Inhibitory effect of natural phenolic lipids upon NAD-dependent dehydrogenases and on triglyceride accumulation in 3T3-L1 cells in culture

A comprehensive review of wheat phytochemicals: From farm to fork and beyond

The health benefits of whole wheat consumption can be partially attributed to wheat's phytochemicals, including phenolic acids, flavonoids, alkylresorcinols, carotenoids, phytosterols, tocopherols, and tocotrienols. It is of increasing interest to produce whole wheat products that are rich in bioactive phytochemicals. This review provides the fundamentals of the chemistry, extraction, and occurrence of wheat phytochemicals and includes critical discussion of several long-lasting issues: (1) the commonly used nomenclature on distribution of wheat phenolic acids, namely, soluble-free, soluble-conjugated, and insoluble-bound phenolic acids; (2) different extraction protocols for wheat phytochemicals; and (3) the chemistry and application of in vitro antioxidant assays. This review further discusses recent advances on the effects of genotypes, environments, field management, and processing techniques including ultrafine grinding, germination, fermentation, enzymatic treatments, thermal treatments, and food processing. These results need to be interpreted with care due to varied sample preparation protocols and limitations of in vitro assays. The bioaccessibility, bioavailability, metabolism, and potential health benefits of wheat phytochemicals are also reviewed. This comprehensive and critical review will benefit scientific researchers in the field of bioactive compounds of cereal grains and also those in the cereal food industry to produce high-quality functional foods.

An Overview of Alkylresorcinols Biological Properties and Effects

The investigation of alkylresorcinols has drawn an increasing interest recently. Alkylresorcinols (ARs) are natural chemical compounds synthesized by bacteria, fungi, sponges, and higher plants, possessing a lipophilic polyphenol structures and a myriad of biological properties. Human takes ARs as a component of a whole grain diet (from whole grain rye, wheat, and barley products), and thus, alkylresorcinols are frequently used as whole grain intake markers. Besides, ARs are considered as promising bioregulators of metabolic and immune processes, as well as adjuvant therapeutic agents for antimicrobial and anticancer treatment. In this review, we attempted to systematize the accumulated information concerning ARs origin, metabolism, biological properties, and their effect on human health.

Bioavailability and Bioactivity of Alkylresorcinols from Different Cereal Products

Cereal products are the most important dietary source for energy intake and several bioactive compounds with high concentrations in the bran and the germ. Different cereal products provide a rich source of bioactive phytochemicals, namely, phenolic acids, carotenoids, tocopherols, alkylresorcinols, benzoxazines, phytosterols, and lignans. The bioactive substance alkylresorcinols (ARs) present in the whole cereal can inhibit enzyme activity, prevent bacterial or fungal infection, reduce cholesterol absorption, prevent cancer, and resist oxidation. In this paper, we discussed the biological activity of ARs in whole cereal products. Understanding the effects of processing on cereal phytochemicals will help us to develop improved processes for processing cereal foods with higher retention rates of bioactive compounds.

Phytochemicals in whole grain wheat and their health-promoting effects

Accumulated evidence in epidemiological studies has consistently shown that consumption of whole grains (WGs) is inversely associated with risk of major chronic diseases such as certain types of cancer, type 2 diabetes, and cardiovascular diseases. Dietary fiber (DF) has been reported to be responsible for the health effects of WG consumption. Evidence from in vitro and in vivo studies is emerging that, in addition to DF and minerals, the unique phytochemicals in WGs may in part contribute to these health-promoting effects. WGs are rich sources of various phytochemicals. However, phytochemical contents and profiles in WG wheat are not systematically summarized yet, and the rapid rate of discovery of wheat phytochemicals necessitates an update on the current state of this field. Furthermore, the biological roles of phytochemicals in protective effects of WGs are also relatively underestimated compared to DFs. This manuscript summarized current research literature regarding phytochemicals that have been identified and characterized from wheat grains and wheat bran, and their corresponding contributions to the major health benefits of WG wheat consumption.

Alkylresorcinols activate SIRT1 and delay ageing in Drosophila melanogaster

Sirtuins are enzymes that catalyze NAD+ dependent protein deacetylation. The natural polyphenolic compound resveratrol received renewed interest when recent findings implicated resveratrol as a potent SIRT1 activator capable of mimicking the effects of calorie restriction. However, resveratrol directly interacts with fluorophore-containing peptide substrates. It was demonstrated that the SIRT1 activation of resveratrol is affected by the amino acid composition of the substrate. Resveratrol did increase the enzyme activity in cases in which hydrophobic amino acids are at the +1 position to the acetylated lysine in the substrate. Alkylresorcinols (ARs) are compounds that belong to the family of phenolic lipids, and they are found in numerous biological species. Here we show that the natural activators ARs increased the V_max of recombinant SIRT1 for NAD+ and peptide substrate, and that ARs decreased acetylated histone in human monocyte cells by stimulating SIRT1-dependent deacetylation of substrates. ARs also extended the lifespan of Drosophila melanogaster, which was shown to be dependent on functional Sir2. Our results demonstrated that ARs are natural catalytic activators for sirtuin.

Antibacterial coating on in-line suction respiratory catheter to inhibit the bacterial biofilm formation using renewable cardanyl methacrylate copolymer

Health-care materials associated with infections are very common in hospital admitted patients. There are generally infected by contact with the catheter or other multipurpose devices which are contacted with microbes. The respiratory infections associated with the pathogens having strong biofilm forming ability on catheter surface, causes life-threatening in every year. Therefore, a catheter coating material is of great interest which inhibits the biofilm formation of pathogens on a catheter to prevent respiratory infections. In this study, we synthesized cardanol containing copolymers as antimicrobial healthcare material via radical polymerization of cardanyl methacrylate (CMA) with styrene (St) monomer in presence of free radical initiator. The rate of polymerization was drastically reduced with the increase of feeding CMA monomer in copolymer. The thermal and mechanical properties were found to increase with incorporation of cardanol moiety in brittle and hard polystyrene. This soft copolymer was grafted onto polyvinyl chloride respiratory catheter which showed high antibacterial activity, inhibit the biofilm formation and also prevent bacterial adhesion. Therefore, the developed coating material on respiratory catheter surface is effective way to control the respiratory catheter-associated nosocomial infections.

A high-throughput method for liquid chromatography-tandem mass spectrometry determination of plasma alkylresorcinols, biomarkers of whole grain wheat and rye intake

Plasma alkylresorcinols are increasingly analyzed in cohort studies to improve estimates of whole grain intake and their relationship with disease incidence. Current methods require large volumes of solvent (>10 ml/sample) and have relatively low daily sample throughput. We tested five different supported extraction methods for extracting alkylresorcinols from plasma and improved a normal-phase liquid chromatography coupled to a tandem mass spectrometer method to reduce sample analysis time. The method was validated and compared with gas chromatography-mass spectrometry analysis. Sample preparation with HybridSPE supported extraction was most effective for alkylresorcinol extraction, with recoveries of 77-82% from 100 μl of plasma. The use of 96-well plates allowed extraction of 160 samples per day. Using a 5-cm NH2 column and heptane reduced run times to 3 min. The new method had a limit of detection and limit of quantification equivalent to 1.1-1.8 nmol/L and 3.5-6.1 nmol/L plasma, respectively, for the different alkylresorcinol homologues. Accuracy was 93-105%, and intra- and inter-batch precision values were 4-18% across different plasma concentrations. This method makes it possible to quantify plasma alkylresorcinols in 100 μl of plasma at a rate of at least 160 samples per day without the need for large volumes of organic solvents.

Wheat alkylresorcinols suppress high-fat, high-sucrose diet-induced obesity and glucose intolerance by increasing insulin sensitivity and cholesterol excretion in male mice

BACKGROUND

Epidemiologic studies have shown that the consumption of whole grains can reduce the risk of type 2 diabetes mellitus, cardiovascular disease, and all-cause mortality. However, the underlying mechanisms remain a matter of debate.

OBJECTIVE

We aimed to determine the effects of wheat bran-derived alkylresorcinols on diet-induced metabolic disorders in mice.

METHODS

We fed C57BL/6J mice a normal refined diet or a high-fat, high-sucrose diet [29.1% fat, 20.7% protein, 34.0% carbohydrates containing 20.0% sucrose (w/w)] alone (FS) or containing 0.4% (wt:wt) alkylresorcinols (FS-AR) for 10 wk.

RESULTS

The alkylresorcinols suppressed FS-induced increases in body weight by 31.0% as well as FS-induced hepatic triglyceride accumulation (means ± SEMs: 29.6 ± 3.18 and 19.8 ± 2.42 mg/g tissue in the FS and FS-AR groups, respectively), without affecting energy intake. We measured circadian changes in blood metabolic hormones and found that FS-induced hyperinsulinemia (5.1 and 2.1 μg/L at night in the FS and FS-AR groups, respectively) and hyperleptinemia (21.6 and 10.8 μg/L at night in the FS and FS-AR groups, respectively) were suppressed by alkylresorcinols. Glucose and insulin tolerance tests showed that alkylresorcinols significantly reduced fasting blood glucose concentrations (190 ± 3.62 and 160 ± 8.98 mg/dL in the FS and FS-AR groups, respectively) and suppressed glucose intolerance as well as insulin resistance induced by the FS diet. Furthermore, alkylresorcinols significantly increased insulin-stimulated hepatic serine/threonine protein kinase B phosphorylation compared to the FS diet (+81.3% and +57.4% for Ser473 and Thr308, respectively). On the other hand, pyruvate and starch tolerance tests suggested that alkylresorcinols did not affect gluconeogenesis and carbohydrate digestion, respectively. Alkylresorcinols significantly increased fecal cholesterol excretion by 39.6% and reduced blood cholesterol concentrations by 30.4%, while upregulating the expression of hepatic cholesterol synthetic genes such as sterol regulatory element binding protein 2 (Srebf2) and 3-hydroxy-3-methylglutaryl-Coenzyme A synthase 1 (Hmgcs1).

CONCLUSIONS

These findings suggest that wheat alkylresorcinols increase glucose tolerance and insulin sensitivity by suppressing hepatic lipid accumulation and intestinal cholesterol absorption, which subsequently suppresses diet-induced obesity in mice.

Increasing whole grain intake as part of prevention and treatment of nonalcoholic Fatty liver disease

In conjunction with the rise in rates of obesity, there has been an increase in the rate of nonalcoholic fatty liver disease (NAFLD). While NAFLD at least partially originates from poor diet, there is a lack of nutritional recommendations for patients with suspected or confirmed diagnosis of NAFLD, beyond eating a healthy diet, increasing physical activity, and emphasising weight loss. The limited current literature suggests that there may be opportunities to provide more tailored dietary advice for people diagnosed with or at risk of NAFLD. Epidemiological studies consistently find associations between whole grain intake and a reduced risk of obesity and related diseases, yet no work has been done on the potential of whole grains to prevent and/or be a part of the treatment for fatty liver diseases. In this review, we examine the potential and the current evidence for whole grains having an impact on NAFLD. Due to their nutrient and phytochemical composition, switching from consuming mainly refined grains to whole grains should be considered as part of the nutritional guidelines for patients diagnosed with or at risk for fatty liver disease.

Analysis of alkylresorcinols in cereal grains and products using ultrahigh-pressure liquid chromatography with fluorescence, ultraviolet, and CoulArray electrochemical detection

Alkylresorcinols are phenolic lipids, with homologues ranging from C17 to C25, found in high concentrations in whole grain wheat and rye, lower concentrations in barley, and negligible concentrations in refined wheat flour. The analysis of alkylresorcinols is of importance due to their potential as biomarkers of whole grain intake and emerging evidence for some biological effects. Present HPLC methods have insufficient resolution for accurately quantitating the mix of alkyl- and alkenylresorcinols found in rye. An ultrahigh-pressure liquid chromatography method was developed, and three detection methods (CoulArray (CAED), ultraviolet (UV), and fluorescence detection (FD)) were compared for cereal alkylresorcinol analysis. The lower limits of quantitation and detection were 50 and 20 pg injected, 5 pg and 2 pg injected, and 500 and 1250 pg injected for FD, CAED, and UV, respectively. FD and CAED provided similar results, with some bias for higher results with FD (<10% difference). UV detection generally resulted in overestimation of alkylresorcinol concentrations. The method was applied to cereal (15) and cereal product (90) samples mainly from the United States with results in the same range as previous methods. The improved resolution with this method allows facile analysis of alkylresorcinols from cereal products, including minor unsaturated homologues such as those found in rye.

Rye bran alkylresorcinols suppress adipocyte lipolysis and hormone-sensitive lipase activity

The effects of alkylresorcinols (ARs) isolated from rye bran on adipocyte lipolysis, hormone-sensitive lipase activity and phosphorylation and on phosphorylation of protein kinase A substrates were studied. Preincubation with ARs for 18 h suppressed catecholamine-stimulated lipolysis in 3T3-L1 adipocytes. Furthermore, phosphorylation of hormone-sensitive lipase (HSL), a key lipase responsible for stimulated lipolysis, and phosphorylation of protein kinase A substrates, were diminished after preincubation with ARs, whereas HSL protein expression was unaltered. ARs were also shown to inhibit HSL activity in an in vitro assay.

Quantification of alkylresorcinols in human plasma by liquid chromatography/tandem mass spectrometry

Alkylresorcinols (AR) are of interest as biomarkers of wholegrain wheat and rye intake in epidemiological studies and are currently mainly measured by gas chromatography/mass spectrometry (GC/MS) after labour-intensive sample preparation including liquid-liquid extraction, solid-phase extraction (SPE) and chemical derivatization. This manuscript describes and validates an alternative approach based on normal-phase liquid chromatography/tandem mass spectrometry for the quantification of alkylresorcinols in human plasma. The method requires neither SPE nor chemical derivatization and has a shortened run time compared to GC/MS. Normal- and reversed-phase columns and various mobile phases were evaluated with and without previous SPE of the samples. Normal-phase chromatography allowed separation of AR from the interfering triacylglycerols, diacylglycerols and sterols and enabled detection of AR even without SPE of the samples. The described method has instrumental lower limits of detection in the 25-75 pg range, and lower limits of quantification in the 75-250 pg range. Pooled human plasma and (2)H(4)-nonadecylresorcinol (internal standard) was applied to calibrate the method in the 20-12 000 nM range. The overall method showed intra-batch precision of 8.6% and an averaged accuracy of 100.2%. Applications for diverse human plasma samples are presented and are compared with the results determined by GC/MS. Based on the presented data; this method requiring less sample preparation is suggested for further evaluation as an alternative to GC/MS for analysis of biomarkers of wholegrain wheat and rye intake in epidemiological studies.

Biological activity of phenolic lipids

Phenolic lipids are a very diversified group of compounds derived from mono and dihydroxyphenols, i.e., phenol, catechol, resorcinol, and hydroquinone. Due to their strong amphiphilic character, these compounds can incorporate into erythrocytes and liposomal membranes. In this review, the antioxidant, antigenotoxic, and cytostatic activities of resorcinolic and other phenolic lipids are described. The ability of these compounds to inhibit bacterial, fungal, protozoan and parasite growth seems to depend on their interaction with proteins and/or on their membrane-disturbing properties.

Rapid and sensitive analysis of alkylresorcinols from cereal grains and products using HPLC-Coularray-based electrochemical detection

Alkylresorcinols (AR) present in the bran fraction of wheat, rye, and barley grains are of current interest as biomarkers of wholegrain cereal intake. This paper reports the development of a rapid quantitative HPLC method allowing sensitive analysis of AR in cereals in 14 min using coularray (CA) detection. The LOD was 1 ng injected and the LOQ 2.5 ng injected, whereas the intrarun and inter-run CVs were 0.8 and 6.4%, respectively. Analytical recovery determined by spiking ranged from 98 to 107% for AR homologues C15:0-C25:0. The method was used to analyze 79 flour and cereal products, with results in the same range as previous studies using GC analysis. Analysis of wholegrain white wheat were in the same range as other wheat varieties (420-556 microg/g). Use of the CA detector allowed detection of low concentrations of AR in white wheat flour (13-51 microg/g) that had not been reliably detected using previous methods. This method allows rapid throughput analysis of cereal samples, required for validation studies on the use of AR as biomarkers of wholegrain cereal intake.

An expedient synthesis of 5-n-alkylresorcinols and novel 5-n-alkylresorcinol haptens

The first synthesis of bioactive long alkyl chain 5-n-alkylresorcinols, present in whole grain products, by a novel modification of the Wittig reaction is described. All the main long chain 5-n-alkylresorcinols present in rye and wheat, including C(23) and C(25) analogues and haptens, which have not been previously prepared, were synthesised. Microwave-promoted reactions of a semi-stabilized ylid and alkanals in water gave good yields in both pressurized and open systems. An alternative microwave-promoted synthesis starting from non-stabilized alkyltriphenylphosphonium salts and 3,5-dimethoxybenzaldehyde worked as well. Aqueous media were suitable for the reactions even if the starting materials were not soluble in water. The 5-n-alkylresorcinols are potential biomarkers of whole grain intake, and the new hapten derivatives of 5-n-alkylresorcinols will open the way for the immunochemical detection techniques of alkylresorcinols.

Genome-scale reconstruction of the metabolic network in Staphylococcus aureus N315: an initial draft to the two-dimensional annotation

Background

Several strains of bacteria have sequenced and annotated genomes, which have been used in conjunction with biochemical and physiological data to reconstruct genome-scale metabolic networks. Such reconstruction amounts to a two-dimensional annotation of the genome. These networks have been analyzed with a constraint-based formalism and a variety of biologically meaningful results have emerged. Staphylococcus aureus is a pathogenic bacterium that has evolved resistance to many antibiotics, representing a significant health care concern. We present the first manually curated elementally and charge balanced genome-scale reconstruction and model of S. aureus' metabolic networks and compute some of its properties.

Results

We reconstructed a genome-scale metabolic network of S. aureus strain N315. This reconstruction, termed iSB619, consists of 619 genes that catalyze 640 metabolic reactions. For 91% of the reactions, open reading frames are explicitly linked to proteins and to the reaction. All but three of the metabolic reactions are both charge and elementally balanced. The reaction list is the most complete to date for this pathogen. When the capabilities of the reconstructed network were analyzed in the context of maximal growth, we formed hypotheses regarding growth requirements, the efficiency of growth on different carbon sources, and potential drug targets. These hypotheses can be tested experimentally and the data gathered can be used to improve subsequent versions of the reconstruction.

Conclusion

iSB619 represents comprehensive biochemically and genetically structured information about the metabolism of S. aureus to date. The reconstructed metabolic network can be used to predict cellular phenotypes and thus advance our understanding of a troublesome pathogen.

Dietary alkylresorcinols: absorption, bioactivities, and possible use as biomarkers of whole-grain wheat- and rye-rich foods

The biologic and chemical properties of alkylresorcinols (ARs) have been reviewed previously, but there has been relatively little research or focus on the importance of ARs in food and diet. ARs represent a significant proportion of the phytochemicals present in wheat and rye, in which they normally exist in concentrations between 300 and 1500 microg/g. ARs are concentrated in the bran fraction of these cereals, and are therefore a significant component of food products rich in whole grain wheat and rye but not in products containing only refined cereal flour. In this review, we discuss the presence of ARs in food, methods of analysis, their absorption and role in the diet in light of their in vitro bioactivities, and their possible use as biomarkers of whole-grain wheat and rye intake.

Cereal alkylresorcinols elevate gamma-tocopherol levels in rats and inhibit gamma-tocopherol metabolism in vitro

Alkylresorcinols (AR) are a class of amphiphilic phenolic lipids present in high amounts in wheat and rye bran. They have been reported to be both growth retarding and innocuous when fed to rats, and to have a broad range of bioactivities in vitro, suggested to be related to their ability to bind to proteins and modify membranes. This study was designed to test the effects of AR (purified from rye bran) on growth, tocopherol levels, and cholesterol levels in rats. Rats were fed 1 of 4 different levels of AR for 4 wk: 0 (control), 1, 2, and 4 g/kg diet. AR did not affect final body, liver, or lung weights. The AR diets increased the levels of gamma-tocopherol in liver and lungs (P < 0.05). To investigate whether AR could have increased gamma-tocopherol levels via inhibition of tocopherol-omega-hydroxylase, HepG2 cells were incubated with AR and the metabolism of gamma-tocopherol measured. AR significantly inhibited the conversion of gamma-tocopherol to its water-soluble hydroxychroman metabolite in vitro, indicating that AR may increase gamma-tocopherol levels via inhibition of tocopherol metabolism in vivo. The 4 g AR/kg diet decreased liver cholesterol (P < 0.001), but did not affect plasma lipids. AR were detected in the perirenal adipose tissue samples of rats fed AR, indicating that they can accumulate in the fatty tissues of rats. High levels of dietary AR moderately affect gamma-tocopherol, possibly via inhibition of tocopherol metabolism, and decrease liver cholesterol in rats.