Impact of supercritical CO2 and traditional solvent extraction systems on the extractability of alkylresorcinols, phenolic profile and their antioxidant activity in wheat bran

Dissecting dietary alkylresorcinols: a compile of their distribution, biosynthesis, extraction and functional properties

Alkylresorcinols (ARs) are natural bioactive ingredients produced by: bacteria, fungi, sponges, and higher plants, possessing a lipophilic polyphenol structure with a myriad of biological properties. Focusing on the importance of ARs, several analogs can be extracted from different natural resources. Interestingly, the composition of ARs is usually reflective of their source, with structural differences to exist among ARs isolated from different natural sources. The identified compounds from marine are distinguished by sulfur atom and disulfide bond, while the alkyl chain of bacterial homologs are recognized for their saturated fatty acid chains. ARs occurrence in fungi is still poorly documented however most of the isolated fungal molecules are characterized by a sugar unit attached to their alkylated side chains. The biosynthetic pathway of ARs is postulated via a type III polyketide synthase in which the fatty-acyl chain is elongated and cyclized to generate ARs. The structure-activity relationship (SAR) has gained an increasing interest to mediate for ARs biological activities as discussed herein for the first time from their different resources. ARs extraction procedures showed much progress compared to classical methods compiling organic solvents with supercritical extraction appearing as a potential technique for producing highly purified food-grade of AR homologs. The current review also presents on the rapid qualitative and quantitative determination of ARs to increase accessibility for screening cereals as potential sources of these bioactives.

Antioxidant Properties and Geroprotective Potential of Wheat Bran Extracts with Increased Content of Anthocyanins

In recent years, there has been a focus on breeding wheat with high anthocyanin levels in order to improve food quality and human health. The objective of this study was to examine the antioxidant and geroprotective properties of wheat bran extracts using both in vitro and in vivo research methods. Two wheat lines were used: one with uncolored pericarp (anthocyanin-free) and another with colored pericarp (anthocyanin-containing). These lines differed in a specific region of chromosome 2A containing the Pp3/TaMyc1 gene, which regulates anthocyanin production. High-performance liquid chromatography-mass spectrometry revealed the presence of cyanidin glucoside and cyanidin arabinoside in the anthocyanin-containing wheat bran extract (+AWBE), while no anthocyanins were found in the anthocyanin-free wheat bran extract (-AWBE). The +AWBE showed higher radical scavenging activity (DPPH and ABTS assays) and membrane protective activity (AAPH oxidative hemolysis model) compared to the -AWBE. Both extracts extended the lifespan of female Drosophila, indicating geroprotective properties. This study demonstrates that wheat bran extracts with high anthocyanin levels have antioxidant and geroprotective effects. However, other secondary metabolites in wheat bran can also contribute to its antioxidant and geroprotective potential.

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.

Effect of alkyl chain length on the antioxidant activity of alkylresorcinol homologues in bulk oils and oil-in-water emulsions

The antioxidant cut-off theory details the importance of fine-tuning antioxidant hydrophobicity to optimize antioxidant effectiveness for a given food system; however, previous research has utilized synthetic antioxidant homologues which fail to align with the food industry's demand for natural ingredients. Alkylresorcinols represent a natural homologous series of phenolipid antioxidants. The antioxidant activities of individual alkylresorcinol homologues were investigated in bulk oils and oil-in-water emulsions. In oils, antioxidant activity decreased as alkyl chain length increased and there was no effect on rate of loss. In emulsions, optimum antioxidant activity was observed at intermediate alkyl chain length (C21:0) and longer homologues were lost more rapidly. Radical scavenging capacity decreased as alkyl chain length increased but alkylresorcinols were unable to chelate iron. This suggests that intrinsic properties (e.g. radical scavenging capacity) are responsible for the antioxidant activity of alkylresorcinols in oils while physicochemical phenomena (e.g. partitioning) drive antioxidant activity of alkylresorcinols in emulsions.

Phenolic lipids as unique bioactive compounds: a comprehensive review on their multifunctional activity toward the prevention of Alzheimer's disease

Phenolic lipids are multifunctional compounds which play an important biological role in the body. Their unique biologic functionality stems from their strong amphiphilic character which allows them to be incorporated in erythrocytes. Through membrane incorporation, these compounds exert their biological effects on neurons which are not modulated by hydrophilic compounds. These bioactive compounds are present in nature as secondary plant metabolites, and consequently their availability is limited, for dietary and medical purposes. In this review, the pathways and mechanisms associated with the pathogenesis of Alzheimer's disease will be described. In addition, the modulatory effects of phenolic lipids on these pathways and a list of several synthetic, semi synthetic and natural sources of phenolic lipids will be examined as having the potential to prevent or combat Alzheimer's disease.

Developing emulsion gels by incorporating Jerusalem artichoke inulin and investigating their lipid oxidative stability

Abstract

This study investigated physical, chemical and lipid oxidative properties of emulsion gels (W/O) incorporating Jerusalem artichoke (JA) inulin. Primary purified inulin extract (PPIE, 1%) improved the homogeneity of emulsion gel (with no syneresis) and developed smaller particle size droplets (average 40 μm) than control (average size 60 μm). HPLC revealed that PPIE had 80.28% inulin content compared with commercial inulin (CI, 100%). Crude inulin extract (CIE, 0.08–0.33 mg/mL) delayed linoleic acid oxidation because of higher total phenolic content (4.96 ± 0.01, mg GAE/g), compared with PPIE (0.72 ± 0.03). Lipid oxidative stability of emulsion gels with inulin samples was in the order of CI > PPIE > CIE (P < 0.05) by Rancimat analysis, which agreed with volumetric gel index results. This study suggests that emulsion gels with JA inulin (PPIE) could act as a potential fat replacement in food systems.

Graphical abstract

Distribution of Phenolic Acids and Antioxidant Activities of Different Bran Fractions from Three Pigmented Wheat Varieties

Phenolic acid profiles and antioxidant activities of outer bran, coarse bran, and shorts from blue, black, and purple wheat were analyzed. Phenolic acids were mainly in the bound form in pigmented wheat bran fractions. Phenolic acid content decreased in the order of outer bran, coarse bran, and shorts for the three pigmented wheat varieties. HPLC analysis of phenolic extracts demonstrated that the bound form of phenolic acids contained more ferulic, isoferulic, and p-coumaric acids compared to their free counterparts. Among the three pigmented wheat varieties, the bran fractions from blue wheat contained higher bound phenolic acids than the other two pigmented wheat bran fractions, except for purple coarse bran. The blue wheat outer bran had the highest total bound phenolic acid of 3458.71 μg/g while the purple wheat shorts had the lowest of 1730.71 μg/g. The contribution of bound phenolic acids to the total phenolic content and antioxidant activity was significantly higher than that of free phenolic acids. Blue wheat bran fractions had the highest radical scavenging activity against DPPH∙ while those of purple wheat gained the highest ABTS∙+ scavenging activity. High correlations were observed between TPC and radical scavenging capacities for DPPH and ABTS (R2>0.85, P<0.05).

Triticale Bran Alkylresorcinols Enhance Resistance to Oxidative Stress in Mice Fed a High-Fat Diet

Triticale (× Triticosecale Whitm.) is a cereal grain with high levels of alkyresorcinols (AR) concentrated in the bran. These phenolic lipids have been shown to reduce or inhibit triglyceride accumulation and protect against oxidation; however, their biological effects have yet to be evaluated in vivo. The purpose of this study was to determine the effects of ARs extracted from triticale bran (TB) added to a high–fat diet on the development of obesity and oxidative stress. CF-1 mice were fed a standard low-fat (LF) diet, a 60% high-fat diet (HF) and HF diets containing either 0.5% AR extract (HF-AR), 10% TB (HF-TB), or 0.5% vitamin E (HF-VE). Energy intake, weight gain, glucose tolerance, fasting blood glucose (FBG) levels, and body composition were determined. Oxygen radical absorbance capacity (ORAC), superoxide dismutase (SOD) activity, and glutathione (GSH) assays were performed on mice liver and heart tissues. The findings suggest that ARs may serve as a preventative measure against risks of oxidative damage associated with high-fat diets and obesity through their application as functional foods and neutraceuticals. Future studies aim to identify the in vivo mechanisms of action of ARs and the individual homologs involved in their favorable biological effects.