Investigations on Two Algerian Argan Oils: Phenolic composition and Antioxidant Activity

Extraction solvent is a very important factor in the recovery of antioxidants from natural matrices. In this study, the effect of three solvents (ethanol, ethanol/water and water) on the phenolic composition, antioxidant and anti-cholinesterase activities and electrochemical behaviour of four winemaking byproducts (seeds, skins, stems, and pomace) was evaluated. Phenolic composition was determined by the Folin–Ciocalteu method and ultra-high-performance liquid chromatography (UHPLC), antioxidant activity by the capacity to scavenge 2,2-diphenyl-1-picrylhydrazyl and hydroxyl radicals, anti-cholinesterase activity by the Ellman’s method, and electrochemical behaviour by cyclic voltammetry. Eight phenolic compounds were quantified with higher content in water/ethanol extracts (e.g., epicatechin in pomace: 17 mg/100 g vs. 7 and 6 mg/100 g in ethanol and water extracts, respectively), although there were some exceptions (e.g., gallic acid in seeds was most abundant in water extracts). Moreover, the highest total phenolic content (TPC) and antioxidant activity were found in ethanol/water extracts (between 2 and 30-fold the values of the other extracts). Overall, the most active extracts in inhibiting both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes were ethanol/water and ethanol extracts from seeds (between 31.11 and 53.90%). The electrochemical behaviour allowed for differentiating the extracts depending on the solvent and the byproduct. Our findings indicate that winemaking byproducts represent a source of phenolic compounds with antioxidant and anti-cholinesterase activities and suggest that cyclic voltammetry is a promising technique to evaluate the phenolic extraction process from these byproducts.

Background and objectivesRice bran (RB), a by‐product of the rice milling process, is known to be a rich source of bioactive phytochemicals. This study aimed to evaluate the influence of RB stabilization treatments, usually applied to inhibit rancidification, on its phenolic composition and antioxidant activity.FindingsTotal phenolic content (TPC) and antioxidant assays were performed on RB that was exposed to extrusion, drum‐drying, microwave, and oven stabilization treatments. Chemical profiling was conducted using ultra‐high performance liquid chromatography (uHPLC) coupled to an online ABTS system, and liquid chromatography quadrupole time‐of‐flight mass spectrometry (LC‐QTOF‐MS).Extrusion and drum‐dried stabilization significantly increased TPC when compared to non‐stabilized RB (NS‐RB). All stabilization treatments increased antioxidant capacity and radical scavenging activity. uHPLC/online ABTS and LC‐QTOF‐MS identified all treatments to increase the concentration of free phenolic compounds and antioxidant activity compared to NS‐RB. More specifically, drum‐dried RB significantly altered RB phenolic composition when compared to all other treatments.ConclusionsAll stabilization treatments significantly altered TPC and antioxidant activity of RB. Drum‐dried RB treatment was most effective in improving free phenolic composition and antioxidant activity.Significance and noveltyThis study demonstrated that drum‐dried stabilization treatment may be a crucial technique that can be applied to RB to ensure essential phenolic compounds with antioxidant activity remain intact, thereby adding value to the functional and nutritional quality of RB.

The study focuses on the comparative evaluation of extraction methods (ultrasonication and agitation) based on phenolic composition and antioxidative activities of Mammillaria prolifera and it is the first report on this subject. The effects of extraction conditions of temperature (25° and 60°), time (15, 30 and 60 min) and solvent type (water and 70 % and 100 % methanol) on total phenolic compounds, 2,2'-azinobis( 3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl anti-radical activities and ferric ion reducing antioxidant power values were determined. Moreover, the phenolic acid compositions of the extracts were investigated by high performance liquid chromatography. The extracts prepared with the ultrasonic method showed stronger antioxidant activity than those prepared with agitation methods. In both methods total phenolic compounds and antioxidant activity values were the lowest in the aqueous extracts. The results showed a positive correlation observed between total phenolic compounds and antioxidant activities of the studied extracts. The optimal conditions for the extraction of phenolic compounds from Mammillaria prolifera were found as 60 min extraction time, 60° extraction temperature and 70 % methanol concentration by using the ultrasonication method. Notably, protocatechualdehyde, gallic acid, para hydroxy benzoic acid and ferulic acid were identified in Mammillaria prolifera by using the high performance liquid chromatography-diode array detector system and 14 phenolic standards. Consequently, Mammillaria prolifera cladodes can be used in food or pharmaceutical practices, as a potential natural source of antioxidants.

The aim of this study is determining the phenolic acid composition and antioxidant activity potential of Vitis vinifera collected from Osmaniye-Turkey. For determining the phenolic acid composition of the grapes collected in different seasons, samples were screened via a high performance liquid chromatography-diode array detection (HPLC-DAD) instrument. By this way, amounts of gallic acid, 2,3-dihydroxybenzoic acid, vanillic acid, caffeic acid,p-coumaric acid, ferulic acid, cinnamic acid, luteolin and apigenin were determined quantitatively. September sample was the riches one in terms of phenolic acids and flavonoids studied. This is followed by August and October samples, respectively. Total phenolic and flavonoid contents of the samples were also evaluated, using the Folin–Ciocalteu method. October sample was found as the richest one among the samples tested. Antioxidant activities of the samples were evaluated by using four complementary test systems. Results obtained from these samples showed a strong correlation with their phytochemical contents. The most active sample was found as the grape collected in October. Key words: Vitis vinifera, high performance liquid chromatography (HPLC), extract, antioxidant activity, phenolic, flavonoid.

The influence of numerous factors on sweetpotato phenolic content and antioxidant activity was determined. Simplified, robust, and rapid methodologies were developed to quantify total phenolics and individual phenolic acids in sweetpotatoes. Quantification of total phenolic content using Folin-Denis reagent provided more reliable results than Folin-Ciocalteu reagent. Individual phenolic acids were quantified by reversed-phase high performance liquid chromatography (HPLC) and the best separation was achieved using a 5-µm, 4.6 × 250 mm column with a mobile phase of 1% (v/v) formic acid aqueous solution: acetonitrile: 2-propanol (70:22:8), pH 2.5. Methanol and ethanol provided higher phenolic extraction efficiency than acetone. In general, chlorogenic and 3,5-dicaffeoylquinic acid were the most prominent phenolics acids in sweetpotato root and leaf tissues. Immature roots and leaves at the initial stages of growth had the highest concentration of phenolics and antioxidant activity. In a comparison of plant parts, sweetpotato leaves had a significantly higher phenolic content and antioxidant activity than roots. Thermal processing of sweetpotato storage roots resulted in a significant loss of phenolic content and antioxidant activity. The outer skin tissue (raw or processed) contained the highest amounts of phenolic acids but also exhibited higher losses than cortex or pith tissue. After a 4 week exposure to 5 °C, the rate of increase in phenolic content and antioxidant activity in non-cured sweepotatoes was significantly higher than in cured roots. An ambient temperature exposure following low temperature storage accentuated the increase in phenolics and antioxidant activity. Minimally processed sweetpotatoes held at 5 °C accumulated more phenolic compounds and had a higher antioxidant activity than sweetpotatoes held at 0 °C. The increase in total phenolic content and antioxidant activity after 8 days was higher than 4 days. No fresh-cut tissue browning was observed after 8 days and the products were considered to be marketable. Sweetpotato genotypes differ in their phenolic content and antioxidant activity. A purple-fleshed breeding line was found to have higher total phenolic content and antioxidant activity than orange-fleshed and white-fleshed cultivars.

Whole wheat consumption is associated with reduced risk of chronic diseases. This study determined total phenolic content (TPC), total flavonoid content (TFC), free radical scavenging activities, metal chelating activity, and phenolic acid composition of 12 hard red winter wheat varieties. TPC, TFC, antioxidant activity, and metal chelating activity varied significantly among different varieties. Trans-ferulic acid, syringic acid, vanillic acid, p-coumaric acid, sinapic acid, and 4-hydroxybenzoic acid were detected and quantified in free, conjugated, and bound fractions. Overall, LCS Mint and WB Grainfield varieties have higher phenolic and flavonoid content. Everest, SY Monument and T158 varieties have stronger antioxidant activity. Positive correlations were obtained between total phenolic acid content and antioxidant activity. Our result suggested that phenolic acid composition and antioxidant activity of hard wheat are highly dependent on their genotypes. Practical applications The health benefits of whole grain products are in part attributed to their unique antioxidant activities. Phenolic compounds, especially phenolic acids, are believed to be one of the major contributors to the antioxidant activity of cereal grains. The breeders and food industry can be benefited by a comprehensive understanding of phenolic compositions and antioxidant activities of different wheat varieties. Identifying wheat varieties with significant levels of phenolic content and strong antioxidant activity has the potential not only to promote the value-added cultivation and use of wheat rich in these factors, but also to provide health benefit to consumers, thereby enhancing wheat profitability, agricultural economy, and public health.

Eleven cultivars of celery, belonging to 2 species, were collected and analyzed for their phenolic compound composition and antioxidant activities. Major phenolic acids identified in the extracts of these celeries were caffeic acid, p-coumaric acid, and ferulic acid, while the identified flavonoids were apigenin, luteolin, and kaempferol. The contents of total phenolics were measured using a Folin-Ciocalteu assay and the total antioxidant capacity was estimated by the 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH) and 2, 2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS.(+)) methods. Apigenin was the major flavonoid in these samples and the most abundant phenolic acid was p-coumaric acid. Many of the investigated cultivars had high levels of phenolics and exhibited high antioxidant capacity. Among these 11 cultivars, Shengjie celery had the highest antioxidant activity whereas Tropica had the lowest. An extremely significant positive correlation between the antioxidant activity and the contents of total flavonoids, total phenolic acids, or total phenolics was observed in this study.

Antioxidant activity and phenolic compounds of Swiss chard (Beta vulgaris subspecies cycla) extracts

In this current special issue, different aspects related to phenolic compounds in fruit beveragesare presented.[...]

Potatoes are one of the most consumed crops worldwide. They contain a high amount of bioactive compounds such as phenolic compounds and vitamins with important antioxidant activities, which makes this crop of high biological value for human health. The goal of this research was to biochemically evaluate polyphenol levels and antioxidant capacities in parent and control genotypes compared to advanced mutant potato lines in the M1V8 generation. This will reveal the genetic changes that result from induced mutagenesis. The quantified compounds and the evaluated antioxidant activity boost the health benefits of consuming the improved mutant potatoes. In the present study, the phenolic composition and antioxidant activity of eighteen mutant and initial potato genotypes were analyzed by UPLC-qTOF-MS/MS and the ORAC method, respectively. In each of the hybrid combinations, mutant lines with an improved phenolic compound profile were observed. Representative samples from the third hybrid combination had notable increases in phenolic compound concentrations, as well as the presence of metabolites not found in the parental lines. With one exception, the remaining nine mutants showed significantly higher antioxidant capacities. The results will be used in future potato breeding programs, with participation of the valuable mutant lines containing new phenolic substances not present in the initial genotypes.

Background and Objectives Hulless barley grass is rich in phenolic compounds. Yield‐optimized cultivation methods, including frequent harvesting and plant factory production, may affect these bioactive compounds, requiring systematic evaluation. Materials/Methods Two hulless barley varieties, Nanlonggela and Qinghaihuang, were cultivated in a natural field and a controlled‐environment plant factory. The field‐grown hulless barley grass was harvested three times. Phenolic content, antioxidant activity, and composition were determined across all samples. Results and Conclusion Total phenolic content of second harvest extracts (N‐2, Q‐2) was 1.45 and 1.71 times higher, respectively, while total flavonoid content was 1.39 and 1.92 times higher than the first harvest (N‐1, Q‐1). The second and third harvests showed higher antioxidant activity than the first harvest. FRAP values for N‐2 and Q‐2 were 1.36 and 1.04 times higher than N‐1 and Q‐1, respectively. Plant factory‐grown Nanlonggela and Qinghaihuang extracts exhibited FRAP values of 201 ± 9.6 μmol TE/mg GAE and 141 ± 9.5 μmol TE/mg GAE, respectively, which were lower than those from the field. HPLC and UPLC‐Q‐TOF/MS identified the main phenolic compounds in Nanlonggela as 3‐O‐[β‐ D ‐glucopyranosyl‐(1 → 2)]‐β‐ D ‐glucopyranosyl‐kaempferol and 7‐O‐α‐L‐rhamnosyl‐3‐O‐β‐D‐glucopyranosyl‐kaempferol, and in Qinghaihuang as (‐)‐suspensaside B, schinicoumarin, and apigenin‐6‐C‐glucosylglucoside. Significance This study supported cultivation of high‐quality hulless barley grass to facilitate functional product development.

This study evaluated the incorporation of two ingredients as a source of bioactive compounds: amaranth flour (AF) and grape pomace peels flour (GP) to improve the nutritional qualities and functional properties of a wheat bread, emphasising the revalorisation of agricultural residues from grape winemaking as an ethical and economically viable source of bioactive compounds. Specifically, wheat flour (WF) substitutions were carried out for the individual ingredients, replacing 20% WF (A20 bread) or 5% GP (GP5 bread) and a mixture of both ingredients 20% WF and 5% GP (A20GP5 bread), and the antioxidant potential of the breads was analysed. The effect of simulated gastrointestinal digestion (SGID) on the phenolic profile and antioxidant activity of the fortified breads was also investigated. The substitution of WF by AF or GP introduced several phenolic compounds, digestion increased the bioaccessibility of phenolic compounds and reshaped their phenolic composition profiles. The combined presence of AF and GP in the breads modified the phenolic compounds composition and improved their antioxidant activity after SGID. Interactions between the phenolic compounds and other AF components (possibly proteins) were observed, which could protect the phenols from degradation during SGID, allowing them to be released after SGID.

Orange processing generates peel by-products rich in phenolic compounds, particularly flavanones like hesperidin and narirutin, offering potential health benefits. Utilizing these by-products is of significant interest in supporting Spain's circular bioeconomy. Therefore, the aim of this study was to investigate the fermentation of orange peels by different lactic acid bacteria (LAB) strains and its impact on phenolic composition and antioxidant activity. Three different LAB strains, two Lactiplantibacillus plantarum, and one Levilactobacillus brevis were utilized. The phenolic compounds were measured by HPLC-ESI-TOF-MS, and antioxidant activity was assessed using DPPH and ABTS methods. The growth of the LAB strains varied, showing initial increases followed by gradual declines, with strain-specific patterns observed. Medium acidification occurred during fermentation. A phenolic analysis revealed an 11% increase in phenolic acids in peels fermented by La. plantarum CECT 9567-C4 after 24 h, attributed to glycosylation by LAB enzymes. The flavonoid content exhibited diverse trends, with Le. brevis showing an 8% increase. The antioxidant assays demonstrated strain- and time-dependent variations. Positive correlations were found between antioxidant activity and total phenolic compounds. The results underscore the importance of bacterial selection and fermentation time for tailored phenolic composition and antioxidant activity in orange peel extracts. LAB fermentation, particularly with La. plantarum CECT 9567 and Le. brevis, holds promise for enhancing the recovery of phenolic compounds and augmenting antioxidant activity in orange peels, suggesting potential applications in food and beverage processing.

The objective of this work was to study the phenolic profile and composition in relation to antioxidant activity of fifteen samples of commercial red, rosé and white wines originating from six native grape varieties and produced in important wine regions from Romania. The profile and quantification of major phenolic compounds were performed by direct injection of wines in the LC-MS system, using DAD and ESI (+) MS techniques, in parallel with the total phenolic content (TPC) measured by spectrometry and the free radical scavenging activity, against 2,2-diphenyl-1-picrylhydrazyl (DPPH). There were identified 38 polyphenols in wines, including 3 flavan-3-ols, 17 flavonols, 12 anthocyanins and 6 stilbenes. The red wines had significant higher phenolic content and antioxidant capacity, followed by rosé and white wines. The richest phenolic content and antioxidant activity was obtained for ‘Feteasca Neagra’ (Tohani) among red wines and for ‘Feteasca Regala’ (Jidvei) among white wines. TPC values were positively correlated with the antioxidant capacity in all white wines and only for the red ‘Feteasca Neagra’ assortment, while for the ‘Babeasca Neagra’ assortment negative correlations were obtained. From the 38 variables, flavan-3-ols have exerted the greatest influence on wine differentiation, based on their colour (red, rosé and white). The study also revealed significant differences between cultivars, both qualitative and quantitative, in terms of their polyphenolic composition, that could be important in the cultivar authentication of wines from these varieties.

Phenolic compounds and antioxidant activity were quantified in the principal sweetpotato cultivars marketed in the European Union. Total phenolic content, individual phenolic acids, and antioxidant activity in each cultivar were determined using Folin-Denis reagent, reversed-phase HPLC, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods, respectively. Significant differences in phenolic composition and antioxidant activity were found between cultivars. A Jamaican-grown, white-fleshed cultivar had the highest total phenolic content [4.11 mg·g-1 chlorogenic acid (dry tissue weight)], while the highest antioxidant activity [3.60 mg·g-1 Trolox (dry tissue weight)] was observed in the orange-fleshed California-grown cultivar Diane. Chlorogenic acid and 3,5-dicaffeoylquinic acid were the predominant phenolic acids, while caffeic acid was the least abundant in most cultivars. The highest content of chlorogenic acid (0.42 mg·g-1 dry tissue weight); 3,5-dicaffeoylquinic acid (0.43 mg·g-1 dry tissue weight); and 3,4-dicaffeoylquinic acid (0.25 mg·g-1 dry tissue weight) was present in the white-fleshed Jamaican cultivar. The orange-fleshed cultivars Diane and Beauregard had the highest content of caffeic acid (0.13 mg·g-1 dry tissue weight) and 4,5-dicaffeoylquinic acid (0.32 mg·g-1 dry tissue weight), respectively.