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

Effects of Wheat Bran-Derived Alkylresorcinols on the Physical and Oxidative Stability of Oil-in-Water Emulsions as related to pH

Alkylresorcinols (ARs), a homolog series of phenolipids naturally occurring in many by-products, can meet the high demand of the food industry for natural antioxidants. In this study, ARs (C17-C25) were isolated from wheat bran, and their antioxidant activity was tested in oil-in-water emulsions at pH 3.5 and pH 7.0 at two concentrations (15 and 30 mg/L of emulsion) during 14 days of storage at 35 °C. Results revealed that lipid oxidation was affected by both ARs concentration and pH of the emulsion. Indeed, when ARs were added, a significant suppression of hydroperoxides and aldehydes (hexanal and nonanal) formation with a consequent prolongation of their lag phases (5-fold) was observed at pH 3.5, while at pH 7.0 the lag phases were doubled. No influence of ARs on emulsion particle size was found. The present work demonstrated how ARs could represent sustainable and innovative natural antioxidants for emulsion-based food.

Alkylresorcinols trap malondialdehyde in whole grain crackers

To study the alkylresorcinols ability to trap lipid oxidation products in foods, crackers were prepared with either whole grain rye, wheat, spelt, or oat flour, and either sunflower or linseed oil, and were stored for up to 36 days at room temperature. During storage, polyunsaturated fatty acyl chains degraded, malondialdehyde was produced, and alkylresorcinol content decreased. At the end of the storage, alkylresorcinol content in crackers was reduced by 61-78 % and a part of disappeared alkyresorcinols (3-8 %) appeared as malondialdehyde/alkylresorcinol adducts. Formed adducts were unambiguously identified by using synthesized and characterized (NMR, MS) labelled and unlabelled standards, and determined by LC-MS/MS. This ability of alkylresorcinols to trap malondialdehyde, and most likely other lipid oxidation products, might be playing a role in both the reduction of hazardous reactive carbonyls in whole grain foodstuffs and the observed flavor differences between whole and refined grain food products.

Lipophilized rosmarinic acid: Impact of alkyl type and food matrix on antioxidant activity, and optimized enzymatic production

In this study, the initial focus was on exploring the simultaneous impact of the oil-based food matrix and the polarity of rosmarinic acid derivatives on the antioxidant properties. Rosmarinic acid (RA) showed remarkable DPPH, FRAP, and ABTS radical scavenging activities, followed by methyl rosmarinate (MR) and ethyl rosmarinate (ER). In bulk oil, both conjugated dienes and p-AnV values reached a peak in the following order after 30 days: ER > MR > RA = BHT > control (no antioxidant). In the oil structured using monoacylglycerol, MR was more effective than ER and RA. For ethyl cellulose oleogel, emulsion, and gelled emulsion systems, RA was more effective. Additionally, after confirming the importance of the food matrix on the antioxidant activity of RA derivatives, the lipophilization of RA with ethanol was optimized as a model with Lipozyme 435 in hexane. A conversion yield of as high as 85.59% for ER was achieved, as quantified by HPLC-UV and confirmed by HPLC-DAD-ESI-qTOFMS.

Effect of Alkylresorcinols Isolated from Wheat Bran on the Oxidative Stability of Minced-Meat Models as Related to Storage

Due to their antioxidant activity, alkylresorcinols (ARs) extracted from by-products could represent promising natural and innovative antioxidants for the food industry. This study tested the ability of ARs isolated from wheat bran to increase the shelf-life of minced-meat models stored at 4 °C for 9 days. Fifteen alk(en)ylresorcinols (C17-C25) were recognized by GC/MS, showing good radical-scavenging (200.70 ± 1.33 μmolTE/g extract) and metal-chelating (1.38 ± 0.30 mgEDTAE/g extract) activities. Two ARs concentrations (0.01% and 0.02%) were compared to sodium ascorbate (0.01% and 0.10%) on color (CIELAB values L*, a*, b*, chroma, and hue) and oxidative stability (lipid hydroperoxides, thiobarbituric acid reactive substances (TBARS), and volatile organic compounds (VOCs)) of minced-beef samples. ARs-treated samples were oxidatively more stable than those formulated with sodium ascorbate and the negative control, with significantly lower contents of hydroperoxides and VOCs (hexanal, 1-hexanol, and 1-octen-3-ol) throughout the experiment (p < 0.001). However, no effect on color stability was observed (p > 0.05). Since 0.01% of ARs was equally or more effective than 0.10% sodium ascorbate, those results carry important implications for the food industry, which could reduce antioxidant amounts by ten times and replace synthetic antioxidants with natural ones.

O-Alkyl derivatives of ferulic and syringic acid as lipophilic antioxidants: effect of the length of the alkyl chain on the improvement of the thermo-oxidative stability of sunflower oil

Lipid oxidation is the major cause of the deterioration of fat-containing foods, especially those containing polyunsaturated fatty acids (PUFAs). Antioxidant additives of synthetic origin are added to matrices rich in PUFAs, such as sunflower oil (SO). However, there is controversy regarding their safety, and their low solubility in both water and fat has led to the search for new covalent modifications through lipophilicity. This work presents the synthesis of O-alkyl acid derivatives from ferulic and syringic acids and the study of their antioxidant capacity and effect on the thermoxidative degradation of SO. Antioxidant activities were evaluated by employing ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays in a concentration range of 10-100 µg mL-1. The IC50 values for DPPH scavenging activity ranged from 15.61-90.43 µg mL-1. The results of the FRAP assay for both O-alkyl ferulic (3a-f) and syringic (5a-f) series revealed a "cut-off" effect on antioxidant activity in carbon five (C5). Thermoxidation study of additives 3b-c and 5b-c showed a decrease in the slope of extinction coefficients K 232 and K 270 in comparison with SOcontrol. Furthermore, 3c presented higher antioxidant activity than 3b and 1, with a power to decrease the thiobarbituric acid reactive species (TBARS) 6 times higher than SOcontrol at 220 °C. Additives 5b-c exerted a protective effect on the thermoxidation of SO. The results suggest that increasing lipophilic and thermal properties of antioxidants through O-alkyl acid derivatization is an effective strategy for accessing lipophilic antioxidant additives with potential use in food matrices.

Lipid oxidation in emulsions: New insights from the past two decades

Lipid oxidation constitutes the main source of degradation of lipid-rich foods, including food emulsions. The complexity of the reactions at play combined with the increased demand from consumers for less processed and more natural foods result in additional challenges in controlling this phenomenon. This review provides an overview of the insights acquired over the past two decades on the understanding of lipid oxidation in oil-in-water (O/W) emulsions. After introducing the general structure of O/W emulsions and the classical mechanisms of lipid oxidation, the contribution of less studied oxidation products and the spatiotemporal resolution of these reactions will be discussed. We then highlight the impact of emulsion formulation on the mechanisms, taking into consideration the new trends in terms of emulsifiers as well as their own sensitivity to oxidation. Finally, novel antioxidant strategies that have emerged to meet the recent consumer's demand will be detailed. In an era defined by the pursuit of healthier, more natural, and sustainable food choices, a comprehensive understanding of lipid oxidation in emulsions is not only an academic quest, but also a crucial step towards meeting the evolving expectations of consumers and ensuring the quality and stability of lipid-rich food products.

Computational assessment of the primary and secondary antioxidant potential of alkylresorcinols in physiological media

Alkylresorcinols are a group of natural phenolic compounds found in various foods such as whole grain cereals, bread, and certain fruits. They are known for their beneficial health effects, such as anti-inflammatory and anti-cancer properties. This study aimed to evaluate the antioxidant activity of two typical alkylresorcinols namely olivetol and olivetolic acid (Oli and OliA) under physiological conditions. The free radical scavenging capacity of Oli and OliA toward oxygenated free radicals (HO˙ and HOO˙ radicals) was investigated using thermodynamic and kinetic calculations. The results revealed that Oli and OliA are potent scavengers of HO˙ radical in both polar and lipid media, acting exclusively via the FHT (formal hydrogen transfer) mechanism. Moreover, they demonstrated excellent scavenging activity toward HOO˙ radical in water via the SET (single electron transfer) mechanism, outperforming the common antioxidant BHT. In lipid media, Oli and OliA showed moderate scavenging activity toward HOO˙ radical via the FHT mechanism. Significant prooxidant potential of OliA- was also demonstrated through the formation of complexes with copper ions. Additionally, docking studies indicate that the compounds exhibited a good affinity for ROS-producing enzymes, including myeloperoxidase (MP), cytochrome P450 (CP450), lipoxygenase (LOX), and xanthine oxidase (XO), highlighting their potential as natural antioxidants with promising therapeutic applications.

Interfacial behavior of gallic acid and its alkyl esters in stripped soybean oil in combination with monoacylglycerol and phospholipid

The effect of gallic acid alkyl esters and their combination with monoacylglycerol (MAG) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) on the formation of hydroperoxides and hexanal were determined during the oxidation of stripped soybean oil. Interfacial tension, water content, and droplet size were evaluated to monitor the physical properties of the oil system. Adding MAG and DOPC, especially MAG/DOPC, to the oil promoted the partitioning of antioxidants into the water-oil interfaces by further reducing the interfacial tension. The stripped oil containing methyl gallate (MG) accompanied by MAG/DOPC had lower values of the critical micelle concentration of hydroperoxides and larger micellar size at the induction period. This confirms that MG was able to more effectively reduce the free hydroperoxides concentration and inhibit them in an interfacial way. The conjunction of surfactants has been shown as a promising strategy to improve the interfacial and antioxidant activity of gallates in the oxidative stability of soybean oil.

Estimated dietary intake of polyphenols from cereal foods and associated lifestyle and demographic factors in the Melbourne Collaborative Cohort Study

Cereal foods are consumed globally and are important sources of polyphenols with potential health benefits, yet dietary intakes are unclear. We aimed to calculate the dietary intakes of polyphenols from cereal foods in the Melbourne Collaborative Cohort Study (MCCS), and describe intakes by demographic and lifestyle factors. We estimated intakes of alkylresorcinols, lignans and phenolic acids in n = 39,892 eligible MCCS participants, using baseline dietary data (1990-1994) from a 121-item FFQ containing 17 cereal foods, matched to a polyphenol database developed from published literature and Phenol-Explorer Database. Intakes were estimated within groups according to lifestyle and demographic factors. The median (25th-75th percentile) intake of total polyphenols from cereal foods was 86.9 mg/day (51.4-155.8). The most consumed compounds were phenolic acids, with a median intake of 67.1 mg (39.5-118.8), followed by alkylresorcinols of 19.7 mg (10.8-34.6). Lignans made the smallest contribution of 0.50 mg (0.13-0.87). Higher polyphenol intakes were associated with higher relative socio-economic advantage and prudent lifestyles, including lower body mass index (BMI), non-smoking and higher physical activity scores. The findings based on polyphenol data specifically matched to the FFQ provide new information on intakes of cereal polyphenols, and how they might vary according to lifestyle and demographic factors.

Antioxidant Activities of Dihydromyricetin Derivatives with Different Acyl Donor Chain Lengths Synthetized by Lipozyme TL IM

Dihydromyricetin (DHM) is a phytochemical with multiple bioactivities. However, its poor liposolubility limits its application in the field. In this study, DHM was acylated with different fatty acid vinyl esters to improve its lipophilicity, and five DHM acylated derivatives with different carbon chain lengths (C2-DHM, C4-DHM, C6-DHM, C8-DHM, and C12-DHM) and different lipophilicity were synthesized. The relationship between the lipophilicity and antioxidant activities of DHM and its derivatives was evaluated with oil and emulsion models using chemical and cellular antioxidant activity (CAA) tests. The capacity of DHM derivatives to scavenge 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS+•) was similar to that of DHM, except for C12-DHM. The antioxidant activity of DHM derivatives was lower than that of DHM in sunflower oil, while C4-DHM exhibited better antioxidant capacity in oil-in-water emulsion. In CAA tests, C8-DHM (median effective dose (EC₅₀) 35.14 μmol/L) exhibited better antioxidant activity than that of DHM (EC₅₀: 226.26 μmol/L). The results showed that in different antioxidant models, DHM derivatives with different lipophilicity had various antioxidant activities, which has guiding significance for the use of DHM and its derivatives.

Targeting Interfacial Location of Phenolic Antioxidants in Emulsions: Strategies and Benefits

It is important to have larger proportions of health-beneficial polyunsaturated lipids in foods, but these nutrients are particularly sensitive to oxidation, and dedicated strategies must be developed to prevent this deleterious reaction. In food oil-in-water emulsions, the oil-water interface is a crucial area when it comes to the initiation of lipid oxidation. Unfortunately, most available natural antioxidants, such as phenolic antioxidants, do not spontaneously position at this specific locus. Achieving such a strategic positioning has therefore been an active research area, and various routes have been proposed: lipophilizing phenolic acids to confer them with an amphiphilic character; functionalizing biopolymer emulsifiers through covalent or noncovalent interactions with phenolics; or loading Pickering particles with natural phenolic compounds to yield interfacial antioxidant reservoirs. We herein review the principles and efficiency of these approaches to counteract lipid oxidation in emulsions as well as their advantages and limitations.

The Influence of Farming Systems, Genotype and Their Interaction on Bioactive Compound, Protein and Starch Content of Bread and Spelt Wheat

An increase in the production and consumption of spelt products can be associated with positive effects on human health, which are attributed to bioactive compounds present in the grain. The basic success of spelt wheat in organic farming might be explained by the fact that spelt wheat belongs to the group of hulled wheat where the presence of a husk protects the seed from abiotic and biotic stress factors, thus demanding less chemical protection. The goal of this study was to investigate the variations in the bioactive compound (alkylresorcinol, arabinoxylan, β-glucan), protein, starch and fructan content of bread and spelt wheat under different farming systems (conventional and organic). The results showed higher protein and alkylresorcinol but lower fructan content in spelt wheat. Organic spelt had significantly higher starch, fiber and alkylresorcinol content but lower β-glucan and protein content than conventionally grown spelt. The spelt variety 'Oberkulmer-Rotkorn' was characterized by the highest values for the majority of analyzed traits under both farming systems. Overall, the environmental conditions (Hungary and Serbia), farming systems (conventional and organic) and wheat species (bread and spelt) contributed to the variations of the compositional traits in different manners.

Carbonyl-trapping abilities of 5-alkylresorcinols

In an attempt to investigate the carbonyl-trapping abilities of 5-alkylresorcinols, this study describes the role of these compounds in inhibiting the formation of the 2,5-dialkylpyridines (5-ethyl-2-methylpyridine, 5-butyl-2-propylpyridine, and 5-hexyl-2-pentylpyridine) produced by 2-alkenals (crotonaldehyde, 2-hexenal, and 2-octenal) in the presence of ammonia. 5-Alkylresorcinols (as well as orcinol and olivetol) inhibited the formation of pyridines to an extend that depended on the 2-alkenal involved and the reaction conditions. This inhibition was consequence of the trapping of 2-alkenals by the phenolics. Thus, the major adducts produced between the C21:0 alkylresorcinol and crotonaldehyde were isolated and characterized by nuclear magnetic resonance (NMR) and mass spectrometry (MS). These results confirm that, in addition to their free radical scavenging abilities, 5-alkylresorcinols also trap reactive carbonyls. Because trapped carbonyls are involved in the formation of flavors and processing-induced antioxidants, 5-alkylresorcinols might be implied in some of the observed differences between whole and refined grain products.

Subtercola endophyticus sp. nov., a cold-adapted bacterium isolated from Abies koreana

A novel Gram-stain-positive, aerobic bacterial strain, designated AK-R2A1-2 ^T, was isolated from the surface-sterilized needle leaves of an Abies koreana tree. Strain AK-R2A1-2 ^T had 97.3% and 96.7% 16S rRNA gene sequence similarities with Subtercola boreus K300^T and Subtercola lobariae 9583b^T, respectively, but formed a distinct phyletic lineage from these two strains. Growth of strain AK-R2A1-2 ^T was observed at 4–25 °C at pH 5.0–8.0. Strain AK-R2A1-2 ^T contained menaquinone 9 (MK-9) and menaquinone 10 (MK-10) as the predominant respiratory quinones. The major cellular fatty acids were anteiso-C_15:0 and summed feature 8 (C_18:1ω7c or/and C_18:1ω6c), and the polar lipids included diphosphatidylglycerol (DPG) and three unknown aminolipids, AKL2, AKL3, and AKL4. The complete genome of strain AK-R2A1-2 ^T was sequenced to understand the genetic basis of its survival at low temperatures. Multiple copies of cold-associated genes involved in cold-active chaperon, stress response, and DNA repair supported survival of the strain at low temperatures. Strain AK-R2A1-2 ^T was also able to significantly improve rice seedling growth under low temperatures. Thus, this strain represents a novel species of the genus Subtercola, and the proposed name is Subtercola endophyticus sp. nov. The type strain is AK-R2A1-2 ^T (= KCTC 49721 ^T = GDMCC 1.2921 ^T).

Discovery, preparation and characterization of lipid-lowering alkylphenol derivatives from Syzygium jambos fruit

The chemical characteristics and hypolipidemic effects of alkylphenols in the fruit of Syzygium jambos were investigated in this study. Three cardanols (1-3; 1 as a new compound) and three alkylresorcinols (4-6) were isolated and identified from S. jambos fruit. Cardanols 1 and 2 (10-40 μM) suppressed lipids accumulation and reduced triglyceride content in oleic acid-overloaded HepG2 cells via the activation of AMPK/PPARα signaling pathways. Furthermore, the biological distribution of cardanols after an oral intake in mice was investigated. Compound 2 was detected in mice plasma, feces, and adipose tissues after a single oral intake (80 mg/kg body weight). In addition, an alkylphenols-enriched S. jambos fruit extract containing two bioactive compounds (95.9 and 198.6 μg/mg of compounds 1 and 2, respectively) was prepared. Findings from the current study highlight the potential usage of cardanols as well as S. jambos fruit for the management of dyslipidemia.

Isobornylchalcones as Scaffold for the Synthesis of Diarylpyrazolines with Antioxidant Activity

The pyrazoline ring is defined as a "privileged structure" in medicinal chemistry. A variety of pharmacological properties of pyrazolines is associated with the nature and position of various substituents, which is especially evident in diarylpyrazolines. Compounds with a chalcone fragment show a wide range of biological properties as well as high reactivity which is primarily due to the presence of an α, β-unsaturated carbonyl system. At the same time, bicyclic monoterpenoids deserve special attention as a source of a key structural block or as one of the pharmacophore components of biologically active molecules. A series of new diarylpyrazoline derivatives based on isobornylchalcones with different substitutes (MeO, Hal, NO2, N(Me)2) was synthesized. Antioxidant properties of the obtained compounds were comparatively evaluated using in vitro model Fe2+/ascorbate-initiated lipid peroxidation in the substrate containing brain lipids of laboratory mice. It was demonstrated that the combination of the electron-donating group in the para-position of ring B and OH-group in the ring A in the structure of chalcone fragment provides significant antioxidant activity of synthesized diarylpyrazoline derivatives.