced. For all characters the means of the different anther derived lines exceeded the means of the controls in both directions, to the positive as well as to the negative side. The incorporation of such a haploid breeding step into breeding programs is discussed.

Content of 5-alkyl resorcinols in selection lines of triticale grown in South Australia

Nine advanced lines of triticale were grown at seven sites in South Australia. The alkyl resorcinol content of samples from each site was negatively correlated (r = - 0.62) with yield at that site, indicating an environmental influence on resorcinol content. A small, but significant, correlation between resorcinol content and neutral detergent fibre was found. Eight of the nine lines had mean resorcinol contents significantly higher than wheat grown at the same sites. One line, T507, was not significantly different from Warimba wheat, and also resembled that of wheat in its uniformity of resorcinol content across the range of environments.

VARIABILITY IN THE ALKYLRESORCINOL CONTENT OF RYE GRAIN

A rapid fluorometric technique was used to analyze the alkylresorcinol content in the seed of 397 spring and winter rye (Secale cereale L.) cultivars. The alkylresorcinol content ranged from a low of 0.036% to a high of 0.322%, the greater variability being in the spring cultivars. A number of the spring cultivars were planted and self-pollinated through four generations. Each cultivar progeny was selected for high and low alkylresorcinol content in the seed, high self-fertility, and superior seed characteristics. It was apparent that selection was effective in increasing and decreasing alkylresorcinol content with each successive self-pollinated generation.